表面活性剂包覆型纳米零价铁活化过硫酸盐体系对沉积物中多环芳烃的去除过程及机理研究

Polycyclic aromatic hydrocarbons (PAHs) in the sediments pose a big threat to water ecological environment. The activation of persulfate with nanoscale zero-valent iron (nZVI) is a new kind of advanced oxidation process which can effectively degrade PAHs and other persistent organic pollutants, but its performance in polluted sediment remediation is limited by some factors, such as the stability, migration and affinity to pollutants of nZVI. Surfactant is expected to be used as nZVI stabilizer to help achieve the efficient and safe remediation of contaminated sediments, but the applications and related mechanisms are rarely reported. This project intends to construct a compost fermentation obtained rhamnolipid-coated nZVI (RL-nZVI)/persulfate system with the purpose to remove the PAHs from the sediment of Xiangjiang River (Changsha section). Firstly, the key preparation parameters of RL-nZVI will be optimized, and the optimal control of the application process will be realized through batch experiments. Then the migration and agglomeration of RL-nZVI in sediments, the desorption/solubilization of PAHs, persulfate activation as well as PAHs degradation mechanisms will be investigated through a box-type experiment. Together with the results obtained in the batch experiments, the process and mechanism of the remediation of PAHs contaminated sediments by RL-nZVI/persulfate system will be fully discussed. Finally, the microbial toxicity of remediated sediment will be evaluated in order to have a comprehensively understand of the feasibility of this system for remediation of PAHs contaminated sediments. This study is expected to provide theoretical basis and technical support for the development of a low-cost, efficient and environmentally friendly remediation strategy for PAHs polluted sediments.

沉积物中多环芳烃(PAHs)污染对水生态环境危害极大。纳米零价铁(nZVI)活化过硫酸盐是一类可有效降解PAHs等持久性有机物的新方法，但其对沉积物的修复受到nZVI的稳定性、迁移性及对污染物亲和性的限制。表面活性剂有望作为稳定剂，协助实现PAHs污染沉积物的高效安全修复，但相关应用及机理鲜有报道。本项目针对湘江长沙段沉积物PAHs污染问题，拟采用堆肥发酵液中提纯的鼠李糖脂(RL)制备包覆型nZVI，构建RL-nZVI/过硫酸盐体系，优化催化剂关键制备参数，通过批量实验优化控制应用过程；设置箱式实验探究沉积物中RL-nZVI的迁移与团聚、PAHs的解吸附和增溶行为、过硫酸盐活化及PAHs降解机理，结合批量实验结果，全面探讨该体系对PAHs的去除效能及机制；考察体系的微生物毒性，综合评价其应用可行性。本研究有望为发展一种廉价、高效、环保的PAHs污染沉积物修复方法提供理论依据与技术支撑。

河湖沉积物中多环芳烃(PAHs)污染对水生态环境危害极大。生物表面活性剂鼠李糖脂（Rhamnolipid, RL）稳定化纳米零价铁（RL-nZVI）活化过硫酸盐体系在修复有机物污染沉积物方面具有较好的应用潜力，但尚无将该体系应用于沉积物中PAHs处理的报道，且相关过程和机理尚不清楚。因此，本项目采用简单的一锅法制备出RL-nZVI催化剂材料，并构建RL-nZVI/过硫酸盐氧化体系，用于沉积物中PAHs的去除。采用扫描电子显微镜(SEM)、X射线衍射（XRD）、X射线光电子能谱分析(XPS)、傅里叶变换红外光谱（FTIR）等多种现代表征手段研究了RL-nZVI的形态结构、表面特性、纳米颗粒分散性等性质，探究了鼠李糖脂改性作用对nZVI性质的影响。采用沉降实验考察了鼠李糖脂对nZVI的稳定效果，且构建了柱实验探究了材料的迁移性能。通过批量实验研究了pH、氧化剂投加量以及催化剂投加量等因素对PAHs去除效率的影响，优化了操作条件，并对RL-nZVI催化过硫酸盐的机理进行了分析。研究了修复作用对底泥pH、有机质含量等理化性质的影响，此外，重点考察了该体系对沉积物微生物可能的毒性效应，探究了nZVI材料对底泥微生物群落结构及关键功能的影响，综合评价该体系的实际应用可行性。本研究有望为发展一种高效、经济、环保的有机物污染沉积物修复方法提供理论依据与实践参考。