Polyoxyethylene sorbitan monooleate(Tween-80) and oleic acid(OA) with different molar ratios were mixed and spread at air/water interface on subphases with varied pH values by using a Langmuir trough to investigate th...Polyoxyethylene sorbitan monooleate(Tween-80) and oleic acid(OA) with different molar ratios were mixed and spread at air/water interface on subphases with varied pH values by using a Langmuir trough to investigate the laws governing the performance of the two components.The surface excess free energy(△G_M^(exc)) of mixed monolayers with various mixed molar ratios at different pH values under the surface pressure of 10 mN/m was analyzed,for the compatibility evaluation of mixtures in the monolayer.The results indicated that Tween-80 and OA could be miscible in thermodynamics under almost all the conditions in the experiments,except when the molar ratios of OA were more than 0.5 on the alkaline subphase at pH 9.5.The better thermodynamic compatibility between OA and Tween-80 occurred as the surface pressure was 10 mN/m,when the molar ratios of OA were 0.7 and 0.1 respectively in our experiments.展开更多
Reversible double water in oil in water(W/O/W)emulsions were developed to contain subsurface hydrocarbon spills during their remediation using surfactant flushing.Double emulsions were prepared by emulsifying CaCl2 so...Reversible double water in oil in water(W/O/W)emulsions were developed to contain subsurface hydrocarbon spills during their remediation using surfactant flushing.Double emulsions were prepared by emulsifying CaCl2 solutions in canola oil,and subsequently by emulsifying the W/O emulsions in aqueous sodium alginate solutions.The formation of double emulsions was confirmed with confocal and optical microscopy.The double emulsions reversed and gelled when mixed with the surfactants sodium dodecyl sulfate(SDS)and cocamidopropyl betaine(CPB).Gels can act as’emulsion locks’to prevent spreading of the hydrocarbon plume from the areas treated with surfactant flushing,as shown in sand column tests.Shear rheology was used to quantify the viscoelastic moduli increase(gelation)upon mixing the double emulsion with SDS and CPB.SDS was more effective than CPB in gelling the double emulsions.CPB and SDS could adsorb at the interface between water and model hydrocarbons(toluene and motor oil),lowering the interfacial tension and rigidifying the interface(as shown with a Langmuir trough).Bottle tests and optical microscopy showed that SDS and CPB produced W/O and O/W emulsions,with either toluene or motor oil and water.The emulsification of motor oil and toluene in water with SDS and CPB facilitated their flow through sand columns and their recovery.Toluene recovery from sand columns was quantitated using Gas-Chromatography MassSpectroscopy(GC-MS).The data show that SDS and CPB can be used both for surfactant flushing and to trigger the gelation of’emulsion locks’.Ethanol also gelled the emulsions at100 mL/L.展开更多
文摘Polyoxyethylene sorbitan monooleate(Tween-80) and oleic acid(OA) with different molar ratios were mixed and spread at air/water interface on subphases with varied pH values by using a Langmuir trough to investigate the laws governing the performance of the two components.The surface excess free energy(△G_M^(exc)) of mixed monolayers with various mixed molar ratios at different pH values under the surface pressure of 10 mN/m was analyzed,for the compatibility evaluation of mixtures in the monolayer.The results indicated that Tween-80 and OA could be miscible in thermodynamics under almost all the conditions in the experiments,except when the molar ratios of OA were more than 0.5 on the alkaline subphase at pH 9.5.The better thermodynamic compatibility between OA and Tween-80 occurred as the surface pressure was 10 mN/m,when the molar ratios of OA were 0.7 and 0.1 respectively in our experiments.
基金funded by the Natural Sciences and Engineering Research Council of Canada through a Discovery Grant awarded to Dr.Erica Pensini(No.RGPIN-2018-04636)
文摘Reversible double water in oil in water(W/O/W)emulsions were developed to contain subsurface hydrocarbon spills during their remediation using surfactant flushing.Double emulsions were prepared by emulsifying CaCl2 solutions in canola oil,and subsequently by emulsifying the W/O emulsions in aqueous sodium alginate solutions.The formation of double emulsions was confirmed with confocal and optical microscopy.The double emulsions reversed and gelled when mixed with the surfactants sodium dodecyl sulfate(SDS)and cocamidopropyl betaine(CPB).Gels can act as’emulsion locks’to prevent spreading of the hydrocarbon plume from the areas treated with surfactant flushing,as shown in sand column tests.Shear rheology was used to quantify the viscoelastic moduli increase(gelation)upon mixing the double emulsion with SDS and CPB.SDS was more effective than CPB in gelling the double emulsions.CPB and SDS could adsorb at the interface between water and model hydrocarbons(toluene and motor oil),lowering the interfacial tension and rigidifying the interface(as shown with a Langmuir trough).Bottle tests and optical microscopy showed that SDS and CPB produced W/O and O/W emulsions,with either toluene or motor oil and water.The emulsification of motor oil and toluene in water with SDS and CPB facilitated their flow through sand columns and their recovery.Toluene recovery from sand columns was quantitated using Gas-Chromatography MassSpectroscopy(GC-MS).The data show that SDS and CPB can be used both for surfactant flushing and to trigger the gelation of’emulsion locks’.Ethanol also gelled the emulsions at100 mL/L.
