University of Guelph, School of Engineering, 50 Stone Road East, Guelph ON, N1G 2W1, Canada.
University of Guelph, Food Science Department, 50 Stone Road East, Guelph ON, N1G 2W1, Canada.
J Environ Sci (China). 2020 Apr;90:98-109. doi: 10.1016/j.jes.2019.11.021. Epub 2019 Dec 18.
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 CaCl 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 Mass-Spectroscopy (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 at 100 mL/L.
可逆的双水包油包水（W/O/W）乳液被开发出来，用于在使用表面活性剂冲洗修复过程中容纳地下烃类泄漏物。通过将 CaCl2 溶液乳化在菜籽油中，然后将 W/O 乳液乳化在海藻酸钠水溶液中，制备了双乳液。通过共焦和光学显微镜证实了双乳液的形成。当与表面活性剂十二烷基硫酸钠（SDS）和椰油酰胺丙基甜菜碱（CPB）混合时，双乳液会反转并凝胶。凝胶可以作为“乳液锁”，防止烃羽流从用表面活性剂冲洗处理的区域扩散，如砂柱试验所示。剪切流变学用于量化双乳液与 SDS 和 CPB 混合时粘弹性模量的增加（胶凝）。SDS 比 CPB 更有效地凝胶双乳液。CPB 和 SDS 可以在水和模型烃（甲苯和机油）之间的界面上吸附，降低界面张力并使界面变硬（如 Langmuir 槽所示）。瓶试验和光学显微镜表明，SDS 和 CPB 可与甲苯或机油和水一起产生 W/O 和 O/W 乳液。SDS 和 CPB 可将机油和甲苯乳化在水中，便于它们在砂柱中流动并回收。使用气相色谱-质谱法（GC-MS）定量测定甲苯从砂柱中的回收量。数据表明，SDS 和 CPB 既可以用于表面活性剂冲洗，也可以用于触发“乳液锁”的凝胶化。乙醇在 100 mL/L 时也能使乳液凝胶化。
