基于开关表面活性剂的重金属污染土壤可控泡沫修复

Due to serious contaminated soils by heavy metals, especially in contaminated sites, China needs urgently the remediation technologies for contaminated soils. Complexant enhanced surfactant foam remediation is one of the most effective remediation methods for heavy metal contaminated soils. Because of intrinsic thermodynamics stability of surfactant micelles, it is difficult to separate surfactant from the mixed system containing heavy metal pollutants resulting in the high cost and complex processes for the separation of flushing foams in the whole remediation process. Aiming at the key scientific problem for the effective separation of surfactants foams and heavy metal pollutants during the regeneration process, this project propose the method of reversible surfactant foam-enhanced remediation (RSFR) for heavy metals polluted soils based on the principle of reversible and controllable solubilization of switchable surfactants. The recycle of CO2/air switchable surfactant micelle solubilization-release can be conducted based on the solubilization characteristic in its active state and micelles disassembled in its inactive state. This study will focus on the following issues: the foaming ability and foam stability of switchable surfactants and the mixed system of switchable surfactants with conventional surfactants; the delivery and spatial distribution characteristics of switchable surfactant foams in soils; the solubilization ability of switchable surfactant foams for heavy metal pollutants and reversible solubilized mechanism of heavy metals; the sorption behavior and multiphase partition characteristic of switchable surfactants in soils. These results may will provide the new approach for the recycling utilization of surfactants and promote the application of SFR in the chemical remediation of contaminated soils.

我国土壤重金属污染严重，场地污染问题尤为突出，修复技术需求迫切。络合剂增强表面活性剂泡沫修复是最具前景的重金属污染修复技术之一。重金属易与泡沫发生静电和配位作用，形成稳定的络合体系，分离困难，因而导致修复过程中抽出泡沫分离成本高且工艺复杂。针对重金属与表面活性剂泡沫有效分离难这一关键科学问题，基于开关表面活性剂增溶作用可逆可控原理，提出重金属污染土壤可逆泡沫修复方法(RSFR)。采用CO2/空气开关表面活性剂在活性态具有增溶及非活性态胶束破坏的特性，实现表面活性剂分离。拟开展以下研究：开关表面活性剂及其复配淋洗液的发泡能力及泡沫稳定性；可逆泡沫在土壤介质中的迁移及空间分布特征；可逆泡沫对重金属的增溶效能及可逆可控作用规律；开关表面活性剂在土壤介质中的吸附行为、多相间分配特征。研究成果可为泡沫修复技术提供表面活性剂回收与利用新途径，推动该技术在污染土壤化学修复中的应用。

我国土壤重金属污染严重，场地污染问题尤为突出，修复技术需求迫切。络合剂增强表面活性剂泡沫修复是目前最具前景的重金属污染修复技术之一。胶束具有热力学稳定性，络合态重金属与表面活性剂泡沫体系分离困难，因而导致修复过程中抽出泡沫分离成本高且工艺复杂。针对重金属与表面活性剂泡沫有效分离难这一关键科学问题，基于开关表面活性剂增溶吸附作用可逆可控原理，提出了重金属污染土壤可逆泡沫修复方法(RSFR)。通过研究开关表面活性剂及其复配体系的发泡能力和泡沫稳定性，泡沫在土壤介质上的迁移、吸附分配特征，以及对重金属的吸附络合作用与可逆可控作用规律，探明RSFR方法的可行性。通过本项目的实施初步证实了基于开关表面活性剂泡沫修复重金属污染土壤是可行的。相比于单一的开关表面活性剂泡沫，复配体系泡沫具有更好的稳定性；淋洗土壤实验发现优选的开关表面活性剂和柠檬酸的复配体系淋洗液对重金属污染土壤具有更好的去除效果，当体系淋洗液由溶液转变为泡沫时，因其较低的孔道效应，对重金属的淋洗效率明显提升，表明复配开关表面活性剂体系泡沫淋洗效率高于溶液淋洗效率。开关表面活性剂复配体系淋洗液在淋洗通过污染土壤后，其淋洗废液仍然具有良好的可逆转换特性，可实现开关表面活性剂物质与重金属的有效分离，同时开关表面活性剂可在在活性态与非活性态之间可逆转换。研究成果可为化学淋洗修复污染土壤技术提供了表面活性剂回收与利用新途径。