核壳结构铁铝双金属材料制备及其对土壤氯代烃类污染物的还原机制研究

It was well reported that the reductive dechlorination induced by zero-valent iron is one of the best ways for chlorinated hydrocarbon degradation and remediation. However, there is a phenomenon that the zero-valent iron is prone to oxidation and agglomeration of particles. Studies have shown that bimetallic materials can improve the reducibility of zero valent iron, but there are still a lot of scientific problems that have not been clarified. In theory, iron and aluminum can constitute the original battery to improve the reduction performance of zero-valent iron, so this project takes Iron/Aluminium composite as the object to explore the means and mechanism of reduction process. The chlorinated hydrocarbon could be absorbed by Iron/Aluminium composite with core-shell structure in soil environment. The proposal aimed to load zero-valent iron to the surface of aluminum by different methods. With the optimal preparation method, the Iron/Aluminium composite is used to degrade chlorinated hydrocarbon soil. The mechanism of chlorinated hydrocarbon degradation on the surface of Iron/Aluminium composite were studied by investigating the composite with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) before and after the degradation of chlorinated hydrocarbon. With the pot experiments the mechanism, the environmental behavior, the degradation product were detected using HPLC-MS and the degradation pathway could be researched.

现有研究表明零价铁还原是氯代烃类污染物环境降解的最佳途径之一，但是零价铁存在表面易于氧化和颗粒易团聚等问题。双金属材料是改善零价铁的还原性能的有效方式之一，但尚有诸多科学问题没有阐明，其降解效率的提升机制也不清晰。铁铝结合可构成原电池，理论上具有提升零价铁的还原性能的可行性，所以本项目以“铁铝”复合为对象，探讨零价铁还原能力的提升手段和机制。研究中将制备核壳结构铁铝双金属材料，优化制备方法，分析不同材料对氯代烃的降解能力；通过材料表面特征、元素分析、物质构成在反应前后的差异，明确氯代烃类污染物在核壳结构铁铝双金属材料表面的反应机制；通过降解产物分析，推断污染土壤修复过程中氯代烃类污染物的代谢途径；利用盆栽实验评估环境安全性，最终构建“材料制备方法-材料结构表征-土壤环境修复效果-反应机制与降解途径-生态效应提升”五者之间的科学关系，为氯代烃类污染土壤的修复提供理论支持和技术方法。

零价铁为当前环境修复的热点材料，但零价铁存在表面易氧化和颗粒易团聚等问题。双金属材料是改善零价铁还原性能的有效方式之一，但尚有诸多科学问题没有阐明，其降解效率的提升机制也不清晰。所以本项目以“铁铝”复合为对象，探讨零价铁还原能力的提升手段和机制。首先，采用化学沉积法制备铁铝双金属材料，并提出铁铝双金属材料还原降解六价铬的主要机理包括铁铝原电池效应、零价金属还原性、形成铁铬共沉淀物三方面。第二、通过正交实验、去除实验、反应后材料表征等手段得出铁铝双金属材料去除水中新型非甾体类污染物双氯芬酸的去除效果良好，降解机理主要为超声空化作用产生强氧化自由基、芬顿及类芬顿反应两个方面，并评估修复过程中可能产生的负效应，为水环境中双氯芬酸去除提供新思路及有效方法。第三、材料设计目的为应用材料解决实际问题，故本研究优化原有铁铝双金属材料，合成CA铁铝双金属微球材料，可在特定环境中对污染物实现智能修复，并分析所制材料对水中四氯化碳的去除效果及降解机制，为环境氯代烃修复实施提供理论支持。