Anionic Surfactants In Aqueous Solutions Research Articles

The interaction between co‐polymer of vinylpyrrolidone and vinylacetate and anionic surfactants in aqueous solutions

AbstractThe interaction of co‐polymers of vinylpyrrolidone‐vinylacetate with anionic surfactants, such as lithium dodecyl sulfate (LiDS), lithium perfluorooctane sulfonate (LiFOS) in aqueous solution, has been studied. When the content of vinylacetate in the co‐polymers increases, reduction in the surface tension of co‐polymers alone becomes significant. In mixtures of co‐polymers and surfactants, co‐polymer‐LiFOS complexes are formed at lower surfactant concentration than that of co‐polymer‐LiDS. The micropolarity of the co‐polymers‐surfactant complexes depends on the composition of co‐polymers and is higher for co‐polymer‐LiFOS than that for co‐polymer‐LiDS. Further, the solubilization behavior of α‐(o‐tolylazo‐)‐β‐naphthylamine (Yellow OB) (Tokyo Kasei Co., Ltd., Tokyo, Japan) in the co‐polymer‐surfactant complexes is almost independent of the co‐polymer composition, but different from the surfactants, where a very low solubilized amount of Yellow OB is observed for co‐polymer‐LiFOS.

Interaction between zwitterionic fluorocarbon and anionic surfactants in aqueous solutions

Interaction between zwitterionic fluorocarbon and anionic surfactants in aqueous solutions

Interaction of sodium carboxymethylamylose with aqueous surfactants in both the presence and the absence of added salt: mixed micelles and inclusion complexes

Fluoresence probe techniques have been employed to monitor interactions of sodium carboxymethylamylose (NaCMA) with cationic and anionic surfactants in aqueous solution in both the absence and the presence of added salt. The changes of the I 1 I 3 ratio of the fluorescence of pyrene in NaCMA solution were measured as a function of hexadecyltrimethylammonium chloride (HTAC) and sodium dodecyl sulphate (SDS) concentration. In the absence of added salt, mixed micelle formation of NaCMA with both HTAC and SDS was observed with an apparent critical micelle concentration ( CMC) of 1 × 10 −4 and 3 × 10 −3 M respectively. These are the first observations of mixed micelle formation between an anionic surfactant and an anionic polyelectrolyte. The average aggregation numbers of the mixed micelles were measured by the analysis of the fluoresence decay curve of the micelle-solubilized pyrene to be smaller than that for the micelles in the absence of NaCMA. In the presence of 2% NaCl the apparent CMC values of the surfactants are greater than those in the absence of NaCMA, suggesting that NaCMA forms inclusion complexes with both HTAC and SDS. The association constant of NaCMA with HTAC is 4.1 × 10 4 M −1, and the maximum amount of bound HTAC per anhydroglucose residue is 0.014. This result is consistent with the model of interrupted 6-helix conformation of NaCMA.

Determination of anionic surfactants by two‐phase titration with tetrabromophenolphthalein ethyl ester as indicator

AbstractA method has been developed for the determination of anionic surfactants in aqueous solution. It is based on solvent extraction titration of an ion pair. Zephirmine (tetradecyldimethyl ammonium chloride) is used as a titrant with tetrabromophenolphthalein ethyl ester as an indicator in the presence of chloroform. In the two‐phase titration (chloroform/water), the proposed procedure gives sharp end‐points as the organic phase changes from yellow to blue. The aqueous phase is colorless throughout the titration.

Mixed micelles of polyoxyethylene-type nonionic and anionic surfactants in aqueous solutions

Critical micelle concentrations (CMC) and the solubilization toward dyestuff yellow OB in aqueous solutions of mixed polyoxyethylene-type nonionic and anionic surfactants at 30°C were measured. As for the CMC, the stabilization of the mixed micelles relating to polyoxyethylene chains was suggested by application of the pseudo-phase-separation model. Concerning solubilization, the same measurements were also performed for various other surfactant mixed systems, and we defined the solubilizing power of the mixed surfactant solution and the ratio of this quantity to that in the additivity law. Solubilization in the system of mixed polyoxyethylene-type nonionic and anionic surfactants showed a specific behavior as compared with the other systems. From the CMC and solubilization studies, we proposed the model concerning the mixed micelles of polyoxyethylene-type nonionic and anionic surfactants. In the model, polyoxyethylene chains in the mixed micelle have an attracting interaction with anionic head groups, and the interaction is enhanced by the formation of a hydrocarbon core. This status is different from that in free polyethylene glycol and surfactant systems.

THE INTERACTION BETWEEN <i>p</i>-AMINOAZOBENZENE AND ANIONIC SURFACTANTS

The interaction between p-aminoazobenzene and anionic surfactants in aqueous solution was studied by spectral change of the mixed solution and decrease of equilibrium adsorption on dyeing of cellulose acetate in this system.A p-aminoazobenzene molecule with an anionic surfactant molecule, such as sodium dodecylsulfate or sodium dodecylbenzenesulfonate likely forms 1:1-complex in aqueous soltion and a new adsorption band due to this complex spears at about 510mμ, while intensity of maximum adsorption of p-aminoazobenzene at 377mμ decreases.Up to C. M. C. the new band increases in intensity with the concentration of anionics. The spectral change with a fixed concentration of p-aminoazobenzene and varying concentration of anionics has definite isosbestic point at 337mμ and 456mμ.As the absorption of new band decreases with rising temperature, the formation of such complex is an exothermic reaction. There is little difference between the absorption spectra of the cellulose acetate film dyed in p-aminoazobenene aqueous solution in the presence and absence of anionics. From this results, it can be concluded that the complex itself is not taken up by acetate fiber, hence the formation of the complex in the dye bath leads to diminish the effective concentration of p-aminoazobenzene for dyeing.The concentration of the complex in the infinite dye baths which contain different amount of anionics is determined from the decrease of apparent partition coefficient in acetate dyeing at different temperature. The equilibrium coefficients of the complex formation are thus determined at different temperature.The heat of formation, ΔH° and entropy change, ΔS° of the complex formation between p-aminoazobenzene and sodium dodecylsulfate are caluculated to be -11Kcal/mol, -25cal/mol/deg, respectively. As the equiliblium coefficients of the complex formation are in the order of 102 at room temperature and pH=6.4_??_6.6, only a small amount of complex may exist in the dye bath at pratical dyeing temperature.