氧化/还原型开关表面活性剂对硝基苯污染土壤的淋洗及分离效果

Flushing and separating effects for nitrobenzene contaminated soil by a redox-switchable surfactant

合成了一种氧化/还原型开关表面活性剂11-二茂铁十一烷酰基三甲基溴化铵(FcCOC10N),通过二茂铁基团氧化及还原态的转变来实现自身表面活性的“开”与“关”,以期在强化有机污染土壤淋洗修复的同时,实现表面活性剂的分离回收.FcCOC10N发生氧化/还原反应前后的理化性质差异表明其具有良好的氧化/还原可逆特性.FcCOC10N溶液与硝基苯易乳化成液滴小而均匀的乳液,向其中添加氧化剂随即破乳分离,且FcCOC10N反复开关5次后与硝基苯形成的乳液性质几乎无变化,破乳率在80%以上,二者之间具有良好的乳化破乳循环能力.对硝基苯污染土壤进行淋洗,以乳化的方式去除土壤中非水相污染物,乳化去除率最高为92.40%,通过破乳分离硝基苯,对FcCOC10N进行回收利用,进一步去除土壤中残余硝基苯,最终去除率达到94.70%.

A redox-switchable surfactant,11-ferrocene undecanoyl trimethylammonium bromide(FcCOC10N),was synthesized in this study,achieving the“on”and“off”of its surface activity through the oxidation and reduction state transition of the ferrocene groups.The aim was to facilitate the separation and recovery of the surfactant while improving the remediation of polluted soil by organic contaminates through soil flushing technique.The differences in physical and chemical properties of FcCOC10N before and after the redox reaction indicated its good redox-reversible characteristics.The FcCOC10N solution and nitrobenzene were easily emulsified into an emulsion with small and uniform droplets,which was immediately demulsified and separated with the addition of an oxidant.Moreover,no change was observed for the properties of the emulsion formed by FcCOC10N and nitrobenzene after repeated 5switches,with a demulsification efficiency of>80%,demonstrating a good emulsification and demulsification cyclic capability between FcCOC10N and nitrobenzene.Flushing of nitrobenzene-contaminated soil was conducted to remove the non-aqueous phase pollutants from the soil via emulsification,with the highest emulsification removal efficiency of 92.40%.Residual nitrobenzene in the soil was further removed through demulsification and separation of nitrobenzene and recycling of FcCOC10N,with a final removal efficiency of 94.70%.