Remediation of oily soil using acidic sophorolipids micro-emulsion

A sophorolipids (SLs) micro-emulsion in Winsor type I form was used for crude oil contaminated soil washing treatment. The micro-emulsion shows higher oil removal rate than SLs aqueous solution and diesel oil. The type I micro-emulsion with w(SLs) = 6%, w(NaCl) = 1%, w(diesel) = 13.36% gave a high oil removal rate of 95.6% and the eluate remained in type I state. The recovered oil showed lower viscos-ity, mainly caused by the entering of diesel from the micro-emulsion phase into the oil phase and the lower removal rate of the heavier components, such as the resin and asphaltene. The initial heavily saline-alkaline soil changed into mildly saline-alkaline state after washing treatment, favoring the germi-nation and growth of plants, with ryegrass showing better germination and growth effect than alfalfa. The ryegrass showed good phytoremediation effect on the contaminated soil after SLs micro-emulsion washing. The combination process of SL micro-emulsion washing and ryegrass phytoremediation is prospective for oily soil treatment.& COPY; 2023 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.