Mixed Surfactant Systems Research Articles

Thermodynamic Analysis of Mixed Adsorbed Film and Micelle Compositions above Critical Micelle Concentration.

In this paper, we proposed a thermodynamic procedure to evaluate binary surfactant mixed adsorbed film and mixed micelle compositions above critical micelle concentrations. This theory first calculates the change in the molar ratio of two surfactants in monomer and micelle states based on the phase-separation model and then imposes the chemical equilibrium between the mixed adsorbed film and mixed micelle of known composition and concentration. We applied this theory to a cationic-nonionic surfactant mixed system, and the relationship between the calculated mixed adsorbed film composition and foam film stability was discussed using the DLVO theory.

Rheology and surface active properties of sodium N-lauroyl sarcosinate in mixed surfactant system

Anionic surfactant sodium N-lauroyl sarcosinate (SNLS) forms elongated wormlike micelles with cocamide monoethanolamine (CMEA) and lauryl glucoside (LG) a nonionic surfactants in the pH range 5.5–6.0. The total surfactant concentration was examined between 10% and 20% wt/v, and the pH was lowered from 7.5 to 4.5. The presence of CMEA/LG diminishes electrostatic repulsion amid SNLS head groups and prompts micellar transition displaying moderate viscosity. The viscosity peak of each system occurred in the pH range 5.5–5.8, close to the system’s pKa. This might prove to be a novel approach for SNLS surfactant formulation which otherwise was difficult to thicken. Additionally, mixed surfactant systems of SNLS/CMEA/LG portrays high surface activity, enhanced foaming behavior and improved skin mildness. Further, this study demonstrated a cost-effective and thickener-free method for cleansing compositions with the desired viscosity.

Micellization, aggregation, interaction, and solubilization behaviors of mixed solutions of cationic gemini and nonionic surfactants

AbstractThe micellization properties of mixed aqueous solutions of a cationic gemini surfactant (CGS) and Triton X‐100, a conventional non‐ionic surfactant, with various mole fractions, were determined by measuring the surface tension at different temperatures. Various theoretical models were used to analyze the behavior of this mixed system. The interactions between CGS and Triton X‐100 were determined to be non‐ideal and synergistic. The calculated interaction parameters (βM) have negative values at all temperatures and for all mole fractions, showing attractive interactions. It was found that increasing the mole fraction of Triton X‐100 significantly increased the synergistic effect (more negative values). Micellar aggregation number (Nagg) values of pure surfactants and their mixtures in different ratios were obtained with the steady‐state fluorescence quenching method. Furthermore, the molar solubilization ratio of Sudan III organic dye in all surfactants aqueous systems was obtained using UV–Visible spectrophotometry. At concentrations above critical micelle concentration, the solubility of Sudan III in water was substantially increased linearly for all systems and it was observed that the enhancement was even more significant for mixed surfactant systems.

Molecular Dynamics Simulations of the Short-Chain Fluorocarbon Surfactant PFHXA and the Anionic Surfactant SDS at the Air/Water Interface.

The research and development of alternatives to long-chain fluorocarbon surfactants are desperately needed because they are extremely toxic, difficult to break down, seriously harm the environment, and limit the use of conventional aqueous film-forming foam fire extinguishing agents. In this study, mixed surfactant systems containing the short-chain fluorocarbon surfactant perfluorohexanoic acid (PFHXA) and the hydrocarbon surfactant sodium dodecyl sulfate (SDS) were investigated by molecular dynamics simulation to investigate the microscopic properties at the air/water interface at different molar ratios. Some representative parameters, such as surface tension, degree of order, density distribution, radial distribution function, number of hydrogen bonds, and solvent-accessible surface area, were calculated. Molecular dynamics simulations show that compared with a single type of surfactant, mixtures of surfactants provide superior performance in improving the interfacial properties of the gas-liquid interface. A dense monolayer film is formed by the strong synergistic impact of the two surfactants. Compared to the pure SDS system, the addition of PFHXA caused SDS to be more vertically oriented at the air/water interface with a reduced tilt angle, and a more ordered structure of the mixed surfactants was observed. Hydrogen bonding between SDS headgroups and water molecules is enhanced with the increasing PFHXA. The surface activity is arranged in the following order: PFHXA/SDS = 1:1 > PFHXA/SDS = 3:1 > PFHXA/SDS = 1:3. These results indicate that a degree of synergistic relationship exists between PFHXA and SDS at the air/water interface.

Observation of Electrostatically Driven Surface Adsorption in Mixed Surfactant Systems.

We employed heterodyne-detected vibrational sum-frequency generation (HD-VSFG) spectroscopy to obtain a molecular-level understanding of the interaction between the anionic surfactant sodium dodecyl ammonium sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). We observed that these surfactants show a strong cooperative effect on their adsorption to the water-air interface. Even at bulk concentrations 1000 times lower than the critical micelle concentrations of SDS and DTAB, a nearly complete surface surfactant layer is observed when both surfactants are present. This strong enhancement of the surface concentrations of DS- and DTA+ can be quantitatively explained from the favorable Coulomb interaction of the oppositely charged headgroups of DS- and DTA+ and the electrostatic interactions with their counterions. The HD-VSFG results are complemented by a modified Langmuir adsorption model in which we include the free energy associated with the electrostatic interactions of the surfactant ions and their counterions.

Synergistic anionic/zwitterionic mixed surfactant system with high emulsification efficiency for enhanced oil recovery in low permeability reservoirs

Emulsification is one of the important mechanisms of surfactant flooding. To improve oil recovery for low permeability reservoirs, a highly efficient emulsification oil flooding system consisting of anionic surfactant sodium alkyl glucosyl hydroxypropyl sulfonate (APGSHS) and zwitterionic surfactant octadecyl betaine (BS-18) is proposed. The performance of APGSHS/BS-18 mixed surfactant system was evaluated in terms of interfacial tension, emulsification capability, emulsion size and distribution, wettability alteration, temperature-resistance and salt-resistance. The emulsification speed was used to evaluate the emulsification ability of surfactant systems, and the results show that mixed surfactant systems can completely emulsify the crude oil into emulsions droplets even under low energy conditions. Meanwhile, the system exhibits good temperature and salt resistance. Finally, the best oil recovery of 25.45% is achieved for low permeability core by the mixed surfactant system with a total concentration of 0.3 wt% while the molar ratio of APGSHS:BS-18 is 4:6. The current study indicates that the anionic/zwitterionic mixed surfactant system can improve the oil flooding efficiency and is potential candidate for application in low permeability reservoirs.

Highly efficient oil-fouling and foam removal achieved by surfactant mixed systems

Reducing surfactant usage & promoting safety, efficiency, sustainability.

Study on anionic-nonionic mixed surfactant for enhanced oil recovery in a hypersaline reservoir.

Hypersaline reservoirs are characterized by high salinity and high calcium and magnesium concentration. In order to enhance oil recovery of the hypersaline reservoirs, a specialized ternary mixed surfactant system composed of nonionic alkanolamide surfactants and anionic surfactant was developed in this study. Through careful analysis and optimization, lauric acid diethanolamide (LDEA), octanoic acid diethanolamide (ODEA), and sodium dodecyl sulfonate (SDS) were identified as promising candidates for the surfactant compounding system, and formed a ternary surfactant system composed of LDEA, ODEA, and SDS with the mass ratio of 4.64 : 0.66 : 1.00. Experimental results revealed that the interfacial tension of the system was consistently below 10-2 mN m-1 and could even reach ultra-low levels (10-3 mN m-1) under conditions of calcium and magnesium ion content of 2000 mg L-1, surfactant concentrations ranging from 0.05 to 0.3 wt%, temperature ranging from 50 to 80 °C, and salinity ranging from 20 000 to 50 000 mg L-1. Furthermore, the mixed surfactant system exhibited favorable wetting capacity and emulsifying power. The static adsorption capacities of the mixed surfactant on oil sands were less than 2 mg g-1. This study offered a novel strategy for the actual exploitation of reservoirs with high calcium-magnesium and high salinity.

Construction of middle-phase microemulsion system and its micro-mechanism on displacing residual oil in low-permeability porous media.

The application of medium-phase microemulsion in enhancing oil recovery technology represents a significant area of research, particularly for improving production in low-permeability reservoirs. The oil recovery can be increased to 80%~90%. In order to further improve the recovery rate of low-permeability reservoirs in the late stage of water flooding, a medium-phase microemulsion flooding system was constructed in this paper. The micro-displacement mechanism of the medium-phase microemulsion flooding system was clarified by experimental methods such as phase change and micro-remaining oil distribution. The ability of enhancing oil recovery and the mechanism of increasing oil production were discussed, which provided a basis for establishing a new method of enhancing oil recovery. This study utilizes a mixed surfactant system composed of sodium dodecyl benzene sulfonate and coconut oil fatty acid lipopolyoxyethylene betaine at a mass ratio of 1:3, with n-butanol serving as the cosurfactant. The fish phase diagram was instrumental in determining the critical concentration range for alcohol (1.3%-3.7%) necessary for the formation of middle-phase microemulsions, along with a corresponding surfactant mass concentration of 0.3%-0.7%. Key salinity thresholds for middle-phase formation and disappearance were identified at 1.5% and 6.0%, respectively. Optimal solubilization effects were observed at approximately 4.8% NaCl mass concentration, which effectively reduced interfacial tension to 10-3mN/m. Under specific kinetic conditions, in-situ formation of middle-phase microemulsions occurs as surfactants interact with crude oil within reservoir pores. In comparison to traditional water flooding, middle-phase microemulsions enhance viscosity and create an oil wall at the forefront of displacement. This mechanism facilitates the aggregation and movement of residual oil, which is crucial for enhancing crude oil recovery. Moreover, middle-phase microemulsions exhibit strong solubilization capabilities, making them particularly effective for mobilizing oil in blind-end and unswept areas. The ultra-low interfacial tension achieved between the microemulsion and crude oil promotes the elongation and fragmentation of pore-trapped oil into smaller droplets, ultimately aiding in their displacement and recovery via micro-pore outlets. This unique interaction underscores the potential of middle-phase microemulsion flooding to optimize oil recovery processes, especially in challenging reservoir environments such as those encountered in the Changqing Oilfield formations.

Critical Analysis of Surfactant-Dye Interaction: A Review

The interaction between surfactants and dyes is fundamental in achieving the desired coloration and properties in various applications, shaping the functionality and effectiveness of dye-related processes across multiple industries. Further research and advancements in this field will continue contributing to innovative solutions and improved sustainability. While mixed surfactants offer these advantages, the choice between using a single surfactant or a mixture depends on the specific application, the desired properties, cost considerations, and compatibility with other formulation components. It's important to carefully evaluate the application requirements and conduct appropriate testing to determine the most effective approach. In this work, the physical-chemical characteristics and solubilization of reactive dyes in single and mixed micellar media are elaborated. Compared to the single-micellar medium, the mixed-micellar medium showed improved reactive dye trapping, which was attributed to the presence of both cationic and nonionic surfactants, namely cetyltrimethylammonium bromide (CTAB) and triton X-100. In this interactional study, two reactive dyes were used: Reactive Black 5 (RB) and Reactive Yellow 145 (RY). It is noteworthy to examine the modeling and micellization of mixed surfactant systems in an aqueous medium including dodecyl trimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS). The anionic-rich and cationic-rich interactions between methylene blue (MB) and methyl orange (MO) in aqueous solutions were clearly shown in the diagram.

Influence of Surfactant Structure on Polydisperse Formulations of Alkyl Ether Sulfates and Alkyl Amidopropyl Betaines.

Surfactants provide detergency, foaming, and texture in personal care formulations, yet the micellization of typical industrial primary and cosurfactants is not well understood, particularly in light of the polydisperse nature of commercial surfactants. Synergistic interactions are hypothesized to drive the formation of elongated wormlike self-assemblies in these mixed surfactant systems. Small-angle neutron scattering, rheology, and pendant drop tensiometry are used to examine surface adsorption, viscoelasticity, and self-assembly structure for wormlike micellar formulations comprising cocoamidopropyl betaine, and its two major components laurylamidopropyl betaine and oleylamidopropyl betaine, with sodium alkyl ethoxy sulfates. The tail length of sodium alkyl ethoxy sulfates was related to their ability to form wormlike micelles in electrolyte solutions, indicating that a tail length greater than 10 carbons is required to form wormlike micelles in NaCl solutions, with the decyl homologue unable to form elongated micelles and maintaining a low viscosity even at 20 wt % surfactant loading with 4 wt % NaCl present. For these systems, the incorporation of a disperse ethoxylate linker does not enable shorter chain surfactants to elongate into wormlike micelles for single-component systems; however, it could increase the interactions between surfactants in mixed surfactant systems. For synergy in surfactant mixing, the nonideal regular solution theory is used to study the sulfate/betaine mixtures. Tail mismatch appears to drive lower critical micelle concentrations, although tail matching improves synergy with larger relative reductions in critical micelle concentrations and greater micelle elongation, as seen by both tensiometric and scattering measurements.

Binding and occupancy properties of gabapentin in mixed surfactant systems

AbstractThis research highlights the efficacy of mixed micellar systems as an innovative chemical formulation for improving the binding properties of active pharmaceutical drugs. The formulations based on the mole fraction were utilized for preparing mixed micelles with anionic sodium dioctyl sulfosuccinate (AOT) and sodium dodecyl sulphate (SDS). DLS measurements demonstrated the formation of small micelles and mixed micelles in SDS‐AOT combinations. A UV absorbance investigation demonstrated the effectiveness of the SDS‐AOT mixed micelles for determining the binding constant (Kb) and mean ion occupancy (i0) of the anticonvulsant gabapentin (GBP) drug. Kb values increased, but the occupancy (i) of GBP per micelle decreased by decreasing the mole fraction (α) of SDS from αSDS 0.9 to 0.1, predicting a shift in occupancy of drugs from the Palisade to the Stern layer. To get a better comprehension of micellization behavior and preferential interaction of the drugs under study, molecular docking studies were performed. According to the docking studies, the GBP displayed significant binding in the presence of SDS‐AOT when compared to pure SDS and AOT molecules. Ultimately, in pharmaceutical applications, mixed micelle played an important role in enhancing the binding and encapsulation efficiency of drugs.

Anionic-nonionic and nonionic mixed surfactant systems for oil displacement: Impact of ethoxylate chain lengths on the synergistic effect

Compound surfactant system has been extensively studied in enhanced oil recovery (EOR) as the synergistic effect of mixed surfactants can increase the density of surfactants distributed at the oil/water interface, enhancing the interfacial activity and decreasing the interfacial tension. The system can further increase the capillary number and enhance oil recovery for oil-wet reservoirs. Studying the interactions between surfactant molecules is of great significance to the enhancement of practical application performances. In this study, N, N-dihydroxyethyl alkyl amide (CDEA), and Alkylphenol polyoxyethylene carboxylate (APEC) with different EO numbers were mixed to prepare a binary compound oil displacement system. The influence of the EO number on the synergistic effect of the CDEA/APEC system and the EOR potential was measured by interfacial tension, nanomechanical tests and oil-displacement experiments. The results indicate a synergistic effect between CDEA and APEC due to the formation of hydrogen bonds between the hydroxyl groups of CDEA and the EO chains of APEC. An optimal synergistic effect in the system was obtained when the EO number was four. The CDEA/APEC-4 system exhibited an oil/water interfacial tension decrease to 10−2 mN/m at 75 °C and the oil recovery was 57.14 %, which was increased by 19.2 % compared to primary water flooding. However, a longer EO chain length weakened the interaction forces between CDEA and APEC, which diminished the synergistic effect of the system, leading to an increase of the interfacial tension. Due to the flexibility of the EO chain, the increase in the EO number leads to the bending of APEC molecules. The longer EO chain length weakened the interaction forces between CDEA and APEC, which diminished the synergistic effect of the system, leading to an increase of the interfacial tension. The oil-displacement experiment revealed that the EO chains changed the oil recovery and injection pressure by affecting the interfacial tension of the mixed system. This study has significant implications for the formulation design and optimization of agents for oilfield development.

Free energy decompositions illuminate synergistic effects in interfacial binding thermodynamics of mixed surfactant systems.

Recent vibrational sum frequency generation spectroscopic experiments [Sengupta et al., J. Phys. Chem. Lett. 13, 11391-11397 (2022)] demonstrated synergistic interfacial adsorption effects between the anionic dodecyl sulfate (DS-) and the polar, but charge-neutral hexaethylene glycol monododecyl ether (C12E6), surfactants. In this study, the interfacial adsorption thermodynamics underlying these synergistic effects are analyzed through free energy decompositions. A general decomposition method utilizing alchemical intermediate states is outlined. Combining free energy decompositions with the potential distribution theorem illuminates the statistical interpretations of correlated effects between different system components. This approach allows for the identification of the physical effects leading to synergistic adsorption thermodynamics of DS- binding to the air-C12E6-water interface. The binding properties are found to result from a combination of effects predominantly including energetic van der Waals stabilization between DS- and C12E6, as well as competing energetic and entropic effects due to changes in the interfacial water structure as a result of introducing a C12E6 monolayer into the bare air-water interface.

Innovative study in renewable energy source through mixed surfactant system for eco-friendly environment.

Actual plan of research work was proposed for systematic investigating in the field of photogalvanic (PG) cells for solar energy transformation. It was necessary and proposed to carry out experimental work under the solar parameters for PG cells. The object of the research work is to enhance the solar energy conversion into electricity and store it through PG cells. Various parameters were studied in a PG cell having D-Xylose + MB + Brij-35 + NaLS system (mixed surfactants). In this study, the observed optimum results in terms of the open circuit voltage, photopotential, maximum photocurrent, and short circuit current are 921.00mV, 698.00mV, 311uA, and 245.0uA, respectively. The observed equilibrium photocurrent, current at power point, fill factor, and conversion efficiency were 243.0uA and 142.0uA, 0.4521, and 0.6769%, respectively. For individual surfactants, the observed results in terms of the open circuit voltage, photopotential, maximum photocurrent, and short circuit current are 870.00mV, 635.00mV, 175uA, and 90.0uA, respectively. For individualsurfactant system,the observed equilibrium photocurrent, current at power point, fill factor, and conversion efficiency were 84.0uA and 55.0uA, 0.3630, and 0.3100%, respectively. The impact of solar energy was studied by varying the various parameters in PG cells. On the basis of above obtained values, the mixed surfactants (NaLS + Brij-35) have experimentally proved the efficient system as the desired object of research with special reference to enhance electrical out and storage of solar energy.

Effect of interfacially-engineered nanoemulsions of linoleic acid stabilized by mixed surfactant systems and curcumin on their physicochemical properties, induction times, and peroxidation stability

Nanoemulsions have become the best candidates for loading hydrophobic bioactive molecules and enhancing their shelf-life and bioavailability in the food, pharmaceutical and cosmetic industries. Mixture of different surfactants modulates their interfacial characteristics, thereby imposing a direct effect in improving their physicochemical and nutritional characteristics. Herein, we report the formulation of oil-in-water nanoemulsions stabilized with either single or mixture of surfactants having different electric charges like Tween 20 (T20, nonionic), sodium salt of Lauroyl Sarcosine (LS, anionic) and 3-(N,N-dimethylmyristylammonio)propanesulfonate (DPS, zwitterionic) to control the peroxidation of linoleic acid by using curcumin as the potential antioxidant. The distribution of H+ ions at the interface and the variation in the values of observed rate constant (kobs) is assessed by employing the novel Chemical Kinetic method based on the reaction between arenediazonium ions and the antioxidant. For single-surfactant systems, nanoemulsions containing pure T20 or LS showed good oxidative stability whereas for mixed-surfactant systems, the oxidative stability increases with increasing concentration of LS and decreasing concentration of DPS. This could be explained on the basis of physicochemical characterization of nanoemulsions, interfacial H+ ion concentration, and solubility characteristics of curcumin. The study shows great promise of such mixed surfactant systems, ignored so far, for providing a novel and tailored formulation of nanoemulsions for improving the oxidative stability of linoleic acid.

High unimer concentration and asymmetric bilayer observed in small unilamellar vesicles of mixed surfactants TDMAO/LiPFO.

The mixed surfactant system of tetradecyldimethylamine oxide (TDMAO) and lithium perfluorooctanoate (LiPFO) is known to spontaneously self-assemble into well-defined small unilamellar vesicles. For a quantitative analysis of small-angle x-ray scattering on this model system, we complemented the measurements with densitometry, conductimetry, and contrast-variation small-angle neutron scattering. The analysis points to two main findings: first, the vesicles formed to contain a much higher mole fraction (0.61-0.64) of TDMAO than the bulk sample (0.43) and predicted by Regular Solution Theory (RST, 0.46). In consequence, the unimer concentration of LiPFO is more than 5 times higher than predicted by RST. Second, the vesicle bilayer is asymmetric with a higher fraction of LiPFO on the outside. These findings on a model system should be of broader relevance for the understanding of similar mixed surfactant vesicle systems and thereby also be of importance for their use in a number of applications.

Effect of Phenoxyethanol and Sodium benzoate on the liquid crystal phase behavior of mixed surfactant system

Surfactants in a mixed concentrated (∼30 wt% and higher)-surfactant system self-assemble to form a variety of liquid crystal (lc) types depending the lc curvature determined by the surfactant chemistries and their relative compositions. Preservatives, fragrances and other minor additives present in an industrial formulation can either incorporate into the lc and/or influence the aqueous phase ionic strength to alter the spatial arrangements of the surfactants and the lc curvature. These mechanisms could additively or competitively determine the lc curvature and thereby the lc types formed. We report on the mechanisms for preservatives Phenoxyethanol (PE) and Sodium benzoate (NaB) governing the lc phase behavior for a mixed concentrated-surfactant system: 16 wt% zwitterionic Cocoamidopropyl betaine (CAPB), and 7 wt% each of anionic Sodium Lauroyl isethionate (SLI), Sodium Methyl Lauroyl Taurate (SMLT), and 6 wt% Lauric acid. The lc type(s), the lc dimensions including inter-lc distances were derived from SAXS and polarized microscopy images. The predominant lc phase without preservatives was H1lc, while anionic SLI and SLMT present in excess were insoluble to form dispersed crystals. The addition of PE molecules resulted in their incorporation in the lc surfactant film to cause a transition to micelles, and Lα lc due to incorporation-induced flattening of the film. NaB molecules prevented micelles formation and preserved the H1lc by serving as a hydrotropic agent. The NOESY spectra for the lc systems with PE or NaB at 0–3 wt% confirmed incorporation of PE in surfactant film as opposed to NaB. For both PE and NaB present in a lc system, the dominance of hydrotropic nature of NaB causing film bending rather than the film flattening effect of PE at low (∼1 wt%) PE levels resulted in H1lc as the predominant phase, and reduced dominance of film bending effect at a high PE level (≥ 2 wt%) led to the formation of Lα lc.

Chemical Demulsification of Oil-in-Water Emulsion from Gas Condensate Field

Produced water, also known as oily wastewater, is one of the major wastes in the oil and gas industry. During the hydrocarbon production, formation of emulsion takes place such as oil-in-water emulsion which has a huge financial effect on the sector. Oil and gas industry seeks highly effective and reasonable demulsifying chemicals to separate the oil-in-water emulsions into water and crude oil. Thus, in this publication, resin alkoxylate, cationic polyamine, cationic surfactant and ethylene oxide/propylene oxide (EO/PO) block copolymers are utilized to resolve the oil-in-water emulsion from a gas condensate field. According to the findings of preliminary screening, a unique demulsifier DB was formulated by incorporating resin alkoxylate and cationic surfactant at an optimal weight percentage ratio. Demulsification efficiency (De) of 96 % based on measurement of turbidity was attained after treating the oil-in-water (O/W) emulsion with demulsifier DB at a dosage of 7 ppm. To determine the demulsifier's efficiency further, the oil-in-water content (OiW) of the produced water was evaluated after the treatment with demulsifier DB. Oil removal efficiency (ORe) of 90% was achieved as the formulated demulsifier DB reduced the oil-in-water content (OiW) of O/W emulsion from 1008.3 ppm to 97.1 ppm within 15 minutes at the dosage of 7 ppm. Furthermore, interfacial tension (IFT) and Turbiscan analysis were performed to further study the demulsification process of blank sample and the addition of the demulsifier DB at the optimized dosage of 7 ppm. At demulsifier DB dosage of 7 ppm, the interfacial tension between oil and water reduced significantly compared to blank sample from 24.98 mN/m to 9.38 mN/m. The produced water sample after treatment with 7 ppm of demulsifier DB resulted in a significant increase of Turbiscan Stability Index (TSI) value of 8 which indicates the rate at which the separation of oil and water occurred. The attained results of IFT and Turbiscan analysis further validate that mixed surfactant system is more efficient than single surfactant system. By combining surfactants with different functional groups, mixed surfactant systems can exhibit greater surface activity than single surfactants.

Study on the bactericidal activity of dodecyl dipropylene triamine and anionic mixed surfactant systems

In this study, we anticipated that cocamidopropyl betaine (CAPB) and isomeric alcohol ethoxylates (TO) could protect the antibacterial properties of dodecyl dipropylene triamine (BDA) under the influence of anionic surfactants. Different concentrations of anionic surfactants such as sodium lauryl polyoxyethylene ether sulfate (AES) and sodium dodecyl sulfate (SDS) were added to a mixture of the cationic surfactants BDA and benzalkonium chloride (BZK) with two protective agents: a branched nonionic surfactant TO and a zwitterionic surfactant CAPB. Opticaldensity (OD) and Cell Counting Kit-8 (CCK-8) methods were used to evaluate the antibacterial activity of these systems against sulfate-reducing bacteria (SRB) such as Escherichia coli, Staphylococcus aureus, and Desulfovibrio sp. The protective mechanisms of the different protective agents were studied by measuring their respective viscosities. The protective agents (TO and CAPB) had a negative effect on the biocidal performance of the BZK (C12-C14) but had an excellent protective effect in the presence of anionic surfactants. In the BDA systems (AES and SDS concentrations of 100 mM), the BDA-CAPB-AES, BDA-CAPB-SDS, BDA-TO-AES, and BDA-TO-SDS systemseliminated almost all E.coli and S.aureus bacteria within 2 min of exposure, among which the BDA-CAPB-AES and BDA-TO-AES systems showed the strongest bactericidal activity against sulfate reducingbacteria (SRB). Therefore, these multicomponent surfactant antibacterial systems can potentially be used to replace traditional cationic surfactant systems in the chemical industry, thereby reducing the microbial corrosion caused by SRB.