Surfactant Enhanced Electrorenlediation of Phenanthrene

Removal of hydrophobic organic contaminants (HOCs) from soil of low permeability by electroremedia-tion was investigated by using phenanthrene and kaolinite as a model system. Tween 80 was added into the purging solution in order to enhance the solubility of phenanthrene. The effects of pH on the adsorption of phenanthrene and Tween 80 on kaolinite and the magnitude of -potential of kaolinite were examined, respectively. The effects of electric field strength indicated by electric current on the electroremediation behavior, including the pH of purging solution, the conductivity, phenanthrene concentration and flow rate of effluent, were experimentally investigated, respectively. In case of an electric field of 25 mA applied for 72 hours, over 90% of phenanthrene was removed from 424 g (dry mass) of kaolinite at an energy consumption of 0.148 kW-h. The experimental results described in present study show that the addition of surfactant into purging solution greatly enhances the removal of HOCs by electro     

Application of the Hydrophilic–Lipophilic Deviation Concept to Surfactant Characterization and Surfactant Selection for Enhanced Oil Recovery

The hydrophilic–lipophilic deviation (HLD) concept has been demonstrated to be useful in determining characteristic curvature (Cc) of a surfactant. Cc is a surfactant parameter that reflects the hydrophobicity/hydrophilicity or the tendency of the surfactant to form microemulsions in an oil–water system. In order for the Cc value to be calculated, the formation of the optimum Winsor III microemulsion of oil and water systems under specific salinity and temperature conditions is required. Surfactant Cc values have been widely used to quantitatively screen and select a suitable surfactant in formulations for different application areas, especially enhanced oil recovery (EOR). The HLD concept is an effective tool for designing new surfactant molecules to meet the target Cc value for a specific formulation condition. The HLD equation indicates the dependence of a microemulsion system on the changes of various system parameters. This article demonstrates how the HLD equation can be derived in different ways depending on the characteristics of the surfactant to identify the proper experimental approach so that the Cc values of different types of surfactants can be determined. Three types of surfactants were studied, including nonionic alcohol ethoxylates, anionic alkyl propoxy ethoxy sulfates, and carboxylates. The application of the HLD concept to surfactant selection for EOR application was also demonstrated.     

Rheological Behavior of Selected Water-Nonionic–Anionic Surfactant Quasi-ternary Systems

The results of studies on the rheological behavior of ternary mixtures comprising water, linear alkylbenzenesulfonic acid, and a non-ionic surfactant from a group comprising ethoxylated fatty acid methyl esters are presented in this paper. In the latter group, those examined include ethoxylated rapeseed and coconut fatty acid methyl esters, and ethoxylated lauryl acid methyl ester. The flowing curves, effect of temperature on viscosity, as well as the relationship between viscosity and composition of the examined ternary systems were studied. As a practical objective, the studies were intended to utilize the findings for optimizing unit operations which are applied in the process of technology to make washing powder formulations.     

Characteristics of the Surfactant Properties of Sf—Polyelectrolyte Complexes Based on Carboxymethylchitin

High surface activity of mixed solutions of carboxymethylchitin (CMCT) and tetradecyltrimethylammonium bromide (TAB) is observed in the concentration range in which both components are not surface-active. The synergistic effect of the concentration curve of the surface pressure is due to cooperative (not competitive) adsorption on the interface of TAB and CMCT.     

Development of Novel Amidosulfobetaine Surfactant–Polymer Systems for EOR Applications

Experimental studies were conducted to evaluate the thermal stability and rheological properties of novel surfactant–polymer (SP) systems for enhanced oil recovery applications. One in-house synthesized amphoteric amidosulfobetaine surfactant 3-(N-pentadecanamidopropyl-N,N-dimethylammonium)propanesulfonate and three different polymers were evaluated. Polymer A was a terpolymer of acrylamide, acrylamido tert-butyl sulfonate, and acrylic acid, whereas polymers B and C were terpolymers of acrylamide, N-vinylpyrrolidone, and acrylamido tert-butyl sulfonate with different anionicity. Long-term thermal stability of the surfactant was assessed using FTIR, ¹H NMR, and ¹³C NMR. The surfactant was compatible with seawater at 90 °C and no precipitation was observed. Structural analysis showed good thermal stability and no structural changes were observed after aging at 90 °C. The effects of surfactant concentration, shear rate, salinity, and polymer concentration on rheological properties of the SP systems were determined. Polymer A showed highest viscosity among the investigated polymers in deionized and seawater. The interactions between the surfactant and polymer A were assessed using rheological measurements. In the presence of salts, the viscosity of all three polymers reduced significantly as a result of charge screening. At low shear rates, the added surfactant slightly decreased the viscosity and storage modulus of polymer A. At high shear rates, the effect of the surfactant on the viscosity and storage modulus of polymer A was insignificant.     

Adsorption of Anionic–Cationic Surfactant Mixtures on Metal oxide Surfaces

This research evaluates the adsorption of anionic and cationic surfactant mixtures on charged metal oxide surfaces (i.e., alumina and silica). For an anionic-rich surfactant mixture below the CMC, the adsorption of anionic surfactant was found to substantially increase with the addition of low mole fractions of cationic surfactant. Two anionic surfactants (sodium dodecyl sulfate and sodium dihexyl sulfosuccinate) and two cationic surfactants (dodecyl pyridinium chloride and benzethonium chloride) were studied to evaluate the effect of surfactant tail branching. While cationic surfactants were observed to co-adsorb with anionic surfactants onto positively charged surfaces, the plateau level of anionic surfactant adsorption (i.e., at or above the CMC) did not change significantly for anionic–cationic surfactant mixtures. At the same time, the adsorption of anionic surfactants onto alumina was dramatically reduced when present in cationic-rich micelles and the adsorption of cationic surfactants on silica was substantially reduced in the presence of anionic-rich micelles. This demonstrates that mixed micelle formation can effectively reduce the activity of the highly adsorbing surfactant and thus inhibit the adsorption of the surfactant, especially when the highly adsorbing surfactant is present at a low mole fraction in the mixed surfactant system. Thus surfactant adsorption can be either enhanced or inhibited using mixed anionic–cationic surfactant systems by varying the concentration and composition.

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Interaction of DNA with Cationic Gemini Surfactant Trimethylene-1, 3-bis （dodecyldimethyl-ammonium bromide） and Anionic Surfactant SDS Mixed System

The interaction of DNA with cationic gemini suffactant trimethylene-1,3-bis （dodecyl dimethyl-ammonium bromide） （12-3-12） and anionic surfactant sodium dodecyl sulfate （SDS） mixed system has been investigated by measuring the fluorescence, zeta potential, UV-Vis spectrum, and circular dichroism. In the absence of SDS, owing to the electrostatic and hydrophobic interactions, 12-3-12 forms micelle-like structure on the DNA chain before the micellization in bulk phase. For the mixed system of 12-3-12 and SDS, the negative charges on SDS can compete against DNA to bind with cationic 12-3-12 because of the stronger interaction between oppositely charged surfactants, and thus, the catanionic mixed micelles are formed before the formation of DNA/12-3-12 complexes. There-after, the positive charges on the mixed micelles bind with DNA, and thus, the change of the zeta potential from negative to positive is distinctly different from the system without SDS. Meanwhile, the existence of SDS postpones the exclusion of ethidium bromide （EB） from DNA/EB complexes. The conformation of DNA undergoes a change from native B-form to chiral ψ-phase as binding with 12-3-12 process. Upon adding SDS to the DNA/12-3-12 complex solution, however, DNA is released to the bulk and the ψ-phase returns to B-form again.     

Synergistic Behavior Between Zwitterionic Surfactant α-Decylbetaine and Anionic Surfactant Sodium Dodecyl Sulfate

Here, we present experimental surface tension isotherms of mixed solutions of a zwitterionic surfactant α-decylbetaine (DB) and an anionic surfactant sodium dodecyl sulfate (SDS) in different molar ratios. These mixed solutions show a composition dependency with respect to both surface tension effectiveness and critical micelle concentration. The pseudo-regular solution theory has been used to evaluate the interaction parameters in the micelle, β ^m and at the surface, β ^s. The results revealed that the mixed solutions of DB/SDS behave synergistically in both surface tension reduction effectiveness and mixed micelle formation at all mole fractions investigated. The values of adsorption area per surfactant molecule at air/solution interface were estimated, which provides some useful information on evaluating the interaction between DB and SDS in mixed adsorbed monolayers. The solubilization behaviors of toluene in DB/SDS mixed solutions were also investigated to help in understanding the structure of mixed micelles of DB and SDS.     

Surfactant‐Enhanced Regeneration of Polymeric Resin in a Vapor‐Phase Application

Abstract

Surfactant enhanced carbon regeneration (SECR) was employed to regenerate a polymeric resin saturated with trichloroethylene (TCE), using an aqueous solution of the anionic surfactant sodium dodecyl sulfate (SDS). More than 95% of the sorbed TCE was removed in the desorption operation with a 0.1 M SDS solution at a superficial flow rate of 1 cm/min. The desorption rate of TCE from pores of the resin is limited by the concentration of SDS in the regenerant and its flow rate. From the breakthrough curve of the subsequent adsorption cycle without a flushing step following the desorption, only 40% of the effective adsorption capacity of the virgin resin is observed for the regenerated resin. With a water flushing step following the surfactant regeneration step, the effective adsorption capacity is significantly improved to about 60% of that of the virgin resin. Thermal gravimetric analysis indicates that the reduction in the effective adsorption capacity of regenerated resin resulted from the residual SDS remaining in the pores of the resin. The regeneration step is equilibrium limited whereas the water flushing step is rate limited under the studied conditions. Despite the loss of subsequent cycle adsorption capacity, SECR may still be economical as an in‐situ, low temperature regeneration method.     

Surfactant Synthesis via Lipase Esterification of Methyl α-d-Glucopyranoside with Selected Aliphatic Carboxylic Acids

Lipase‐catalyzed esterification and properties of synthesized carbohydrate esters were investigated. Methyl α‐d ‐glucopyranoside was the acyl group acceptor and different carbon atom chain lengths of aliphatic carboxylic acids (C12, C14 and C16) as the acyl group donors were applied in the esterification. Physico‐chemical studies on the synthesized carbohydrate esters were carried out. It was found that melting point for the methyl 6‐O‐hexadecanoyl‐α‐d ‐glucopyranoside was the highest consecutively followed by methyl 6‐O‐tetradecanoyl‐α‐d ‐glucopyranoside and methyl 6‐O‐dodecanoyl‐α‐d ‐glucopyranoside. Liquid crystal properties of the synthesized carbohydrate ester synthesized were evaluated via optical polarized microscopy. It was found that the liquid crystal textures for mono‐substituted carbohydrate esters were of the smectic phase. In a quaternary system (carbohydrate ester/n‐butanol/n‐hexadecane/water), a maximum 34 % of water (by mass) was contained in the monophasic region of methyl 6‐O‐tetradecanoyl‐α‐d ‐glucopyranoside and a maximum of 52 % water (by mass) was contained in a monophasic methyl 6‐O‐dodecanoyl‐α‐d ‐glucopyranoside. For methyl‐6‐O‐dodecanoyl‐α‐d ‐glucopyranoside, its concentration at aggregation was 5.2 × 10^?4 mM, with minimum air/water surface tension of 26 mN m^?1. The Gibbs energy of micellization was calculated at ?50 kJ mol^?1. The maximum adsorption density of methyl 6‐O‐dodecanoyl‐α‐d ‐glucopyranoside was determined at 4 × 10^?6 mol m^?2 while its minimum area per surfactant molecule at the air/water surface was 47 Ų.     

Sorption of Azo Dyes onto a Mexican Surfactant‐Modified Clinoptilolite‐Rich Tuff

Abstract

The selectivity of a Mexican surfactant‐modified clinoptilolite‐rich tuff to retain azo dyes (red‐40, yellow‐5 and a mixture of them) from aqueous solutions has been investigated. The zeolitic material was modified with hexadecyltrimethylammonium bromide and then left in contact with azo dyes. The uptake was determined at different contact times and concentrations of dyes solutions. First order Elovich, and pseudo second order models as well as the lineal, Langmuir, and Freundlich isotherms were used to describe the experimental data. It was found that in single and binary solutions, under the experimental conditions, the modified zeolitic material retain preferentially the dye red‐40 in comparison to yellow‐5. The best models to describe the reaction rate and the sorption of azo dyes red‐40 and yellow‐5 by Mexican surfactant modified clinoptilolite‐rich tuff were pseudo‐second order and Langmuir models, respectively. These results show that surfactant modified clinoptilolite‐rich tuff from Villa de Reyes (San Luis Potosi, Mexico) could be considered as a potential adsorbent of azo dyes from aqueous solutions.     

Preparation and Characterization of C10–C14 Alkyl Cellulose Ester Sulfate Surfactant

The aim of this work is to synthesize surfactants based on cellulose with different molecular weights. Raw cotton cellulose was tailored into cellulose segments with different molecular weights by a hydrothermal process, then the average degree of polymerization (DP) was determined by viscosimetry and the molecular weight distribution was estimated by gel permeation chromatography. The C₁₀–C₁₄ alkyl cellulose ester sulfate surfactants were prepared by hydrophilic sulfonation and hydrophobic esterification. The surface tension of the surfactants solution was obtained by the Wilhelmy plate method. Results showed that the cellulose segments presented a broader distribution compared with the raw material. The critical micelle concentration (CMC) value decreased from 1.08 to 0.86 wt% as the hydrophobic chain length was increased from 10 to 14. The CMC values of cellulose surfactants with C₁₄-acyl chloride hydrophobization decreased from 1.32 to 0.86 wt% as the DP was decreased from 2,700 to 296.     

Micellization and Interfacial Interaction Behaviors of Gemini Cationic Surfactants–CTAB Mixed Surfactant Systems

The interfacial and micellization behaviors of binary mixtures of two gemini cationic surfactants and conventional the cetyl trimethyl ammonium bromide surfactant were studied at various molar ratios. From the equilibrium surface tension measurements, the critical micelle concentrations (CMC) data were obtained as functions of the composition. Values of the CMC were analyzed according to the regular solution model developed by Rubingh for mixed micelles. Two interaction parameters were obtained for each system, the interaction at the interface, and in the micellar phase. The results showed that micellization and adsorption properties of the studied mixed systems depend on the spacer chain lengths of the gemini surfactants and their ratio in the mixed systems.     

Influence of a Zwitterionic Surfactant on the Surface Properties of Electroless Ni–P Coating on Mild Steel

3-(N,N-Dimethyl myristyl-ammonio) propane sulfonate zwitterionic surfactant (C14-SB) which possessed both positive and negative charges was evaluated in the electroless Ni–P coating process. It was observed that the deposition rate, morphology and microhardness of the deposits were enhanced by the addition of C14-SB surfactant. The excess attractive forces from the negative head of C14-SB were strong enough to draw metallic nickel particles towards the substrate. Ni particles attempting to deposit on the electrolyte container were eliminated by the repulsive force from the positive head of the surfactant monomers. Thus, the deposition rate of the coating process was improved. The surfactant at its critical micelle concentration (CMC) doubles the deposition rate when compared to the substrate without surfactant. In addition, the microhardness of the deposit at the surfactant CMC increased by 62 %. The corrosion rate of the substrate without surfactant was 7.15 mpy, while it was 3.97 mpy for the substrate deposited with C14-SB zwitterionic surfactant at the CMC.     

Rheological Investigation of Wormlike Micelles Based on Gemini Surfactant in EG–Water Solution

The self‐assembly behavior of gemini surfactants in ethylene glycol (EG)‐water (5/95, v/v) mixed solvent was investigated by rheological measurements at 10 °C. The influence of molecular structure of the gemini surfactant and added hydrotrope on the solution properties was studied. Sodium salicylate (NaSal) showed stronger ability to induce 2‐hydroxyl‐propanediyl‐α,ω‐bis‐(dimethyldodecylammonium bromide), referred to as 12‐3(OH)‐12, to form wormlike micelles than sodium benzoate. Less NaSal is required to promote a sphere to rod transition and to reach the peak viscosity. Moreover, the concentrations of hydrotrope and gemini surfactant are both lower than conventional single‐chain surfactant systems to reach a comparable viscosity. The strong hydrophobicity of gemini surfactants and hydrotropes is responsible for the high efficiency in forming wormlike micelles in EG/water systems. The geometric structure of gemini surfactants also plays a vital role in self‐assembly into wormlike micelles. Dimethylene‐1,2‐bis‐(dodecyl dimethylammonium bromide), referred to as 12‐2‐12, shows absolute superiority over 12‐3(OH)‐12 in constructing wormlike micelles. The present study will be helpful for developing de‐icing fluids and anti‐freezing solutions, which need rheology control in EG‐aqueous medium at low temperature.     

Effect of Ionic Liquids on Surface and Aggregation Properties of Non-ionic Surfactant Triton™ X-100 in Aqueous Media

The effect of the hydrophilic ionic liquids (ILs) 1-butyl-2,3-dimethylimidazolium bromide [bdmim][Br] and 1-hexyl-2,3-dimethylimidazolium bromide [hdmim][Br] on the aggregation and surface active behaviour of the non-ionic surfactant Triton? X-100 (TX-100) was studied in aqueous media. Several aggregation properties of TX-100 + IL/water systems, such as critical micelle concentration (CMC), surface active parameters, aggregation number (N _agg) and aggregate size, were determined by surface tension, fluorescence and dynamic light scattering (DLS) techniques. It was found that the average micellar size and aggregation number decrease, whereas the CMC increases with increasing concentration of ILs. Interestingly, the CMC value of TX-100 is reduced slightly below 0.5 wt% of both the ILs in the medium. At higher wt% of IL in the system the CMC increases. It was demonstrated that ILs [bdmim][Br] and [hdmim][Br] can be judiciously used at different wt% for modifying the physico-chemical properties of TX-100.     

Effect of Head Groups,Temperature, and Polymer Concentration on Surfactant—Polymer Interactions

The micellization behaviour of sodium dodecyl sulphate, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and cetylpyridinium chloride in water and in aqueous solutions of polyethylene oxide (PEO, molecular weight = 100,000) having concentrations (0.005–0.04 %, w/v) has been studied at different temperatures (288.15–318.15 K) using conductivity, surface tension, and viscosity methods. From conductivity measurements various micellar parameters, like critical micellar concentration (CMC), critical aggregation concentration (CAC), polymer saturation point (PSP), degree of ionization (β), and standard free energy of transfer ( \( \Delta G_{t}^{0} \) ), have been calculated. CAC values have been found to decrease with polymer concentration and increase with temperature. However, the PSP values increase with both polymer concentration and temperature for all surfactants. Similar parameters have also been calculated from surface tension data (CMC^σ, CAC^σ, PSP^σ) along with other parameters such as maximum surface excess concentration at the air/water interface ( \( \Gamma_{\hbox{max} } \) ), minimum area per molecule (A _min), and packing parameter (p). The CMC^σ, CAC^σ, and PSP^σ values are smaller than the corresponding CMC, CAC, and PSP values, but both show similar behaviour with temperature and concentration of polymer. Various parameters indicate that the presence of the aromatic ring in the head group of surfactant decreases its interaction with PEO, whereas the increased hydrophobicity in the tail leads to stronger interactions with PEO. Viscosity studies further supplement the conclusions drawn from the above results.     

Characteristics of Amine Surfactant Modified Peanut Shell and Its Sorption Property for Cr（VI）

Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area anysis showed the physicochemical characterist!cs of the samples. The results of zeta potential,Fourier transform infrared （FT-IR） and Raman spectra analysis illustrated that chemical adsorption and ion exi change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity （qm） of MPS for Cr（VI） increased with temperature, which indicated that the Cr（VI） sorption rocess was endothermic. The saturated sorption capacity of Cr（VI） in the colunm sorption test was 138.34 mg.g-1, which accounted for 93.9% of the qmax at 25 ℃. The regeneration capacity of MPS was evaluated using HC1 solution as an eluent. The high regeneration efficiency （82.6%） validated the dominance of the ion exchange mechanism in the Cr（VI） sorption process with C1ions displacing Cr（VI） oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.     

Evaluation of Rheological and Thermal Properties of a New Fluorocarbon Surfactant–Polymer System for EOR Applications in High-Temperature and High-Salinity Oil Reservoirs

Thermal stability and rheological properties of a novel surfactant–polymer system containing non‐ionic ethoxylated fluorocarbon surfactant was evaluated. A copolymer of acrylamide (AM) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) was used. Thermal stability and surfactant structural changes after aging at 100 °C were evaluated using TGA, ¹H NMR, ¹³C NMR, ¹⁹F NMR and FTIR. The surfactant was compatible with AM–AMPS copolymer and synthetic sea water. No precipitation of surfactant was observed in sea water. The surfactant was found to be thermally stable at 100 °C and no structural changes were detected after exposure to this temperature. Rheological properties of the surfactant–polymer (SP) system were measured in a high pressure rheometer. The effects of surfactant concentration, temperature, polymer concentration and salinity on rheological properties were studied for several SP solutions. At low temperature (50 °C), the viscosity initially increased slightly with the addition of the surfactant, then decreased at high surfactant concentration. At a high temperature (90 °C), an increase in the viscosity with the increase in surfactant concentration was not observed. Overall, the influence of the fluorocarbon surfactant on the viscosity of SP system was weak particularly at high temperatures and high shear rate. Salts present in sea water reduced the viscosity of the polymer due to a charge shielding effect. However, the surfactant was found to be thermally stable in the presence of salts.