Search

Application of CO2 gas in foam enhanced oil recovery (EOR) processes has emerged as a win-win strategy for achieving higher oil recovery factor and reducing greenhouse gas emission, which can significantly help the protection of the ozone layer from depletion. However, lower stability of CO2-foam, as compared to the N2- and CH4-foams, has tempted us to examine combinations of CO2 with these gases to not only improve the stability of the produced foam but also have CO2 as the gaseous phase of the foam. In this study, we investigated the effect of different gases and the mixture thereof on the performance of foams in EOR while the aqueous phase of foams is a constant mixture of Cocamidopropyl betaine surfactant (0.03 wt %) and silica nanoparticle (0.1 wt%). To this end, seven different gases, including N2, CO2, CH4, 80% N2 + 20% CO2, 80% CH4 + 20% CO2, 50% CH4 + 50% CO2, 50% N2 + 50% CO2 were used as the gases phase for foam generation, and the performance of the produced foams were examined through the following experiments: bulk foam stability tests, apparent foam viscosity measurements, and core flooding tests. The results of foam stability tests showed that half-life time for the CO2-, CH4-, and N2-foams are 13.5, 17.0, and 44.0 min, respectively. Also, as revealed from apparent viscosity measurements, the N2- and 80% N2+20% CO2 foams have higher apparent foam viscosity values followed by 50% N2+50% CO2 foam. Furthermore, we showed that a combination of 80% N2 + 20% CO2 as the gaseous phase for foam generation could not only improve CO2-foam stability, as compared to other foams, but also can substantially increase ultimate oil recovery (56.6 %OOIP), even more than that for N2 foam (48.6 %OOIP), obtained from core flooding experiments.

Initial wettability of rock surfaces plays a crucial role in displacement efficiency during core flooding experiments. In this study, linear alkylbenzene sulfonic acid (LABSA) and silica nanoparticles (NPs) were utilized as enhanced oil recovery (EOR) agents to improve oil recovery from carbonate rock samples. Prior to the core flooding experiments, effects of the presence of LABSA and SiO2 NPs on oil-water interfacial tension (IFT), wettability alteration, and surfactant adsorption on the rock surfaces were evaluated. The results of IFT/contact angle measurements showed that by adding 0.03 wt% LABSA, the IFT, and contact angle reduced from the initial values of 36.9 mN/m and 115.6° ± 0.2° to 8.3 mN/m and 100.3° ± 0.4°, respectively. Furthermore, incorporating SiO2 NPs (0.1 wt %) into the system causes a further decrease in IFT value (dropped to 2.2 mN/m), along with a substantial reduction in contact angle (final contact angle after 6 h soaking into the solution was measured as 64.8° ± 0.3°). In addition, surfactant loss due to the adsorption on the rock surfaces decreased up to 35% in the presence of SiO2 NPs (0.1 wt %). Moreover, various core flooding scenarios in carbonate plugs with different initial wettability conditions were conducted, and the performance of the EOR agents in enhancing oil recovery from oil-wet and water-wet core samples in the secondary and tertiary mode of flooding was evaluated. The outcomes revealed that the injection of a combination of chemicals, containing LABSA (0.03 wt %) and SiO2 (0.1 wt %) in the secondary mode leads to the highest ultimate oil recovery from sister carbonate core samples.

A hybrid enhanced oil recovery (EOR) method by combining low salinity water (LSW) and low salinity surfactant (LSS) flooding techniques was designed. Different experiments were done to screen the Caspian seawater (SW) with altered ionic composition and surfactant, for the optimized performance in Kazakhstani carbonate oil fields. Changing to a more water-wet state and creating the middle phase were studied as the main criteria to select the best-engineered brine and anionic surfactant. The largest alteration towards the water-wet condition was recorded at 10 times dilution of the SW with 3- and 6- times spiked calcium and sulfate ions, respectively (10xSW-6SO4, Mg, 3Ca). This combination of anionic surfactants with carbonate formations is considered as a new approach in hybrid EOR methods. Among the anionic surfactants screened, Soloterra-113H (Alkyl Benzenesulfonic acid) showed the best solubilization ratio, aqueous stability, and Winsor type 3 microemulsions. The wettability alteration by the combination of optimized brine and screened surfactant was greater compared to the standalone LSW, which was confirmed by the 10° difference in contact angle measurement. The microemulsion phase constituted nearly 40% of the total height of the oil/brine column by the hybrid method. The recovery factor after injecting formation water was 52%, and it increased to 61% after optimized LSW injection. After switching to the engineered brine/surfactant, the recovery factor reached 70%, which proves the effectiveness of the hybrid method. The proposed combined method works better than either standalone EOR method due to the higher alteration in capillary number by changing wettability and reducing IFT, which leads to higher oil recovery.

This work numerically investigates surfactant effects on spontaneous water imbibition in oil-wet carbonates. An open boundary core-scale imbibition model with 9 × 9 × 10 gridblocks was used in UTCHEM to simulate carbonate core plug exposure to a vast water body. The simulation models were developed based on surfactant-assisted imbibition tests that were conducted in secondary and tertiary oil production modes using Amott cells at 75 °C. Capillary and gravity forces were captured by history matching the experiments. Through history matching, the inputs for surfactant adsorption and diffusion, capillary pressure and relative permeability were calibrated. In tertiary mode, the surfactants-assisted imbibition process presents the performance in mixed-wet state rather than oil-wet state, which is governed by wettability alteration. A simulation model for surfactant-assisted imbibition in secondary mode was used to investigate the effects of various factors including interfacial tension (IFT) reduction, wettability alteration, adsorption, volume of surrounding water, and capillary force. The simulation results suggest that surfactant-assisted water imbibition in secondary mode is gravity dominant, which is facilitated by both IFT reduction and wettability alteration caused by addition of proper surfactants. Different from water imbibition in water-wet core, it presents vertically dominant oil flow with a hemispherical oil-rich area and uneven remaining oil saturation. It is obvious that sufficient surfactant supply in vast water is required to make effective imbibition, in consideration of surfactant consumption and changes in concentration gradients. This core-scale modeling provides insights of surfactant-assisted imbibition in initially oil-wet carbonates and helps scale up the application in a cost-effective way.

The addition of surfactants and nanoparticles in minimizing wax deposition related problems such as flow assurance is considered an attractive alternative among other techniques but limited researches have been carried out in investigating the method. High viscosity crude oil needs to be treated with viscosity reducer to facilitate transportation and processing. In this study, the efficiency of the viscosity reducer, a Gemini surfactant 2,5,8,11 Tetramethyl 6 dodecyn-5,8 Diol Ethoxylate, three different nanoparticles: silicon dioxide (SiO2), tin oxide (SnO) and nickel (III) oxide (Ni2O3) and their novel blends at different range of concentration, temperature, shear rate and surfactant/nanoparticle loading ratio are assessed in order to study their influence on the viscosity of Malaysian crude oil using Brookfield DV-III viscometer. The separate use of Gemini surfactant and nanoparticles alone resulted in significant reduction in crude oil viscosity. The combined use of Gemini surfactant and nanoparticles showed better performance as compared to their corresponding individual use. The presence of surfactant improves the adsorption of nanoparticles by functionalizing their surfaces. Adsorption and adhesion of wax molecules onto the surface of nanoparticles and surfactants prevents them from aggregating. This results in increment in viscosity reduction. Overall, the viscosity of crude oil was reduced about 85–92% at 10 ℃ with the aid of Gemini surfactant and nanoparticles. The highest viscosity reduction obtained was 92.8% using the blend of Gemini surfactant and silicon dioxide. The findings of the study are expected to contribute to the crude oil industry in improving flow in production and transportation.

This paper presents an experimental and analytical study of comprehensive effects of surfactant and polymer in aqueous solutions on the propagation in carbonates. Single-phase flow tests of surfactant, polymer and surfactant-polymer mixture were respectively conducted on natural carbonate core plugs at high temperature and high salinity reservoir conditions. The effect of different factors on chemical propagation was taken into account by use of a convection-dispersion model. The dynamic adsorptions of two amphoteric surfactants at 2000 mg/L concentration onto the carbonate rocks were 0.21 and 0.17 mg/g-rock, respectively. The dynamic adsorptions of a sulfonated polymer at 2000 and 5000 mg/L were 0.11 and 0.17 mg/g-rock, respectively. Surfactant-polymer mixtures in aqueous solutions were co-injected to evaluate their competitive adsorption, showing the surfactant adsorption was reduced by approximatively 50%. The dispersion coefficient of the chemicals in the carbonate cores was in the magnitude of 10−3 cm2/s. Caused by dispersion and adsorption, chemical concentration reduction occurred obviously during the propagation in carbonate porous media. Chromatographic separation took place in the surfactant-polymer co-injection scheme, which was estimated by modeling as well.

Carboxymethyl cellulose (CMC) has emerged in oil and gas industries as a superior substitution to the conventional HPAM and xanthan gum (XG) for high viscosity polymer flooding application. In this study, the combined effect of conventional surfactant, sodium dodecylbenzenesulfonate (SDBS) and CMC for potential surfactant-polymer (SP) flooding in enhanced oil recovery (EOR) has been investigated. Thereafter, SDBS – CMC interaction and the functional groups present in CMC were appropriately identified. The presence of various C–O bonds signifies the existence of carboxymethyl group which greatly influence the rheological properties of CMC solution. The behaviour of SDBS–CMC was characterized by their viscosity, shear rate, solubilization, wettability, and surface tension. Tertiary flooding utilizing SDBS-CMC was performed and compared to commercial SDBS-XG SP flooding. The results indicate several SDBS-CMC combinations are favourable for EOR application. Solution viscosity shows direct relationship with CMC concentrations. Consequently, at any given SDBS concentrations, significant increment was observed at 0.3 wt% and above. However, the trend displayed inconclusive relation to SDBS fractions. Majority of the SDBS-CMC combinations generate Winsor III emulsions particularly at CMC of 0.2 and 0.3 wt%, while Type II were observed in few combinations. Increasing CMC concentrations increased the contact angle, while gradual reductions were observed with SDBS concentrations. The gradual reduction in surface tension was highly influenced by the addition of CMC rather than SDBS. A novel combination of 0.3 wt% SDBS and 0.4 wt% CMC possessed an encouraging criterion in term of viscosity, solubilization, and surface tension reduction for EOR application. Flooding experiment from several SDBS-CMC combinations proved to recover additional oil ranging 16.4–20.2% of oil initially in place (OIIP). The trend in incremental oil recovery is similar to that of when utilising SDBS-XG.

[EN] Metal-Organic Frameworks (MOFs) are extensively used in different applications, including heterogeneous catalysis given the fact that practically any center can be designed on demand and is accessible for reactants. Just like any other microporous catalysts, the limited diffusion of reactants and products is an endemic drawback also in MOFs. To face it, the use of nanocrystalline MOFs is a proven alternative, which in addition is often accompanied by improvements in sustainability of synthesis procedure (room temperature, water as solvent, etc.). This work goes further adding surfactant-induced mesoporosity to the nanocrystallinity of these materials. As a proof of concept, the nanocrystalline NH-MIL-53(Al) and CTA (cetyltrimethylammonium) were selected as the sustainably-prepared nanocrystalline MOF and a cationic surfactant, respectively. The MOF system is formed by massive and practically instantaneous precipitation entrapping the surfactant, which generates mesopores in the aggregates. The simple washing with ethanol at room temperature leads to a nanocrystalline NH-MIL-53(Al) material containing outstanding intercrystalline mesoporosity. The so-obtaining hierarchically-porous NH-MIL-53(Al) is able to effectively remove bisphenol A (BPA) from aqueous solution (more than 90% of a 25 ppm BPA aqueous solution in just 10 min at room temperature), duplicating the performance given by its counterpart nanocrystalline NH-MIL-53(Al) prepared in the absence of surfactant., This work has been financed by the Spanish State Research Agency (Agencia Estatal de Investigación AEI) and the European Regional Development Fund (Fondo Europeo de Desarrollo Regional, FEDER) through the Project MAT2016-77496-R and CSIC (2019AEP076). M.A. M. acknowledges Spanish MINECO for Ph.D. student contract BES-2017-082077. N.R.H. acknowledges CSIC for the I-COOPA-2019 (COOPA20376) grant and M.S.S the I-COOPA-2018 (COOPA20271) project

Surfactant-based oil recovery processes are employed to lower the interfacial tension in immiscible displacement processes, change the wettability of rock to a more water-wet system and emulsify the oil to displace it in subsurface porous media. Furthermore, these phenomena can reduce the capillary pressure and enhance spontaneous imbibition. The key factors affecting such immiscible displacement process are temperature, salinity and pH of the fluids, surfactant concentration and adsorption. Therefore, before any surfactant flooding process is applied, extensive studies of fluid-fluid and rock-fluid interactions are needed. The use of other chemicals along with surfactants in chemical enhanced oil recovery (cEOR) processes have been widely considered to exploit the synergy of individual chemicals and complement the weakness arises from each of them during immiscible displacement of fluids in porous media. Therefore, such combinations of chemicals lead to alkaline-surfactant (AS), surfactant- polymer (SP), alkaline-surfactant- polymer (ASP), and nanoparticles- surfactant (NS) flooding processes, among others. In this review study, we categorised the role and displacement mechanisms of surfactants and discussed the key factors to be considered for analysing the fluid displacement in porous media.

Highly transparent and super-wettable nanocoatings for multifunctional applications with outstanding physical properties are in high demanded. However, such nanocoatings resistant to water invasion and Ultraviolet (UV) weathering remain a significant challenge. In this work, physically durable coatings based on inorganic nanoparticles (NPs) and an organic segment (isocyanate-silane modified surfactant) have been synthesized via a sol-gel approach. It is noteworthy the isocyanate-silane with –NH–C O- functional group creates a strong bonding between the highly hydrophilic surfactant and the inorganic NPs. This in-house synthesized organic segment can render the coating long-lasting wetting properties and resist to be washed away by water, while the inorganic NPs can form sturdy covalent bonds with the nano-scale hierarchical structure on the glazing substrate to improve the durability. This nanocoating demonstrates high transparency with superwetting property (water contact angle, WCA ​= ​4.4 ​± ​0.3°), effective de-frosting performance. Water invasion or UV accelerated weathering tests do not significantly affect the self-cleaning performance of nanocoating. Physical properties, including coating adhesion, hardness, Young's modulus, and abrasion resistance are systematically investigated. Interestingly, this clear coating shows prominent infrared shielding property attributed to Antimony-doped tin oxide (Sb-doped SnO2) NPs. The developed nanocoating process is easy to scale up for larger areas that require multipurpose self-cleaning functions.

Nanofluid offers more opportunities and challenges over the traditional surfactant and polymer solutions during enhanced oil recovery (commonly referred to as tertiary oil recovery) due to its remarkable properties. This review mainly discusses the preparation methods of amphiphilic nanoparticles due to their higher interface activity than sole hydrophilic or hydrophobic nanoparticles (SHNPs). The nanofluids’ stability is reviewed in this work. Moreover, the mechanisms of nanofluids in enhancing oil recovery (N-EOR) in terms of interfacial tension reduction, wettability alteration, foam stabilization, emulsion stabilization, structural disjoining pressure, and depressurization-increasing injection are mainly summarized and reviewed. Also, the synergistic effects of nanofluids and traditional surfactants and polymers are discussed. Finally, nanofluids’ challenges and prospects are also outlined. The nanofluids can still be regarded as an outstanding candidate for enhancing oil recovery significantly in the future although there are limitations on their applications from laboratory scale to field scale.

Reducing the oil-water interfacial tension (IFT) to ultra-low is believed the primary mechanism for surfactant-based enhanced oil recovery (EOR) process. However, field trials have shown that low concentration surfactant flooding can also improve oil recovery without ultra-low IFT. To clarify the mechanism behind, the currently-used surfactant, naphthenic arylsulfonate (NAS), was used to unravel its function during surfactant flooding from the horizon of micron- and nano-scale. The solubilization capacity of NAS micelle to petroleum fractions was evaluated through light absorbance strategy, small-angle neutron scattering, dynamic light scattering and transmission electron microscopy. It was found that micellar solubilization plays a significant role during the surfactant flooding. In-situ emulsification was visualized in microfluidics with three types of microchips, respectively. A series of displacement tests were carried out with NAS solution pumping into oil-saturated chip. The results show that in-situ emulsification improve oil recovery mainly through blocking and entrainment effects. Results from this work aid in understanding the interaction between surfactant solution and petroleum fractions at low surfactant concentration, which is helpful for design surfactant-based displacing system for EOR process.

Carbon dots (CDs) have attracted more interest in tumor theranostics, but they suffer from the rapid renal clearance due to small size and high hydrophilicity. To solve such problems, hydrophobic pH-triggered carbon dot-drug conjugate (CDs-Hy-DOX) with high doxorubicin (DOX) content of 48.23% were designed by covalent conjugation of DOX onto the CDs via acid-labile linkage with hydrazine (Hy) as bridge. Then the fluorescent traceable hybrid prodrug nanoparticles were fabricated via co-self-assembly with the CDs-Hy-DOX as pH-sensitive prodrug and a pH/reduction dual-triggered degradable hyperbranched polymer PEG-PO-Cy as polyethylene glycol (PEG)-based surfactant, as well as gatekeeper for pH/reduction dual-triggered DOX release. The hybrid prodrug nanoparticles with hydrodynamic diameter of 220 nm and DOX content of 22.99% were obtained with the optimized co-self-assembling condition. They could release 68.98% of DOX in the simulated tumor microenvironment within 3 days in a sustained release mode, with a premature drug leakage of 7.58%. After the acid-triggered DOX release from the CDs-Hy-DOX, which was accelerated by the pH/reduction dual-triggered degradation of the hyperbranched polymer, the strong fluorescence of CDs-Hy was recovered, demonstrating the promising potential in future tumor nanotheranostics.

Janus particles (JPs) and surfactants express different behaviors at the oil-water interface under compression. When both are present at the interface, their synergies result in a different collapse mechanism than when present individually depending on the concentration of the JPs and surfactants.Coarse-grained modeling methods were used to probe the synergies between Janus nanoparticles and nonionic surfactants on the stability of an oil-water interface under compression. When both JPs and surfactants were present, the interface was covered at 0-55% area by JPs and contained surfactants at 0-40% of the interfacial surfactant concentration corresponding to the critical micelle concentration (CMC).Compression of the interface with only surfactants resulted in the expulsion of surfactant molecules to the water phase once the interfacial concentration of surfactant molecules reached the CMC value. Compression of a Janus particle-laden interface past the closed-packing point led to a buckled interface, so that the total interfacial area remained constant upon further compression. When both surfactants and JPs were present on the interface, JPs still caused buckling, which helped retain the surfactant molecules on the interface. The interface exhibited a higher level of deformation in presence of surfactants. When the surfactant concentration was high, under compression, the surfactants partitioned into the water phase, but the buckling of the interface persisted.

Hypothesis Photoswitchable surfactants are used in the design of many light-responsive colloids and/or self-assemblies. Photo-isomerization enables to control molecular equilibrium, and triggers transient reorganizations with possibly out-of-equilibrium intermediate states that have been overlooked. Here, we address this question by an in depth structural investigation of intermediate lipid-surfactant assemblies that occur during fast isothermal photo-triggered transition in lipid:surfactant mixtures. Experiments The structural parameters of mixed assemblies of azobenzene-containing cationic surfactant (AzoTMA) and dioleoylphosphatidylcholine (DOPC) lipids were studied by light scattering and time-resolved small angle X-ray scattering. Structural and compositional information about the assemblies and unimers in bulk were determined at the photostationary states, as well as at intermediate kinetic states formed during UV or blue light illumination. Findings DOPC:AzoTMA systems form mixed assemblies representative of phospholipid:cationic surfactant mixtures, that evolve from spheroid, to rod-like micelles, and vesicles with increasing DOPC fraction. Transient assemblies detected during the photo-triggered kinetics are similar to the ones found in stationary states. But changes of AzoTMA unimers in bulk can be considerably faster than mass reorganizations of the mixed assemblies, suggesting that out-of-equilibrium conditions are transiently reached. Mass reorganization of the surfactant-enriched assemblies is much faster than in the lipid enriched ones, providing insight into the role of lipids in a slow reorganization of the assemblies.

The aim of this research is to study the effect of hydrophilic silica nanoparticles, sizes as CO2 foam stabilizer in the presence of nonionic TX100 surfactant. Two nanosilica sizes, 15 and 70 nm, have been examined thoroughly. Physisorption of TX100 on silica nanoparticles (nanosilica) was characterized by adsorption isotherm and surface tension measurement, while CO2 foams stability was quantified based on their foamability, foam stability, particle partitioning in the foams, and bubble sizes. Results show that direct contact of TX100 with nanosilica does altered the wettability of hydrophilic nanosilica surface, enable them to lengthen CO2 foams life at certain surfactant and nanoparticles concentrations. For 15 nm nanosilica, CO2 foam stability shows excellent performance at 0.1 and 0.5 wt% TX100 concentrations. As for 70 nm nanosilica, CO2 foam demonstrates longer lifetime at much lower TX100 concentration, 0.01 wt%. Without the presence of TX100, CO2 foams exhibit undesirable lifetime performances for both nanosilica sizes. Nanosilica partitioning in CO2 foams structures demonstrate consistent relation with contact angle measurement. Estimated bubble sizes shows insignificant effect on CO2 foams life. With the assists of nanosilica and TX100, enhanced oil recovery via CO2 foam injection succeeds in increasing oil production by 13–22% of original oil-in-place (OOIP).

Background For Melatonin, the pineal gland hormone, also known as the neuroendocrine hormone, influences angiogenesis by exerting a positive effect on fibroblast, monocyte, and cytokine proliferation. Formulation and study of characteristics of gelation-based Melatonin sponge crosslinked with fructose using the surfactant foaming and freeze-drying method for wound healing application was the objective of our study. The structure of the formulated gelatin sponge was observed using a scanning electron microscope and showed to have abundant and uniform pores. Characteristics were studied using digestibility test, water uptake test, porosity measurement test, moisture uptake test, tensile strength test, folding endurance test, scanning electron microscopy, Fourier transform infrared spectroscopy, and drug entrapment efficiency analysis. Results The obtained data showed that the formulated sponge had good mechanical properties, water uptake, and water retention capacities. In animal experiments, histological and macroscopic observations showed that wounds covered by gelatin loaded with a Melatonin sponge healed quickly. Conclusion The formulated sponge was a potential wound healing material having suitable physical, mechanical properties and biocompatibility. The graphical abstract is shown in Figure 1.

Hypothesis . A large number of papers discuss merits and mechanisms of low salinity waterflooding. For each mechanism proposed, there are counter examples to invalidate the stated mechanism. The effect of wettability from low salinity water, which is predominantly stated in literature as the dominant mechanism, may not be valid. We introduce a direct correlation between oil-brine interfacial viscoelasticity and oil recovery from waterflooding. Experiments . The oil recovery is investigated in carbonate rocks for three light crude oils , by injection of a wide range of aqueous phases, ranging from deionized water to very high salinity brine of 28 wt%, and low concentration of a non-ionic surfactant at 100 ppm. The oil-brine interfacial viscoelasticity is quantified and supplementary measurements of interfacial tension and wettability are performed. Findings . In our experiments, oil recovery is higher from high salinity water injection than from low salinity water injection. A strong relationship is observed between interface elasticity and oil recovery for different concentrations of salt in the injected brine as well as for ultra-low concentration surfactant. An elastic oil-brine interface results in high oil recovery. The surfactant molecule we have selected prefers the oil–water interface despite high solubility in the oil phase and makes ultra-low concentration of 100 ppm in injection water very effective. Contrary to widespread assertions in the literature, we find no definitive correlation between oil recovery and wettability.

To obtain superior surface-active properties while minimizing environmental risks, new fluorinated surfactants (F2HX-nEO) were designed to include a hybrid multi-chain with a short fluorocarbon (–CF2CF3) and nonionic ethylene oxide. They were simply synthesized by a straightforward reaction involving the addition of ethylene oxide to a hybrid fluorine alcohol, and their surface-active properties were optimized by controlling the hydrocarbon length and number of ethylene oxide units. Therefore, the desirable values of critical micelle concentration (0.3 mmol/L) and surface tension (24.3 mN/m) were obtained in spite of containing the short fluorocarbon chain. Particularly, F2HX–nEO showed excellent wetting properties on hydrophobic surfaces and very low toxicity level, which can be used in various fields as a promising alternative to long fluoroalkyl chain surfactants.

Although surfactants have been widely used in skin care and other related applications, our knowledge about how surfactants interact with stratum corneum (SC) lipids remains limited. This work reports how surfactants interact with a lipid SC model by neutron diffraction and molecular dynamics (MD) simulations, focusing on examining the impact of surfactant molecular architecture. The surfactant-SC mixed membrane was constructed by an equimolar mixture of ceramide/cholesterol/fatty acids and surfactant at 1% molar ratio of total lipids. The arrangements of water and surfactant molecules in the membrane were obtained through neutron scattering length density (NSLD) profiles via contrast variation method, meanwhile, MD simulation clearly demonstrated the mechanism of hydration change in the surfactant-model SC mixed membrane. No drastic difference was detected in the repeating distance of the short periodicity phase (SPP) upon adding surfactants, however, it significantly enhanced the membrane hydration and reduced the amount of phase separated crystalline cholesterol, showing a strong dependence on surfactant chain length, branching and double bond. This work clearly demonstrates how surfactant architecture affects its interaction with the SC membrane, providing useful guidance for either choosing an existing surfactant or designing a new one for surfactant-based transdermal application.

Hypothesis The unexpected formation of a lamellar structure with concomitant gelation in solutions containing high urea concentration (40 wt%) and relatively low amount of cationic surfactant (3 wt%), indicates that a hierarchically structured complex is formed by both molecules. Experiments Gels formed by combination of aqueous solutions of urea and C12TAB, C14TAB or C16TAB were prepared in different proportions and their structures at microscopic and mesoscopic levels were investigated using XRD and SAXS, respectively. The elastic and viscous moduli and yield stress of the samples were determined and correlated with the composition and structuration of the gels. The lamellar structure is reversibly thermically destroyed and this process was investigated using DSC. Findings XRD revealed that, at microscopic scale, the gels are formed through crystallization of adducts containing surfactant molecules loaded into the cavities of honeycomb-like urea assemblies. Such crystalline phase arranges itself in lamellae with interplanar distance around ∼20–30 nm, which were observed by SAXS. This hierarchical structure is independent of the chain length of the cationic surfactants. The blocks of lamellae dispersed in the continuous phase form a three-dimensional rigid particulate network structure, giving the characteristic rheological behavior of a hydrogel. DSC revealed a reversible thermal transition at around 20–25 °C, beyond which the adducts and the lamellar phase are destroyed and micelles are formed. The characteristic transition temperature is independent of the chain length of the surfactant, and thus, it is not associated with their Krafft temperatures. The structures of the gels indicate that they resemble alpha-gels formed by fatty-alcohols and surfactants, although they self-assemble by different driving forces.

In vitro dissolution testing as a form of quality control has become a necessity in the pharmaceutical industry. As such, the need to establish a method that investigates the in vitro dissolution profile of inhaled products should be taken into account. The prime focus in this study was to examine the in-vitro in-vivo correlation utilising a modified version of the Twin Stage Impinger and to promote an in vitro dissolution model by enhancing the Fine Particle Dose (FPD) collection method for dry powder inhalers. The Twin Impinger was modified by inserting a stainless steel membrane holder disk in the base of the lower chamber. The design, with optimum drug deposition, was adopted for the dissolution study of budesonide and salbutamol. Afterwards, the membrane holder system was placed in the bottom of the dissolution vessel. Phosphate buffer saline (PBS), simulated lung fluid (SLF, Gamble solution) and Phosphate buffer (PB) were used in the study. The paddle dissolution apparatus, containing 300 mL of the medium, was operated at 75 rpm paddle speed. Samples were collected at defined time intervals and analysed using a validated HPLC method. The largest proportion of the budesonide dose was dissolved in PBS compared to PB and SLF. This was due to the presence of surfactant (0.2% w/v polysorbate), which enhances the wettability and the solubility of the poorly soluble drug (budesonide). The similarity factors for PBS and PB were 47.6 and 69.7, respectively, using SLF as a reference, whereas the similarity factor for salbutamol dissolution between PB and SLF was 81.3, suggesting PB is a suitable substitute. Comparison using both the predicted and actual in vivo pharmacokinetics (PK) values of the two drugs, as well as the pattern of their Concentration-Time (c-t) profiles, showed good similarity, which gave an indication of the validity of this in vitro dissolution method.

Hypothesis. Surface active anionic nanoparticles (NPs) with strategically designed covalent ligands may be combined with a liked-charged surfactant to form a highly elastic gas-water interface leading to highly stable gas/water foams. Experiments. The colloidal stability of the NPs was determined by dynamic light scattering, and the surface elastic dilational modulus E’ of the interface by sinusoidal oscillation of a pendant droplet at 0.1 Hz, which was superimposed on large-amplitude compression-expansion cycles. The foam stability was measured with optical microscopy of the bubble size distribution and from the macroscopic foam height. Findings. The NPs played the key role the formation of a highly elastic air-water interface with a high E’ despite a surfactant level well above the critical micelle concentration. Unlike the case for most previous studies, the NP amphiphilicity was essentially independent of the surfactant given the very low adsorption of the surfactant on the like-charged NP surfaces. With high E’ values, both coalescence and coarsening were reduced leading to highly foam up to 80 °C. However, the surfactant facilitated foam generation at much lower shear rates than with NPs alone. The tuning of NP surfaces with ligands for colloidal stability in brine and simultaneously high amphiphilicity at the gas-water interface, over a wide range in surfactant concentration, is of broad interest for enabling the design of highly stable foams.

Hypothesis While surfactant solutions mobilize residual oil under optimal conditions by lowering the water–oil interfacial tension, emulsion phases outside of the optimum tend to be immobile. How are mobility and texture of such phases related, and how can the stability of these phases be understood? Can non-optimized surfactant solutions improve displacement processes through mobility control? Experiment Emulsification and miscibility during surfactant flooding were investigated in microfluidics with generic oil and surfactant solutions. The salt concentration was varied in an exceptionally wide range across the optimal displacement conditions. The resulting emulsion textures were characterized in situ by optical and fluorescence microscopy and ex situ visually and by Small-Angle X-ray Scattering. Findings During displacement, oil is increasingly solubilized and transported in a phase with a foam-like texture that develops from a droplet traffic flow. The extent and stability of these emulsion phases depend on the salinity and surfactant efficiency. The similarity with textures of classic foam phases is used to hypothesize the mechanisms that stabilize such macroemulsions in porous media. The observed microscopic displacement mechanisms can be traced back to foam formation, quality and transport. The resulting phases are of particular interest for mobility control during surfactant flooding, which, however, requires further investigation.

Hypothesis Lung surfactant protects lung tissue and reduces the surface tension in the alveoli during respiration. Particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5), which invades primely through inhalation, can deposit on and interact with the surfactant layer, leading to changes in the biophysical and morphological properties of the lung surfactant. Experiments Langmuir monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and clinical surfactant Calsurf were investigated with a PM2.5 model injected into the water subphase, which were characterized by surface pressure-area isotherms, Brewster angle microscopy, atomic force microscopy, fluorescent microscopy, and x-ray photoelectron spectroscopy. The binding between DPPC/Calsurf and PM2.5 was studied using isothermal titration calorimetry. Findings PM2.5 induced the expansion of the monolayers at low surface pressure (п) and film condensation at high п. Aggregation of PM2.5 mainly occurred at the interface of liquid expanded/liquid condensed (LE/LC) phases. PM2.5 led to slimmer and ramified LC domains on DPPC and the reduction of nano-sized condensed domains on Calsurf. Both DPPC and Calsurf showed fast binding with PM2.5 through complex binding modes attributed to the heterogeneity and amphiphilic property of PM2.5. This study improves the fundamental understanding of PM2.5-lung surfactant interaction and shows useful implications of the toxicity of PM2.5 through respiration process.

Soil washing is a promising technology for the remediation of PAH-contaminated sites, but surfactant needs to be recovered to reduce remediation cost and avoid secondary pollution. In this study, activated carbon (AC), prepared from waste walnut shells, was applied to the adsorptive removal of phenanthrene (PHE) from synthetic soil washing effluent with Tween 80 as a model surfactant. Box-Behnken statistical experiment design (BBD) and response surface methodology (RSM) were used to investigate the influence of AC dosage, Tween 80 concentration and adsorption time, and their potential interaction effect on PHE removal. A response surface model was established based on the BBD experimental results. The goodness of fit of the model was confirmed by determination coefficient, coefficient of variation (CV) and residuals analysis. The RSM model indicates that AC dosage or adsorption time had positive effect on PHE removal while Tween 80 concentration had negative effect. The interaction effect between AC dosage and Tween 80 concentration was significant but the other two interaction effects were not. The 3D response surface plots were developed based on the RSM equation. The RSM model was validated by an additional experiment and the obtained result of PHE removal was very close to the model prediction, indicating the RSM model can effectively predict the PHE removal from soil washing effluent with activated carbon adsorption.

Hypothesis High and medium internal phase Pickering emulsions stabilized with cellulose nanocrystals (CNCs) exhibited very different performance compared to their peers stabilized with a surfactant. In this paper, we ascribed the difference to the formation of hydrogen bonding and van der Waals interactions between the CNC nanoparticles on adjacent oil droplets. Experiments Rheological properties of CNC-stabilized oil-in-water medium internal phase emulsions (MIPEs, oil content = 65% v/v) and high internal phase emulsions (HIPEs, oil content = 80% v/v) were comprehensively characterized using both oscillatory and rotational tests. Findings It was found that in the MIPEs, the van der Waals and hydrogen bonding interactions dominate the emulsion properties, whereas the compact structure of oil droplets plays a more important role in the HIPEs. CNC concentration in the aqueous phase also affects the emulsion properties, especially for the HIPEs, and the results can be correlated to the stabilization mechanisms we previously reported. The information from these tests provides a much-needed guidance for the practical application of CNC-stabilized emulsions.

Hypothesis For conventional high internal phase emulsions (HIPEs) with an external osmotic pressure greater than Laplace pressure, once the osmotic balance is broken, the swelling or shrinking of the aqueous phase can easily trigger phase separation. Mixing two immiscible dispersed phases in a double HIPE can evolve differently following an osmotic shock, which is expected to create a synergistic effect that can frustrate the phase separation of the system. Experiments Osmotic responses of double HIPEs were studied at the surface of a NaCl solution at a range of molarities. Fluorescence confocal microscopy studies were carried out to track the responses on microscopic scales. Measurements on surface tensions revealed the interfacial behaviors of the used surfactant. Findings A synergistic effect is achieved by a symbiotic process between the dispersed oils, where one type of droplets become more stable and pack around the other ones to halt their coalescence. The essential drive comes from the adsorption/desorption of surfactant molecules at oil–water interfaces. By directly adjusting the osmotic pressure difference, transitions between osmotic down-shock and osmotic up-shock can also be realized. This symbiosis greatly expands the potential technological applications of multiple-liquid systems, and can be used to design novel multi-functional composite materials.

This paper depicts the utilization of sodium dodecyl sulphate (SDS) that replaces and enhances traditional use of cationic surfactant that is acetylene tri alkyl bromide (CTAB) for improving oil recovery. The SDS was assessed in Alkaline Surfactant Polymer (ASP) slugs containing regularly utilized surfactants with polymers. The impact of SDS on interfacial tension (IFT), adsorption and recovery was contrasted with that of a CTAB in these applications. The SDS was seen as good with saline solutions containing high total dissolved salt and greater volumes of double cations. They can be utilized in saline solutions without the requirement for softening and they give preferable outcomes over traditional CTAB in frameworks where either can be utilized. The SDS has the favourable position of improved recovery with unsoftened saline solution. Their non-reactive properties make them especially appropriate for ecologically delicate applications at on land and offshore oil fields.

Hydroxyapatite (HAP), which is chemically represented as (Ca10(PO4)6(OH)2), is one of the main inorganic material of vertebrate bone and teeth. The bioceramic material is used as a substitute for deficient bone tissue because of its similarities to crystallographic and chemical composition of teeth and bone. HAP is extensively used in various biomedical applications because of its excellent properties, such as bioactivity, non-toxicity, biocompatibility, non-immunogenicity and osteoconductivity. In this work, hydroxyapatite powder was synthesized using polyoxyethylene lauryl ether (Briji-35) as a surfactant and dimethyl sulfoxide as a primary surfactant through microemulsion method. The obtained products were characterized by FTIR, XRD and SEM. The result indicated that, the Briji-35 played an important role for the formation of nano-hydroxyapatite particle with good crystallinity and particles with uniform morphology besides controlling the particle size of nano-HAP. The biomedical application studies of the as-synthesised material are yet to be studied.

Crude oil is fossil fuel formed from the decomposition of decaying plants and animals in the ground. In crude oil, there is a high percentage of asphaltene that leads to wax deposition along the transport pipeline. The objective of this research is to study the effect of temperature, shear rate and nanoparticle loadings towards viscosity, interfacial tension, surface tension as well as the weight of wax deposit form. Two types of nanoparticles were used in this study, which were GOHSENX Anionic PVOH L-3266 and NICHIGO G-polymer AZF8035W. Whereas, Gemini YND1233 was used as a surfactant. Nanoparticle with different amount of loading (2 mg, 3 mg, 4 mg and 5 mg) was prepared using cyclohexane as the solvent. The nanofluid was prepared according to the load ratio of Gemini surfactant to nanoparticles of 3:1. With 5 mg of nanoparticle, L-3266 loading in Gemini surfactant showed the best performance where it resulted in the lowest viscosity, interfacial tension, surface tension and wax deposition as compared to the 2 mg of nanoparticle AZF8035W loading in Gemini surfactant. This is due to the carboxylic acid group present in AZF8035W. The optimum temperature and shear rate in reducing the crude oil viscosity was obtained at 35 °C and 80 rpm. In order to investigate the effect of nanoparticle loading and the stirring rate of impeller on the formation of wax deposit, the cold finger test had been conducted. From the cold finger analysis, the lowest weight of wax deposit was obtained at the cold finger temperature of 20 °C and the stirring rate of 500 rpm by adding 5 mg of nanoparticles L-3266 in Gemini surfactant. In conclusion, the best performance of wax inhibitor from this research was obtained by adding 5 mg of nanoparticles GOHSENX Anionic PVOH L-3266 in Gemini surfactant in order to improve the rheology of the crude oil and decrease the formation of wax deposition.

In this study a series of CoFe2O4 NPs have been synthesized successfully in presence of various surfactant viz. cationic, anionic and non-ionic.CoFe2O4 NPs was prepared in aqueous medium by Co-precipitation technique using Cobalt nitrate (Co2+) and Ferric nitrate (Fe3+) as the precursor and CTAB, SDS and Tween-20 were used as the templating agent. The structural as well as the magnetic properties were investigated by XRD, FT-IR, FESEM and VSM analysis. The XRD study of the NPs confirms that the phases corresponding to the cubic spinel structure of the CoFe2O4 NPs were retained even after the addition of templating agent. The crystallite size has been restricted to within 6–9 nm respectively.

Foam-assisted gas has been widely employed in enhanced oil recovery (EOR) by improving the volumetric sweep efficiency gas mobility of injected gas. However, the major obstacle of foam-assisted gas EOR is maintaining foam lamellae’s stability, especially in harsh reservoir conditions. As mentioned above, the study focused on the effect of silica nanoparticles (SiO2 NPs) in an anionic/nonionic surfactant mixture in enhancing the stability of foam film. The optimum concentration of silica nanoparticles was determined through various experimental approaches. The surface tension and interfacial tension in the presence and absence of SiO2 NPs were measured and recorded. The Bartsch shaking method was applied to analyse the foam half-life and foam static stability. Anionic surfactant Sodium Dodecyl Sulfate (SDS) was utilised with the nonionic surfactant Triton X100 (TX100) at a ratio of 4:1. Addition of various concentration (0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt% and 1.0 wt%) SiO2 NPs in two surfactant mixtures. The screening method was utilised to determine the optimum concentration of SiO2 NPs in SDS-TX100 surfactant mixture at 25 °C and 70 °C. The optimisation from the screening process demonstrated 0.4 wt% SiO2 NPs was suitable in SDS-TX100 surfactant mixture for stabilising the foam films.

In this study, monoclinic bismuth oxide (α-Bi2O3) was synthesized using in the presence and absence of surfactant, and its performance was compared for the photocatalytic degradation of methylene blue. The usage of surfactant alters the morphology of α-Bi2O3/P123 as nanorods. XRD and Raman Spectroscopy analysis confirms the monoclinic phase of the prepared catalyst and the SEM shows cubes with nano whiskers. TEM image confirms nanorods for the surfactant aided synthesis of α-Bi2O3/P123 which plays a significant role in the degradation of methylene blue. Nanorods of α-Bi2O3/P123 shows 95% photo catalytic degradation of methylene blue than compared to 84% for α-Bi2O3 and 78% for P25. The effect of catalyst loading, kinetics of degradation and the comparison of performance with the standard catalyst were reported.

Hierarchical structure Bi2MoxW1-xO6 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) solid solutions with high surface area are prepared by hydrothermal method without employing any surfactant. All the as-prepared products are hierarchical microspheres self-assembled by nanosheets. The piezocatalytic performance of Bi2MoxW1-xO6 solid solutions are investigated by the degradation of RhB under ultrasonic vibration. The experimental results show that the x value of Bi2MoxW1-xO6 has great influence on the piezocatalytic efficiency. Among which, the Bi2Mo0.4W0.6O6 presents a high value of the rate constant k of 0.119 min-1 by degrading 97.5% of RhB dye solution in 30 min. It is about 43.4% higher than that of pure Bi2WO6 sample, for which k is 0.083 min-1. Radical trapping test indicates that holes (h+) are the dominating active species in the degradation process. The improved piezocatalytic performance for Bi2Mo0.4W0.6O6 sample ascribes to the larger piezoelectric potential generated under a strained state, which facilitates the transfer of charge carriers and accelerate the piezocatalytic process. Our work presents a new design strategy of piezocatalysts for remediation of water pollution.

Liquid crystalline nanoparticles (Cubosomes) are unique structures for the effective delivery of many pharmaceutical drugs. The present study is aimed to develop and characterize novel cubosomal formulation containing dexamethasone (DMS). The cubosomes were incorporated into hydrogel for prolonged delivery of DMS to treat vitiligo. The cubosomes were prepared via top-down technique using different concentrations of glyceryl monooleate (GMO) (lipid phase), poloxamer 407 (P 407) (non-ionic surfactant), oleic acid (fatty acid) and water (aqueous phase). The formulated cubosomal formulations were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), zeta size analyzer for their surface morphology, particle size and zeta potential. Further, they were evaluated for % entrapment efficiency and in-vitro drug release. The optimized F-12 formulation exhibited a particle size of 250.40 nm and a zeta potential of −36.10 ± 2.56 mV. The in-vitro drug release of 88.12% was achieved at 12th h. The F-12 formulation was incorporated into 1% carbopol 940 to form cubogel (CG). The F-12 loaded CG was evaluated for physical characteristics, pH, drug content, viscosity, spreadability, and in-vitro drug release studies. All the evaluation parameters for the CG formulation were said to be within the standard limits. The in-vitro drug release for DMS loaded CG was found to be 83.58% at end of 12 h, thus indicating its potential as a better sustained drug delivery system for vitiligo.

The technique of foam fractionation has already been well received in the field of isolation of proteins using a suitable surfactant. The lower operating cost also makes this technique eligible for treating various wastewater streams. In view of this, methylene blue dye was separated and recovered from its solution by employing sodium dodecyl benzene sulfonate as a collector in a foam fractionator operated in a semi-continuous manner. The separation characteristics were accessed at varying aeration rates, dye concentrations and liquid loadings. Prior to this, the values of other operating variables such as operation time, concentration of the surfactant and solution initial pH were fixed. Subsequently, in order to attain maximum removal fraction and enrichment ratio, individually, Taguchi methodology yielded the optimum values of operating variables, which are crucial for the optimal operation of any foam fractionator. The results revealed implementation of foam fractionation technique in isolating methylene blue dye from dyeing wastewater to be fairly good.

Hypothesis Ferrihydrite (Fh) nanoparticles are receiving considerable scientific interest due to their large reactive surface areas, crystalline structures, and nanoparticle morphology. They are of great importance in biogeochemical processes and have the ability to sequester hazardous and toxic substances. Here, the working hypothesis was to entrap fractal-like Fh nanoparticles, with a radius of gyration of 6.2 nm and a primary building block of polydisperse spheres with a radius of 0.8 nm, in a shear-induced multilamellar vesicle (MLV) state using a 40 wt.% polyethylene glycol dodecyl ether surfactant. Experiments Small- and Wide- Angle X-ray scattering revealed the equilibrium state of the non-ionic planar lamellar phase, the Fh dispersion, and their mixture. The MLV state was induced by using a shear flow in a Taylor-Couette geometry of a rheometer. Findings The nonionic surfactant initially exhibited a lamellar gel phase with two distinct d-spacings of 11.0 and 9.7 nm, which collapsed into the MLV state under shear flow. The Fh nanoparticles induced bilayer attraction by suppressing lamellar layer undulations, decreasing the d-spacing. These results are helpful in the understanding of the relationship between nanoparticle size and nanoparticle-bilayers interactions and provides insight on Fh encapsulations in a kinetically stable MLVs state.

Hydroxyapatite (HAP) [Ca10(PO4)6(OH)2] is an excellent bio-ceramic material for artificial bone substitution in biomedical field owing to its chemical and crystallographic similarities of natural bone and teeth. In this research work, we have attempted the synthesis of hydroxyapatite powders with controllable size in the presence of three different surfactants sodium dodecyl sulphate (SDS) which is an anionic surfactant, cetyl trimethylammonium bromide (CTAB) as a cationic surfactant and poly vinyl alcohol (PVA) as a non-ionic surfactant. The as-synthesised HAP powders were characterised by analytical techniques such as FTIR, XRD and SEM. The results have shown that the non-ionic surfactant is a better choice for developing this bio-nanomaterial due to its good dispersing power than CTAB and SDS. The results have also indicated that, nano-hydroxyapatite particle has a uniform morphology, well crystallinity and the particle size was controlled with the use of non-ionic surfactant. The crystallite size was calculated using Scherer’s formula. Experiments were performed under controlled environment by maintaining the required pH, concentration and temperature. The biomedical application studies of the as-synthesised material are yet to be studied.

Cadmium oxide is one of the captivating nanomaterials possess semiconductor and piezoelectric characteristics which has diverse applications. Most of the nanoparticles synthesis methods are expensive and complex and also difficulty in controlling their shapes and uniformity. The present research work focus on synthesis and characterization of pure and surfactants (SDS) assisted cadmium oxide nanoparticles through co-precipitation method. SDS was used as a stabilizer below its critical micelle concentration. The synthesized nanomaterials were characterized using XRD, SEM, FTIR and photoluminescence spectroscopy. XRD pattern reveal the presence of well indexed CdO nanoparticles with cubic structure. Pure cadmium oxide nanoparticles exhibited ixora flower with needle structure and SDS assisted nanoparticles displayed rosette shaped structure. Optical properties of prepared samples were analyzed using UV and Photoluminescence spectra and the energy gap for pure and surfactants (SDS) assisted cadmium oxide nanoparticles were found to be 3.74 and 3.52 eV. FTIR spectra showed the presence of functional groups in the pure and surfactants (SDS) assisted cadmium oxide nanoparticles. Furthermore, the authors examined the influence of surfactants on size and morphology of nanoparticles.

Electrocoalescence is widely used to separate water from crude oil in petroleum industry. However, the electric field often forces water droplets distributed in chain shape, thus improving the danger of short circuit by bridging electrodes. To understand the mechanism of water chain phenomenon, an in-situ observation experiment were conducted to investigate the effect of voltage, frequency, water content and surfactant concentration. The results showed that the water chain length and growth rate of droplet diameter varied synchronously with the voltage and frequency. Additionally, the water chain length and growth rate of droplet diameter increased firstly and then decreased with the initial water content. The initial droplet diameter decreased with the surfactant concentration, which inhibit formation of water chains and coalescence. As the surfactant concentration reached a critical value, the initial droplet diameter remained constant, while the inhabitation of micelle for the coalescence strengthened with the surfactant concentration. These conclusions are helpful to understand the mechanism of formation of water chains.

Due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR) techniques have been considered by a large number of scientists. In this study, the surfactant-polymer injection(SP) was firstly tested in a designed-micro model by using sand, gasoil and a crude oil to evaluate its performances, and then it was applied in the Y- field by involving a Single Well Chemical Tracer Test (SWCTT) to determinate the residual oil saturation (Sor) and the ability of the field to EOR. The results indicate that SP-flooding leads to the recovery of 95% of residual oil contained in 5 m radius.

In this work, graphene is initially dispersed in surfactant sodium dodecyl sulfonate (SDBS) in an aqueous solution. Sonication followed by centrifugation is the process used to disperse the graphene in an aqueous solution with the aid of SDBS. The concentration of graphene is determined using UV–Vis-NIR spectroscopy. A higher concentration of graphene is achieved just above the critical micelle concentration of SDBS in an aqueous solution. To further improve the concentration of graphene in an aqueous solution of SDBS, a second surfactant polyvinyl pyrrolidone (PVP) is used. The mixed surfactant strategy has increased the concentration of graphene in an aqueous solution by ∼ 400% as compared to SDBS aided dispersion of graphene in an aqueous solution. Atomic force microscopy (AFM) observations reveal the few-layer dispersion of graphene in an aqueous solution with the aid of mixed surfactants; while SDBS assisted dispersion of graphene in an aqueous solution shows the few layers to 10 s of layers of graphene nanosheets.

Biologically synthesized surfactant are commercially used in various biotechnology sectors as cosmetic, cleaning, and agriculture products. In this study, Bacillus paramycoides was isolated as new bacterial strain from plastic disposal site of Banasthali Vidyapith (Rajasthan) for producing lipopeptide biosurfactant. Surface tension, emulsification index, oil-displacement are some primary screening methods done to validate the production of biosurfactant. The emulsification analysis elucidated at 62.50% and reduction of surface tension noticed at 33.10 mN/m. The nano-encapsulation of this biosurfactant onto silver nanoparticles had efficiently improved its ability for biodegradation of polyethylene. UV sterilized polyethylene films were treated with biosurfactant mediated silver nanoparticles and its maximum degradation was observed within 70 days. The synthesized silver nanoparticles were characterized by UV spectrum, zeta size potential, scanning electron microscope analysis. The total weight loss of low-density polyethylene (cling films) and high-density polyethylene (grocery bags) was observed 36.30% and 31.11%, respectively after treatment with silver nanoparticles for these lipopeptide biosurfactant. The higher degree of biodegradation rate of LDPE and HDPE polyethylene after treating with silver nano-biosurfactant might be due to their high degree of biocompatibility and stability. These nano-biosurfactant could be effectively used for biodegradation of plastic pollutant at large scale.

Background Increasing the molecular weight and addition contents of pore forming agents have been acknowledged as effective ways to improve permeability in membranes fabricated via nonsolvent induced phase separation (NIPS). However, these techniques negatively impact the overall pore size and mechanical strength of the resulting membranes. Facilitating the mutual diffusion of water (coagulant) and dope solutions (MDWDS) during NIPS is the key to obtain porous membranes with high permeability. Methods Here, surfactants assisted nonsolvent induced phase separation (SA-NIPS) is proposed and used to regulate MDWDS during NIPS. Significant findings Surfactants facilitate MDWDS. More importantly, MDWDS can be advanced by elevating the hydrophilic interaction force of water and the hydrophilic heads of surfactants while keeping the hydrophobic interaction in the dope solutions constant. SA-NIPS improves the surface porosity of polysulfone (PSF) membranes, thus increasing the permeability of PSF membranes (up to 2.9 times). Moreover, the tensile strength and pore sizes of PSF membranes are maintained. This research may provide a feasible insight into regulation of the morphology and permeability of NIPS-prepared membranes without compromising their pore size and tensile strength.

Background Previous research shows that a lung ultrasound score (LUS) can anticipate CPAP failure in neonatal respiratory distress syndrome. Research Question Can LUS also predict the need for surfactant replacement? Study Design and Methods Multicenter, pragmatic study of preterm neonates who underwent lung ultrasound at birth and those given surfactant by masked physicians, who also were scanned within 24 h from administration. Clinical data and respiratory support variables were recorded. Accuracy of LUS, oxygen saturation to F io 2 ratio, F io 2, and Silverman score for surfactant administration were evaluated using receiver operating characteristic curves. The simultaneous prognostic values of LUS and oxygen saturation to F io 2 ratio for surfactant administration, adjusting for gestational age (GA), were analyzed through a logistic regression model. Results Two hundred forty infants were enrolled. One hundred eight received at least one dose of surfactant. LUS predicted the first surfactant administration with an area under the receiver operating characteristic curve (AUC) of 0.86 (95% CI, 0.81-0.91), cut off of 9, sensitivity of 0.79 (95% CI, 0.70-0.86), specificity of 0.83 (95% CI, 0.76-0.89), positive predictive value of 0.79 (95% CI, 0.71-0.87), negative predictive value of 0.82 (95% CI, 0.75-0.89), positive likelihood ratio of 4.65 (95% CI, 3.14-6.89), and negative likelihood ratio of 0.26 (95% CI, 0.18-0.37). No significant difference was shown among different GA groups: 25 to 27 weeks’ GA (AUC, 0.91; 95% CI, 0.84-0.99), 28 to 30 weeks’ GA (AUC, 0.81; 95% CI, 0.72-0.91), and 31 to 33 weeks’ GA (AUC, 0.88; 95% CI, 0.79-0.95), respectively. LUS declined significantly within 24 h in infants receiving one surfactant dose. When comparing F io 2, oxygen saturation to F io 2 ratio, LUS, and Silverman scores as criteria for surfactant administration, only the latter showed a significantly poorer performance. The combination of oxygen saturation to F io 2 ratio and LUS showed the highest predictive power, with an AUC of 0.93 (95% CI, 0.89-0.97), regardless of the GA interval. Interpretation LUS is a reliable criterion to administer the first surfactant dose regardless of GA. Its association with oxygen saturation to F io 2 ratio significantly improves the prediction power for surfactant need.

Bone defects accompanied by infection or inflammation can significantly delay the healing process. To simultaneously achieve controlled release of local antibiotics for infection control and bone healing, bone-implantable delivery systems have been considered as a promising strategy. This study aims to improve drug loading capacity of bone-implantable delivery systems by introducing hollow structure mesoporous bioactive glass nanospheres (HMBGs) through a sol–gel process. Particularly, such core–shell bimodal-porous structured nanoparticles were prepared through a sacrificing template using cetyltrimethylammonium bromide (CTAB) as surfactant. It was found that varying the amount of CTAB during the synthesis process is a simple and effective approach for tuning the particle size, morphology, and structure of HMBGs. For in vitro drug release, HMBGs could sustain storage and release of vancomycin hydrochloride (VAN) via diffusion-controlled mechanism, thereby inhibiting the bacteria growth in the subsequent bacterial study. Moreover, HMBGs incorporated with VAN provided a biomimetic microenvironment favored by cell adhesion and proliferation. These findings support the compatibility of HMBG nanoparticles with antibiotics and their potential application in the treatment of infectious bone defects.