Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to...Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.展开更多
A metal-ligand coordinated surfactant system formed by calcium dodecylsulfate(Ca(DS)2)/tetradecyldimethylamine oxide (C14DMAO)/H2O was studied in terms of surface tension,conductivity,negative-staining TEM,phase behav...A metal-ligand coordinated surfactant system formed by calcium dodecylsulfate(Ca(DS)2)/tetradecyldimethylamine oxide (C14DMAO)/H2O was studied in terms of surface tension,conductivity,negative-staining TEM,phase behavior and rheological operation.In C14DMAO solution,when Ca(DS)2 is added,metal-ligand complexes form between the Ca 2+and N→O group of C14DMAO.Under this metal-ligand driving force,different phases can be obtained at different concentrations and different ratios of Ca(DS)2 and C14DMAO.At the fixed C14DMAO concentration,L1-phase consisting of spherical micelles forms at first.With the addition of Ca(DS)2,the spherical micelles elongate to be wormlike micelles and then after an L1/L-two phase region,the birefringent vesicle-phase(Lv-phase)region is observed.When Ca(DS)2 concentration continues to increase,a gel-phase region is found after the Lv-phase region and then precipitates of undissolved Ca(DS)2 appear.The transition between different phases is affected by temperature remarkably.The wormlike micellar solutions and vesicle solutions were checked by rheological measurements and showed apparent viscoelasticity at high surfactant concentrations.展开更多
文摘Biologically produced surfactants （SACs） can mobilize and solubilize non-aqueous phase liquids （NAPL） adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties （critical micelle concentration （CMC）, minimum surface tension） of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds （kerosene Jet A-l）, aromatic and aliphatic hydrocarbons （represented by toluene and hexane）. The solution of biosurfactant Yarrowia lipolytica （YAR） in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola （CAN） was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane （HCH） isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status （Yarrowia lipolytica, Candida sp., etc.） seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes.
基金supported by the National Natural Science Foundation of China (20833010 and 20803045)the Foundation of Ministry of Education of China for New Teachers (200804221008)
文摘A metal-ligand coordinated surfactant system formed by calcium dodecylsulfate(Ca(DS)2)/tetradecyldimethylamine oxide (C14DMAO)/H2O was studied in terms of surface tension,conductivity,negative-staining TEM,phase behavior and rheological operation.In C14DMAO solution,when Ca(DS)2 is added,metal-ligand complexes form between the Ca 2+and N→O group of C14DMAO.Under this metal-ligand driving force,different phases can be obtained at different concentrations and different ratios of Ca(DS)2 and C14DMAO.At the fixed C14DMAO concentration,L1-phase consisting of spherical micelles forms at first.With the addition of Ca(DS)2,the spherical micelles elongate to be wormlike micelles and then after an L1/L-two phase region,the birefringent vesicle-phase(Lv-phase)region is observed.When Ca(DS)2 concentration continues to increase,a gel-phase region is found after the Lv-phase region and then precipitates of undissolved Ca(DS)2 appear.The transition between different phases is affected by temperature remarkably.The wormlike micellar solutions and vesicle solutions were checked by rheological measurements and showed apparent viscoelasticity at high surfactant concentrations.
