Conventional Cationic Surfactants Research Articles

Aggregation behaviour and thermodynamics of mixed micellization of 1-hexadecylpyridinium bromide and ionic liquid in ethylene glycol/water binary mixtures

Micellar behavior of binary combinations of ionic liquid, 1-tetradecyl-3-methylimidazolium bromide, with conventional cationic surfactant 1-hexadecylpyridinium bromide was investigated by means of conductometry to study the effect of cosolvent and water content and temperature. The critical micelle concentration and the degree of counterion association were calculated from the conductometry data. Thermodynamic parameters were obtained from the temperature dependence of the critical micelle concentration. The standard Gibbs energy of micellization increased with the increasing percentage of cosolvent as well as the mole fraction of C14mimBr. The standard enthalpy and standard entropy of micelle formation were both decreased with the increasing temperature and the concentration of cosolvent. The entropy contribution was larger than the enthalpic one in pure water, whereas in the ethylene glycol/H2O mixture the enthalpy contribution was predominant

CATIONIC MICELLAR EFFECT ON THE REACTION BETWEEN DIPEPTIDE GLYCYL-ALANINE (GLY-ALA) AND NINHYDRIN WITH AND WITHOUT SALT ADDITIVES

The effect of cationic conventional surfactants myristyltrimethylammonium bromide (TTAB),cetyltrimethylammonium bromide (CTAB), and cetylpyridinium chloride (CPC) on the interaction ofdipeptide glycyl-alanine (Gly-Ala) with ninhydrin has been studied spectrophotometrically underdifferent conditions. The reaction rates are higher in the presence of surfactants but the reaction orderremains the same in both the media (first- and fractional-order with respect to [Gly-Ala] and[ninhydrin]). Quantitative kinetic analyses of kψ[surfactant] data were performed on the basis ofpseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton andRomsted) and Piszkiewicz model wherein the micellar binding constants KS for Gly-Ala and KN forninhydrin with surfactant micelles were evaluated. The catalytic efficiency in TTAB increased byadded electrolytes which had been discussed in detail.

Synthesis, micellization properties, and cytotoxicity trends of N-hydroxyethyl-3-alkyloxypyridinium surfactants

N-hydroxyethyl-3-alkyloxypyridinium amphiphiles have been synthesized and characterized by various spectroscopic techniques. Self-assembling properties of these amphiphiles have been studied by surface tension, conductivity, and fluorescence measurements. Basic micellization parameters like critical micelle concentration (cmc), surface tension at the cmc (γ cmc), adsorption efficiency (pC20), effectiveness of surface tension reduction (Π cmc), maximum surface excess concentration (Γ max) and minimum surface area/molecule (A min), and Gibbs free energy of the micellization (ΔG0 mic) have also been determined. The micellization of these 3-alkyloxypyridinium halides in aqueous phase have been found to be exothermic and entropy-driven as assessed by conductivity measurements at different temperatures. Thermal degradation of these surfactants has also been assessed by thermal gravimetric analysis under nitrogen atmosphere. Further, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of these surfactants on C6 glioma cells show them to be less toxic than conventional cationic surfactants.

Application of surfactant assisted dispersive liquid–liquid microextraction as an efficient sample treatment technique for preconcentration and trace detection of zonisamide and carbamazepine in urine and plasma samples

A simple, rapid, and efficient method, based on surfactant assisted dispersive liquid–liquid microextraction (SA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and trace detection of zonisamide and carbamazepine in biological samples. A conventional cationic surfactant called cethyltrimethyl ammonium bromide (CTAB) was used as a disperser agent in the proposed approach. 1.5mL of CTAB (0.45mmolL−1) (disperser solvent) containing 50.0μL of 1-octanol (extraction solvent) was injected rapidly into the 7.0mL of water or diluted plasma or urine. A cloudy solution (water, 1-octanol, and CTAB) was formed in the test tube. After formation of cloudy solution, the mixture was centrifuged and 20μL of collected phase was injected into HPLC for subsequent analysis. Some parameters such as the type and volume of the extraction solvent, the type and concentration of surfactant, pH, ionic strength and centrifugation time were evaluated and optimized. Under optimum extraction conditions, the limits of detections (LODs) were 2.1 and 1.5μgL−1 (based on 3Sb/m) for urine samples, and 2.3 and 1.6μgL−1 for plasma samples. Linear dynamic range of 5–300 and 5–200μgL−1 were obtained for zonisamide and carbamazepine in all samples. Finally, the applicability of the proposed method was evaluated by extraction and determination of the drugs in urine and plasma samples.

Study on Mixed Micelles of Cationic Gemini Surfactants Having Hydroxyl Groups in the Spacers with Conventional Cationic Surfactants: Effects of Spacer Group and Hydrocarbon Tail Length

Gemini surfactants, being more surface-active than their conventional counterparts, have potential applications in various industries. The properties of mixed surfactant systems are far better than those of neat surfactants in many cases, and as a result, mixed surfactants are used in many industrial applications. In the present work, the micellar properties of binary mixtures of the monomeric cationic surfactants hexadecyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB), and dodecyltrimethylammonium bromide (DTAB) with the cationic gemini surfactants 1,3-bis(dodecyl-N,N-dimethylammonium bromide)-2-propanol and 1,4-bis(dodecyl-N,N-dimethylammonium bromide)-2,3-butanediol were studied in aqueous solution at 303.15 K by means of conductivity, steady-state fluorescence, and fluorescence anisotropy techniques. The presence of a small amount of gemini surfactant was found to improve the physicochemical properties of the conventional surfactant. For example, the cmc value of DTAB was reduced to one-sixth of its original value in the presence of 0.1 mole fraction of a gemini surfactant. The spacer group of the gemini surfactant and the hydrocarbon chain of the monomeric surfactant play a significant role in the interactions between the surfactants in mixed micelles. These interactions are greatest when there are similarities in the structures of their hydrocarbon chains; however, the micellization process is favored by increasing hydrophobicity of the monomeric surfactant. The microenvironments of mixed micelles were studied using fluorescence techniques.

Self-Assembled CTAB Nanostructures in Aqueous/Ionic Liquid Systems: Effects of Hydrogen Bonding

Aggregation behavior of a conventional cationic surfactant, n-hexadecyl-trimethylammonium bromide (CTAB), in three imidazolium-based ionic liquids, N-butyl imidazolium chloride (N-BImCl), 1-butyl-3-methyl imidazolium chloride (BMImCl) and 1-hexyl-3-methyl imidazolium bromide (HMImBr)/water systems was investigated by tensiometry, fluorescence, 1H NMR spectroscopy and dynamic light scattering (DLS). Different physicochemical properties such as the critical micelle concentration (CMC), interfacial properties, aggregate size, and polydispersity were determined. Just like in aqueous medium, micelles formed and CMC values were found to be larger in ionic aqueous/liquids (IL) than in water. The results revealed that the surface activity is much lower in aqueous/IL than in water. The types of anion and alkyl substitutions on the imidazolium ring were shown to be affecting the aggregation behavior. The variation of chemical shifts in the presence of surfactant revealed that the hydrogen bonding is an important fa...

Interactions of new 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based surface active ionic liquids with amitriptyline hydrochloride: Micellization and interfacial studies

A new series of cationic surface active ionic liquids (SAILs) based on DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) was synthesized through the quaternization of DBU by alkyl bromides. The SAILs viz. DBU-C12 (8-N-dodecyl-1,8-diazabicyclo[5.4.0]undec-7-en-8-ium bromide), DBU-C14 (8-N-tetradecyl-1,8-diazabicyclo[5.4.0]undec-7-en-8-ium bromide) and DBU-C16 (8-N-hexadecyl-1,8-diazabicyclo[5.4.0]undec-7-en-8-ium bromide) were obtained and their aggregation behaviour was examined by surface tension and conductivity measurements. The SAILs investigated displayed better surface activity than the imidazolium based SAILs (CnmimBr) as well as the conventional cationic surfactants, alkyltrimethylammonium bromides (CnTAB). They also showed a decrease in critical micelle concentration (cmc) values with an increase in the alkyl chain length. Further, their interactions with amphiphilic drug, amitriptyline hydrochloride (AMT) have also been studied by employing the theoretical models proposed by Rubingh, Motomura and Gibbs. The micellar interaction parameter (βm) is negative for most of the mole fractions of AMT (αAMT) in DBU-C14/DBU-C16+AMT systems, indicating attractive interactions. The interfacial parameters such as surface tension reduction efficiency (pC20), effectiveness of surface tension reduction (πcmc), maximum surface excess concentration at the air-water interface (Γmax) and minimum area per surfactant molecule (Amin) were also evaluated for the mixed systems of DBU based SAILs with AMT. The standard Gibbs free energy of micellization (ΔG°m) and the standard free energy of adsorption at the air/water interface (ΔG°ad) for these systems were found to be negative, confirming the feasibility of these drug–SAIL interactions.

Vesicle Formation with an Anionic Surfactant and a Conventional Cationic Surfactant in Mixed Systems

The self-assembly behavior of mixed systems consisting of sodium fatty alcohol ether sulfate (AE3S) and the conventional cationic surfactant cetyltrimethylammonium bromide (CTAB) is investigated. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and small-angle x-ray diffraction (XRD) have been utilized to characterize the microstructures of AE3S/CTAB mixtures in aqueous solutions. Spherical vesicles are formed spontaneously in the AE3S/CTAB mixed systems. The results indicate that these surfactants have excellent efficiencies of vesicle formation and surface tension reduction in the aqueous phase.

Mixed Micellization Behavior of Gemini (Cationic Ester-Bonded) Surfactants with Conventional (Cationic, Anionic and Nonionic) Surfactants in Aqueous Medium

Abstract Two cationic ester-bonded cleavable gemini surfactants of different hydrophobic chain length ethane-1,2-diyl bis(N,N-dimethyl-N-alkylammoniumacetoxy)dichloride, C n H2n+1(CH3)2N+(CH2COOCH2)2N+(CH3)2C n H2n+1. 2Cl- (n-E2-n, n=12, 16), having ester linkage in the spacer, were synthesized adopting the reported procedure. Physicochemical properties of the single and binary gemini-conventional mixed micelles of different mole fractions were studied by conductivity measurements at 30 ºC. The conventional surfactants used were: DTAC (dodecyltrimethylammonium chloride), CTAC (hexadecyltrimethylammonium chloride), CPC (cetylpyridinium chloride), SDS (sodium dodecyl sulfate), SDBS (sodium dodecylbenzene sulfonate), TX-100 (t-octylphenoxypolyethoxyethanol) and Brij 58 (polyoxyethylene (20) cetyl ether). Whereas the critical micelle concentration (cmc) values for the dicationic geminis (12-E2-12 and 16-E2-16) were found to be very low as compared to the respective monomeric surfactant with the same number of carbon atoms in the hydrophobic chain per hydrophilic head group, those for all the binary systems were found to be less than the ideal cmc values studied at different mole fractions of the geminis. This synergistic interaction between the surfactants has been analyzed in the light of various theoretical models such as Clint, Rubingh, Motomura and Maeda.

Solution Properties of Tadpole-type Cationic Amphiphilic Dendrimers Consisting of an Alkyl Chain, a Quaternary Ammonium, and a Poly(amidoamine) Dendron

Tadpole-type amphiphilic dendrimers consisting of an alkyl chain, a quaternary ammonium bromide (qb) and a poly(amidoamine) dendron (den) (CnqbdenGm, where n represents an alkyl chain with a length of 10,14, or 18 carbons; m is the generation number G of dendron taking the value -0.5, 0.5, or 1.5) were synthesized using N, N-dimethylethylenediamine as a central scaffold. Electrical conductivity, surface tension, pyrene fluorescence, and dynamic light scattering measurements were used to characterize the properties of the dendrimers. In addition, the effect of the alkyl chain length and the generation number of a dendron on these properties was evaluated through a comparison with those of the corresponding previously reported amphiphilic dendrimers with lactobionamide sugar terminal groups (CnqbdenGmLac) and conventional cationic monomeric surfactants (CnTAB). Both critical micelle concentration (cmc) and surface tension (except for C18 series) were lower than those of CnqbdenGmLac and CnTAB with the same alkyl chain length, indicating that the synthesized amphiphilic dendrimers have an excellent micelle-forming ability in solution and high adsorption ability at the air/water interface, in spite of the large bulky dendron structure. When the alkyl chain length and the generation number of the amphiphilic dendrimers were increased, the surface tension became high because of the curved long alkyl chain and the bulky structure of dendron. Further, CnqbdenGm formed micelles with a small size in solution, and the micelles of CnqbdenG(-0.5) had almost a constant size despite the changes in the concentration, while those of CnqbdenG0.5 and CnqbdenG1.5 became smaller with increasing concentration. The difference in the behavior results from the difference in the number of amide groups in the low- and high-generation dendrons.

The effect of degree of polymerization on intra- and interchain micellization of a tail-type cationic polysoap

We have used Reversible Addition Fragmentation chain Transfer (RAFT) to polymerize the T-type surfactant monomer α,ω-methacryloylundecyltrimethylammonium bromide (MUTAB) to various degrees of polymerization, and thereby investigate how its self-assembly is affected. Small-angle neutron scattering (SANS) shows that the interchain aggregation into micelles with an approximately constant number of MUTAB monomer equivalents occurs at low degrees of polymerization, but that micelle elongation occurs when the degree of polymerization exceeds a critical value. In this regime interchain aggregation gives way to intrachain assembly into unimolecular or “unimer” micelles. As with conventional cationic surfactant solutions, addition of salicylate produces long, worm-like micelles containing many amphiphilic polymer chains at all degrees of polymerization. Oscillatory rheology reveals a transition from scission- to reptation-dominated relaxation as increasing polymer chain length also increases the distance between potential scission points. The measured relaxation times lie in the range of hundredths to a few seconds – thus demonstrating the rapidly equilibrating nature of these micellar systems even at the highest degrees of polymerization achieved.

Mixing Behavior of Conventional Cationic Surfactants and Ionic Liquid Surfactant 1-Tetradecyl-3-methylimidazolium Bromide ([C14mim]Br) in Aqueous Medium

The surface properties and mixed micellization behavior of binary combinations of ionic liquid surfactant, namely, 1-tetradecyl-3-methylimidazolium bromide ([C14mim]Br) with common cationic surfactants viz. dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), and cetylpyridinium bromide (CPB) have been investigated by surface tension and conductivity measurements. The composition of mixed micelles and the interaction parameter were evaluated from the critical micelle concentrations of single and mixed systems using Rubingh's theory. Activity coefficients of mixed systems show the extent of ideality of individual surfactant. In all mixed systems examined, deviation from ideal behavior was seen. Γmax, Amin, πCMC, and the standard Gibbs free energies of adsorption , standard Gibbs free energies of micellization have been determined. The and values are negative indicating the spontaneity of micelle formation.

Gemini ester quat surfactants and their biological activity.

Cationic gemini surfactants are an important class of surface-active compounds that exhibit much higher surface activity than their monomeric counterparts. This type of compound architecture lends itself to the compound being easily adsorbed at interfaces and interacting with the cellular membranes of microorganisms. Conventional cationic surfactants have high chemical stability but poor chemical and biological degradability. One of the main approaches to the design of readily biodegradable and environmentally friendly surfactants involves inserting a bond with limited stability into the surfactant molecule to give a cleavable surfactant. The best-known example of such a compound is the family of ester quats, which are cationic surfactants with a labile ester bond inserted into the molecule. As part of this study, a series of gemini ester quat surfactants were synthesized and assayed for their biological activity. Their hemolytic activity and changes in the fluidity and packing order of the lipid polar heads were used as the measures of their biological activity. A clear correlation between the hemolytic activity of the tested compounds and their alkyl chain length was established. It was found that the compounds with a long hydrocarbon chain showed higher activity. Moreover, the compounds with greater spacing between their alkyl chains were more active. This proves that they incorporate more easily into the lipid bilayer of the erythrocyte membrane and affect its properties to a greater extent. A better understanding of the process of cell lysis by surfactants and of their biological activity may assist in developing surfactants with enhanced selectivity and in widening their range of application.

Salt Effect on Mixed Micelle and Interfacial Properties of Conventional Cationic Surfactants and the Ionic Liquid Surfactant 1‐Tetradecyl‐3‐methylimidazolium Bromide ([C14mim]Br)

AbstractThe surface properties and mixed micellization behavior of binary combinations of an ionic liquid surfactant, namely, 1‐tetradecyl‐3‐methylimidazolium bromide ([C14mim]Br) with common cationic surfactants viz. tetradecyltrimethylammonium bromide and tetradecylpyridinium bromide in the presence of sodium bromide (NaBr) were investigated by surface tension and conductivity measurements. The critical micelle concentration (CMC) and interfacial parameters, such as the maximum surface excess (Γmax), minimum area per molecule (Amin) and surface pressure at the CMC (πCMC) were determined from the surface tension data. The CMC and Γmax values were found to decrease with increasing salt concentrations. The and values are negative indicating the spontaneity of micelle formation.

Probing Dynamics and Mechanism of Exchange Process of Quaternary Ammonium Dimeric Surfactants, 14-s-14, in the Presence of Conventional Surfactants

In this Article, we investigated effects of different types of conventional surfactants on exchange dynamics of quaternary ammonium dimeric surfactants, with chemical formula C(14)H(29)N(+)(CH(3))(2)- (CH(2))(s)-N(+)(CH(3))(2)C(14)H(29)·2Br(-), or 14-s-14 for short. Two nonionic surfactants, TritonX-100 (TX-100) and polyethylene glycol (23) laurylether (Brij-35), and one cationic surfactant, n-tetradecyltrimethyl ammonium bromide (TTAB), and one ionic surfactant, sodium dodecyl sulfate (SDS) were chosen as typical conventional surfactants. Exchange rates of 14-s-14 (s = 2, 3, and 4) between the micelle form and monomer in solution were detected by two NMR methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). Results show that the nonionic surfactants (TX-100 and Brij-35), the cationic surfactant (TTAB), and the ionic surfactant (SDS) respectively accelerated, barely influenced, and slowed the exchange rate of 14-s-14. The effect mechanism was investigated by the self-diffusion experiment, relaxation time measurements (T(2)/T(1)), the fluorescence experiment (I(1)/I(3)) and observed chemical shift variations. Results reveal that, nonionic conventional surfactants (TX-100 and Brij-35) loosened the molecule arrangement and decreased hydrophobic interactions in the micelle, and thus accelerated the exchange rate of 14-s-14. The cationic conventional surfactant (TTAB) barely changed the molecule arrangement and thus barely influenced the exchange rate of 14-s-14. The ionic conventional surfactant (SDS) introduced the electrostatic attraction effect, tightened the molecule arrangement, and increased hydrophobic interactions in the micelle, and thus slowed down the exchange rate of 14-s-14. Additionally, the two-step exchange mechanism of 14-s-14 in the mixed solution was revealed through interesting variation tendencies of exchange rates of 14-s-14.

An Investigation of Drug Binding Ability of a Surface Active Ionic Liquid: Micellization, Electrochemical, and Spectroscopic Studies

Keeping in view the use of surfactants in drug delivery, the interactions of surface active ionic liquids, such as 1-tetradecyl-3-methylimidazolium bromide (C(14)mimBr), with drugs, viz., dopamine hydrochloride (DH) and acetylcholine chloride (AC), have been studied, and the results are further compared with that of the structurally similar conventional cationic surfactant tetradecyltrimethylammonium bromide (TTAB). The micellization and interfacial behavior of C(14)mimBr and TTAB, in the presence of DH and AC, has been investigated from conductivity and surface tension measurements. Various micellar and adsorption characteristics for these drug-surfactant systems (DH/AC + C(14)mimBr/TTAB) have been investigated, indicating favorable interactions between them. The more detailed information regarding the nature of interactions between C(14)mimBr/TTAB and DH/AC is obtained from cyclic voltammetry (CV) and (1)H NMR measurements. CV measurements have been employed to evaluate the binding constant (K) and the Gibbs free energy change (ΔG) for these drug-surfactant complexes. These measurements indicate the existence of cation-π as well as π-π interactions between drugs and surfactants. A detailed analysis of chemical shifts of protons of drug molecules (DH and AC) in the presence of C(14)mimBr and TTAB has been done by (1)H NMR. The results obtained from (1)H NMR are in agreement with those of CV measurements. (1)H NMR studies along with the conductivity and surface tension measurements help in predicting the possible location of adsorption of these drug molecules in C(14)mimBr and TTAB micelles.

Adsorption of cationic gemini surfactants at solid surfaces studied by QCM-D and SPR—Effect of the presence of hydroxyl groups in the spacer

A series of cationic gemini surfactants with dodecyl tails and with hydroxyl groups in the spacer has been prepared. The self-assembly was studied both in bulk and at solid surfaces. This series of surfactants, denoted 12-n(pOH)-12, with n=3 or 4 and p=1 or 2, was compared with conventional cationic gemini surfactants of 12-n-12 type, with n=2 or 4. The critical micelle concentration was determined by conductometry and tensiometry and the area per polar headgroup was determined using the Gibbs equation. The CMC values were found to follow the trend 12-4-12>12-4(OH)-12>12-4(2OH)-12, showing that, contrary to expectations, the presence of the hydroxyl group(s) promoted the formation of micelles.The adsorption was studied on gold and on gold hydrophobized by a self-assembled monolayer presenting methyl groups towards the bulk phase, using quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR) as measuring tools. The results indicated that all surfactants gave monolayer adsorption on both surfaces. SPR, which measures only adsorbed amount of the solute, showed that an increase in spacer length gave a reduction in adsorbed amount, which is most likely an effect of the longer distance between the tails. The results from the QCM-D experiments, which take into account also the water bound in the adsorbed film, were very different. The hydroxyl-containing surfactants gave the highest adsorbed amount, indicating that the presence of hydroxyl groups in the spacer leads to a much enhanced hydration of the surfactant layer.

Mixed Micellization Behavior of Gemini (Cationic Ester-Bonded) Surfactants with Conventional (Cationic, Anionic and Nonionic) Surfactants in Aqueous Medium

Mixed Micellization Behavior of Gemini (Cationic Ester-Bonded) Surfactants with Conventional (Cationic, Anionic and Nonionic) Surfactants in Aqueous Medium

Physico‐Chemical Investigations of Mixed Micelles of Cationic Gemini and Conventional Surfactants: a Conductometric Study

AbstractThe interaction of cationic gemini and cationic conventional surfactants by conductivity was systematically overviewed, paying attention to synergism observed in micellization. These mixed systems were found to show remarkable synergism in micelle formation. The experimental critical micelle concentration values being lower than the value predicted by ideal solution theory indicate that the mixed micellization is due to attractive interaction between the two components. Gemini/conventional systems form mixed micelle due to attractive interactions (negative β values). The values of micellar mole fraction of constituent 1 (X1) in surfactant mixtures are more than in the ideal state (X1ideal), which means that, the mixed micelles are rich in conventional surfactants in comparison to that in the ideal state.

Removal of phenol from synthetic waste water using Gemini micellar-enhanced ultrafiltration (GMEUF)

Comprehensive studies were conducted on the phenol wastewater ultrafiltration (UF) with the help of various concentrations of cationic Gemini surfactant (N1-dodecyl-N1,N1,N2,N2-tetramethyl-N2-octylethane-1,2-diaminium bromide, CG), conventional cationic surfactant (dodecyl trimethyl ammonium bromide, DTAB), anionic surfactant (sodium dodecyl sulfate, SDS) and nonionic surfactant ((dodecyloxy)polyethoxyethanol, Brij35). A flat sheet module with polyethersulfone (PES) membrane was employed in this investigation. The effects of feed concentration (phenol and surfactant) on the retention of phenol and surfactant, permeate flux and membrane fouling by micelles were evaluated. The distribution coefficient (D), the loading of the micelles (Lm) and the equilibrium distribution constant (K) were also utilized to estimate the micellar-enhanced ultrafiltration ability for phenol. Scanning electron microscope (SEM), Fourier transform infrared spectrometer with attenuated total reflectance accessory (ATR-FTIR) and mercury porosimeter were applied to analyze membrane surface morphology, membrane material characteristics and membrane fouling for the original and fouled membranes. Based on the above analysis, the performance of the selected Gemini surfactant was proved superior in the following aspects: retention of phenol/surfactant (peak value is 95.8% for phenol retention), permeate flux and membrane fouling with respect to other conventional surfactants possessing equal alkyl chain length. These results demonstrated that CG surfactant with exceptional structure has favorable prospects in the treatment of phenol wastewater by the micellar-enhanced ultrafiltration.