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In this investigation, cationic surfactant cetyltrimethylammonium chloride (CTAC)-modified nanofiltration (NF) membranes were investigated for sodium diclofenac (DFS) removal from aqueous solution. The effects of CTAC incorporation on the membranes at various concentrations below, at, and above the critical micelle concentration (CMC) were evaluated in terms of membrane permeability, morphology, antifouling properties, and performance. CTAC-modified membranes exhibited enhanced structural properties, increased hydrophilicity, higher pure water flux (461 L/m2 h), and superior antifouling resistance (98% BSA protein rejection, 82.1% FRR). Consequently, the optimized 0.1 wt% CTAC-modified membrane at CMC concentration exhibited superior rejection efficiency compared to the unmodified membrane, increasing from 35.62 to 65.17% for sodium diclofenac removal. The findings of this study demonstrate that the optimized membrane exhibited the best performance in all parameters, making it suitable for practical application in the removal process of sodium diclofenac.Highlights: Cationic surfactant were used to modify the NF membrane in three concentrations of CMC, above CMC and below CMC. Reactive cationic surfactant was used to improve the anti-fouling and pure water flux performance of membranes. Antifouling performance and hydrophilicity of membranes were enhanced. Drug removal according to membrane surface charge by Donnan's exclusion mechanism. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach for transforming the cationic surfactant, cetyltrimethylammonium bromide (CTAB), into fluorescent carbon dots (CDs) capable of detecting cadmium ions at ultralow concentrations. The current approach involves preparing CDs through hydrothermal process at various pH levels. The CDs synthesized using pH 10, CTAB-CDs-10, exhibited the highest fluorescence quantum yield (QY), 14.22%. UV-Vis spectroscopy helped identify specific peaks between 210 and 300 nm, corresponding to the π–π* transitions of the aromatic C=C bonds. Transmission electron microscopic (TEM) analysis verified the uniform spherical morphology with a particle size < 2.45 nm. FT-IR analysis confirmed the presence of C=C stretching vibrations. The Box–Behnken (BB) Design was used to reconnoiter the influence of three variables on the response parameter: the F0/F ratio. The best performance could be achieved at a pH of 9, after only 300 s, and a temperature of 50 °C. The developed CTAB-CDs-based nanoprobe showed an ON–OFF behavior when came in contact with cadmium (II) and demonstrated high sensitivity with a limit of detection as low as 0.06 µM (0.007 ppm) over a wide linear range of 2–103 µM. Validation tests confirmed the applicability of the CTAB-CDs-based nanoprobe for detecting cadmium (II) in tap and drinking waters with high accuracy and precision. [ABSTRACT FROM AUTHOR]

New hexadecylpiperidinium surfactants, containing one or two butylcarbamate fragments, were synthesized. The antimicrobial activity, toxicity, aggregation behavior in aqueous solutions, and solubilization capacity of these surfactants towards the hydrophobic drug ibuprofen were characterized. These surfactants demonstrated a high antimicrobial activity against a wide range of pathogenic bacteria, including both Gram-positive and Gram-negative strains, as well as fungi. By forming mixed-micellar compositions of the cationic surfactant 1-CB(Bu)-P-16 and the nonionic surfactant Brij®35, highly functional and low-toxic formulations were obtained. Furthermore, the transition from mixed micelles to niosomes was accomplished, enhancing their potential as drug delivery systems. Niosomes were found to be less toxic compared to mixed micelles, while also increasing the solubility of ibuprofen in water. The modification of niosomes with cationic surfactants made it possible to increase the stability of the system and improve the solubility of the drug. The data obtained indicate that these new carbamate-containing hexadecylpiperidinium surfactants have significant potential in biomedical applications, particularly in the formulation of advanced drug delivery systems. [ABSTRACT FROM AUTHOR]

The network formed by wax precipitation at low temperature and colloid asphaltene at high temperature leads to poor fluidity of heavy oil, and the gelling characteristics of crude oil lead to pipeline blockage, which affects the exploitation, transportation and refining of crude oil. This work prepares a series of cationic surfactant-modified nano hydrotalcite (CSNH) to weaken the network structure and enhance the fluidity of the crude oil by the interaction of organic and inorganic functional groups on the CSNH surface and the components of the crude oil. The results show that CSNHs can all reduce the viscosity of crude oil from different oilfields, among which BTNH can reduce the viscosity of Yanglou (YL) crude oil by 98.8% (31 °C) and depress the pour point by 16.0 °C at most. In the investigation of the universality of crude oil, the modified hydrotalcite was applied to the mixed crude oil (CQH) of Changqing Oilfield, the crude oil (J76) of Jidong Oilfield, the high pour point oil (GN) of Huabei Oilfield, and the crude oil (HQ) of Tuha Oilfield. The viscosity reduction rates were 53.2%, 86.2%, 42.7%, and 63.8%, respectively. The characterization of this nano material confirms the modification of quaternary ammonium cationic surfactant on the surface, resulting in a smaller particle size, and the nano particles are stable under conventional conditions. The mechanism of viscosity and pour point reduction in crude oil by BTNH was discussed by DSC and optical microscopy analysis. The OH- and long-chain alkyl groups on the BTNH surface may interact with the resins, asphaltene and wax through hydrogen bonding and co-crystal, weakening or dispersing their aggregates, thereby improving the fluidity of crude oil. Finally, a cost evaluation was conducted on BTNH, providing useful support for subsequent promotion and application. [ABSTRACT FROM AUTHOR]

Polydiacetylenes (PDAs) have extensively received attention as colorimetric sensors because of their stimulus-responsive properties. This contribution presents a simple technique to modify polydiacetylene/zinc (II) ion/zinc oxide (PDA/Zn2+/ZnO) nanocomposites for colorimetric detection of an anionic surfactant. Incorporation of cetyltrimethylammonium bromide (CTAB) into the nanocomposite structure is achieved through a simple mixing process in an aqueous medium. Interestingly, the resultant PDA/Zn2+/ZnO-CTAB sensors exhibit a unique yellow-to-red color change in response to the anionic surfactant, sodium dodecyl sulfate (SDS). Furthermore, the colorimetric detection of SDS at different concentrations can be achieved by varying the added CTAB concentrations. The detectable concentration range of SDS in this study extends from 0.3 to 7 mM. Our study offers a simple and low-cost method to fabricate colorimetric sensors for anionic surfactant detection using PDA materials.

Abstract Organoclays have been used as efficient adsorbents for pharmaceutical pollutants present in waters. Carbamazepine (CBZ) is one of the drugs most frequently found in water bodies. In this study, four organoclays were prepared by modifying bentonite with the cationic surfactants hexadecyltrimethylammonium bromide (HDTMA) and octadecyltrimethylammonium bromide. The synthesized materials were characterized by XRD, CHN, FTIR, TG, BET and SEM analyses, confirming organophilization. The surfactants were interspersed in different arrangements in the interlayer space. CBZ sorption was investigated through batch equilibrium experiments, under variation of the pH, contact time, dosage of adsorbent, and initial drug concentration. Changes in pH showed no adsorption influence. CBZ sorption by the organoclays followed a pseudo-second-order kinetics. The best sorption performance was obtained for the BCN1-HDTMA100 clay, with a capacity of 34.34 ± 1.41 mg g−1, about ten times greater than the unmodified bentonite under the same conditions. This may be attributed to the higher surfactant content. The adsorption isotherm at 25 ºC showed linear behavior. Toxicity tests of the organoclays and corresponding medium in presence of CBZ were carried out. This is a novelty report. Most of the organoclays had no toxicity against Artemia salina. The toxicity of the medium after adsorptive treatment was eliminated. Organoclay-CBZ hybrids were also characterized after adsorption. FTIR and TG analyzes confirmed the incorporation of the drug. Hydrophobic interaction was the dominant contribution evaluated to the adsorption of CBZ. The results demonstrated that organoclays can be a promising alternative adsorbent for the removal of pharmaceutical pollutants in water remediation.

The study explored the capacity of modified pinewood dust (S-dust) for adsorbing acid blue 193 dye. The novel adsorbent was prepared via the insitu intercalation of quaternized ammonium copolymer (cationic surfactant) onto pinewood dust. The synthesized biosorbent was characterized using the Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersion X-ray (EDX) and Brunauer–Emmett–Teller (BET) surface area equipment. To establish the variable effects on the dye uptake, the ranges of solution pH, initial adsorbate concentration, contact time and adsorbent dosage were varied. The maximum monolayer adsorption capacity of 117.58 mg/g was recorded at pH 4.0, 0.1 g/L adsorbent dose and 2 h sorption duration. The process kinetics and isotherm modelling fitted best to the pseudo-first-order and Freundlich models, respectively. From the mechanistic/diffusion studies, intraparticle and pore diffusion mechanisms were respectively postulated at low and high initial adsorbate concentrations. Also, the occurrence of a nonspontaneous endothermic uptake process was inferred from the thermodynamics evaluations. Therefore, the effective acid blue 193 dye uptake onto novel S-dust was confirmed in this study.

Double epoxy group double quaternary ammonium salts (DEpDQAS) were synthesized by epichlorohydrin (ECH) reacting with N,N,N'N'-tetramethylethylenediamine (TMEDA) and N,N,N'N'-tetramethyl-1,6-hexanediamine (TMHDA), respectively. The results of orthogonal experiments showed that temperature and time were the key factors influencing on epoxy value and quaternarization ratio respectively. The optimal condition for higher epoxy value was the reaction temperature at 15 °C and methanol as solvent. The reaction kinetic process was determined by conductivity, which showed that the reaction had a short induction period and appeared discontinuity in progress that the reaction rate of the first stage was almost constant, while the reaction rate of the second stage decreased gradually. The product was characterized by infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR). The results of surface tension testing showed that DEpDQAS-6 with longer spacer chain had better surface activity and lowered the solution surface tension to 26 mN·m−1 at 25 °C and CMC 0.27 mol·L−1. The thermodynamic parameters of micellization were obtained basing on charged pseudo-phase model. The studies of cytotoxicity in vitro and antibacterial activity showed that DEpDQAS was biocompatible and its antibacterial activity was more effective against Escherichia coli than against Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

In search of efficient electrode material with good redox sites, better wettability, high-rate transfer and rate capability, here we adapted a linear template method like by adding CTAB as surfactant. Transition metal tungstate is a promising electrode material for supercapacitor devices because of its exceptional electrical conductivity and electrochemical property. This work deals with the effect of surfactant on their structure, morphology and electrochemical properties of the material, elaborately. Through the physiochemical characterization, it is observed that morphology of NiWO4 is stable and significantly altered by different ratio of templating agent. NiWO4 with 0.03 M of CTAB as surfactant delivered a specific capacitance of about 958 F/g at a current density of 2 A/g, respectively with low-charge transfer resistance of 5.6 Ω. [ABSTRACT FROM AUTHOR]

Organoclays have been used as efficient adsorbents for pharmaceutical pollutants present in waters. Carbamazepine (CBZ) is one of the drugs most frequently found in water bodies. In this study, four organoclays were prepared by modifying bentonite with the cationic surfactants hexadecyltrimethylammonium bromide (HDTMA) and octadecyltrimethylammonium bromide. The synthesized materials were characterized by XRD, CHN, FTIR, TG, BET and SEM analyses, confirming organophilization. The surfactants were interspersed in different arrangements in the interlayer space. CBZ sorption was investigated through batch equilibrium experiments, under variation of the pH, contact time, dosage of adsorbent, and initial drug concentration. Changes in pH showed no adsorption influence. CBZ sorption by the organoclays followed a pseudo-second-order kinetics. The best sorption performance was obtained for the BCN1-HDTMA100 clay, with a capacity of 34.34 ± 1.41 mg g−1, about ten times greater than the unmodified bentonite under the same conditions. This may be attributed to the higher surfactant content. The adsorption isotherm at 25 ºC showed linear behavior. Toxicity tests of the organoclays and corresponding medium in presence of CBZ were carried out. This is a novelty report. Most of the organoclays had no toxicity against Artemia salina. The toxicity of the medium after adsorptive treatment was eliminated. Organoclay-CBZ hybrids were also characterized after adsorption. FTIR and TG analyzes confirmed the incorporation of the drug. Hydrophobic interaction was the dominant contribution evaluated to the adsorption of CBZ. The results demonstrated that organoclays can be a promising alternative adsorbent for the removal of pharmaceutical pollutants in water remediation. [ABSTRACT FROM AUTHOR]

Cationic surfactant (CS) is one of the alarming emerging contaminants often found in municipal and industrial wastewater. Various research articles have already reported about the toxicity of CS. In the current research work, sustainable and green alginate (Ag) and alginate composite beads with xanthan gum (AgX) are explored for the adsorptive elimination of model CS, cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB), from wastewater. The composite (AgX) beads showed relatively better performance than Ag beads in terms of mechanical strength and equilibrium time. Studies on FTIR spectra, SEM analysis, size distribution, pHzpc measurement, and elemental analyses were conducted in order to characterize the adsorbent and to get an insight into the adsorption phenomenon. At the end of 8 days' equilibrium time, the maximum adsorptive retention capacity of the AgX beads was obtained as ~ 310 mg/g with an initial CPC concentration of 600 mg/L, using an adsorbent dose of 1.5 g/L. A layered isotherm with varying slopes was obtained, indicating different stages of CPC adsorption. CPC uptake by hydrogel beads was associated with significant shrinkage of the beads. Removal of CPC from real wastewater was possible with good efficiency. The effect of pH and interfering ions on CPC removal was examined. The results showed that the pH range of 5.5–6 was the optimum, and there was no interference from Co(II), Ni(II), and Mg(II) ions. The results showed good reproducibility with a relative standard deviation (RSD) < ± 10%. [ABSTRACT FROM AUTHOR]

Highlights Cetyltrimethylammonium cations can shield the repelling force on anions to attract more anions into electric double layer region during lithium plating process, facilitating the formation of inorganic-rich solid-state electrolyte interphase (SEI). An inorganic-rich (N/F-containing species) structure of SEI can be evidenced by the in-depth analysis. The cycling lifetime of Li||Li symmetric cell in the designed electrolyte can be extended from 500 to 1300 h. Moreover, full cells with a high cathode mass loading of >10 mg cm-2 can be stably cycled over 180 cycles.

This study presents an innovative approach to eliminating the pharmaceutical pollutant diclofenac sodium (DFS) by combining nanofiltration membrane technology with an electrochemical oxidation process. The nanofiltration membrane was prepared by phase inversion, and modified with cetyltrimethylammonium chloride (CTAC) to improve surface properties and pore structure. The concentrate from the nanofiltration treatment has been utilized as the input feed for the electrochemical section, employing Ti/SnO2-α-Fe2O3 electrodes. The PES/CTAC membrane exhibits a more uniform and stable pore structure, leading to increased permeability and antifouling properties. Additionally, the inclusion of CTAC through the surface adsorption mechanism improved the DFS rejection performance, achieving a maximum rejection rate of 65.2% for the membrane with a composition of 0.1 wt% CTAC. The obtained results show that the titanium electrode coated with SnO2 and α-Fe2O3 nanoparticles removed the DFS pollutant by 56%. In total, both membrane and electrochemical process removed 80.5% of the primary Diclofenac pollutant. According to the low energy consumption of this process (EEC=0.014144 US$/m3) and other results, the combination of the PES/CTAC membrane and Ti/SnO2-α-Fe2O3 electrode is an efficient method for diclofenac sodium pollutant removal.

New hexadecylpiperidinium surfactants, containing one or two butylcarbamate fragments, were synthesized. The antimicrobial activity, toxicity, aggregation behavior in aqueous solutions, and solubilization capacity of these surfactants towards the hydrophobic drug ibuprofen were characterized. These surfactants demonstrated a high antimicrobial activity against a wide range of pathogenic bacteria, including both Gram-positive and Gram-negative strains, as well as fungi. By forming mixed-micellar compositions of the cationic surfactant 1-CB(Bu)-P-16 and the nonionic surfactant Brij®35, highly functional and low-toxic formulations were obtained. Furthermore, the transition from mixed micelles to niosomes was accomplished, enhancing their potential as drug delivery systems. Niosomes were found to be less toxic compared to mixed micelles, while also increasing the solubility of ibuprofen in water. The modification of niosomes with cationic surfactants made it possible to increase the stability of the system and improve the solubility of the drug. The data obtained indicate that these new carbamate-containing hexadecylpiperidinium surfactants have significant potential in biomedical applications, particularly in the formulation of advanced drug delivery systems.

AbstractTetraalkylammonium-based quaternary ammonium ([R4N+][DHP−]; R = Ethyl, Propyl, Butyl) salts were synthesized and subjected to in-depth analysis using NMR, FTIR and TG analysis. Subsequent investigations involved examining their impact on the aggregation patterns of the cationic surfactant Cetyltrimethylammonium bromide (CTAB) through the use of conductometry, fluorescence measurements, and UV-Visible spectroscopy. To gain a deeper understanding of the colloidal behavior of CTAB, the critical micelle concentration (cmc) of the surfactant was determined, both in the absence and presence of the quaternary ammonium salts. The observed variations in cmc values were attributed to structural changes within the surfactant-water mixture, made by the presence of these additives. In addition, the investigations include thermodynamic analysis, with a focus on studying the dependence of the cmc on temperature. The resultant thermodynamic parameters were utilized to elucidate the contributions of [R4N+][DHP−], to the electrostatic and hydrophobic interactions involved in the formation of surfactant micellar aggregates. Furthermore, the study assessed the impact of [R4N+][DHP−], on the surfactant’s antibacterial activity by quantifying the zone of inhibition, against both gram-positive and gram-negative bacterial species. [ABSTRACT FROM AUTHOR]

This study presents an innovative approach to eliminating the pharmaceutical pollutant diclofenac sodium (DFS) by combining nanofiltration membrane technology with an electrochemical oxidation process. The nanofiltration membrane was prepared by phase inversion, and modified with cetyltrimethylammonium chloride (CTAC) to improve surface properties and pore structure. The concentrate from the nanofiltration treatment has been utilized as the input feed for the electrochemical section, employing Ti/SnO2-α-Fe2O3 electrodes. The PES/CTAC membrane exhibits a more uniform and stable pore structure, leading to increased permeability and antifouling properties. Additionally, the inclusion of CTAC through the surface adsorption mechanism improved the DFS rejection performance, achieving a maximum rejection rate of 65.2% for the membrane with a composition of 0.1 wt% CTAC. The obtained results show that the titanium electrode coated with SnO2 and α-Fe2O3 nanoparticles removed the DFS pollutant by 56%. In total, both membrane and electrochemical process removed 80.5% of the primary Diclofenac pollutant. According to the low energy consumption of this process (EEC=0.014144 US$/m³) and other results, the combination of the PES/CTAC membrane and Ti/SnO2-α-Fe2O3 electrode is an efficient method for diclofenac sodium pollutant removal. [ABSTRACT FROM AUTHOR]

[Display omitted] Saponins are highly surface active glycosides, and are extensively used to stabilise emulsions and foams in beverages, foods, and cosmetics. Derived from a variety of plant species these naturally occurring biosurfactants have wider potential for inclusion in many low carbon and or sustainably sourced products. Although their adsorption at the air-solution and liquid–liquid interfaces has been extensively studied, the nature of their adsorption at solid surfaces is much less clear. The aim of this study was to establish the criteria for and nature of the adsorption of saponins at both hydrophilic and hydrophobic solid surfaces. Adsorption at the hydrophilic and hydrophobic solid surfaces was investigated using neutron reflectivity. Measurements were made for the saponins escin, quillaja and glycyrrhizic acid. At the hydrophilic surface measurements were also made for escin / cetyltrimethyl ammonium bromide, C 16 TAB, mixtures; using deuterium labelling to determine the surface structure and composition. At a range of solution concentrations, from below to well in excess of the critical micelle concentration, cmc, there was no saponin adsorption evident at either the hydrophilic or hydrophobic surface. This implies an inherent incompatibility between the surface OH– groups at the hydrophilic surface and the saponin sugar groups, and a reluctance for the hydrophobic triterpenoid group of the saponin to interact with the octadecyltrichlorosilane, OTS, hydrophobic solid surface. Above a critical composition or concentration escin / C 16 TAB mixtures adsorb at the hydrophilic solid surface; with a surface composition which is dominated by the escin, and a structure which reflects the disparity in the molecular arrangement of the two surfactant components. The results provide an important insight into how cooperative adsorption can be utilised to promote adsorption of saponins at the solid- solution interface. [ABSTRACT FROM AUTHOR]

The effects of benzalkonium chloride (BC) as a cationic surfactant on the mechanical, water barrier, microstructural, and thermal properties of adlay millet starch (AS) films were investigated in this study. With increasing BC concentration, tensile strength (from 5.93 to 6.15 MPa) and elongation at break (from 41.39 to 45.48%) of AS-BC films significantly increased, whereas their moisture content, water solubility, and water vapor permeability were reduced, indicating water resistance improvement. Fourier transform infrared spectroscopy and scanning electron microscopy analysis showed that BC at concentrations below 1% did not cause noticeable changes in the microstructure of AS-BC films. In addition, the thermal stability of AS-BC films was not affected by BC, indicating good miscibility between AS and BC. Therefore, BC could improve the physicochemical properties of starch films, and AS-BC films developed in this study can be applied as novel biodegradable packaging materials in the food packaging industry. [ABSTRACT FROM AUTHOR]

Wetting the surface area of an electrode material as completely as possible is desirable to achieve optimum specific capacity of an electrode material. Keeping this surface area utilized even at high current densities and even when inside pores is required for high capacitance retention. The addition of surfactants at very small concentrations to aqueous supercapacitor electrolyte solutions has been suggested as a way to improve performance in terms of capacitance, capacitance retention at increased current density and stability. Effects are pronounced with carbon materials used in electrochemical double-layer capacitors; they are also observed with redox materials. The causes of the observed improvements and mode of operation of the added surfactants seem to need further investigation; they are inconclusive beyond the obvious statement of increased wetting. Reported examples and the current state of understanding are reviewed. [ABSTRACT FROM AUTHOR]

The network formed by wax precipitation at low temperature and colloid asphaltene at high temperature leads to poor fluidity of heavy oil, and the gelling characteristics of crude oil lead to pipeline blockage, which affects the exploitation, transportation and refining of crude oil. This work prepares a series of cationic surfactant-modified nano hydrotalcite (CSNH) to weaken the network structure and enhance the fluidity of the crude oil by the interaction of organic and inorganic functional groups on the CSNH surface and the components of the crude oil. The results show that CSNHs can all reduce the viscosity of crude oil from different oilfields, among which BTNH can reduce the viscosity of Yanglou (YL) crude oil by 98.8% (31 °C) and depress the pour point by 16.0 °C at most. In the investigation of the universality of crude oil, the modified hydrotalcite was applied to the mixed crude oil (CQH) of Changqing Oilfield, the crude oil (J76) of Jidong Oilfield, the high pour point oil (GN) of Huabei Oilfield, and the crude oil (HQ) of Tuha Oilfield. The viscosity reduction rates were 53.2%, 86.2%, 42.7%, and 63.8%, respectively. The characterization of this nano material confirms the modification of quaternary ammonium cationic surfactant on the surface, resulting in a smaller particle size, and the nano particles are stable under conventional conditions. The mechanism of viscosity and pour point reduction in crude oil by BTNH was discussed by DSC and optical microscopy analysis. The OH- and long-chain alkyl groups on the BTNH surface may interact with the resins, asphaltene and wax through hydrogen bonding and co-crystal, weakening or dispersing their aggregates, thereby improving the fluidity of crude oil. Finally, a cost evaluation was conducted on BTNH, providing useful support for subsequent promotion and application.

A potentiometric poly (vinyl chloride) (PVC) membrane cationic surfactant‐selective sensor based on a dodecyltrimethylammonium‐phosphotungstate ion pair as an electroactive material was suggested for the determination of dodecyltrimethylammonium bromide. Membrane optimization studies revealed that the PVC membrane in the composition of 0.5 % dodecyltrimethylammonium‐phosphotungstate ion pair, 69.5 % o‐nitrophenyloctylether and 30.0 % PVC displayed the best potentiometric performance properties. The sensor exhibited a linear response to dodecyltrimethylammonium ions in the concentration range of 1.0×10−6–1.0×10−2 mol L−1 with a detection limit and sensitivity of 5.0×10−7 mol L−1 and 56.6 mV/decade, respectively. The response of the sensor to dodecyltrimethylammonium cation was quite stable, sensitive, selective and rapid (<10 s). The life span of the sensor was found to be about 3 months. The analytical applications of the sensor were successfully carried out with the developed sensor as an indicator electrode for the determination of the end‐point of dodecyltrimethylammonium ions titration and dodecyltrimethylammonium contents of synthetic water samples. [ABSTRACT FROM AUTHOR]

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The clinoptilolite natural zeolites (NZs) posses low herbicide adsorption capacity demanding acid-, alkali-, or salt chemical modifications that enhance its adsorption. However, this may affect the material structure and charge distribution. Alternatively, zeolites may be synthesized at a high cost and time-consuming process. Consequently, new methods, such as the hydrothermal method, for NZ modification needs to be studied. In this sense, a novel surface-modified zeolite (SMZ), using hexadecyltrimethylammonium bromide (CTAB), in acid media was produced by the hydrothermal method and applied for the adsorption of Atrazine (ATZ), Diuron (DIU) and 2,4-D. Commercial NZ and SMZ were characterized by SEM, XRD, TGA, FT-IR, AA spectroscopy, pHPZC, Zeta potential and N2-physisorption. The SMZ chosen for the adsorption experiments was the one with the highest modification yield and adsorption capacity obtained from a complete design of experiments (CTAB=0.74 ; D=12 Mesh; HCl=0.1 M; t=6 h and T=205 ºC). The adsorption experiments revealed that the SMZ adsorption capacity for the herbicide 2,4-D (qmax=9.02 mg/g) was greater than that obtained for ATZ (qmax=2.11 mg/g) and DIU (qmax=1.85 mg/g), which was explained by the presence of the hydroxyl group and by geometric characteristics of the 2,4-D. Adsorption models' fitting showed that the adsorption of 2,4-D onto SMZ were best described by pseudo-second order kinetic (k2=0.005-0.006 g/mg.min; qe,exp=7.122-8.614 mg/g) and Langmuir isothermal model (KL=0.283-0.499 L/mg; qm=7.167-7.995 mg/g). These results indicate that the hydrothermal method is a viable alternative to enable the use of NZs for the adsorption of emerging contaminants from wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A flocculation and in-situ solidification strategy for soluble polysulfides is proposed by using antistatic agent SN. • SN shows strong charge and bonding interactions with soluble polysulfides to inhibit the shuttle effect. • Multifunctionalities of catalytic effect and enhanced lithium-anode protection are demonstrated. • With 0.1 wt% SN addition, an ultra-low capacity decay rate of 0.014 % per cycle is obtained for cells cycled at 2C. Lithium-sulfur batteries (LSBs) are among the most promising next-generation high energy density energy-storage systems. However, practical application has been hindered by fundamental problems, especially shuttling by the higher-order polysulfides (PSs) and slow redox kinetics. Herein, a novel electrolyte-based strategy is proposed by adding an ultrasmall amount of the low-cost and commercially available cationic antistatic agent octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate (SN) into a routine ether electrolyte. Due to the strong cation–anion interaction and bridge-bonding with SN, rapid flocculation of the soluble polysulfide intermediates into solid-state polysulfide-SN sediments is found, which significantly inhibited the adverse shuttling effect. Moreover, a catalytic effect was also demonstrated for conversion of the polysulfide-SN intermediates, which enhanced the redox kinetics of Li–S batteries. Encouragingly, for cells with only 0.1 % added SN, an initial specific capacity of 783.6 mAh/g and a retained specific capacity of 565.7 mAh/g were found at 2C after 200 cycles, which corresponded to an ultralow capacity decay rate of only 0.014 % per cycle. This work may provide a simple and promising regulation strategy for preparing highly stable Li–S batteries. [ABSTRACT FROM AUTHOR]

This research is based on the concept that mitochondria are a promising target for anticancer therapy, including thatassociated with the use of oxidative phosphorylation blockers (mitochondrial poisons). Liposomes based on L-α-phosphatidylcholine (PC) and cholesterol (Chol) modified with cationic surfactants with triphenylphosphonium (TPPB-n, where n = 10, 12, 14, and 16) and imidazolium (IA-n(OH), where n = 10, 12, 14, and 16) head groups were obtained. The physicochemical characteristics of liposomes at different surfactant/lipid molar ratios were determined by dynamic/electrophoretic light scattering, transmission electron microscopy, and spectrophotometry. The hydrodynamic diameter of all the systems was within 120 nm with a polydispersity index of no more than 0.24 even after 2 months of storage. It was shown that cationization of liposomes leads to an increase in the internalization of nanocontainers in pancreatic carcinoma (PANC-1) and duodenal adenocarcinoma (HuTu 80) cells compared with unmodified liposomes. Also, using confocal microscopy, it was shown that liposomes modified with TPPB-14 and IA-14(OH) statistically better colocalize with the mitochondria of tumor cells compared with unmodified ones. At the next stage, the mitochondrial poison rotenone (ROT) was loaded into cationic liposomes. It was shown that the optimal loading concentration of ROT is 0.1 mg/mL. The Korsmeyer–Peppas and Higuchi kinetic models were used to describe the release mechanism of ROT from liposomes in vitro. A significant reduction in the IC50 value for the modified liposomes compared with free ROT was shown and, importantly, a higher degree of selectivity for the HuTu 80 cell line compared with the normal cells (SI value is 307 and 113 for PC/Chol/TPPB-14/ROT and PC/Chol/IA-14(OH)/ROT, respectively) occurred. It was shown that the treatment of HuTu 80 cells with ROT-loaded cationic liposomal formulations leads to a dose-dependent decrease in the mitochondrial membrane potential. [ABSTRACT FROM AUTHOR]

In this study, the electrical conductivity of the antidepressant drug—nortriptyline hydrochloride and conventional surfactant—cetyldimethylethylammoniumbromide are investigated. The experimental critical micelle concentration and related thermodynamic parameters, such as Gibbs free energy, enthalpy, entropy change, as well as and excess change in Gibbs free energy are calculated using standard equations. The values of change in Gibbs free energy for the mixed nortriptyline hydrochloride with cetyldimethylethylammoniumbromide are found to be more negative further suggesting the mixed micellization to be favourable. However, the high values of change in entropy are observed owing to the charge on the head groups which are being partially neutralized by the counter ions upon micelle formation. [ABSTRACT FROM AUTHOR]

Hypothesis: A key question in the kinetics of surfactant self-assembly is whether exchange of unimers or fusion/fission of entire micelles is the dominant pathway. In this study, an isomerizable surfactant is used to explore fundamental out-of-equilibrium kinetics and mechanisms for growth and dissolution of micelles. Experiments: The kinetics of cationic surfactant 4-butyl-4'-(3-trimethylammoniumpropoxy)-phenylazobenzene was studied using molecular dynamics simulations. The fusion and exchange processes were investigated using umbrella sampling. Equilibrium states were validated by comparison with small-angle X-ray scattering data. The photo-isomerization event was simulated by modifying the torsion potential of the photo-responsive group to emulate the trans -to- cis transition. Findings: Micelle growth is dominated by unimer exchange processes, whereas, depending on the conditions, dissolution can occur both through fission and unimer expulsion. Fusion barriers increase steeply with the aggregation number making this an unlikely pathway to equilibrium for micelles of sizes that fit with the experimental data. The barriers for unimer expulsion remain constant and are much lower for unimer insertion, making exchange more likely at high aggregation. When simulating photo-conversion events, both fission and a large degree of unimer expulsion can occur depending on the extent of the out-of-equilibrium stress that is put on the system. [ABSTRACT FROM AUTHOR]

Spirulina sp. (AlgS) was modified with the cationic surfactant hexadechyltrimethylammonium bromide (HDTMA-Br) to produce a positively charged adsorbent (AlgS-HDTMA) through a cation exchange reaction. The functional groups contained in the adsorbent were studied using an infrared (IR) spectrometer, while the surface morphology and constituent elements were studied using SEM-EDX. The AlgS-HDTMA adsorbent was applied to the mono-component and bi-component adsorption of methyl orange (MO) and crystal violet (CV) dyes. The adsorption experiments were carried out using the batch method to determine the kinetics, isotherms, mechanisms, and adsorption competition of MO and CV against the adsorbent. The amount of MO and CV adsorbed by AlgS-HDTMA was compared with the adsorbent modified by Spirulina sp. algae with Na+ ions (AlgS-Na) in the form of both mono-component and bi-component which showed greater results than AlgS-Na. MO and CV adsorption competition against AlgS-HDTMA was dominated by MO with the bi-component Langmuir isotherm constant (bj) for MO and CV of 15.60 and 2.80 × 10–2 L/mmolequiv, respectively. Surface modification of AlgS with cationic surfactant HDTMA-Br has resulted in a rich positive charge, making it more effective to adsorb anionic dyes such as MO. Data on the ability to reuse adsorbents are an important aspect in handling wastewater treatment because it is very meaningful in reducing water treatment costs. The results of adsorption of MO solution and desorption with 0.1 M hydrochloric acid solution as eluent with 1–4 repetitions were: 97.8, 94.13, 89.39, and 86.27%. These data indicate that the repetition of 4 times did not significantly reduce the adsorption capacity of MO. Lastly, the wastewater study confirms that AlgS-HDTMA adsorbents are promising as biomass for anionic/cationic dye adsorption. The review is highly beneficial for scientists, wastewater treatment, and industrial communities to support the sustainable development of natural resources. [ABSTRACT FROM AUTHOR]

The effect of the ionic liquid analogue tetrabutylammonium bromide on the aggregation behaviour of the cationic surfactant dodecyltrimethylammonium bromide in aqueous medium was investigated with volumetric and compressibility measurements over a wide temperature range (293.15–313.15) K. The data obtained were used to obtain density data. Based on the density data obtained, the volumetric properties (apparent molar volumes and partial molar volumes) of the surfactant in unimeric and micellar forms were evaluated and discussed in terms of the respective ionic and dipolar interactions. The data obtained were analysed to determine the effects of (i) temperature and (ii) salt added to the surfactant. The results were also interpreted in terms of the molecular interactions occurring in the binary mixtures of the present study. The addition of tetrabutylammonium bromide has a lowering effect on the CMC values of the surfactant studied in aqueous medium. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries (LSBs) have received great attention as promising candidates for next-generation energy-storage systems due to their high theoretical energy density. However, their practical energy density is limited by a large electrolyte-to-sulfur (E/S) ratio (>10 µL electrolyte/mg s), and their cycle performance encounters challenges from electrode passivation and Li dendrite formation. In this work, a dual-functional electrolyte additive of tetraethylammonium nitrate (TEAN) is presented to address these issues. NO3− as a high-donor-number (DN) salt anion can promote polysulfide dissolution, increase sulfur utilization, and alleviate electrode passivation. The tetraethylammonium cation can adsorb around Li protrusions to form a lithiophobic protective layer to inhibit the formation of Li dendrites. TEAN LSBs show improving capacity, cycling stability, and higher coulombic efficiency under lean electrolyte (5 μL electrolyte/mg s) conditions. [ABSTRACT FROM AUTHOR]

The textural characteristics of carbon nanomaterials and their adsorption capacity with respect to nonferrous metal ions have been studied. A comparative study of the applicability of adsorption models for describing adsorption isotherms for Cu2+ and Zn2+ ions has been carried out. The results on the electroflotation extraction of carbon nanomaterial particles from aqueous solutions in the presence of a cationic surfactant are shown. [ABSTRACT FROM AUTHOR]

Novel supramolecular nanoparticles were successfully built by sulfobutylether7-β-cyclodextrin and benzyl dodecyl dimethyl ammonium bromide. The assembly and disassembly behavior were determined by UV–Vis, Tyndall effect, dynamic light scattering, transmission electron microscopy, and zeta potential. Upon decreasing pH values, the resulting nanoparticles disassemble. The nanoparticles will be restored to spherical nanoparticles when the pH increases to the initial value. Due to the negative zeta potential, the nanoparticles showed good loading capacity for doxorubicin (DOX). DOX-loaded nanoparticles exhibited pH-responsive drug release behavior and possess higher cytotoxicity than the positive control, cisplatin. Thus, the simple and effective supramolecular nanoparticles with desirable load/release DOX property was constructed as pH-responsive drug delivery system. [ABSTRACT FROM AUTHOR]

Cationic surfactants are widely used in the colloidal synthesis of noble metal nanoparticles in general, and of Pd nanoparticles in particular, to stabilize them toward aggregate formation in solution and to promote shape-specific particle growth. Despite the benefits at the synthesis stage, these surfactants can be problematic once the nanoparticles are to be applied as they may both geometrically block and electronically alter surface sites that are important for surface chemical reactions. This is particularly relevant in applications like bio- and chemosensors where analyte-nanoparticle surface interactions constitute the actual sensing event. Here, H2 sensors based on Pd and its alloys are no exception since the dissociation of H2 on the particle surface is the first step toward hydride formation and thus hydrogen detection, and it has been demonstrated that the presence of surfactant molecules detrimentally affects the hydrogen sorption rate. Here, we therefore develop a scheme to remove cationic surfactants from Pd nanoparticle surfaces by means of subsequent O2 and H2 plasma treatment, whose effectiveness we verify by X-ray photoelectron spectroscopy. Furthermore, we find that the plasma treatment both alters the surface structure of the Pd nanoparticles at the atomic level and leads to surface contamination by so-called H2 plasma swift chemical sputtering of Al, Si and F species present in the plasma chamber, which in combination significantly reduce hydrogen sorption rates and increase apparent activation energies, as revealed by plasmonic hydrogen sorption kinetic measurements. Finally, we show that both these effects can be reversed by mild thermal annealing and that after the complete plasma cleaning–thermal annealing sequence hydrogen sorption rates essentially identical to the ones of neat Pd particles never exposed to cationic surfactants can be achieved. This advertises tailored plasma cleaning and mild heat treatments as an effective recipe for the removal of surfactant molecules from nanoparticle surfaces. [ABSTRACT FROM AUTHOR]

In the process of traditional tailings treatment, it is difficult for fine minerals to settle. Therefore, taking Kaolinite as an example, this paper studies the influence of adding cationic surfactant such as butylamine, dodecylamine, tetradecylamine, hexadecylamine and octadecylamine on the settling process of kaolinite suspension under the condition of using polyacrylamide as flocculant. Through first principles calculation, it is found that, the adsorption of cationic surfactant on the surface of kaolinite is mainly based on ionic hydrogen bond. With the growth of carbon chain, its bond level increases slightly, and its adsorption energy also increases, indicating that the adsorption capacity of cationic surfactant on mineral surface is gradually enhanced with the growth of carbon chain. The experimental study found that when the number of carbon atoms was less than 14, the promoting effect of cationic surfactant on the flocculation of kaolinite suspension was enhanced with the increase of the number of cationic surfactant carbon atoms; when the number of carbon atoms was more than 14, the promoting effect of cationic surfactant on the flocculation of kaolinite suspension was weakened with the increase of the number of cationic surfactant carbon atoms, which was mainly due to the excessive length of its carbon chain and poor dispersion in the suspension. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction (eCO2RR) to high-value chemicals and fuels, especially oxygenates and long-chain hydrocarbons, are of great interest for industrial applications, as well as offering a feasible strategy to reach the global goal of net-zero carbon emissions. Over the past few decades, research efforts have been focused on the development of both the rational design of electrocatalysts and electrolyzer systems, along with understanding the underlying mechanisms behind the electrolyte environment (e.g., cations, anions, and pH effects) on eCO2RR. In this review, we summarize recent progress on investigating the intriguing cation effect which steer the challenging eCO2RR toward the desirable directions. Although several hypotheses have been proposed but no consensus has been reached on the underlying mechanism of cation effects toward the eCO2RR. We overview the complex nature of cation effect to modify the electrode and electrolyte interface for converting CO2 efficiently to the target products based both on the latest experimental and computational findings, and provide our viewpoint of future directions and possible strategies in this topic for further improving the eCO2RR performance.

The complex was prepared with preyssler polyoxoanion and transition metal (Mo), a cationic surfactant as a connector. It has tuneable physical and chemical potential which has been exploited to study novel properties. A new technique of shock wave impulses is also used on the Mo-PHP complex. Extensive use of cationic surfactants could impact accumulation in the environment set off the surfacing of bacterial resistance. Due to the electrostatic binding to bacterial surface, the hydrophobic parts of cationic surfactants tend to penetrate bacterial cell walls and may cause membrane lysis and bacteria death. The surfactant-supported and direct release of metal ions from P5W29Mo against bacterial resistance has been explained schematically. The dielectric study helps to understand the dissociation of cations that generate polarons and the hopping mechanism with neighbouring vacant atomic sites. Structural analysis confirms the formation of cationic surfactant incorporated polyoxoanion (Mo-PHP). A hexagonal shape-like structure for the PHP complex has been observed. The Mo-incorporated PHP complex was characterized using UV-visible (UV), Fourier Transforminfrared (IR), Raman spectra, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques. [ABSTRACT FROM AUTHOR]

Cationic surfactants are adsorbed on the surface of human hair and exhibit a lubricating effect. Here, we evaluated the friction when the hair treated with water or 1 wt% cationic surfactant (cetyltrimethylammonium bromide) aqueous solution was rubbed by a contact probe equipped in a sinusoidal motion friction evaluation system. Because of the rough structure of the cuticle on the human hair surface, an oscillatory phenomenon with a frequency of 50–70 Hz was observed when untreated hair was rubbed with a contact probe. On the other hand, the oscillatory phenomenon was not observed when the hair contained a large amount of water because stick–slip phenomena were inhibited on the soft, swollen hair surface. Furthermore, the change in kinetic friction coefficient and delay time, which is a normalized value of the time difference between the reaction of the friction force to accelerated motion, from untreated hair, Δμk and Δδ, was almost zero. However, we found a large difference in Δμk and Δδ for the hair treated with cationic surfactant aqueous solution. The treatment with cationic surfactant reduced both friction parameters, Δμk and Δδ, indicating that the treatment induced not only the frictional force but also the profile at the beginning of frictional sliding. The significant lubrication is due to cationic surfactant adsorption on the hair surface. These data imply that the smoothness of hair treated with a cationic surfactant is related to a reduction in friction coefficient and delay time δ. [ABSTRACT FROM AUTHOR]

Erythrosine B (EB) is a xanthene dye widely used in many fields such as food, cosmetics and medicine. The interaction between EB and cetyltrimethylammonium bromide (CTAB) was investigated using spectrophotometry. The quantities of the quenching constant of Stern-Volmer, the number of binding sites and the binding constant were calculated for the EB-CTAB system. Liquid crystal-based sensing platform (LC) developed for ultrasensitive and unlabelled EB determination using an LC interface decorated with cationic surfactants. Nematic liquid crystals exposed to CTAB exhibited homeotropic binding, when EB was inserted into LC cells, and the inward arrangement was thus changed to a coplanar shape by electrostatic interaction between CTAB and EB. The sensor was developed based on LC which recognised EB at tracking level too low, up to 2.0 pM. The proposed LC-based sensing system is a quick, comfortable and easy approach for the determination of EB in unlabelled biological samples. [ABSTRACT FROM AUTHOR]

The current research proposes the hexadecyltrimethylammonium bromide‐modified Algerian halloysite nanotubes (HNTs‐CTAB) as adsorbent for nitrate ions removal from aqueous solution via electrostatic interactions. X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier‐transform infrared spectroscopy (FT‐IR), and nitrogen adsorption–desorption analysis techniques have been used to characterize the prepared adsorbants. The different operating condition that may affect the adsorption of nitrate was carried out. HNTs and HNTs‐CTAB adsorption capacities are considerably pH dependent. The optimum conditions for maximum removal of nitrate from aqueous solution were as follows: adsorbent masse was 40 mg, initial pH was 4, temperature was 25°C, initial nitrate concentration of 100 mg/L and equilibrium time was 3 h. Under optimal value of process parameters, maximum NO3− adsorption capacity of 47.4 mg/g was obtained. Kinetic investigation confirmed that the nitrate adsorption on modified HNTs followed a pseudo‐second‐order with correlation coefficients greater than 0.98 (R2 = 0.9870) and that empirical Freundlich isotherm was best fitted nitrate equilibrium adsorption. The thermodynamic studies indicated that the adsorption of nitrate onto HNTs‐CTAB is endothermic and spontaneous. HNTs‐CTAB displayed high regeneration ability by retaining a capacity above 40 mg/g after four reuse cycles. HNTs‐CTAB containing plentiful nitrate could be returned to the soil directly as an economic slow release fertilizers or a soil amendment due to its environmental‐friendly performance. Therefore, HNTs‐CTAB used for remediation of wastewater might be employed easily as farmland fertilizer. [ABSTRACT FROM AUTHOR]

The behavior of a new 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate (DODI-TPB) surfactant sensor was studied in single and complex mixtures of technical grade QACs—benzalkonium chloride (BAC), N,N-didecyl-N,N-dimethylammonium chloride (DDAC), and N,N-dioctyl-N,N-dimethylammonium chloride (DOAC) usually used in COVID-19 disinfecting agents formulations. The results obtained with the new DODI-TPB sensor were in good agreement with data measured by a 1,3-dihexadecyl−1H-benzo[d]imidazol−3-ium-tetraphenylborate (DMI-TPB) surfactant sensor, as well as two-phase titration used as a reference method. The quantitative titrations of a two-component mixture of the cationic homologs (a) DDAC and DOAC; and (b) BAC and DOAC showed that the new DODI-TPB surfactant sensor can clearly distinguish two separate mixture components in a single potentiometric titration curve with two characteristic inflexion points. The consumption of SDS (used as a titrant) in the end-point 1 (EP 1) corresponded to the content of DDAC (or BAC), whereas the consumption in the end-point 2 (EP 2) corresponded to the total content of both cationic surfactants in the mixture. DOAC content in both mixtures can be calculated from the difference of the titrant used to achieve EP1 and EP2. The addition of nonionic surfactants resulted in the signal change decrease from 333.2 mV (1:0; no nonionic surfactant added) to 243.0 mV (1:10, w/w). The sensor was successfully tested in ten two-component COVID-19 disinfecting formulations. [ABSTRACT FROM AUTHOR]

The research of organoclays has been occurring for many years to develop and add value to these inorganic materials for several industrial applications, such as pollutant absorbers or impermeable plastics. The organoclay applications are intrinsically related to organo-modification and the structure of clays. This study shows the preparation and characterization of organoclays produced by a nontronite type clay (calcic bentonite) from the Tosagua Formation in the peninsula of Santa Elena in Ecuador. These clays were purified and centrifuged before organo-treatment. The purification and separation processes were used to remove organic matter and carbonates, and a cationic interchange from calcic to sodic (Ca2+ to Na+) was carried out. Organo-modification was performed using two types of cationic compounds, i.e., Oleylmethylbis (2-hydroxyethyl) ammonium chloride and Di (hydrogenated tallow alkyl) quaternary amine to organoclay with different surface hydrophobicity. The samples were characterized by X-ray diffractometry (XRD), infrared spectrometry (FT-IR), thermo-gravimetry (TGA), and scanning electron microscopy (SEM) to analyze the effect after the mentioned treatment and the resulting organoclays by the addition of these surfactants. The results confirm the significant intercalation of the organic treatment suitable for environmental remediation, compatibilizing recycled plastics, or improving performance in different hydrophobicity systems for industrial applications. [ABSTRACT FROM AUTHOR]