Micelle-water Partition Coefficient Research Articles

Solubilization of Phenanthrene and Fluorene in Equimolar Binary Mixtures of Gemini/Conventional Surfactants

This study deals with the enhanced solubilization of polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene (PHE) and fluorene (FLR) in a pure cationic gemini (G6) and three conventional surfactants [polyethylene glycol dodecyl ether (Brij35), cetyltrimethyl ammonium bromide (CTAB) and sodium lauryl sulfate (SDS)] as well as in their equimolar binary combinations (G6-Brij35, G6-CTAB and G6-SDS). Their solubilization efficiency toward PHE and FLR has been quantified in terms of the molar solubilization ratio (MSR) and the micelle–water partition coefficient (Km). The ideality/nonideality of the mixed micelles is discussed with the help of Clint, Rubingh and Rosen's approaches. These theories determine the deviation of experimental critical micelle concentration (CMC) values from ideal critical micelle concentration, which was measured by evaluating the interaction parameters (βm and βσ). Negative values of βm were observed in all the equimolar binary systems, which show synergism in the mixed micelles. Whereas at air/liquid interface synergism was observed in the systems G6-CTAB and G6-Brij35; G6-SDS exhibited an antagonistic effect. The order of MSR and Km was G6-CTAB>G6-Brij35>G6-SDS for phenanthrene as well as for fluorene.

Mixed micellization of gemini and cationic surfactants: Physicochemical properties and solubilization of polycyclic aromatic hydrocarbons

The micellar and surface properties of single as well as equimolar binary mixed systems of some cationic gemini and monomeric ionic surfactants have been studied by conductivity, surface tension and fluorescence measurements at 300K. The critical micelle concentration (CMC), Γmax (maximum surface excess), Amin (minimum surface area per molecule), πcmc (surface pressure at the CMC) and thermodynamic parameters viz. standard Gibbs free energies of adsorption (ΔGads°), standard Gibbs free energies of micellization (ΔGm°) and minimum free energy of the surface (ΔGmin(s)) of gemini with cationic monomeric surfactants were also evaluated. The negative values of ΔGads° and ΔGm° indicate the spontaneity and stability of the mixed micelle. The experimental CMC values are less than the ideal CMC values, indicating negative deviation from ideal behavior for all the equimolar binary surfactant systems. Aggregation number (Nagg) and Stern–Volmer quenching constant (Ksv) have been evaluated by Fluorescence measurement. The solubilization capacities of selected single and equimolar binary surfactant systems toward polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene, anthracene and pyrene have been evaluated and discussed in terms of the molar solubilization ratio (MSR), the micelle-water partition coefficient (K(m)), the deviation ratio (R), and the free energy of solubilization (ΔGs°) of PAHs. The negative value of ΔGs° shows spontaneity of solubilization process.

Competitive solubilization of low-molecular-weight polycyclic aromatic hydrocarbons mixtures in single and binary surfactant micelles

Abstract The present study aims to assess mutual interaction among low-molecular-weight polycyclic aromatic hydrocarbons (LMW PAHs), predominant contaminants at petroleum contaminated sites, in nonionic, anionic and their mixed micelles. Cosolubilization effects were evaluated by the molar solubilization ratio, the micelle-water partition coefficient and the deviation ratio. Two conditions existed: (i) naphthalene/phenanthrene and naphthalene/fluorene, with significant different hydrophobicities, showed synergistic effect, a new finding compared to previous observations that no more than one solute’s solubility would increase when two solubilizates coexisted, e.g. solubility of naphthalene and phenanthrene in Triton X-100 was increased by 20.8% and 38.5% when cosolubilized, respectively and (ii) phenanthrene/fluorene, with similar hydrophobicity, exhibited inhibitive effect due to competition for the same solubilization sites, i.e. solubility of phenanthrene and fluorene in Triton X-100 was decreased by 36.1% and 6.5% when cosolubilized, respectively. Solubility of PAHs with higher log K ow gained larger enhancement. Synergism was stronger in bisolutes solubilization system where more PAHs could solubilize in the micellar shell region. Solubility inhibition was more intense to PAHs with lower log K ow . The cosolubilization trends were consistent in single and mixed surfactant systems, whereas the enhancing and suppressive extent, on the whole, were weakened and strengthened with increasing mole ratio of anionic surfactant in the mixed micelles because of reduction in micelle size. This study suggested the significance of considering multi-solutes’ interaction to estimate solubilization power of surfactants for selective separation of LMW PAHs from water and soil.

Co-solubilization of the Hydrophobic Drugs Carbamazepine and Nifedipine in Aqueous Nonionic Surfactant Media

Co-solubilization of the hydrophobic drugs Carbamezipine (CBZ) and Nifedipine (NFD) by micellar solutions at 25 °C, using two series of polyoxyethylene based nonionic surfactants, was measured and compared. The first series is composed of surfactants with a 12 carbon (C12) hydrophobic chain while the second series had 16 carbon (C16) hydrophobic chains. Experimental results were obtained for solubilization and co-solubilization of CBZ and NFD within the micelles at saturation and quantification was done in terms of the molar solubilization ratio and the micelle–water partition coefficient employing spectrophotometric and tensiometric techniques. The extent of micellar solubilization of CBZ is much greater than NFD. The C12 series of surfactants exhibit higher solubilization capacities for CBZ than the C16 series while the reverse is the case for NFD. Co-solubilization results showed competitive solubilization of the drugs. A synergistic effect on the solubilization of NFD was observed in the presence of CBZ in Brij30 and Brij56 surfactant systems while, in the remaining surfactants, the solubility of NFD was slightly reduced. Since the surfactants used in the present study are either nontoxic or have minimal toxicity, it is expected that they can be employed as drug delivery vehicles for co-administration of the two drugs in vivo. Both from industrial and research points of view, this paper reports a comprehensive study for co-solubilization of differently structured drugs in micellar media.

Improved solubilities of PAHs by multi-component Gemini surfactant systems with different spacer lengths

Mixed micellization, interface and enhanced solubilization aspects of a series of single cationic Gemini surfactants (alkanediyl-α,ω-bis (dodecyldimethylammonium bromide) as well as their equimolar bi and ternary combinations have been investigated. Several theoretical treatments have been employed to evaluate and compare the mutual interaction parameter, counterion binding, surface excess, free energies of micellization, etc. for finding out synergistic effect of mixed surfactant systems. Nonideality is found to increase with the enlarged difference of spacer length of components in mixtures. Water solubility enhancement of polycyclic aromatic hydrocarbons (PAHs), naphthalene and pyrene, by selected single, equimolar bi and ternary Gemini surfactant systems, has been evaluated from measurements of the molar solubilization ratio, the micelle–water partition coefficient, the deviation ratio and the free energy of solubilization. The spacer length of selected single and mixed Gemini surfactant systems has a different effect on their solubilization capabilities towards PAHs relative to micellar and interfacial behaviors. The results have shown that the solubilization power not only depends on the micellar and interfacial properties of surfactant but also has an association with hydrophilic/hydrophobic properties of solutes. Such studies on binary and ternary Gemini surfactant combinations with the same charge are limited.

Solubilization and Release of a Model Drug Nimesulide from PEO–PPO–PEO Block Copolymer Core–Shell Micelles: Effect of Size of PEO Blocks

The commercially available polypropylene oxide (PPO)–polyethylene oxide (PEO) symmetrical triblock copolymers (Pluronics®) have been recognized as pharmaceutical excipients and used in a variety of applications. This paper reports studies on micellar and solubilization behavior of three PEO–PPO–PEO block copolymers, viz. P103, P104 and P105 (same PPO mol. wt = 3250 g·mol−1 but different % PEO = 30, 40 and 50 %, respectively) in aqueous solutions. Critical micellization concentrations (CMCs), critical micellization temperatures (CMTs), and micelle size/polydispersity for copolymers with and without the drug, nimesulide (NIM), are reported. The solubilization of NIM is significantly enhanced with increasing hydrophobicity (P103 > P104 > P105), concentration, temperature and in the presence of added salt. The copolymer hydrophobicity, temperature and the drug loading strongly affect micelle behavior. The micelle–water partition coefficient (P) and thermodynamic parameters of solubilization, viz. Gibbs energy (\( \Updelta G_{s}^{\text{o}} \)), enthalpy (\( \Updelta H_{s}^{\text{o}} \)) and entropy (\( T\Updelta S_{s}^{\text{o}} \)), were calculated. The solubilization site of the drug in different micellar solutions and its release from Pluronics® micelles in phosphate buffer saline (PBS) solution at 37 °C were examined. The kinetics of NIM exhibits burst release characteristics, which are believed to be controlled by degradation of the copolymers. These studies were carried out to investigate the feasibility of using Pluronics® as a release vehicle of nimesulide in vitro. From the results, it was concluded that Pluronic® based formulations might be practical for drug delivery.

Experimental Study of Surface and Solution Properties of Gemini -conventional Surfactant Mixtures on Solubilization of Polycyclic Aromatic Hydrocarbon

Experimental data are presented on the enhanced solubilities of fluorene (FLR) resulting from solubilization in aqueous solutions of two conventional surfactants: cationic cetyltrimethylammonium bromide (CTAB) , anionic sodium dodecyl sulfate (SDS), nonioinic polyethylene glycol dodecyl ether (Brij35) and a cationic gemini bis (hexadecyldimethylammonium) pentane dibromide (G5). The critical micellar concentration of surfactants was determined by surface tension measurements and aqueous solubilities of fluorene compound in surfactant solutions were measured spectrophotometrically. Solubilization of PAH compound commenced at the surfactant critical micelle concentration and was proportional to the concentration of surfactant in micelle. The results of the mixed systems were analyzed with the help of regular solution theory, in which the deviation of CMCexp values for mixed surfactant systems from CMCideal was measured by evaluating the interaction parameter, βm. Negative values of βm were observed in all equimolar binary systems which show synergism in the mixed micelle. Attraction force between two oppositely charged head groups lead the strongest synergism effect between cationic gemini and anionic conventional surfactant. In addition to molar solubilization ratio (MSR) solubilization efficiency is also quantified in terms of micelle-water partition coefficient (Km).

Solubilization of polycyclic aromatic hydrocarbons by novel biodegradable cationic gemini surfactant ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride and its binary mixtures with conventional surfactants

The aqueous solubility enhancement of the polycyclic aromatic hydrocarbons (PAHs) anthracene and pyrene was investigated by means of micellar solubilization. The solubilization capacity of equimolar binary mixed surfactant solutions of a biodegradable ester-bonded cationic gemini surfactant ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy)dichloride (C16H33(CH3)2N+(CH2COOCH2)2N+(CH3)2C16H33·2Cl−, 16-E2-16) with cationic cetylpyridinium chloride (CPC) and hexadecyltrimethylammonium chloride (CTAC); anionic sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS); nonionic polyoxyethylene (20) cetyl ether (Brij 58) and Triton X-100 (TX-100) towards the PAHs were studied spectrophotometrically. The solubilization capabilities have been discussed in terms of molar solubilization ratio (MSR), micelle–water partition coefficient (Km) and free energy of solubilization (ΔG0S) of the PAHs. While studying the surface and micellar properties of the single/mixed equimolar gemini–conventional surfactant systems by conductometric, tensiometric and fluorescence quenching methods, synergism between the component surfactants in the mixed micellar solutions was observed. The gemini–anionic surfactant mixtures show better solubilization capacity than the gemini–cationic and gemini–nonionic surfactant mixtures.

Competitive solubilization of naphthalene and pyrene in various micellar systems

Cosolubilization of polycyclic aromatic hydrocarbons (PAHs) (naphthalene and pyrene) has been studied in surfactant systems of varying nature of their head-group viz. nonionic: Brij30 and Brij56, cationic: DDEAB and CTAB and anionic: SDS. Solubilization capacity of micelles was quantified in terms of molar solubilization ratio, the micelle–water partition coefficient, the first stepwise association constant and average number of solubilizate molecules per micelle determined by employing spectrophotometric and tensiometric techniques. Solubilization capacity of all the surfactant systems was generally higher for naphthalene than pyrene and followed the order: nonionics>cationics>anionic surfactant. Solubility of naphthalene decreased during cosolubilization in all surfactant systems studied while the solubility of pyrene decreased only in Brij30 and Brij56 surfactant systems due to competitive solubilization of PAHs for the same solubilization site. The solubility of pyrene, however, enhanced in presence of naphthalene in CTAB, DDEAB and SDS surfactant systems owing to increase in core volume of the micelles by the palisade layer solubilization of naphthalene. The results of this study can provide valuable information on the selection of particular surfactant systems for selective separation of naphthalene and pyrene from their mixture relevant to surfactant enhanced remediation (SER) technology at the contaminated sites.

Micellar enhanced ultrafiltration of a rhodium catalyst

Abstract In homogenous catalysis, the retention and reuse of the catalyst, which is extremely important for the feasibility of the process, is more complicated than in heterogeneous catalysis. Micellar enhanced ultrafiltration of Rh(cod)2CF3SO3, a rhodium catalyst precursor for homogeneous hydrogenation reactions, was carried out in a stirred ultrafiltration cell using micellar solutions of Marlophen NP9 without and with the addition of TPP, a phosphine ligand. For two different membranes with a molecular weight cut-off of 5 kDa, made from regenerated cellulose (C) and polyethersulfone (PES), the rhodium retentions without TPP were below 30% while the micelle retentions were almost 100%. In the presence of TPP, the rhodium retentions significantly increased and values of 80% for the PES membrane and 90% for the C membrane were obtained, respectively. The enhanced rhodium retentions are driven by the high micelle–water partition coefficient of TPP that draws the newly formed Rh–P-complex into the micelles. The partition coefficient of TPP was calculated by the enhanced solubility method to be log KMW=5.4±0.1. The C membrane does not only show better rhodium retentions, but also a better performance regarding the flux. In comparison to pure water, the flux for the micellar solutions (cNP9=10 g/L) decreases slightly to a value of 80% for the C-membrane and to a value of 8%–9% for the PES membrane, respectively.

PH Effects in Micellar Liquid Chromatographic Analysis for Determining Partition Coefficients for a Series of Pharmaceutically Related Compounds

Five drugs were studied using micellar liquid chromatography (MLC) to determine micelle-water partition coefficients (Pmw) over a range of mobile phase pH values and column temperatures. In all cases the sodium dodecyl sulphate mobile phase utilised a CN reversed-phase column with UV detection, optimised for the λmax of each drug. The pH of the mobile phase was systematically varied over the range 3 to 7 pH units, incorporating values above and below the pKa‘s of the drugs studied. From this it was possible to determine MLC based values of Pmw and establish their relationships with pKa values, software predicted partition coefficients (clogP), dissociation constants (logD) and published partitioning data (logPow). This study also considered the relationship between column temperature, from 294K to 317K, and Pmw. For all five drugs it was found that Pmw decreased with increasing pH implying a systematic increased preference for the drug to remain in the aqueous phase rather than partition into the micellar phase. In addition, the partition coefficient displayed a linear relationship with log D over the pH range for each drug with a ‘break-point’ observed at the pKa for each drug. With respect to increasing temperature, the results were non-linear indicating that there is no general relationship for these drugs with temperature. Overall, it was found that MLC is suited to the measurement of partition coefficients for pharmaceutical compounds yet it should be noted that both pH and temperature play a significant role in the values obtained. Keywords: HPLC, logP, Micellar Liquid Chromatography, MLC, partition coefficients, pH, CMC, physicochemical property, aromatic hydrocarbons

Enhanced aqueous solubility of naphthalene and pyrene by binary and ternary Gemini cationic and conventional nonionic surfactants

A systematic study has been carried out to get insight into the micellar behavior of Gemini cationic and conventional nonionic in their single as well as equimolar bi and ternary mixed state using the technique of tensiometry. The models proposed by Clint, Rubingh and Motomura et al. have been employed to interpret the formation of mixed micelles and find out synergism. The obtained experimental CMCs are lower than the ideal CMCs, indicating negative deviation from ideal behavior for all multi-component mixed micelles formation. The solubilization capacities of selected equimolar bi and ternary surfactant systems towards polycyclic aromatic hydrocarbons (PAHs), naphthalene and pyrene, have been evaluated from measurements of the molar solubilization ratio (MSR), the micelle–water partition coefficient (Km), the deviation ratio (R) and the free energy of solubilization (ΔGs0) of PAHs. The results show that the solubility of naphthalene and pyrene over that in water in case of Gemini cationic surfactant is dramatically enhanced by adding equimolar nonionic surfactant in both bi and ternary mixed surfactant systems. The studied equimolar ternary surfactant system shows higher solubilizing efficiency than Gemini cationic binary system but lower than their cationic–nonionic counterpart. In addition, the solubilizing power of multi-component mixed surfactants towards naphthalene and pyrene increases with increasing logKow of PAHs. Certainly, the solubilization abilities of the selected surfactants not only depend on their structure and mixing effect but also associate with solubilizing microenvironment and chemical nature of organic solutes.

Monte Carlo simulation of binary surfactant/contaminant/water systems

Surfactant-enhanced remediation (SER) is an effective approach for the removal of absorbed hydrophobic organic compounds (HOCs) from contaminated soils. The solubilization of contaminants by mixed surfactants with attractive and repulsive head–head interactions was studied by measuring the micelle–water partition coefficient (KC) and molar solubilization ratio (MSR) using the lattice Monte Carlo method. The effect of surfactant mixing on the MSR and KC of contaminants displayed the following trend: C4>C3>C2.Synergistic binary surfactant mixtures showed greater solubilization capacities for contaminants than the corresponding individual surfactants. Mixed micellization parameters, including the interaction parameter β, and activity coefficient fi, were evaluated with Rubingh's approach.Synergistic mixed-surfactant systems can improve the performance of surfactant-enhanced remediation of soils and groundwater by decreasing the amount of applied surfactant and the cost of remediation.

Spectroscopic investigations of the molecular interaction of anticancer drug mitoxantrone with non-ionic surfactant micelles

The aim of this study was to investigate the interaction of the anticancer drug mitoxantrone with non-ionic micelles, as simple model systems of biological membranes. UV-VIS absorption spectroscopy was used to quantify the drug-surfactant micelle interactions in terms of the binding constant and the micelle-water partition coefficient of the drug. Interaction of mitoxantrone with non-ionic micelles reduces the dimerization process of mitoxantrone, the drug molecules being encapsulated into micelles as monomer. The strength of the interaction between mitoxantrone and non-ionic micelles is higher at pH10 than at pH7.4, and depends on the surfactant in the order Tween 80>Tween 20>Triton X-100. The higher partition coefficient at pH10 compared to pH7.4 suggests that at basic pH the deprotonated mitoxantrone is incorporated more efficiently into the hydrophobic medium of non-ionic micelles compared to physiological pH, when the protonated drug is predominant. These results on simple model systems miming the drug-membrane interactions contribute to the elucidation of the behaviour of the drug in vivo, as well as the possible utilization of surfactant micelles as drug carriers.

Preparation and optimization of media using Pluronic® micelles for solubilization of sirolimus and release from the drug eluting stents

Understanding the in-vitro release profile of drugs from drug eluting devices such as cardiac stent is crucial in designing and optimizing the drug embedded matrices. Sirolimus (SRL), a widely used anti-inflammatory/antiproliferative/immunosuppressive hydrophobic drug undergoes irreversible changes such as hydrolysis leading to erroneous assessment of the release profile. The release profile mainly depends on the drug release medium. The present study aims to develop and optimize the aqueous medium for the solubilization of SRL and in-vitro release method from drug eluting stent (DES). In the first stage of study several release media containing different buffer compositions, pH, and a series of micelle forming PEO–PPO–PEO block copolymers (known as Pluronic®) were examined for solubility and stability of SRL by reversed phase high performance liquid chromatography (RP-HPLC). SRL showed good solubility and stability at pH 4.0 (both in acetate buffer as well in phosphate buffer) in the presence of block copolymers. Solubilization of SRL was remarkably higher in P103 and P123 micelles than more hydrophilic F68 and F127. To get further insight into the underlying drug dissolution mechanisms, critical micellization temperature (CMT), and hydrodynamic size of micelles with and without drug incorporation were determined by UV–visible spectroscopy and dynamic light scattering (DLS) respectively. The micelle–water partition coefficient (P) and location of solubilized drug were also evaluated from a thermodynamics viewpoint. Finally, the optimized media were examined for the release of SRL from drug eluting stent; the data suggest that a release medium consisting of 0.1% P123 in phosphate buffer pH 4.0 is most suitable for evaluation of in-vitro release of SRL from DES.

Partition Coefficients for Continuous Micellar Reaction Processes

AbstractThe micelle‐water partition coefficients of reactants, products, and catalyst ligands are predicted using UNIFAC‐IF and COSMO‐RS. It is demonstrated that both models represent a reasonable tool for preliminary screening of the micellar systems for a specific continuous reaction process supported by micellar enhanced ultrafiltration (MEUF). The model reaction is the hydrogenation of itaconic acid and its derivatives (dialkyl esters) in the presence of a rhodium‐based catalyst. The effect of the size and nature of the surfactant head group and tail is explored for nonionic and ionic surfactants. The high partition coefficients of the catalyst ligands indicate that no catalyst leakage is expected in MEUF. Based on the concentration dependence of the calculated partition coefficients, the solubilization capacity of micelles is estimated.

Partition Coefficients of Itaconates in Aqueous-Micellar Solutions: Measurements and Predictions with COSMO-RS

The micelle–water partition coefficient KMW is measured for itaconic acid and some of its esters for micellar solutions of the surfactants sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and t-octylphenoxypolyethoxyethanol (Triton X-100). Additionally, KMW is predicted using the conductor-like screening model for real solvents (COSMO-RS) and calculated from log KMW–log KOW relations. We find that, because of the increasing length of the alkyl chain in the ester, KMW increases, and the COSMO-RS predicted values agree well with the experimental ones. Furthermore, COSMO-RS is used to screen the partitioning of the esters in micellar solutions of a homologous series of surfactants (NaCnS, n = 8–16). For hydrophobic solutes, we predicted an increase in KMW with increasing n, while for less hydrophobic solutes, KMW is constant.

Different behaviours in the solubilization of polycyclic aromatic hydrocarbons in water induced by mixed surfactant solutions

Water solubility of polycyclic aromatic hydrocarbons (PAHs), viz, naphthalene and phenanthrene, in micellar solutions at 25°C was investigated, using two series of different binary mixtures of anionic and nonionic surfactants. Tween 80 and Brij-35 were used as nonionic surfactants whereas fatty acids or amphiphilic cyclodextrins (Mod-β-CD) synthesized in our laboratory were used as anionic ones. Solubilization capacity has been quantified in terms of the molar solubilization ratio and the micelle–water partition coefficient, using UV–visible spectrophotometry. Anionic surfactants exhibited less solubilization capacity than nonionics. The mixtures between Tween 80 and Mod-β-CD did not show synergism to increase the solubilization of PAHs. On the other hand, the mixtures formed by Tween 80 and fatty acids at all mole fractions studied produced higher enhancements of the solubility of naphthalene than the individual surfactants. The critical micellar concentration of the mixtures of Tween 80/sodium laurate was determined by surface tension measurements and spectrofluorimetry using pyrene as probe. The system is characterized by a negative interaction parameter (β) indicating attractive interactions between both surfactants in the range of the compositions studied.

Efficiency of single and mixed Gemini/conventional micelles on solubilization of phenanthrene

Water solubility enhancement of phenanthrene (PHE) by a cationic Gemini surfactant (CG), four cationic and nonionic conventional surfactants (Brij35, TX 100, CPC and DTAB) as well as their equimolar binary combinations (CG/Brij35, CG/TX100, CG/CPC and CG/DTAB) have been studied and compared. Their solubilization efficiency and relationship between the structure and the solubilizing capacity towards PHE have been quantified in terms of the critical micelle concentration (CMC), the molar solubilization ratio (MSR) and the micelle–water partition coefficient ( K m ). The ideality/nonideality of the mixed micelles has been discussed in light of Clint, Rubingh, Edwards and Treiner's approaches. It has been observed that both CG and equimolar binary surfactant systems remarkably enhanced the water solubility of PHE. The solubilizing capacity of CG/nonionic surfactants is particularly higher than their corresponding conventional surfactant while the contrary results have been shown by CG/cationic surfactants. This may be attributed to the “complement–counteract” effect between the micellar core solubilization and the micelle–water interface adsorption. The interaction between the Gemini and the conventional surfactants with the same chain length becomes more intense regardless of the positive or the negative effect. These results demonstrate and suggest that CG/nonionic mixed surfactants with the same chain length are more appropriate to employ for soil and water remediation.

Micropartioning and solubilization enhancement of 1,2-bis(bis(4-chlorophenyl) methyl)diselane in mixed micelles of binary and ternary cationic–nonionic surfactant mixtures

The aqueous solubilization of the organoselenium compound viz., 1,2-bis(bis(4-chlorophenyl)methyl)diselane [(ClC6H4)2CHSe]2 has been investigated experimentally in micellar solutions of two cationic (hexadecyltrimethylammonium bromide, CTAB, hexadecyltrimethylammonium chloride, CTAC) and one nonionic (polyoxyethylene(20)mono-n-hexadecyl ether, Brij 58) surfactants possessing the same hydrocarbon “tail” length and in their single as well as equimolar binary and ternary mixed states. Solubilization capacity determined with spectrophotometry and tensiometry has been quantified in terms of molar solubilization ratio and micelle–water partition coefficient. FTIR, UV–vis, fluorescence and zeta potential measurements have been utilized to ascertain the interaction of organochalcogen compound with surfactants. Equimolar cationic–nonionic surfactant combinations show better solubilization capacity than pure cationics or nonionics, whereas equimolar cationic–cationic–nonionic ternary surfactant systems exhibit intermediate solubilization efficiency between their single and binary counterparts. Locus of solubilization of [(ClC6H4)2CHSe]2 in different micellar solutions was probed by UV–visible spectroscopy. The investigation has presented precious information for the preference of mixed surfactants for solubilizing water-insoluble compounds. Indeed the solubilization aptitude of these surfactants is not merely related to molar capacity. The results furnish adequate support to justify comprehensive exploration of the surfactant properties that influence solubilization.