The interaction between N, N′-bis（dimethyldodecyl）-1,6-hexanediammoniumdibromide （G12-6-12） and cetyltrimethylammonium bromide （CTAB） in D20 aqueous medium has been investigated by NMR at 298 K. The G12-6-12 an...The interaction between N, N′-bis（dimethyldodecyl）-1,6-hexanediammoniumdibromide （G12-6-12） and cetyltrimethylammonium bromide （CTAB） in D20 aqueous medium has been investigated by NMR at 298 K. The G12-6-12 and CTAB are about 0.773 and measured critical micelle concentration （cmc） of 0.668 mmol/L, respectively. The cmc^＊ （cmc of mixture） values are less than CMC^＊ （cmc of ideally mixed solution） in the mixed system, and the interaction parameter βM〈0 at different molar fractions α of G12-6-12 in the mixed systems, but just when α≤0.3, cmc^＊ values are much smaller than CMC^＊, and βM satisfies the relation of ｜βM｜〉｜ln（cmc1/cmc2）｜ （cmcl： cmc of pure G12-6-12 and cmc2： cmc Of pure CTAB）. The results indicate that there exists synergism between G12-6-12 and CTAB, and they can form mixed micelles, which is further proven by 2D NOESY and self-diffusion coefficient D experiments. There are intermolecular cross peaks between G12-6-12 and CTAB in 2D NOESY, and the radius of micelles in mixed solution is bigger than that in G12-6-12 pure solution in D experiments, indicating there are mixed micelles. However, when α〉0.3, we find that cmc^＊≈CMC^＊, βM≈0, obviously, the two surfactants are almost ideal mixing fitting the pseudo-phase separation model and regular solution theory.展开更多
The production and properties of the biosurfactant synthesized by Bacillus subtilis CCTCC AB93108 were studied. The maximum concentration of the surfactant is 1.64 g/L when the bacteria grow in a medium supplemented w...The production and properties of the biosurfactant synthesized by Bacillus subtilis CCTCC AB93108 were studied. The maximum concentration of the surfactant is 1.64 g/L when the bacteria grow in a medium supplemented with glucose as carbon sources. The isolated biosurfactant is a complex of protein and polysaccharide without lipids. It reduces the surface tension of distilled water to 45.9 mN/m, and its critical micelle concentration (CMC) is 2.96 g/L. It can stabilize emulsions of several aromatic and aliphatic hydrocarbons, such as benzene, xylene, n-pentane, n-nonane, gasoline and diesel oil. It presents high emulsification activity and stability in a wide range of temperature (4-100 ℃) and a long period of duration.展开更多
Micellar enhanced ultrafiltration （MEUF） is a new effective treatment technology for the filtration removal of organic pollutants through solubilization. The present paper is aimed to study the solubilization of org...Micellar enhanced ultrafiltration （MEUF） is a new effective treatment technology for the filtration removal of organic pollutants through solubilization. The present paper is aimed to study the solubilization of organic compounds such as chlorobenzene （CB）, pyrene and phenol by anionic, cationic and mixed anionic-nonionic surfactants such as sodium dodecyl sulfate （SDS）, cetyltrimethylammonium bromide （CTMAB） and Tween-80 （TW80） and the mixed SDS-TW80 with a batch equilibrium method. This study enables us to supply deeper investigation for MEUF. The results showed that solubilization capacity was not obvious below the critical micellar concentration （CMC）. The apparent solubilities of organic compounds were linearly related to surfactant concentrations over their CMCs. Solubilization capacity by single surfactants follow the order of TW80 〉 CTMAB 〉 SDS. The results also proved that the solubilization of the organic contaminants by the mixed surfactants can significantly be enhanced compared with the single anionic surfactant SDS. Whereas the CMC can be decreased, the solubility can be increased as long as the mass ratio of nonionic surfactant increases. The solubility enhancement efficiency of the different organic compounds follow the order of phenol 〉 CB 〉 pyrene. In addition, the solubilization ratio appears to be positively relative to the intrinsic water solubility of the organic contaminants and negatively correlates to octanol-water coefficients （Kow） of organic compounds and the hydrophile-lypophile balance values （HLB） of the surfactants.展开更多
文摘The interaction between N, N′-bis（dimethyldodecyl）-1,6-hexanediammoniumdibromide （G12-6-12） and cetyltrimethylammonium bromide （CTAB） in D20 aqueous medium has been investigated by NMR at 298 K. The G12-6-12 and CTAB are about 0.773 and measured critical micelle concentration （cmc） of 0.668 mmol/L, respectively. The cmc^＊ （cmc of mixture） values are less than CMC^＊ （cmc of ideally mixed solution） in the mixed system, and the interaction parameter βM〈0 at different molar fractions α of G12-6-12 in the mixed systems, but just when α≤0.3, cmc^＊ values are much smaller than CMC^＊, and βM satisfies the relation of ｜βM｜〉｜ln（cmc1/cmc2）｜ （cmcl： cmc of pure G12-6-12 and cmc2： cmc Of pure CTAB）. The results indicate that there exists synergism between G12-6-12 and CTAB, and they can form mixed micelles, which is further proven by 2D NOESY and self-diffusion coefficient D experiments. There are intermolecular cross peaks between G12-6-12 and CTAB in 2D NOESY, and the radius of micelles in mixed solution is bigger than that in G12-6-12 pure solution in D experiments, indicating there are mixed micelles. However, when α〉0.3, we find that cmc^＊≈CMC^＊, βM≈0, obviously, the two surfactants are almost ideal mixing fitting the pseudo-phase separation model and regular solution theory.
基金Project(IRT0719) supported by the Program for Changjiang Scholars and Innovative Research Team in University of China Project (2004AA649370) supported by the National High-Tech Research and Development Program of China+1 种基金 Projects(50425927, 50225926) supported by the Natural Foundation for Distinguished Young Scholars Project(2007F3102) supported by Technology Foundation for Creative Young Scholars of Fujian Province, China
文摘The production and properties of the biosurfactant synthesized by Bacillus subtilis CCTCC AB93108 were studied. The maximum concentration of the surfactant is 1.64 g/L when the bacteria grow in a medium supplemented with glucose as carbon sources. The isolated biosurfactant is a complex of protein and polysaccharide without lipids. It reduces the surface tension of distilled water to 45.9 mN/m, and its critical micelle concentration (CMC) is 2.96 g/L. It can stabilize emulsions of several aromatic and aliphatic hydrocarbons, such as benzene, xylene, n-pentane, n-nonane, gasoline and diesel oil. It presents high emulsification activity and stability in a wide range of temperature (4-100 ℃) and a long period of duration.
文摘Micellar enhanced ultrafiltration （MEUF） is a new effective treatment technology for the filtration removal of organic pollutants through solubilization. The present paper is aimed to study the solubilization of organic compounds such as chlorobenzene （CB）, pyrene and phenol by anionic, cationic and mixed anionic-nonionic surfactants such as sodium dodecyl sulfate （SDS）, cetyltrimethylammonium bromide （CTMAB） and Tween-80 （TW80） and the mixed SDS-TW80 with a batch equilibrium method. This study enables us to supply deeper investigation for MEUF. The results showed that solubilization capacity was not obvious below the critical micellar concentration （CMC）. The apparent solubilities of organic compounds were linearly related to surfactant concentrations over their CMCs. Solubilization capacity by single surfactants follow the order of TW80 〉 CTMAB 〉 SDS. The results also proved that the solubilization of the organic contaminants by the mixed surfactants can significantly be enhanced compared with the single anionic surfactant SDS. Whereas the CMC can be decreased, the solubility can be increased as long as the mass ratio of nonionic surfactant increases. The solubility enhancement efficiency of the different organic compounds follow the order of phenol 〉 CB 〉 pyrene. In addition, the solubilization ratio appears to be positively relative to the intrinsic water solubility of the organic contaminants and negatively correlates to octanol-water coefficients （Kow） of organic compounds and the hydrophile-lypophile balance values （HLB） of the surfactants.
