微波诱导铁载凹土修复硝基苯类-砷复合污染土壤的作用机理

源于饲料添加剂洛克沙砷生产过程中引起的场地污染是具有代表性的一类，且数量众多，该类场地多呈现高浓度硝基苯类有机物和无机砷复合污染特征。本研究针对该类场地特征污染物提出一种微波辅助铁载凹土(Fe/ATP)的绿色土壤修复技术，同时实现土壤中硝基苯类的矿化和砷的稳定/固化。分析微波催化体系中Fe/ATP界面电子转移行为、活性物种的产生、消亡规律和影响因素，研究活化分子氧/溶剂水的分子机制，探讨土壤中硝基苯类的微波催化历程、去除路径和影响因素。分析砷在Fe/ATP上的吸附、表面沉淀、表面络合、矿化等分子机制和氧化还原的过程，研究微波对铁砷矿化固定的作用机制，揭示砷的稳定性与分布形态特征之间的关系和规律以及影响因素。构建中试放大试验，研究稳定/固化处理后土壤中砷的释放行为，探讨砷的长期稳定性及影响因素等地球环境化学基础问题。本研究可为发展有机-重金属复合污染土壤修复提供理论和技术支持。

Contaminated soil from organoarsenic feed additives industry is one type of typical contaminated sites in China. Microwave-assisted iron modified attapulgite (Fe/ATP) was used in the remediation of nitrobenzenes and arsenic (As)-contaminated soils from organoarsenic feed additives industry. The catalytic oxidation of nitrobenzenes and stabilization/solidification of As in soil could be obtained at the same time induced by Fe/ATP under microwave irradiation. The main contents to be investigated include:(1) the pathway of interfacial electron transfer, active species generation, active species types and their formation on Fe/ATP in the microwave catalytic system; (2) the pathway, kinetic, and mechanism of catalytic oxidation of nitrobenzenes and As(III), the correlation of catalytic performance to structural characteristics of Fe/ATP, the influence of pH value, dissolved oxygen content, soil temperature, and the coexistence of metal; (3) the removal mechanism of As by Fe/ATP via adsorption, surface precipitation, surface complexation, mineralization, and redox process; (4) the stabilization/ solidification mechanism and influence factors of As by Fe/ATP under microwave irradiation, and the relationship between the stability of arsenate and its chemical speciation distribution. On the base of the laboratory studies, pilot scale experiments will be carried out to evaluate the long-term stability of As in soil. Both land disposal in areas where rainwater is stimulated and underground landfill disposal in areas where hydrogeochemistry environment is stimulated will be likely to test As release performance from Fe/ATP stabilized soils and microwave-assisted Fe/ATP stabilized/solidified soils. This project would provide theoretical and technical support for the development of microwave remediation for organic pollutants and heavy metals-contaminated soil.