TX-114+TBAB体系中非电解质对CP的影响(英文)

The effects of nonelectrolytes (ureas, amino acids, sugars) on the cloud point (CP) of nonionic surfactant Triton X-114 (TX-114) and tetra-n-butylammonium bromide (TBAB) system were studied. Ureas as well as thioureas increased the CP. Behaviors of amino acids depended upon their nature. Nonpolar and uncharged polar amino acids were less effective in changing the CP. However, tryptophan and phenylalanine increased the CP sharply. Acidic amino acid (aspartic acid) and sugars decreased the CP. The results were explained in terms of their effect on water structure. Amino acids got solubilized either in the micellar interior or in the bulk phase.

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 （CRAB） 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 （Kin）. 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 concen- tration （CMC） values from ideal critical micelle concentration, which was measured by evaluating the interaction parameters （/3m and/3）. Negative values ofβm 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-CrAB 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.

Micelle Catalyzed Oxidation of D-Mannose by Cerium (IV) in Sulfuric Acid

Kinetics of D-mannose oxidation by cerium (IV) was studied in a sulfuric acid medium at 40 ℃ both in absence and presence of ionic micelles. In both cases, the rate of the reaction was first-order in D-mannose and in cerium (IV), which decreased with increasing [H2SO4]. This suggested that the redox reaction followed the same mechanism. The reaction proceeded through formation of an intermediate complex, which was proved by kinetic method. The complex underwent slow unimolecular decomposition to a free radical that reacted with cerium (IV) to afford the product. The catalytic role of cationic cetyltrimethylammonium bromide (CTAB) micelles was best explained by the Menger-Portnoy model. The study of the effect of CTAB also indicated that a negatively charged species was reactive form of cerium (IV). From the kinetic data, micelle-cerium (IV) binding and rate constants in micellar medium were evaluated. The anionic micelle of sodium dodecyl sulfate plays no catalytic role. The oxidation has the rate expression: -d[Ce(IV)]= k1Kc1[D-mannose][Ce(IV)]dt Different activation parameters for micelle catalyzed and uncatalyzed paths were also calculated and discussed.

水溶液中两亲药物盐酸异丙嗪-表面活性剂体系的胶束化行为(英文)

The behavior of the mixed amphiphilic drug promethazine hydrochloride(PMT) and cationic as well as nonionic surfactants was studied by tensiometry.The cmc values of the PMT-surfactant systems decrease at a surfactant mole fraction of 0.1 and it then becomes constant.The critical micelle concentration(cmc) values are lower than the ideal cmc(cmc*) values for PMT/TX-100,PMT/TX-114,PMT/Tween 20,and PMT/Tween 60 systems.For the PMT/Tween 40,PMT/Tween 80,PMT/CPC,and PMT/CPB systems the cmc values are close to the cmc* values.This indicates that PMT forms mixed micelles with these surfactants by attractive interactions.The surface excess(Γmax) decreases in the presence of surfactants.The rigid structure of the drug makes adsorption easier and the contribution of the surfactant at the interface decreases.The interaction parameters βm(for the mixed micelles) and βσ(for the mixed monolayer) are negative indicating attraction among the mixed components.

混合胶束中Gemini阳离子表面活性剂14-s-14与常规表面活性剂的协同作用:连接臂及反离子效应(英文)

The mixed micelle formation of binary cationic 14-s-14 gemini with conventional single chain surfactants was studied by conductivity measurements.The critical micelle concentration(cmc) and the degree of counterion binding values(g) of the binary systems were determined.The results were analyzed by applying regular solution theory(RST) to calculate micellar compositions(X),activity coefficients(f1,f2),and the interaction parameters(β).The synergistic interactions of all the investigated cationic gemini+conventional surfactant combinations were found to be dependent upon the length of hydrophobic spacer of the gemini surfactant.The excess Gibbs free energy of mixing was evaluated,and it indicated relatively more stable mixed micelles for the binary combinations.

不同浓度和温度时无机盐和尿素对抗抑郁剂药物丙咪嗪盐酸盐的胶束化行为的影响(英文)

In the present study we report the micellization behavior of imipramine hydrochloride(IMP)in absence and presence of different concentrations of inorganic salts(LiCl,NaF,NaCl,NaBr,and KCl)and ureas(urea and thiourea)over the temperature range from 288.15 to 303.15 K.The critical micellization concentrations(cmc)of drug and drug+additive systems were determined by conductometric technique. With increasing temperature the cmc first increases then decreases.Maximum cmc values were obtained at 293.15 K with or without additives.In presence of inorganic salts the cmc value decreases which is explained on the basis of nature and ion size of the added ion.Urea and thiourea also decrease the cmc at low concentrations(0.2 mmo·lL -1 urea and 0.1 mmo·lL -1 thiourea),but,at higher concentrations,increase in cmc is observed.The related thermodynamic parameters are also evaluated and discussed.