负载型纳米零价铁/过硫酸盐耦合去除水体重金属-有机复合污染物的过程及机制研究

In recent years, contaminants including both heavy metals and organic compounds, especially those mixed pollutants, have caused a seriously harmful effect on the aquatic environment due to their toxicity and persistence. The occurrence of these pollutants has given a great threat to the health of humans and organisms, therefore brought out a potentially ecological security to the aquatic ecosystems. The current seriously polluted status of aquatic environment has been paid much attention by the government, scientific community and the public. Based on the co-existence and potentially ecological security risks of heavy metal-organic compound mixed contaminants, a coupling system with supported nanoscale zero-valent iron and presulfate will be established for the simultaneous removal of heavy metal-organic compound mixed contaminants from aqueous solutions. In this project, bentonite will be used as a carring modifier due to its low cost, good adsorption and fine dispersion properties, which could be beneficial for the production of a highly active supported basis to nanoscale zero-valent iron. Continuous and stable ferrous ions could be produced by coupling bentonite supported nanoscale zero-valent iron with presulfate in an acidic solution. Thus, presulfate will be activated by these ferrous ions, and the efficient synergtic removal efficiency will be achieved. Thereby a systematic investigation on the removal efficiency of heavy metal-organic compound mixed contaminants in the coupling system with supported nanoscale zero-valent iron and presulfate will be conducted in the project. In addition, the interaction mechanisms of the coupling system, and degradation process, as well as mechanism of mixed contaminants will be investigated. Meanwhile, the stability of nanoscale zero-valent iron in this coupling system will be explored. Upon the completion of this project, a new wastewater treatment technology for the simultaneous removal of heavy metal-organic compound mixed contaminants will be expected to establish from the coupling system with supported nanoscale zero-valent iron and presulfate, which could provide a technical basis and theoretical foundation for the environmental remediation of heavy metal-organic compound mixed contaminants in the aquatic environment.

近年来，水体中有毒有害的重金属和有机物污染对环境造成严重危害，尤其是重金属-有机复合污染给人类健康和生态安全带来巨大威胁，已引起人们的广泛关注。本项目针对典型水体重金属-有机复合污染共存的现状和潜在的生态风险问题，构建负载型纳米零价铁/过硫酸盐耦合体系去除重金属-有机复合污染物。采用价廉易得且具有良好吸附分散性能的膨润土作为载体改性剂，制备高活性膨润土负载型纳米零价铁，并与过硫酸盐耦合，使纳米零价铁连续稳定地产生亚铁离子以活化过硫酸盐，实现复合污染物的协同高效去除效果。通过系统研究负载型纳米零价铁/过硫酸盐耦合技术对重金属-有机复合污染物的去除效果；探讨耦合体系的相互作用机制和复合污染物去除过程及降解机理；并揭示在该耦合体系下负载型纳米零价铁的稳定性；开发出负载型纳米零价铁/过硫酸盐耦合催化去除重金属-有机复合污染物的水处理新技术，为重金属-有机复合污染物的环境修复提供技术依据和理论基础。

目前，多种污染物共存于各种环境水体中，重金属和有机物的同步去除受到了广泛的关注。本项目构建了一种负载型纳米零价铁/过硫酸盐耦合体系去除Cr(VI)和苯酚。系统地研究了不同条件下负载型纳米零价铁/过硫酸盐耦合体系对Cr(VI)和苯酚的去除效果；探讨了Cr(VI)和苯酚的共去除过程及机理；并揭示了负载型纳米零价铁的稳定性能。结果表明，过硫酸盐的加入不会明显降低Cr(VI)的还原去除，相反，它会显著加强苯酚的氧化去除效果；另外，Cr(VI)的加入能提升苯酚的氧化速率。在负载型纳米零价铁/过硫酸盐耦合体系下成功实现了Cr(VI)还原和苯酚氧化的协同效应，此时Cr(VI)还原和苯酚的共去除效率分别为99.8% 和72.3%。过硫酸盐的分解过程与可溶性Fe2+浓度呈正相关性；负载型纳米零价铁在经四次使用后，还保持较好的活性；过硫酸根是实现苯酚氧化降解的主要活性氧组分。此外，在反应过程中，检测出有Cr2O3, Cr(OH)3的Cr(III)组分产物的产生，而苯酚的产物却有儿茶酚，苯醌，丙酸和甲酸的产生；最后推导出Cr(VI)和苯酚的共同去除机理，Cr(VI)的去除是由于负载型纳米零价铁的还原作用，而苯酚的去除却是通过过硫酸根的氧化作用实现。负载型纳米零价铁/过硫酸盐耦合水处理新技术体系为重金属-有机复合污染物的环境修复提供技术依据和理论基础。