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• Amphoteric surfactant can increase the decolorization rate of dyeing wastewater. • Sustainable reactive dyeing with the recycled dyeing wastewater was achieved. • Surfactants could change degradation efficiency and improve dyeing properties. To enhance the decolorization rate of thermally activated sodium persulfate in dye wastewater, C.I. Reactive Black 5 (RB5) was investigated in this study, which was evaluated by the decolorization of the dye solution. The effect of surfactant concentration (including anionic surfactant sodium dodecyl sulfate (SDS), nonionic surfactant Tween 80 (TW-80) and amphoteric surfactant (BS-12)), SPS concentration, and reaction temperature on the degradation of RB5 was studied. Furthermore, the relationship between free radicals and RB5 degradation was investigated. The results showed that the addition of SDS and TW-80 would inhibit the decolorization of RB5. Correspondingly, the effect would enlarge as the surfactant concentration increased. Nevertheless, the addition of BS-12 wouldn't affect the final decolorization of RB5 dye solution, despite it could increase the decolorization rate in the initial stage. After 10 min of decolorization, compared to the dye liquor without BS-12, the decolorization could increase by 9.07 % and 0.69 %, respectively, after adding 0.5 and 1.0 CMC of BS-12. Besides, when reactive dyes were degraded by thermally activated sodium persulfate, the SO 4 -· and ·OH would work together, and SO 4 -· played a major role while ·OH played an auxiliary part. When the treated wastewater was used for dyeing, the addition of BS-12 could effectively regulate the dyeing rate. The fixation and K/S value were increased by 1.1 % and 0.20, respectively. Furthermore, the dyed fabrics also exhibited improved uniformity, with negligible differences in color fastness. The effects of adding SDS were similar to BS-12, while it decreased the exhaustion and fixation rate of RB5. In addition, non-ionic TW-80 was unfavorable to dyeing. This work provides a new way for efficient treatment of dyeing wastewater as well as reuse, opening an environmentally friendly treatment concept. [ABSTRACT FROM AUTHOR]

• Physicochemical properties of coal analyzed from pore structure and functional group. • Molecular-scale models constructed by the EA, XPS and 13C NMR results. • Theoretical simulation of the adsorption–desorption-diffusion behavior of CH 4 and CO 2. Hydraulic techniques are integral to both coal mining and gas extraction procedures, and the precise inclusion of surfactants in hydraulic fracturing fluids serves as a crucial factor influencing the wettability of coal and facilitating gas desorption. Nevertheless, relatively few investigations have focused on the influence of surfactants within coal on the adsorption–desorption-diffusion dynamics of gases. In this study, Xin Tian high-rank coal was treated with different surfactants, and the pore structure and functional groups of the coal samples were determined by fluid invasion methods, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and 13C nuclear magnetic resonance (13C NMR) spectroscopy. Moreover, molecular-scale models were constructed to simulate the adsorption–desorption-diffusion performance of the gases in the surfactant-modified coal. As per the results, modification with methyltrimethoxysilane (MTMS) and polyethylene oxide (PEO) surfactants reduced the proportion of micropores and relative content of oxygen functional groups, resulting in reduced the adsorption of gases and enhanced diffusion performance, consistent with molecular simulations result. These results provide a theoretical foundation for elucidating the adsorption–desorption mechanisms of surfactant-treated coal and its application in mining areas. [ABSTRACT FROM AUTHOR]

• Carbon dioxide foaming system was selected through comparative analysis: 0.50 wt% EAPMAC-12 + 0.20 wt% SDS + 0.09 wt% TEOA + 0.08 wt% EDTA. • The viscosity, foaming volume, foam half-life and foam composite index are 18.8 mpa·s, 531 mL, 25 min and 9956 mL·min. • The foam solution could form worm-like micelles by self-assembled with viscosity in the range of 5–20 mpa·s and the ultra-micro foam size was 5–31 μm. • The experiment indicated that the foam had good injection and oil displacement effects in ultra-low permeability reservoirs. Given the problem that the conventional foam injection and salt resistance are poor, the oil displacement effect is not obvious, and it is difficult to enhance oil recovery in the ultra-low permeability and high salinity reservoirs of Yanchang Oilfield, it is imperative to study a new foam flooding agent. Based on the surfactant's self-assembled properties, foaming agent, stabilizer and complexing agent were screened in the absence of polymer and non-alkali. Three sets of self-assembly worm-like micelle systems were screened, and then a set of carbon dioxide foaming system was selected through comparative analysis: 0.50 wt% EAPMAC-12 + 0.20 wt% SDS + 0.09 wt% TEOA + 0.08 wt% EDTA. Under this condition, its viscosity, foaming volume, foam half-life and foam composite index are 18.8 mpa·s, 531 mL, 25 min and 9956 mL·min, respectively. Under the condition of the ratio of gas to liquid 3:1, the ultra-micro foam was obtained by gas–liquid co-injection in the sand pack, and the foam was round rather than the traditional pentagonal or hexagonal shape and the size was 5–31 um, indicating that the foam had good injection. Oil displacement experiment showed the average enhanced recovery rate was 12.84 % in ultra-low permeability cores, indicating that the foam had good oil displacement effect in ultra-low permeability reservoirs. [ABSTRACT FROM AUTHOR]

• By combining macroscopic experiments and microscopic simulations, the optimal combination of composite ionic surfactant solutions is derived, which can realize the efficient enhancement of the effect of dust reduction on coal dust. • The dynamic changes of surface tension and contact angle of different solutions were observed, and the microscopic wetting principles of each surfactant were characterized from their structural features by establishing their molecular models. • By constructing adsorption models containing two different ions, it was concluded that the nonionic and anionic surfactants had the most obvious longitudinal distribution between coal and water after compounding, which could form a tighter adsorption layer and allow water molecules to penetrate into the coal molecules, thus enhancing the wetting effect on coal dust. To improve surfactant wetting action on coal dust in the process of mine spray dust reduction, this paper adopts a combination of experiments and molecular simulation to study the wetting properties and mechanism of different kinds of active agents on coal dust and selects the compounded surfactants with better dust reduction effect. The results show that: fatty alcohol polyoxyethylene ether can reduce the surface tension to 34.16 mN·m−1, which is 35.84 mN·m−1 comparatively less than that of pure water; dodecylphenol polyoxyethylene ether and poly(ethylene glycol) octyl phenyl ether have the maximum electrostatic potentials of 0.0892 a.u and 0.0908 a.u, which exceed that of water molecules, which indicate that the nonionic active agents are the most polar, and it is easy for them to form the hydrogen bonding with water, and the ability to reduce surface tension is superior to other types of active agents; molecular simulation results show that the non + anionic complex system can form a tighter adsorption layer between coal and water, so that the water molecules move more vigorously, moving from the molecules of water to those of coal, thus producing a better wetting effect than the monomer active agent. In addition, dust settling experiments and particle size experiments were conducted to verify the reasonableness of the microscopic simulation. The study's findings can provide a reference for identifying and designing compounded surfactants with excellent wetting performance to improve the dust reduction effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • CTAB-LaHAp@PANI composite was synthesized through hydrothermal coupled polymerization. • CTAB-LaHAp@PANI exhibited higher adsorption capacity for Cr(VI) removal. • The adsorption mechanism is primarily governed by electrostatic attraction, followed by complexation. • CTAB-LaHAp@PANI exhibits excellent reusability for Cr(VI) ions removal. The predominant cause of the global clean water deficit is water contamination caused by heavy metals discharged from various industrial effluents. Innovating low-cost adsorbents that can eliminate heavy metals from polluted water is essential to address this challenge. Human health can be negatively impacted by water contamination caused by the increased levels of carcinogenic heavy metals, such as chromium (Cr), found in wastewater. The main goal of this research is to remove chromium ions from an aqueous environment by utilizing the surfactant-assisted lanthanum anchored hydroxyapatite@polyaniline (CTAB-LaHAp@PANI) hybrid composite. Various analytical techniques including FTIR, XRD, SEM, EDX, TEM, TGA, and XPS analysis were utilized for the characterization of the prepared adsorbents. Different influencing factors such as contact time, solution pH, adsorbent dosage, and initial chromium concentration were systematically optimized through the batch method to achieve maximum removal efficiency of the CTAB-LaHAp@PANI hybrid composite. Remarkably, the CTAB-LaHAp@PANI demonstrated a maximal adsorption capacity of 98.2 mg/g, with an optimal contact time of 120 min at pH 3. The isotherm and kinetic analyses indicated that chromium adsorption onto the CTAB-LaHAp@PANI hybrid composite followed the Langmuir and pseudo-second-order kinetic models, supported by high correlation coefficient values. Moreover, the possible removal mechanism of chromium ions on the prepared hybrid composite was explained based on the results obtained from various analytical techniques. The as-prepared CTAB-LaHAp@PANI hybrid composite demonstrates a superior adsorption capacity, exceptional water stability, cost-effectiveness, and various other characteristics that render it an attractive choice for removing chromium ions from the aqueous phase. [ABSTRACT FROM AUTHOR]

[Display omitted] • Correlate structure–performance relationship of LAAS with CMT, CMC/C 20 , (I 1 / I 3) CMC , etc. • Hydrophobic α -substituents improve foamability of LAAS by lowering CMT and raising CMC/C 20. • The poorest foamability of DLGlu resulting from the smallest CMC/C 20 and greatest (I 1 / I 3) CMC. • Hydrophobic α -substituents are favorable for enhancing wetting and emulsifying of LAAS. • SLGly shows better overall detergency than the precursor soap on three soiled swatches. Synthetic soaps of N -lauroyl amino acid surfactants (LAAS) were synthesized in this work from lauroyl chloride and five typical amino acids with different α -substituents including α -alanine or α -aminobutyric acid with a hydrophobic α -substituent, serine with a hydrophilic α -substituent, and glutamic acid with an ionizable α -substituent normalized to Gly with the simplest α -amino acid structure to compare the α -substituent effect on physicochemical properties and application performance of LAAS. The surface adsorption, micellization, foamability, emulsification, wettability, and detergency of these LAAS were investigated. Experimental results indicate that the hydrophobic α -substituent of amino acid can reduce both critical micelle temperature and critical micelle concentration of LAAS, promote surface adsorption and general performance with respect to foamability, emulsifying power, and wetting power, while the hydrophilic α -substituent is on the contrary. Moreover, sodium lauroyl glycinate demonstrates the best overall detergency among five LAAS, and is the solely one performing better detergency than sodium laurate for all three standard soiled swatches, indicating the potential for detergents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comprehensive review on interaction of polymer brush with surfactants. • Studying the effect of different surfactants on polymer brush and their properties. • Studying the responsiveness of polymer brush with surfactant with respect to light. • Identification of challenges to improve the surface properties of polymer brush. Unique macromolecular structures known as polymer brushes are made of individual polymer chains that are free at one end and attached to a solid surface at the other. Polymer brushes show some fascinating characteristics when compared to other polymer materials, due to which they are used in various applications like drug delivery, antifouling coating, antibacterial coating for biomedical devices, and especially as a responsive material where surface topology, architecture, and composition can be changed by changing the external environment. Significant progress in surface and interface engineering has been made possible by surface-initiated controlled radical polymerization techniques. All these properties can also be enhanced by using surfactants. Surfactants when interacting with polymer brush shows changes in thickness, wettability, roughness, etc., depending on the type of polymer brush and surfactants. Surfactants help in boosting the topology of the brush structure. This review article will initially discuss about polymer brushes and surfactants separately and then discuss the interactions involved between them and their possible explanations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Experimentally analyzed the effect of oil SARA contents on quartz wettability. • A generalized surface modeling procedure for quartz was developed. • Quartz wettability varies with hydroxyl density, temperature, surfactants, and oil. • The temperature effect on quartz wettability exhibits a piecewise decreasing trend. The wettability of quartz surfaces is a critical property in numerous energy-related industrial processes. However, accurately quantifying wettability is challenging due to the multitude of factors that can influence wetting behavior. Herein, we proposed a generalized surface modeling procedure addressing microscopic insights to calculate the contact angles of liquids on quartz under different scenarios. An optical goniometer experimentally measured the contact angles and validated the proposed surface modeling procedure. The effects of surface density of hydroxyl groups, temperature, surfactants, and crude oil composition on the wettability of quartz surfaces were studied. The results revealed that an increased hydroxyl group density significantly improved water wettability on a quartz surface. An increased temperature reduced the water contact angle on quartz, and such decreasing rates became steeper at high temperatures. The surfactants' adsorption morphology determined the wettability of a quartz surface. Moreover, the polar components in crude oil significantly increased the hydrophobicity of a quartz surface, making it easier to adsorb more oil molecules to alter the quartz wettability further. The valuable outcomes of this paper contribute to understanding the complex quartz wettability and pave the way for further studies involving quartz surface modeling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solubilization of polycyclic aromatic compounds was studied using supralong-chain surfactants. • The solubilization ability of surfactant was maximized in the system of C22-2Am. • The solubilization site of compounds in the micelles shifted from the palisade layer to the vicinity of the hydrophilic groups. • Extension of the alkyl chain length of the surfactant was advantageous for solubilization. The dissolution of poorly water-soluble compounds in micelles via hydrophobic interactions is termed solubilization. The solubilization of polycyclic aromatic compounds, namely, naphthalene, anthracene, and pyrene, was studied using supralong-chain surfactants with two consecutive cationic hydrophilic groups [C n H 2n+1 N+(CH 3) 2 -(CH 2) 2 -N+(CH 3) 3 2Br-: C n -2Am (n = 18, 20, and 22)] and typical cationic surfactants [C n H 2n+1 N+(CH 3) 3 Br-: C n -Am (n = 12, 14, and 16)]. Long alkyl chains in hydrophobic surfactants are advantageous for forming a large micellar core. The maximum quantity of solubilized polycyclic aromatic compounds increased as the alkyl chain length of the surfactant increased. Therefore, the molar solubilization ratio (MSR), which represents the solubilization ability of the surfactant, was maximized when the alkyl chain length was C22-2Am. Similarly, the Gibbs free energy (Δ G 0) associated with the solubilization of polycyclic aromatic compounds was also lowest for C22-2Am. Surfactants with long alkyl chains functioned as excellent solubilizers. The solubilization sites of the polycyclic aromatic compounds were determined using two-dimensional NMR and small-angle X-ray scattering (SAXS) measurements. As the molecular size of the polycyclic aromatic compounds increased, the solubilization positions in the micelles shifted from the palisade layer to the vicinity of the hydrophilic groups. Extension of the alkyl chain length of the surfactant resulted in an increase in the palisade region of the micelles, which was advantageous for solubilization. [ABSTRACT FROM AUTHOR]

• In this study, magnetic NPs synthesized, functionalized with tartaric and malic acids, found in grapes and apples. • Various characterizations tests, including (ZP), (FTIR), (XRD), (DLS), (FE-SEM), and (EDAX), were used to determine the properties of NPs. • Fe3O4@Tartaric NPs (300 ppm) in optimized salt (20000 ppm) and SDS (300 ppm) solutions significantly lower IFT compared to Fe3O4 and Fe3O4@Malic. • Heavy crude IFT reduction surpasses light crude due to asphaltene and surfactant-like agents, aiding natural surfactant action. In recent years, nanoparticles (NPs) have become a popular choice for improving oil recovery through enhanced oil recovery (EOR) methods. NPs can enhance oil recovery by reducing interfacial tension (IFT), altering wettability, and decreasing the mobility ratio. In this study, magnetic NPs with acidic groups (tartaric acid and malic acid), which are natural acids found in fruits such as grapes and apples, were synthesized and functionalized to reduce the IFT between oil and water. Various characterizations tests, including zeta potential (ZP), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray analysis (EDAX), were used to determine the properties of NPs. Afterwards, the IFT behaviour of crude oil and aqueous solutions, containing surfactant sodium dodecyl sulfate (SDS), two types of salts namely sodium chloride (NaCl) and sodium sulfate (Na 2 SO 4), and functionalized magnetite NPs with tartaric acid and malic acid were investigated. Two crude oils were used in this study: light (A) and heavy (B). The results showed that increasing salt concentration decreases the IFT for crude oils down to an optimum point (20000 ppm for both salts), after which the IFT increases with increasing salt concentration. The presence of functionalized Fe 3 O 4 @Tartaric acid NPs (300 ppm) in the aqueous solutions containing salts at their optimum concentration (20000 ppm) and SDS (300 ppm) can decrease the IFT more significantly than that of Fe 3 O 4 and Fe 3 O 4 @Malic acid for both crude oils. This is due to higher stability and higher ZP of functionalized Fe 3 O 4 @Tartaric acid NPs compared to Fe 3 O 4 @Malic. The IFT for oil A decreases from 20.8 mN/m to 2.87 mN/m for light crude oil and from 32.96 mN/m to 1.91 mN/m for heavy crude oil. The IFT for heavy crude oil was more reduced than that of light crude oil, which was due to the presence of asphaltene, resin, and other surface-active agents in heavy crude oil, which can act as a natural surfactant in oil and help reducing the IFT. [ABSTRACT FROM AUTHOR]

• HTO adsorbents with nanoscale high hydrophilicity were prepared by surface etching with surfactants. • HTO-T exhibits remarkable selectivity and an excellent adsorption capacity for Li+ from brine with a high Mg/Li ratio. • The adsorption of Li+ by HTO-T is primarily achieved through the disruption of O–H bonds and the formation of O-Li bonds. Titanium-based lithium ion sieve adsorbents (HTOs) are considered among the most promising materials for lithium extraction from aqueous sources. In this study, four surfactants—sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), hydroxypropyl cellulose (HPC), and tannic acid (TA)—were used to surface-etch HTOs, preparing adsorbents with enhanced hydrophilicity at the nanoscale. Correlation studies between the hydrophilicity of the HTO-X and their adsorption performance revealed that all HTO-X had lower contact angles than the unetched counterparts, indicating improved adsorption capacities. Notably, TA plays a synergistic role of "killing two birds with one stone". The TA-etched HTO-T adsorbent exhibited the lowest contact angle (8.8°) and the highest specific surface area (62.10 m2/g). In a LiCl solution, HTO-T's adsorption capacity for Li+ reached 33.61 mg/g, a 26 % increase over the unetched HTO adsorbent (26.56 mg/g). Simultaneously, HTO-T significantly reduces the adsorption time and enhances the adsorption efficiency during the surface diffusion phase. Additionally, HTO-T demonstrated remarkable selectivity for lithium ions, with separation factors α(Li/Na), α(Li/K), α(Li/Mg), and α(Li/Ca) of 397.13, 181.55, 1288.47, and 1345.19, respectively, showcasing an excellent separation effect. The adsorption mechanism indicates that Li+ adsorption by HTO-T primarily occurs through the disruption of O–H bonds and the formation of new O-Li bonds. This research presents an efficient strategy for the development of HTOs, demonstrating HTO-T as a potential adsorbent for lithium recovery from brine sources. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hydrophilic chain length of surfactant affects the kinetics of hydrate formation. • Surfactants improve the scatter of the induction time of hydrate formation and hydrate production. • The emulsion stability affects the promoting effect of surfactants on hydrate formation. • LAE-9 has the most effective on improving hydrate formation. To address the problems of slow crystallization and nucleation in two-phase miscibility in the application of refrigerant hydrates, adding surfactants can be taken as an effective way to promote hydrate formation. Three kinds of polyoxyethylene laurate (LAE) surfactant with different hydrophilic chain lengths (LAE-4, LAE-9 and LAE-24) were selected as accelerators to study their effects on hydrate formation. LAE series surfactants significantly reduce hydrate nucleation induction time. The hydrate induction time of the system with 4.0 wt% LAE-9 is shortest (98 min). The hydrate formation with 4.0 wt% LAE-9 has small randomness and is more stable. Micelles formed by LAE surfactants provide more nucleation sites and accelerate hydrate growth. The hydrate cold storage density is related to the hydrophilic chain length of surfactant. The system with 4.0 wt% LAE-9, which has a suitable hydrophilic chain length, achieves the largest hydrate cold storage density (246.10 kJ·kg−1). Hydrate has the fastest growth rate of 4.80 kJ·kg−1·min−1 in the system with 2.0 wt% LAE-24. There is a "memory" effect during hydrate formation and dissociation cycle, eliminating the need for induction time during hydrate re-formation. Hydrate can be re-formed quickly. [ABSTRACT FROM AUTHOR]

Surfactant-cyclodextrin based complexes, are ideal guest-hosts for fundamental studies since both surfactant hydrophobic region with head group, and cyclodextrin cavity can be systematically varied. This allows, better understanding of the contributions that different chemical entities do to the stabilization of the complex and subsequent surfactant micellization. We studied systematically the interaction of hexadecyltrimethylammonium bromide (▪) with native α -, β - and γ -CDs, 2-hydroxypropylated and methylated α - and β -CDs, using isothermal titration calorimetry (ITC), measuring below critical micellization concentration (CMC) at least at three temperatures in the range (288.15 to 318.15) K. Data were treated simultaneously allowing the estimation of thermodynamically consistent temperature dependences of the equilibrium constant, the enthalpy and heat capacity for the inclusion complex formation. The data for cation/CD interaction were analysed mostly by the sequential binding model with 1:1 and 1:2 (cation:CD) stoichiometries, while some cation-CD combinations were examined using only 1:1, or more complicated 1:1, 2:1 and 2:2 stoichiometries. Thermodynamic quantities for complexation are discussed in terms of structural features, their temperature dependence with previous literature being examined. The shift of the CMC in presence of CDs was calculated founding large discrepancies with data in the literature. An extended mass-action chemical equilibrium model is proposed including free surfactant, free CD, complexes of the above mention stoichiometries, also including micelle, surfactant-cyclodextrin complexes of higher order stoichiometry, similar to that found for sodium dodecylsulfate-CDs systems. The new model provides a qualitative match with our own calorimetric titration curves measured above CMC for all studied ▪/CD combinations, and matches quantitatively with literature CMC values. • Binding of α -, β -, γ -, HP- α -, HP- β -, randomly Me- α -, and 2,6-DiMe- β -CDs with ▪ cation examined using ITC. • Formation of C+:CD inclusion complexes of 1:1; 1:1 and 1:2; or more complicated stoichiometries considered. • T -dependence of binding K and mostly also of binding Δ H established for formed inclusion complexes, but 2,6-DiMe- β -CD. • Effect of cyclodextrin structure and temperature variation on thermodynamic properties disclosed below surfactant CMC. • Extended mass-action model which includes micelle, [C+.CD], [C+.CD 2 ] and [C a +.CD b ] used to predict CMC shift. [ABSTRACT FROM AUTHOR]

• N 2 molecules prefer adsorption near C 12 EO 15 carbon atoms. • Increased amounts of surfactants boost N 2 adsorption capacity. • C 12 EO 15 adsorption layer hinders N 2 diffusion and the generation of micro-nanobubble. In flotation processes, gas molecules adhere to and accumulate on the target mineral surface, forming micro-nanobubbles, which can significantly enhance the efficiency of particle-bubble adhesion. Surfactants are commonly employed as auxiliary agents and play pivotal roles in flotation. However, the effect of surfactant pre-adsorption at the solid–liquid interface on the microscopic process of gas molecule adsorption and accumulation remains unclear. In this study, varying degrees of roughness surface in carbon substrates, the fatty alcohol polyoxyethylene ether (C 12 EO 15), nitrogen molecules (N 2), and water molecules (H 2 O) were employed to construct a gas–liquid–solid model for molecular dynamics simulations aimed at elucidating the underlying mechanisms of N 2 molecule adsorption and accumulation on surfactant-modified substrates at the molecular level. The research findings revealed that N 2 molecules preferred adsorption in close proximity to carbon atoms along the alkyl chain of the C 12 EO 15 molecule. C 12 EO 15 molecules exhibit a bending and intertwining behaviour on the hydrophobic carbon substrate surface, thereby forming a "network" adsorption layer. An increase in the quantity of surfactants provides abundant adsorption sites for N 2 molecules at the solid–liquid interface, consequently augmenting the adsorption capacity of N 2 molecules. Nonetheless, the presence of interstitial gaps between the surfactant-formed adsorption sites impedes the diffusion of the N 2 molecules at each adsorption locus. This hindrance may obstruct the subsequent generation of micro-nano bubbles at the solid–liquid interface. [ABSTRACT FROM AUTHOR]

[Display omitted] • APG could tune rheological and foaming properties of thermo-responsive PF127 foam. • Competition of APG and PF127 in mixed micelles affected the foaming ability. • Transition of orderly packed micelles into disordered micelles led to the foam instability. Thermoresponsive liquid foams stabilized with the triblock copolymer (EO) 100 (PO) 65 (EO) 100 (PF127) have been proved to be effective in suppressing pool fire. Understanding how the low-molecular-weight surfactants affect the properties of thermoresponsive foam stabilized by PF127 is important in the development of fluorine-free firefighting foam. In this work, the effects of the non-ionic surfactant alkyl polyglucoside (APG) on the properties of the foam stabilized by the triblock copolymer PF127 were studied. The relationships among molecular self-assembly, interfacial properties, and foam properties were investigated by conducting scattering experiments and foam aging tests. The results demonstrated that the APG molecules participated in the organization of the mixed micelles with PF127 molecules and the competition of both components in the mixed micelles affected the foaming properties. For the systems containing APG and 20 wt% PF127, APG acted as a foam inhibitor, suppressing foam generation at low concentrations. In contrast, APG acted as the foam booster at high concentrations since the mixed micelles were relatively unstable, allowing more unimers to diffuse to the interfacial region. In the absence of APG, the liquid foam from PF127 exhibited high stability and elasticity under heat due to the ordered structure formed by PF127 micelles inside the foam. As the APG concentration increased, the transition of orderly packed PF127-rich mixed micelles into disordered APG-rich mixed micelles caused the originally inhibited liquid drainage to restart rapidly, making the foams unstable upon heating. The results of this work can give theoretical guidance for the development of thermoresponsive firefighting foams. [ABSTRACT FROM AUTHOR]

[Display omitted] • The properties of cationic surfactants were studied by surface tension measurements. • The performance of TPC was found better than DPC due to more hydrophobic interaction. • The adsorption capacity of SMZ for removal of AR87 was higher than that of Br46. • The fast removal of AR87 (5 min) shows that SMZ is a good adsorbent for anionic dyes. • The kinetic adsorption data of two dyes on SMZ was fitted better by FL-PFO model. In this work, the surfactant-modified natural zeolite (SMZ) as a low-cost and eco-friendly adsorbent have been used for the removal of Eosin Y or Acid Red 87 (AR87) and Basic Red 46 (BR46) dyes from aqueous solutions. In order to modify the surface of zeolite, a new approach was proposed based on the surface properties of the surfactants. Two cationic surfactants with the same head group structure and different alkyl chain length (dodecylpyridinium chloride, DPC and tetradecylpyridinium chloride, TPC) were investigated using surface tension measurements and then surfactant TPC was selected as the better option for the preparation of modified zeolite. Natural and modified zeolite are characterized with Fourier transform infrared spectroscopy (FT–IR), BET surface area analysis, thermogravimetric analysis (TGA), pore volume measurement, XRD, the scanning electron microscopy (SEM) images and Zeta potential techniques. To identify the performance of the surfactant modified zeolite (SMZ) in the removal of ionic compounds were selected two different types of dyes with oppositely charged head groups (AR87: anionic and BR46: cationic). The adsorption equilibrium and kinetic data were analyzed using different models (ten isotherms and eight kinetic models in nonlinear forms). The rate of removal of dyes by SMZ shows two different ranges, very fast for AR87 (less than 5 min) and slow for BR46 (45 min.). The maximum adsorption capacity (q m) are 21.02 and 8.62 mg/g for removal of AR87 and BR46, respectively. The results indicate that SMZ can be used as efficient adsorbent for the removal of the anionic dyes such as AR87 form aqueous solutions. [ABSTRACT FROM AUTHOR]

• Three surfactants aggregated and encapsulated Laccase in different degrees. • Effect of environment on Laccase activity was weakened and conformation of residues was changed. • The results explain the lower degradation rate of BPA by adding TX-100 than by adding CTAB and SDBS. Laccase catalyzes the formation of phenoxyl radicals as an intermediate in Bisphenol A (BPA) degradation, and certain surfactants can affect the effectiveness of laccase in removing BPA from various effluents, yet the specific molecular details remain unclear. In this study, based on laccase and BPA complex, three surfactants, cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzene sulfonate (SDBS), and TritonX-100 (TX-100), were introduced to construct four systems. We applied MD simulation along with MM-PBSA method to investigate the effects of different surfactants on the binding of laccase with BPA. During the MD simulations, these three surfactants enveloped the enzyme surface to varying degrees, causing the solvent to separate from parts of the laccase surface. The addition of CTAB and SDBS suppressed BPA degradation mainly by influencing the polar solvation free energy and van der Waals (vdW) interactions between laccase and BPA. In contrast, TX-100 promoted the degradation of BPA by reducing polar solvation free energy. This explains why in the laccase-BPA complex system the addition of a certain concentration of TX-100 resulted in a higher degradation rate compared to CTAB or SDBS. Our work clarifies the molecular mechanisms of the interaction between laccase and BPA under the influence of CTAB, SDBS, and TX-100 surfactants, and provides some guidance for laccase degradation of BPA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solubilization of H Acid has been compared in simple and mixed micellar systems. • Spontaneous mixed micelles formation improves solubilization capability. • Surfactant interaction was also investigated by DFT and absorption/emission spectra, MESP, FMO, DOS and band gap were successfully computed. • Micellization becomes less convenient with the increase in the CMC due to increase in temperature. • Thermodynamic parameters reveal the feasible and entropy driven nature of micellization process. The present research work investigates the solubility of an anionic dye 8-amino-1-naphthol-3,6-disulfonic acid (H Acid) within the micellar media of two cationic surfactants cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB) as well as in the mixed micellar media of each cationic surfactant with Triton X-100 (TX-100). The data from differential absorption spectroscopy across a concentration range spanning from pre-micellar to post-micellar regions was used to determine the degree of solubilization by calculating the partition coefficient (K x), binding constant (K b) and Gibbs free energy associated with the relevant processes. Electrical conductivity of each cationic surfactant in the presence of H Acid was recorded in aqueous media and used to determine the CMC and subsequent thermodynamic parameters including entropy (ΔS m), enthalpy (ΔH m) and Gibbs free energy change (ΔG m) associated with the process of micellization. The computational analysis was carried out with GAUSSIAN 09 using a 6-311G + basis set with a DFT/ B3LYP hybrid approach and each set of energy minimization was executed to perform frequency calculations for Frontier molecular orbital analysis and to evaluate absorption spectra. Moreover, the molecular electrostatic potential surfaces (MESP) were also computed to find their suitable hydrophobic and hydrophilic interactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phenol's absorption spectra are dependent upon the pH. • Phenol's binding and partitioning interactions in CTAB micelles at different pH. • Determined maximum binding and partition coefficient as well as the maximum number of molecules per micelle at different pH. • Surface properties and interfacial properties of Phenol/CTAB system at different pH. • Phenol decreased the CMC of CTAB. Phenol is an aromatic compound with toxic effects on the environment and living organisms. Cetrimonium bromide (CTAB) is a cationic, quaternary ammonium surfactant, constituent in industrial formulations, and is employed for solubilization as well as removal of pollutants. This study explores the impact of pH on the behavior of phenol in the micellar solution of CTAB via UV–Visible spectroscopy and surface tension measurements at room temperature. Binding coefficient (K b), free energy change of binding (ΔG b), change in molar absorptivity (Δε), partition coefficient (K c), free energy change of partitioning (ΔG p) and number of molecules per micelle (n) were determined at different pH. Results showed that phenol exhibits no appreciable interaction with the CTAB, however phenolate ions have the tendency to bind with CTAB micelles and penetrate in the palisade layer of CTAB. Surface properties such as surface excess (τ max), minimum area per molecule (A min), packing parameter (P), surface area per head group (a s), free energy changes of micellization (ΔG m), adsorption ΔG ads , and transfer (ΔG trans), and surface pressure (Π) for CTAB, and phenol in CTAB solutions were also determined. Interfacial studies supported the role of phenol in facilitating micellization of CTAB thermodynamically and hence a fall in CMC values of CTAB except for pH 7.11. Calculated interfacial parameters established the influence of phenol over rearrangement and surface adsorption of CTAB molecular ions at air/water interface. Surface tension results also showed that unionized phenol molecules have low surface activity (62.23mN/m), but when phenol is ionized into phenolate ion surface dramatically increased (44.17 mN/m). [ABSTRACT FROM AUTHOR]

• Molecular interaction is affected by oils with different density and emulsification. • Foamability decreases under fuel due to emulsification between fuel and surfactants. • Presence of liquid fuel accelerates foam drainage and liquid film thinning behavior. • Oil resistivity of foam depends on difference in nature and emulsification of oils. In this study, the influence mechanism of typical fuels (oils) on the foam properties of mixture of hydrocarbon and fluorocarbon surfactants was investigated. A mixed solution was prepared based on a nonionic hydrocarbon surfactant (APG-0810) and a zwitterionic C6 fluorocarbon surfactant (short-chain). The effect of different oils (heptane, kerosene, diesel, and transformer oil) on the physical property parameters, foamability, oil resistivity of foam and single vertical liquid film of the mixture are systematically investigated. Results indicate that the viscosity of mixture increases, but the conductivity, surface activity, and initial foam height decreases with addition of the four oils. The drainage and volume decay of the foam are accelerated by the presence of oils. In addition, the presence of oils accelerates liquid film thinning through affecting drainage, especially for the oil with higher density, water solubility, and volatility. The four oils showed different effect on foam properties due to the difference in nature and emulsification of them. Among them, the foam properties under the action of heptane is the best, and the oil resistivity of foams is the best. This study can provide theoretical guidance for oil resistivity of hydrocarbon and fluorocarbon surfactant stabilized foams. [ABSTRACT FROM AUTHOR]

• Carbonate-rich shale became more oil-wet with the increasing temperature. • Higher CTAB concentration made all the shales more oil-wet. • Higher SDS concentration made clay-/organic-rich shale more water-wet. • Higher SDS concentration had a non-monotonous effect on carbonate-rich shale. Shale wettability affects pore-scale oil/water distribution and reservoir-scale oil extraction efficiency. For enhanced oil recovery, a common method to modify rocks' wettability is adding surfactant. However, previous experiments mainly focused on room temperature conditions, which are not representative of the high-temperature conditions in shale oil reservoirs. Meanwhile, shale consists of various compositions (e.g., clay, carbonate, organic matter), and each composition is expected to have a different influence on shale wettability in a complex way. So far, a comprehensive investigation of shale wettability modification by surfactants and temperature in oil reservoir conditions is still lacking. Therefore, in this work, the effects of temperature (25 ℃ vs 50 ℃), surfactant type (Cetyltrimethylammonium bromide [CTAB] vs Sodium dodecyl sulfate [SDS]) and concentration (0 ∼ 0.2 wt%), and shale compositions (carbonate-, clay- and organic-rich) on shale wettability were investigated systematically via contact angle (θ) measurements in the water-oil-shale system. It is demonstrated that 1) as the temperature increased, the carbonate-rich shale became more oil-wet, no matter the presence or absence of surfactants, while clay- and organic-rich shale became either more oil-wet or more water-wet; 2) At high temperature (i.e., 50 ℃), higher CTAB concentration made all the shales more hydrophobic; higher SDS concentration modified clay- and organic-rich shale more hydrophilic, while had a non-monotonous influence on carbonate-rich shale; 3) At 50 ℃, clay- and organic-rich shale shifted from strongly water-wet to strongly oil-wet with the addition of CTAB, while it became more water-wet with the addition of SDS; carbonate-rich shale became more oil-wet with the addition of CTAB, while it fluctuated erratically with the addition of SDS. This research provides fundamental guidance on wettability modification via surfactant, which has promising applications in EOR in shale oil reservoirs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sustainable route to deprotection of oximes was reported. • Synergistic role of dual-surfactant systems was determined. • Optimum results obtained in 60: 40 A.auriculiformis: SDS concentration. • Revised mechanism of deprotection of oxime in the micellar core was illustrated. • Chemical reactivity of the surfactants were analyzed using DFT. Deoximation reaction is one of the most essential transformations in organic synthesis for the precise chemical manufacturing of carbonyl compounds. Developing catalytic deoximation techniques is highly demanding for environmental protection and minimizing expenses in fine chemical operations. Herein, we have reported an environmentally friendly, low-cost, and sustainable approach for regenerating carbonyl compounds from numerous oxime derivatives using microwave irradiation. The method uses I 2 and an aqueous solution of Acacia auriculiformis as the green solvent. The concentration of Acacia auriculiformis was discovered to correlate with the percentage production of carbonyl compounds. However, using the dual-surfactant system deliberately improved the regeneration of carbonyl compounds with up to 82% yield at 60:40 ratio. With DFT analysis and quantum chemical parameters, the chemical reactivity and electronic properties of the surfactant systems were determined. Also, the mechanistic interpretation of the actual reaction in the micellar core is depicted, which is well supported by the computational analysis. Overall, our method is green, low-cost, energy-saving, and avoids using toxic reagents and solvents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface tension of HCl dropped to 25.4 mNm−1. • SO-12 enhanced the Rct of CS to 1.3 kΩ.cm2. • SO-12 makes the CS surface smoother. • SO-12 has higher adsorption affinity. • SO-12 follows Langmuir adsorption model. In this study, we synthesized cationic surfactants based on ρ-substituted Schiff base compounds—S-12 (E)-N-dodecyl-N,N-dimethyl1-4-((P-olylimino)methy)benzene aminiumchloride) and SO-12 (E)-N-dodecyl-4-(((4-methoxyphenyl)imino)methyl)-N,N-dimethyl benzeneaminiumchloride. Their chemical structures were confirmed via FTIR and 1HNMR spectroscopies. SO-12 decreased the surface tension of 1 M HCl (61 mN.m−1) to 24.4 mN.m−1. Weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements were employed to investigate carbon steel (CS) corrosion reactions in blank HCl and HCl containing the synthesized surfactants. The CS corrosion suppression actions of S-12 and SO-12 increased with increasing concentrations until they reached approximately 97 %. Adsorption of S-12 and SO-12 delayed the CS corrosion rate. The adsorption process fitted the Langmuir adsorption isotherm. The thermodynamic properties of the CS reaction are also discussed. The surface morphology and elemental analysis of the outer surface layer of CS were studied at the optimal concentration of SO-12 using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Theoretical results of S-12 and SO-12 agree with experimental data, confirming the effectiveness of S-12 and SO-12 as corrosion inhibitors. Moreover, S-12 and SO-12 have superior performance compared with previously reported cationic surfactants under the same test conditions. [ABSTRACT FROM AUTHOR]

• ILs derived from diethanolamine and fatty acids were applied as emerging sustainable emulsifiers. • Emulsions prepared with [H 2 EA][C 18 OO] and sunflower oil presented highest kinetic stability (>1 month). • Emulsion stabilization was related to IL molecular structure, type and concentration of oil and process. • ILs are highly efficient emulsifiers at very low concentrations and form oil-in-water emulsions. • Bio-based ILs are potential alternatives over non-sustainable additives. Bio-based ionic liquids (ILs), especially those derived from fatty acids (FAs) have been considered promising compounds for the agri-food and bioproduct industries, due to their sustainable appeal, possibly low or non-toxic effect and the nutritional value of FAs. However, studies have been mainly focused on the use of ILs as greener solvents. This work investigated the application of ILs derived from FAs and diethanolamine as emulsifiers to form and stabilize oil-in-water emulsions using ultraturrax (PM) and high-pressure homogenization (H). The influence of the IL type obtained from different FAs (stearic or oleic acids), and vegetable oil type (sunflower or olive oil) and concentration (30:70 or 70:30, oil:water phase ratio) on the formation and stabilization of emulsions was evaluated. This study was focused on the zeta potential of IL aqueous solutions in different pH conditions, interfacial tension between vegetable oils and IL aqueous solutions at different concentrations, kinetic stability, droplet size and size distribution, optical microscopy, viscosity profile and rheological behavior of the emulsions. ILs presented highly negative ZP charge (−12.97–−74.81), high emulsifying ability at low concentrations (1 %) and led to emulsions with high kinetic stability (>30 days). The electrostatic stabilization mechanism may predominate over the steric in IL-based emulsions. The stabilization of emulsions with ILs was associated to lower oil droplet size (D 3,2 = 0.60–4.09 µm, D 4,3 = 0.95–9.91 μm) and emulsion viscosity (4.8 mPa·s-1.13 Pa·s), which were related to the IL molecular structure, oil type and concentration, and process. Emulsions prepared with stearic-based IL and sunflower oil by PM+H presented higher kinetic stability. The proposed ILs are presented as highly effective emulsifiers with potential application in the agri-food, pharmaceutical and cosmetic industries. [ABSTRACT FROM AUTHOR]

• The surfactant type does not change the covellite CuS phase. • The particular morphology of CuS was transformed to the platelike CuS particles by adding the CTAB surfactant. • Spherical CuS//platelike CuS capacitor exhibited energy density of 25.62 Whkg-1 and power density of 1488 Wkg-1, respectively In this research, plate-like CuS particles were synthesized through a hydrothermal method using cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP) as surfactants. The effects of surfactant type and content on the structural, microstructural, and electrochemical properties were explored by the various characterization techniques. Single-phase CuS powders with a space group of P63/mmc were crystallized by decomposition of the copper-thioacetamide complex during hydrothermal treatment. The spherical morphology transformed into plate-like particles by adding the CTAB surfactant, while the PVP surfactant led to an agglomeration of small spherical nanoparticles. With adding the CTAB surfactant, the specific capacitance increased from 630 to 1806 Fg−1 at a current density of 1 Ag−1, while it increased up to 1575 Fg−1 for the PVP surfactant. A symmetric capacitor was assembled on the base of spherical CuS nanoparticles as the negative electrode and the platelike CuS particles as the positive electrode. The CuS//CuS capacitor exhibited comparable electrochemical performance including an energy density of 25.62 Whkg−1 and a power density of 1488 Wkg−1, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The initial presentation of a new two-dimensional parameter for wettability evaluation: wetting area. • Impact wetting experiment evaluates wettability with superior resolution. • The advantages, disadvantages, and applicability of each wettability evaluation method are clarified. • Wetting ability strengthens with increasing impact velocity. • The wettability order of the studied surfactants is SDBS > SDS > OP-10 > OP-7 > OP-4. Dust suppression materials are most commonly used in dust control practices, and evaluating their wettability is crucial in predicting control effectiveness. This study developed an impact wetting experiment that used the wetting area to characterize the wetting behavior of droplets on coal dust. The surface tension test, contact angle test, sink test, penetration test, capillary rise test, and impact wetting experiment were performed for comparative study. The wetting effect of the dust suppression reagent solutions on coal dust was analyzed, and the advantages, disadvantages, and applicability of each method were indicated. The experimental results revealed that the impact wetting experiment was applicable to evaluating wettability and demonstrated a high discriminatory ability, showing superior evaluation efficacy. The wettability order of the selected reagents was SDBS > SDS > OP-10 > OP-7 > OP-4, which was also supported by molecular dynamics simulations. The findings of this study serve as a useful reference for the selection and evaluation of coal dust suppression reagents. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel complex hydrophilic micelle structure. • A solubilization system was suitable for specific organic compounds. • Thousands of formulations can be screened in a week. • Efficient acquisition of chemical pollutant solubilization surfactant. Synthetic capsaicin, also known as pelargonic acid vanillylamide (PAVA), constitutes the primary component in riot control agents. Due to the propensity of PAVA agglomerated in aqueous environments, the interaction between the active site of PAVA molecular and catalyst was restricted, consequently reducing its degradation efficiency in water-based oxidizing agents. This study used a cationic surfactant, dodecyl trimethyl ammonium chloride (DTAC), in combination with KOH for the precise regulation and arrangement of PAVA molecules, resulting in the formation of a distinctive hydrophilic structure. This approach resolved its poor solubility in aqueous solutions while the relationship between solubility and degradation rate was obtained. The frontier orbital distribution and surface electrostatic potential distribution of PAVA molecular were predicted through first-principles calculation. The mechanism of PAVA solubilization was studied by 1H NMR techniques and infrared spectroscopy methods. The results showed that KOH substitutes the phenolic hydroxyl group "–OH" of PAVA, forming potassium phenoxide "–OK", which enhanced the solubility of PAVA in water. Additionally, KOH might reduced the surface tension in the solution. It promotes the formation of the DTAC/PAVA complex micelle structure, which exhibited the PAVA agglomerates to exposing the catalytic activation reaction sites and accelerating the catalytic oxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption behavior of mixtures of surfactant and polymer at the solid/water interface is studied by computational simulations. • After adding polymers, the adsorption conformations are changed to spherical micelle or multilayer. • The adsorption energy of the anionic surfactant is weakened by the polymer at the solid/water interface. • The negatively charged PCA has a strongly competitive adsorption with surfactants. • HPMC with great content of hydroxyl groups strongly interact with the hydrophilic groups of surfactants. In cementitious system, surfactant is used as air-entraining agents, which is often incompatible with other chemical admixtures, such as superplasticizers. The adsorption of surfactants at solid–liquid interface is critical for the bubble stability. The measurement of adsorption properties of surfactant in fresh cement or concrete is very difficult. In this study, classical molecular dynamics simulations is used to analysis the influence of two polymers (call as HPMC and PCA, respectively) on the adsorption behaviors of the two anionic surfactants (call as HSO4 and HPO4, respectively) at the C3A/water and ettringite/water interfaces. At solid/water interface, both of HSO4 and HPO4 molecules form a monolayer with hydrophilic head groups adsorbed on the solid surfaces. After adding polymers, the adsorption conformations are changed to spherical micelle or multilayer. The electrostatic interaction between oxygen atoms of hydrophilic head groups and calcium atoms of solid surface plays a decisive role. Therefore, the value of adsorption energy of HPO4 with more negatively charged hydrophilic head groups is greater than that of HSO4. The adsorption energies of the two surfactants are weakened by the two polymers, but the adsorption energy value of HPO4 is always greater. The influence mechanism of HPMC and PCA is different. The negatively charged PCA has a strongly competitive adsorption with the surfactants. The neutral HPMC has a weak adsorption capacity but it carries many hydroxyl groups to interact with the hydrophilic head groups of surfactants. [ABSTRACT FROM AUTHOR]

[Display omitted] • The flotation efficiency of low rank coal is improved when surfactant and salt ions coexist. • Salt ions can compress the double electric layer thickness and promote the attachment of surfactant on the coal surface. • A methodology to obtain the hydrophobic force constants for bubble-particle attachment interaction. • The mechanism of liquid film drainage and the calculation of additional energy for drainage. Bubble-particle interaction is a fundamental process in froth flotation, where the attachment of bubbles and particles is the crucial process in effective flotation. However, modeling bubble-particle attachment interaction is challenging. This is because advanced methods like AFM (Atomic Force Microscope) characterizations are difficult to quantify hydrophobic interactions reproducibly for air bubbles and non-spherical particles. This study presents a methodology to obtain the hydrophobic force constants for bubble-particle attachment interaction in the presence of salt (KCl) and surfactants (DTAC and SDS). The hydrophobic interaction constants of bubble-particle interactions were acquired from first principles with the Stefan − Reynolds theory and Glembotsky experimental device. The Stefan − Reynolds theory was successfully applied in the determination of the real hydrophobic constants for bubbles and particles interaction in DI water (deionized water). However, in the coexistence of salt and surfactants, the real hydrophobic constants for bubbles and particles interaction cannot be obtained while the fictive hydrophobic constants were acquired with a linear extrapolation method. The results showed that the addition of inorganic salt and surfactants compressed the electronic double layer's thickness and presented a higher hydrophobic force constant, enhancing the interaction between a bubble and a low-rank coal particle. In addition, the evaluations of hydrophobic constants reveal that the hydrogen bond energy and salt ions destruction energy should be considered to the comprehension of attachment interaction mechanism and the hydrophobic force source for bubble − particle attachment interactions. [ABSTRACT FROM AUTHOR]

• Molecular interactions exist in the mixture of FS-50/APG-0810/ nano-MDH. • Nano-MDH apparently delay foam drainage and coarsening of FS-50/APG-0810 solutions. • Aggregates formed by nano-MDH//FS-50/APG-0810 in bubble films enhance foam stability. Nanoparticles and surfactants stabilized foams show immense feasibility for development of environmental-friendly firefighting foam. A mixed dispersion composed of magnesium hydroxide nanoparticles (nano-MDH), hydrocarbon surfactant (APG-0810), and fluorocarbon surfactant (FS-50) is used in this study. This work explores the coactions between nano-MDH and surfactants in mixed dispersion and its effect mechanism on foam properties. Results reveal that with increase in nano-MDH content, the conductivity and viscosity of dispersion liquids rise but the surface activity decreases. The initial foam height of APG-0810/FS-50 solution was reduced, foam stability of APG-0810/FS-50 solution was improved as the foam drainage and coarsening were delayed, due to the existence of nanoparticles. Besides, the foam stability, with increasing nano-MDH content, further increases. Foam containing 5% nanoparticles shows optimal performance of potential application in firefighting field considering relatively low viscosity, high foaming ability, and excellent stability. This research can afford important theoretical guidance for developing environmental-friendly fire extinguishment agent based on nano-MDH, and provide support for promoting the advance of fire extinguishing technology. [ABSTRACT FROM AUTHOR]

• Dynamic viscosity alteration of water-based 2% graphite nanofluid was examined with three different surfactants in current work. • Surprisingly, 2% graphite nanofluid having ammonium citrate surfactant showed weaker stability than the surfactant-free sample. • The results showed that different surfactant usages can change the dynamic viscosity of nanofluids, distinctly. • It is expected that this research will be an informative one for scientists in terms of surfactant usage-viscosity relations. In the current experimental research, the dynamic viscosity alteration of a water-based 2 % graphite nanofluid was examined with three different surfactants: gum arabic, cetrimonium bromide, and ammonium citrate. Surfactant proportions of 5 %, 10 %, 50 %, and 100 % of 2 % graphite nanoparticle amount were chosen. Dynamic viscosity changes were measured at 10 °C, 30 °C, and 50 °C. The maximum dynamic viscosity was measured for the 100 % gum arabic at 10 °C. The relative viscosity was also measured at 10 °C for the 100 % gum arabic sample, which was 2.77 times that of the base fluid. Surprisingly, 2 % graphite nanofluid with ammonium citrate surfactant showed weaker stability than the surfactant-free sample. The three regression equations were placed with R2 = 0.9896 for gum arabic, R2 = 0.9808 for cetrimonium bromide, R2 = 0.9927 for ammonium citrate, and compared with previously presented equations. As a result, different surfactant proportions and types can affect the nanofluid viscosity in different ways and therefore, new enlightening researches will be useful for researchers to understand surfactant behavior. The results showed that different surfactant usages could change the dynamic viscosity of nanofluids distinctly. It is expected that this research will be informative for scientists in terms of surfactant usage-viscosity relations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core scale CFD simulation study of bio-based surfactant flooding. • Same meshed geometry for both water and surfactant flooding. • Mass transfer of surfactant using species transport model. • Species transport model coupled with multiphase VOF model. Bio-based surfactant flooding is encouraged as an EOR method, as it is obtained from natural sources and is economically attractive. In the present study, the EOR efficiency of a natural surfactant synthesized from rapseed oil has been simulated using ANSYS FLUENT. The process of oil recovery from a core by injection of surfactant has been simulated by incorporating core, brine, surfactant, and crude oil properties into the numerical model. Mass transfer of surfactant between the aqueous phase and crude oil has been modeled using species transport without a chemical reaction model. Species transport model has been coupled with the multiphase VOF model, where the flow of each phase is determined as per their respective viscous resistance. Experimental data of inlet pressure and oil production has been used for history matching and later used to visualize the oil flow through the porous media, concluding that simulation of surfactant flooding can be achieved by species transport model. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new aqueous two-phase system was prepared with piperazinium-based surface-active ionic liquid. • The system was cost-effective, water-rich and near-neutral. • Phase behaviors were systematically investigated and phase separation mechanism was revealed. • The system demonstrated high performance for extractions of two different dyes. Aqueous two-phase systems (ATPSs) as alternatives to traditional liquid–liquid extraction systems have been used intensively in recent years. In this work, a new ATPS composed of a piperazinium-based surface-active ionic liquid (SAIL), 1-(2-hydroxyethyl)piperazinium laurate ([HEP][C 11 CO 2 ]), and a commercial cationic surfactant, dodecyldimethylbenzylammonium chloride (DDBAC) was prepared. The phase diagram for the ternary system DDBAC + [HEP][C 11 CO 2 ] + H 2 O was determined, and the effects of composition and temperature on phase behaviors and properties were investigated. Phase separation was found spontaneous and thermodynamically favored when the mass fraction of water (w 3) exceeded 0.60, primarily due to the salting-out of the hydrophilic ions [HEP]+ and Cl− in the bottom phase. Micelles were observed in the top phase where high concentrations of the hydrophobic ions [DDBA]+ and [C 11 CO 2 ]− were present. Increasing the water content at a fixed surfactant-to-SAIL molar ratio resulted in a decreased top phase volume, while the extraction efficiency (EE) and the distribution coefficient (D) were both increased for extractions of Basic Blue 7 and Allura Red AC. When w 3 reached 0.96 and the initial concentration of dye was below 1 × 10−4 mol·L−1, the EE values exceeded 98 % with all the D values surpassing 100, indicating the promising potential for SAIL-ATPS applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acid molecules in the oil phase can act like surfactants and form micelles. • Ions can disturb water-acid and improve acid-surfactant interaction. • Enhanced acid-surfactant interaction keeps acid molecules near the interface. • Ions and acid molecules synergize to orient surfactants parallel to the interface. Low salinity water injection with surfactants is one of the standard approaches in enhanced oil recovery (EOR). This method relies on the interaction of surfactants and ions at oil/water interfaces to reduce the interfacial tensions. However, the details of the mechanisms governing the synergistic effects of these components are still debatable. In this study, molecular dynamic (MD) simulations have been employed to investigate the challenging interactions of chemicals and saline water at a molecular scale. The model oil phase used in this study was defined as a mixture of toluene and decane. In addition, the synergistic materials are NaCl, sodium dodecyl ethoxy sulfate (AES), and decanoic acid. The results of density profiles, planar distribution maps, and PMF calculations imply that the acid molecules in the oil phase act as surfactants and form micelles. A few water molecules are also transferred to the oil phase to form water-acid micelles at high surfactant concentrations. Consequently, the number of acid components in the interfacial area is decreased; hence, the IFT reduction is alleviated. The results showed that micelle formation was decreased by adding ions to the aqueous phase. RDF profiles indicate that surfactant-acid interaction improves by adding ions to the water phase. The higher surfactant-acid interactions keep the polar hydrocarbon molecules near the interface and prevent them from moving to the hydrocarbon phase. This study also highlights the vital role of surfactant-acid interactions in the arrangements and orientations of surface-active materials. Orientation analysis indicates that salts in water and hydrophobic acids synergize to orient surfactants parallel to the interface. These facts signify that the surfactant-acid interaction is one of the main factors that critically affect the water–oil interfacial behavior. [ABSTRACT FROM AUTHOR]

[Display omitted] • New surfactant-like 5-alkyl-1,2,4-triazole-3-thiones were synthesized. • CMC was estimated using the conductivity method and the 1H NMR technique. • Samples of triazole-stabilized spherical silver nanoparticles were obtained. • The synthesized triazoles show moderate antifungal activity against C. albicans. • DFT calculations support similar electronic structure for all the new triazoles. New 5-alkyl-1,2,4-triazole-3-thiones containing structural fragments of anionic surfactants have been synthesized and examined as stabilizers in the wet chemistry synthesis of silver nanoparticles (AgNPs). The synthesis of the new 1,2,4-triazole-3-thiones was done via the cyclization reaction of 4-acyl-thiosemicarbazides in basic conditions. The structure of the new surfactant was analyzed by spectroscopic (infrared and nuclear magnetic resonance) and theoretical DFT methods. The surface activity characteristic, such as critical micelle concentration, was estimated using the conductivity method and the 1H NMR technique. The structural peculiarities of the new compounds testify to their surfactant properties, which is why they were explored as stabilizers in the chemical synthesis of silver nanoparticles from silver nitrate in an aqueous solution. The UV–VIS spectroscopy technique confirmed the formation of AgNPs in aqueous solutions of 5-alkyl-1,2,4-triazole-3-thiones. The stable AgNPs were obtained only using 1,2,4-triazole-3-thiones with longer alkyl chains (pentadecyl and heptadecyl), whereas the 5-pentyl-1,2,4-triazole-3-thione and the 5-heptyl-1,2,4-triazole-3-thione have not shown considerable stabilization activity. To better understand the interaction of the 1,2,4-triazole-3-thiones with AgNPs, Raman spectra analysis, quantum chemical modeling, and force field molecular dynamics were performed. The new triazoles were studied for their antifungal activity by the determination of minimal inhibition concentrations and docking studies. [ABSTRACT FROM AUTHOR]

Liquid/liquid extraction (LLE) as one of the most industrially relevant separation methods, plays a key role in a wide variety of applications. The extraction process is carried out in the presence of extractant molecules, selectively transferring solutes from one phase to another, wherein surfactants are commonly used as extractants. However, the transport process of the class of surfactants itself draws very little attention, which will provide deep insights into understanding the dynamics and mechanisms of the extraction of surfactant-solute complexes. Herein, molecular dynamics simulations were used to investigate the dynamic process of surfactants adsorption on the oil-water interfaces at the molecular level. It was found that hydrophobic interaction drives the quick disintegration and diffusion of micelle-like surfactants upon contact with the oil-water interface. This work provides molecular-level insight into the transport mechanism of surfactants on oil-water interfaces. • This study provides molecular-level insight into transport mechanism of surfactant micelles on liquid-liquid interface. • Surfactant micelle undergo a dynamic process from "formation" to "disintegration" approaching the oil-water interface. • The transport driven force is newly formed interfacial hydrogen bonding network pushing surfactant micelles to spread at the interface. • Newly determined interfacial water can be used to quantify the liquid-liquid interfacial roughness. [ABSTRACT FROM AUTHOR]

• Discuss interactions of three ionic surfactants with antibiotic drug cloxacillin sodium (ClxNa) at different temperatures. • The ClxNa disfavors the micellization of CTAB and TTAB whereas it favors SDS at higher [ClxNa]. • The CMC values show a U-shaped curve against temperature for all the studied systems. • Thermodynamic parameters reveal that the micellization of studied surfactant–ClxNa systems is entropically driven. The physicochemical properties and interactions of surfactant–drug aggregates are regarded as essential features to achieve optimum therapeutic action of the drug. In this article, the effect of various concentrations of anionic antibiotic drug cloxacillin sodium (ClxNa) on the micellization of cationic surfactants such as cetyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB) and anionic surfactant sodium dodecyl sulphate (SDS) have been investigated using electrical conductance measurement at different temperatures (288.15 K, 293.15 K, 298.15 K, 303.15 K, 308.15 K, and 313.15 K). The results suggest an increase in critical micelles concentration (CMC) values for cationic surfactants (CTAB/TTAB) with a rise in drug concentration (0 mM up to 10 mM) whereas anionic surfactant SDS shows a decrease in CMC at higher drug concentrations (from 2.5 mM up to 10 mM) at all the studied temperatures. The degree of counterion dissociation (α) values for TTAB aggregates show a slight increase with [ClxNa], except at a few lower temperature ranges whereas such a regular trend was not obtained for CTAB and SDS aggregates. Temperature-dependent CMC values show a nonlinear nature with a rise in temperatures and follow a U-shaped curve for all studied pure surfactant and surfactant–ClxNa systems. Micellization for all surfactant-drug systems is found to be spontaneous. Investigation of other temperature-dependent thermodynamic parameters such as change in standard enthalpy ( Δ H m 0), and entropy ( Δ S m 0) of micellization suggest that surfactant–drug interactions are both endothermic ( Δ H m 0 < 0, particularly at lower temperatures) and exothermic ( Δ H m 0 < 0, at higher temperatures), whereas micellization is largely entropically driven ( Δ S m 0 > Δ H m 0). [ABSTRACT FROM AUTHOR]

• A mathematical model was developed to predict surfactant solutions' viscosity at operational conditions. • Surfactant solutions' viscosity was studied experimentally to determine the effects of different parameters. • Core flood tests were conducted to evaluate the effects of viscosity changes on oil recovery at operational conditions. • Some surfactants can play the role of both polymer and surface-active agents simultaneously. • TEM images approved the hypothesis of micelle's shape transition at higher surfactant and ion concentrations. Surfactants are widely used for enhanced oil recovery (EOR) purposes by reducing interfacial tension (IFT) of oil–water phases and wettability alteration. Some surfactants with viscoelastic properties can be used as mobility control agents due to enhanced viscosity resulting from the spherical-to-cylindrical shape transition of micelles. Dodecyltrimethylammonium chloride (DAC) shows viscoelastic behavior coupled with dominantly cylindrical shape of the micelle in ambient conditions. Nevertheless, using DAC as an IFT reduction and mobility control agent needs to be industrialized for actual operating conditions. In this study, DAC, as a cationic surfactant, was experimentally studied in reservoir conditions considering dominantly cylindrical micelles for the first time. Results showed that the viscosity of DAC solution is a strong function of DAC concentration, especially at high temperature and high salinity conditions, while it does not depend on pressure significantly. Transmission electron microscope (TEM) images were taken for a better understanding of DAC micellar structures. Analysis of the TEM results indicated the shape transition of the micelles from small spherical to large cylindrical at higher concentrations of DAC. IFT of DAC microemulsion was studied for wide ranges of temperature and DAC concentration, ruling out any significant effect of the temperature on the IFT trend line. A general mathematical model for predicting the viscosity of surfactant solution was developed and evaluated for real reservoir conditions by including all effective terms. Results showed a very good agreement with experimental data of DAC and Cetyltrimethyl ammonium bromide (CTAB, as per previous studies), justifying the applicability of the developed model for predicting the viscosity wherever experimental data is unavailable. Core flood tests were performed with saltwater (SW) and DAC solutions with spherical (SS) and cylindrical (SC) micelles as injecting phases for evaluation of IFT reduction and mobility control effects. Results showed an additional recovery factor of 13 % for SS and 23 % for SC in comparison with SW injection. [ABSTRACT FROM AUTHOR]

• Methylene blue decolorization by permanganate at room temperature. • Azure B, Azure A, Azure C, and thionine detected as the degradation products by GC–MS. • Pre-and post micellar inhibition effects observed with cationic CTAB. • Stern-layer of cationic micelles was the reaction site for electron transfer reaction. Methylene blue (MB)-permanganate redox reaction has been studied spectrophotometrically in absence and presence of cationic cetyltrimethylammonium bromide (CTAB). The UV–visible spectroscopy reveals the presence of intermediate reaction products (Azure B, Azure A, and thionine) during interaction confirming the real degradation of MB. The gas chromatography-mass spectrometry (GC-EIMS) was used to establish the formation of MB degradation products. The electron transfers lead to a rapid N-demethylation oxidative reaction to form colored intermediary compounds. The key factors ([MnO 4 −], [MB], [H 2 SO 4 ], and temperature) that affect the degradation rate of MB solution are analyzed. The redox reaction proceeds through a complex formation between the MB and MnO 4 −. The position of absorption band of MB was shifted from 666 nm to 603 nm with increasing the reaction time. The degradation efficiency decreases drastically from 82.1 % to 41.8 % in presence of 1.0 mM H 2 SO 4. The results show that the degradation rate in acidic solutions is lower than that in neutral reaction media. The MnO 2 was not formed as the product with H 2 SO 4. The degradation efficiency of MB decreases with increasing CTAB concentrations. Sub-micellar inhibitory role of CTAB indicates that the MnO 4 − interact with positive head group of CTAB, and inhibit the oxidation of MB. [ABSTRACT FROM AUTHOR]

• The presence of silica nanoparticle and surfactant molecules at the oil–water interface is investigated. • The silica nanoparticle shows high efficiency in delivering surfactant molecules to the n-decane-water interface. • With increasing the surface coverage of the nonionic surfactant molecules, the interfacial tension of the oil–water systems decreases as well as the thickness of the interfaces increases. • Silica nanoparticle leads the surfactant molecules to be more perpendicular to the oil–water interface. • Surfactant molecules participate mainly as acceptors in the formation of hydrogen bonds with water molecules. In chemical enhanced oil recovery (EOR), the nanoparticles can be employed as conveyors to transfer the surfactants and impede the reduction of surfactant concentration. Here, a set of molecular dynamic simulations were carried out to examine the ability of hydrophobic silica nanoparticle (NP) to deliver the nonionic surfactant (Triethylene glycol monododecyl ether; C 12 E 3) into the n-decane-water interface. Another set of simulations in which only surfactant molecules are initially located at the interface was performed in order to better characterize the influence of NP on the surfactant adsorption film. The NP exhibited high efficiency in delivering surfactant molecules to the n-decane-water interface. In addition, for the C 12 E 3 -NP and n-decane-NP, the Coulombic interactions are weaker than the van der Waals interactions confirming the nonpolar property of the silica nanoparticle. The density profiles indicate that as the concentration of surfactants increases at the interface, NP separates more from the surfactant layer. The interfacial tension (IFT) of n-decane-water systems containing only surfactants decreases as the surface coverage of the surfactants increases. Moreover, it was also proved that the intrinsic width of the interface increases with an increment in the surface coverage of surfactants. The surfactant molecules exhibit a great tendency to contribute as acceptors to the formation of hydrogen bonds with water molecules. With an increment in the surface coverage of surfactant molecules, the 2D radial distribution functions between the centers of mass (COMs) of surfactant tails show oscillations. Appeared oscillations represent the correlation between the surfactant tails. Presence of NP causes the oscillations start at lower surfactant coverage than without NP. The surfactant tails choose a random distribution at the low surface coverage of surfactants. In addition, they tend to be oriented partially perpendicular to the interface with an increase in surfactant surface coverage. Besides, NP causes the surfactant tails to orient more perpendicular to the interface than surfactants alone. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dynamic collision behavior of droplets with respirable dust is studied at the mesoscopic level based on CFD method with 6DOF dynamic grid. • The dust reduction by spraying with the addition of surfactant is investigated by fine level simulation and macroscopic experiment. • At a concentration of 0.14 % AEO-9, surface tension of 22.06 mN·m−1, static contact angle of 21.89°, the best wetting effect and droplet utilization rate were achieved when the droplet-to-dust particle size ratio was 2 ∼ 3 and V 0 = 20 m/s ∼ 30 m/s liquid film was completely spread. • When a 1.2 mm diameter fine atomization nozzle is used, the highest percentage of droplets in the optimal interval is achieved at a spray pressure of 6 MPa. • Study on the mechanism of surfactant droplet wetting and coagulation of respiratory dust: the case of AEO-9. In industrial production, spraying is the most widely used dust control method. However, the traditional pure water spray has poor dust removal effect, and the principles of droplet wetting and dust encapsulation are unclear, resulting in poor dust removal effect. In this study, based on the CLSVOF method, we investigated the dynamic wetting and coalescence process of surfactant droplets and dust particles from a microscopic perspective. By changing the size ratio between the droplets and dust particles, as well as the initial velocity of the droplets, we simulated the spreading and wetting of surfactant droplets on the dust surface and found the optimal parameter range for encapsulating respirable dust. Through the experimental determination of spray atomization characteristics, it was found that the spray pressure of 6 MPa and the use of a 1.2 mm fine atomization nozzle produced a spray field with droplet sizes ranging from 14 to 21 μm, accounting for approximately 62.4 % of the distribution. Around 60 % of the droplets had velocities between 20 and 30 m/s. Dust settling efficiency experiments were conducted under these optimal spray parameters, and the settling efficiency of respirable dust reached 84.33 % within the favorable parameter range. Numerical simulations of the dynamic wetting process of dust-fog coupling at the microscopic level, as well as macroscopic spray experiments, were carried out to validate the reliable results. This method has significant implications for the control of respirable dust. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reporting on the micellization of NPE-9, SDS, CTAB, and their binary mixtures. • Molecular interaction of NPE-9, SDS and CTAB at the air–water interface. • Competitive co-adsorption of surfactants at the air–water interface influence interfacial properties. • The foamability of NPE-9 through a synergistic interaction with ionic surfactants. Nonylphenol ethoxylate (NPE-9) is a widely recognized non-ionic surfactant that finds extensive applications in various industries, including detergency, emulsification, and agriculture. Combining NPE-9 with an ionic surfactant reflects an inexpensive and highly promising approach for enhancing the efficacy of NPE-9. This study explores the molecular interactions between NPE-9 and ionic surfactants (SDS and CTAB) and examines the impact of these interactions on interfacial properties and foaming. The micellization parameters, including the critical micelle concentration (CMC), degree of counterion binding (β), degree of counterion dissociation (α), and change in free energy of micellization (ΔG mic), were investigated for sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) in the presence and absence of NPE-9, using conductometric measurements. The combined effect of NPE-9 and an ionic surfactant resulted in a synergistic interaction, reducing the CMC of the ionic surfactant, and promoting the formation of micelles. The interaction between NPE-9 and ionic surfactants at the air/water interface was investigated using surface tension measurements. The interfacial properties improved through the competitive adsorption and synergistic effect observed between NPE-9 and an ionic surfactant. In this context, the surface tension data of NPE-9 is utilized to calculate interfacial parameters, including maximum surface excess concentration (Γ max), minimum area per molecule (A min), and surface effectiveness (π). Adding SDS and CTAB to NPE-9 solutions resulted in a notable enhancement in foamability and foam stability. The utilization of various techniques consistently produced improvements in the interfacial and foaming properties of NPE-9. [ABSTRACT FROM AUTHOR]

• β-Al 2 O 3 nanoparticles can decelerate drainage and volume decay of foam under thermal radiation. • Foam thermal stability is enhanced due to formation of aggregates in bubbles. • Addition content of β-Al 2 O 3 nanoparticles leading to excellent thermal stability and good foaming ability is above 7.5% Nanoparticle-stabilized foams have a potential prospect used as new environmentally-friendly firefighting foams. The thermal stability of firefighting foam is a significant ability to resist on thermal radiation from flame. In the present study, the mixed dispersions of foams consisting of β-Al 2 O 3 nanoparticles, hydrocarbons (APG-0810), and fluorocarbon surfactants (FS-50), are prepared. The basic properties, including foaming ability and foam drainage at room temperature of the mixed dispersions, are investigated. The foam stability under thermal radiation is evaluated. The results reveal that the presence of β-Al 2 O 3 nanoparticles increases the conductivity and viscosity of the mixed dispersions, while the surface tension and foaming ability of the mixed dispersions first decreases and then increases with increasing β-Al 2 O 3 nanoparticle concentration. The addition of β-Al 2 O 3 nanoparticles significantly retards foam drainage and improves foam stability at room temperature. Also, the foam thermal stability can be effectively improved by the presence of incorporation of β-Al 2 O 3 nanoparticles. The results can provide a basis for the application of β-Al 2 O 3 nanoparticles in the development of POPs-free firefighting foams. [ABSTRACT FROM AUTHOR]

*Hydrophobic tails emerging from NP layers compress the NPs because of the hydrophilic heads present in the water and hydrophobic tails suspended from CO 2. **Viscoelastic surfactant (VS) molecules get entangled to confer stability to the foam. [Display omitted] • CO 2 utilization for EOR to achieve net-zero carbon emissions. • Factors affecting the stability of CO 2 foam in reservoir conditions. • Choice of surfactants and commercial nanoparticles for the generation of stable CO 2 foam. • Usage of functionalized nanoparticles for prolonged stability of CO 2 foam. • Basic requirements for an advanced setup to investigate the stability of CO 2 foam. Modern technology must meet the urgent need for net-zero global carbon emissions to mitigate the deleterious effects of fossil fuel consumption. CO 2 utilization in fields such as oil extraction not only prevents global warming, but also has universal benefits. CO 2 flooding is a well-established and promising technology for enhancing residual oil recovery. Enhanced oil recovery (EOR) from fractured reservoirs is difficult because the injected fluids cannot displace crude oil from the matrix. This may be attributed to the (i) lighter weight and lower viscosity of CO 2 than those of the crude oil in the reservoir and (ii) highly permeable layers in the reservoirs, which provide a "path of least resistance" for CO 2 flow. The injection of large amounts of foam into the matrix can be achieved using a strong and stable foam, which generates high pressure in the fractures by blocking the highly permeable layers and directing the CO 2 towards less permeable zones. Extensive efforts have been devoted to improving the long-term stability of CO 2 foams. Such approaches include the use of surfactants (cationic, anionic, non-ionic, and zwitterionic), viscoelastic surfactants (VES), polymers, and nanoparticles (NPs). This article provides a brief overview of the basic principles underlying CO 2 foam stabilization, selection of surfactants, choice of NPs, the role of surface functionalization of the particles, and various factors affecting CO 2 foam stabilization, reported during 2016–2023. Furthermore, this review highlights the need for experimental protocols to investigate NP-stabilized CO 2 foams. [ABSTRACT FROM AUTHOR]

• Droplets of aqueous surfactant solutions applied to a silica substrate form "coffee rings" on drying. • The thickness of the "coffee rings" so formed varies according to the concentration of the applied surfactant solution. • Variation in the "coffee ring" thickness with concentration provides for a simple means to determine a surfactant's cmc. Surfactants serve a myriad uses as key components of household cleaning, personal care, and cosmetics products, and they are important too in the food, textiles, plastics, oil, agrochemical, and pharmaceutical industries. The majority of those currently in use, however, are fossil fuel-derived and are environmentally unfriendly and/or bio-incompatibly toxic/irritant. There are significant efforts thus now expended in the search for alternatives that are generally "greener". The concentration at which such compounds self-assemble to form micelles – their so-called critical micelle concentration – is one of their key physicochemical characteristics, and the experimental determination of this is central to their development both as analytical tools and as commercial materials. In the following report a methodology is presented that provides for a fast, non-expensive, and potentially high throughput means to determine surfactant critical micelle concentration, utilizing a simple dried drop "coffee-ring" image analysis. [ABSTRACT FROM AUTHOR]

• Maltotriose acylhydrazones were synthesized as novel surfactants. • Structure-surface activity profile was established. • Medium-sized surfactant was proved as a potent UDCA carrier in the in vivo primary cholangitis treatment. Bio-based surfactants derived from carbohydrates have attracted increasing attention due to their environmental friendliness, biodegradability, and biological functions. In this study, we synthesized a novel class of maltotriose acylhydrazone surfactants with different alkyl chain lengths (6–14 carbons) using a simple and efficient three-step protocol. We characterized their structure, surface activity, aggregation behavior, foaming properties, and emulsion stability. We found that these surfactants had high hydrophilicity, low toxicity, and good emulsifying and foaming abilities. We also investigated their potential as drug delivery vehicles for ursodeoxycholic acid (UDCA), a drug for primary biliary cholangitis (PBC). We prepared UDCA-loaded niosomes with these surfactants and evaluated their drug entrapment efficiency, in vitro drug release, and in vivo therapeutic effect in a mouse model of PBC. We demonstrated that these niosomes could efficiently encapsulate and deliver UDCA, resulting in improved liver function and reduced inflammation. Our results suggest that maltotriose acylhydrazone surfactants are promising candidates for bio-based surfactants and drug delivery systems. [ABSTRACT FROM AUTHOR]

• A multicomponent acid solution consisting of SDBS,BS-12, HF and C6H8O7 was used to acidifie coal samples. • Acidification treatment can promote the formation of oxygen-containing functional groups C O and C O. • Provide an effective method for realizing high-efficiency clean mining of coal. • The micro mechanism of wettability was explained using molecular dynamics software. In order to explore the influence mechanism of different surfactants on the wettability of coal samples acidified with multi-component acid solutions, the effects of multi-component acid solutions and surfactant composite acid solutions on the functional groups and microcrystalline structures of coal samples were studied. In this paper, a multicomponent acid solution consisting of sodium dodecyl benzene sulfonate (SDBS), dodecyl dimethyl betaine (BS-12), hydrofluoric acid (HF), and citric acid (C 6 H 8 O 7) was used to acidification and contact angle experiments on coal samples. Fourier transform infrared spectroscopy (FTIR) results show that acidification can promote the formation of C O and C O, and the synergistic effect of surfactant BS-12 on multi-component acid solution is more prominent. X-ray diffraction (XRD) results show that the variation trend of aromatic lamellar diameter L a of coal samples is consistent with the aromatic layer spacing d 002. Surfactants can slow down the damage of multi-component acid solution to the microcrystalline structure of coal samples. The change of contact angle shows that the instantaneous synergistic wetting effect of BS-12 is better than that of SDBS. At the same time, molecular dynamics simulation technology was used to verify the effect of surfactants on the wettability of multi-component acid solutions. Therefore, this study provides a feasible method and theoretical guidance for improving the efficiency of coal production and utilization through chemical means. [ABSTRACT FROM AUTHOR]

• Interaction of SDS with polyvinyl alcohol (PVA) was investigated in presence of diols/hydrotrope. • Influence of temperature/concentration/additive composition on physicochemical variables was investigated. • CMC of SDS + PVA mixture usually undergoes a rise with an increase in temperature. • Thermodynamic parameters provide understanding on feasibility of mixed system. • Obtained results may help to design manufacturing methods for industrial products. This study investigates the interaction between sodium dodecyl sulfate (SDS) and polyvinyl alcohol (PVA) in the presence of additives (ethylene glycol (EG), propylene glycol (PG), 2,3-butanediol (2,3-BD), and resorcinol). The critical micelle concentration (CMC) of the surfactant system was estimated by using the conductometric technique. The influence of temperature, concentration, and additive composition on the physicochemical variables (CMC, micelle ionization (α) and counter ion binding (β)) were also investigated. The observed variation in CMC was attributed to several factors, such as the concentration of additives, the nature of hydrophobicity, and the magnitude of the dielectric constant of the mixed solvents. The CMC of the SDS + PVA mixed system was increased with increasing temperature due to the dominance of hydrophobic hydration over the hydrophilic one. The evaluation of thermodynamic parameters, such as change in standard Gibbs free energy ( Δ G m o), enthalpy ( Δ H m o), and entropy ( Δ S m o) and the estimation of β value for the SDS + PVA mixed system indicate the feasibility and viability of the micelle formation. The negative values of Δ G m o observed within the temperature range of 298.15 to 323.15 K suggest a favorable condition for the formation of surfactant micelle. The that the binding forces in the SDS + PVA mixed system are hydrophobic and ion–dipole interactions in nature. The investigation of the intrinsic enthalpy (Δ H m 0 , ∗ ) determines the stability of the surfactant system, while the compensation temperature (T c) serves as an indicator of the solute-solvent interaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Foaming ability decreases under oil due to interaction between surfactants and oil. • Foam stability decreases under oil due to drainage acceleration and film rupture. • The mixture of FS-50/SDS has the best foaming ability but the worst oil resistivity. • The mixture of FS-50/APG-0810 shows the best ability to stabilize foam under oil. The oil resistivity of aqueous foam is a significant property in many industrial fields. This work aims at studying on oil resistivity of foams generated by mixtures of fluorocarbon and hydrocarbon surfactants, the critical components of firefighting foams. Four kinds of foam solutions were prepared to contain a short-chain fluorocarbon surfactant (FS-50) and four hydrocarbon surfactants with different ionic types, including anionic (SDS), cationic (CTAB), zwitterionic (CAD-40), and nonionic (APG-0810). The effects of the typical liquid fuel (n-heptane) on solution properties, foamability, foam stability, and film stability were studied deeply. The results show that foamability and foam stability were significantly influenced by the addition of n-heptane. The addition of n-heptane leads to significant decrease in foamability of all four foam solutions. The foam volume decay and drainage of all four solutions were accelerated under the action of n-heptane. The film stability of all four solutions decreased upon the presence of n-heptane. The mixture of APG-0810/FS-50 showed the best ability to inhibit liquid fuel. The study can promote the use of mixtures of hydrocarbon and fluorocarbon surfactants in the development of firefighting foams used to extinct liquid fuel fires. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surfactant-modified electrodes: Characterization and applications (Modifications & applications) • Theoretical chemistry aiding experimental design in surfactant modification (Theory guiding design) • Enhanced detection in real samples with surfactant-modified electrodes (Improved detection in samples) • The synergy of theory and experiment optimizing surfactant-modified electrodes (Theory-experiment synergy) • Advancing electrode performance through theoretical insights (Theory-driven performance) Surfactants are a class of materials known to decrease surface tension at the carbon paste electrode (CPE) interface. So utilizing its adsorption property, an increase in surface area and electroactive sites is observed. Hence, are employed to modify the electrode surface and change its nature for faster electron transfer kinetics. Owing to these properties, surfactant-modified electrodes have been employed for the detection of various important biomolecules (dopamine, DA; epinephrine, uric acid, UA; and ascorbic acid, AA), drugs (ciprofloxacin, acetaminophen, diclofenac, etc.) and pollutants such as chlorophenol and bisphenol-A and various ions (Cu2+, NO 3 –, PO 4 3−, SO 4 2−), etc. Among all the electrodes surfactant attachment to CPE is not only advantageous in terms of low toxicity, cost, maintenance, and easy preparation but also the hygroscopic surface of carbon paste with silicon oil provides easy fabrication of surfactant at the electrode surface. This enables the formation of an electroactive interface with enhanced surface area. Therefore, the current article highlights the mechanism of adsorption and the role of surfactants at the CPE for electrochemical sensing. [ABSTRACT FROM AUTHOR]