难降解含强吸电子基苯系污染物的电化学还原-氧化去除与毒性削减评估

The toxic refractory substituted benzene pollutants with strong electron withdrawing groups in industrial wastewater have becoming one the focal points and difficult things towards the treatment of water environment. If adopting simple electrochemical reduction or oxidation technique, the electrondrawing groups on benzene ring led to lower mineralization rate and increased ecotoxicity. This research will focus on the electrochemical treatment of typical toxic refractory substituted benzene pollutants, such as nitrobenzene, p-chloronitrobenzene, etc, utilizing the electrochemical reduction and oxidation integration technology. Polymetallic coupling heterojunction with alloy or core-shell structures would be fabricated by utilizing carbon, metal etc as substrates and loading smaller amounts of precious metals (Pd, Au, etc) and inexpensive metals (Ni, Cu, etc) based on soft chemistry technique. The structure activity relationships between electrode material structure and electrochemical performance will be revealed by exploring pollutants form change process. According to toxicity reduction laws of compounds generated during pollutants form change process, the constitutes and structures of electrocatalytic electrodes can be further optimized, and then the electrocatalytic mechanism would be revised. Aiming at complex polluted water environment, double chamber type reaction device will be construced based on obtained electrochemical reduction oxidation mechanism. By optimising process parameters, the stability and stain resistance properties for a long time will be investigated, a set of electrical catalytic degradation process would be completed. The project would provide theoretical basis and technical support for control of the toxic refractory substituted benzene pollutants in industrial wastewater.

工业废水中含强吸电子苯系难降解毒害有机污染物已成为水环境治理的重点和难点。采用单纯电化学还原或氧化技术，吸电子基致钝性导致了降解矿化率低，产物生态毒性增高等缺陷。本项目围绕电化学还原-氧化集成技术，以典型电子惰性毒害物（硝基苯，对氯硝基苯等）为研究对象，利用软化学技术构建以碳素、金属等材料为基质，担载少量贵金属（Pd，Au等）、廉价金属（Ni，Cu等）耦合的合金或核-壳型多金属异质结催化体系。通过探究污染物形态变化过程，揭示电催化电极材料结构与催化性能的构效关系。依据形态变化过程中产生物质的毒性削减规律，进一步优化催化电极的组成和结构，修订电催化机制。针对复杂污染水环境，基于获得的电化学还原-氧化机制，组装双室隔膜型小试装置，优化工艺参数，研究电极长时间操作的稳定性、耐污染性等，形成一套完成的电催化降解工艺。本项目的研究将为工业废水中难降解典型毒害有机物污染物的控制提供理论基础与技术支撑。

工业废水中含强吸电子苯系难降解毒害有机污染物已成为水环境治理的重点和难点。采用单纯电化学还原或氧化技术，吸电子基致钝性导致降解矿化率低、产物生态毒性增高等问题。本项目围绕电化学还原-氧化集成技术，以典型有机毒害物，苯酚，4-氯酚和2,4-二氯酚等为研究对象，以多壁碳纳米管负载的石墨毡作为三维骨架，进一步采用分步沉积法先后将金属镍和金属钯负载于骨架表面，制得了具有高活性、高稳定性的三维碳基双金属电极（Pd-Ni/MWCNTs/GF）。Pd-Ni/MWCNTs/GF电极具有优异的电催化还原活性，电催化还原4-氯酚反应均符合准一级反应动力学，其主要还原产物苯酚和氯离子，4-氯酚的去除率为100%，反应速率为0.162 min-1；在2, 4-二氯酚的电催化还原中，对位的氯基更容易被脱去，在形成2-氯酚后再被还原为苯酚，间接还原占主导作用，两个氯基的存在使得电催化反应更难发生，而具有更强还原效果的氢自由基间接还原在其中起了更大作用；通过多次循环批次实验，证实金属电极相比于单钯金属能够保持更长的反应活性。另外，基于TiO2纳米管阵列，再采用二次氧化及电化学还原法构筑了Ti3+和氧空位自掺杂的TiO2基电极（DNTA）。DNTA电极对苯酚去除率为63.2%，远优于常见商业钛基形稳态电极，低于昂贵BDD电极，而其对苯酚矿化效果高于BDD电极和形稳态电极。DNTA对对氯酚、对硝基酚、对甲氧基酚和苯酚均有较优异的降解效果。本项目通过探究污染物形态变化过程，揭示了电催化电极材料结构与催化性能的构效关系。依据形态变化过程中产生物质的毒性削减规律，优化了催化电极的组成和结构，修订了电催化机制。针对复杂污染水环境，基于获得的电化学还原-氧化机制，组装双室隔膜型小试装置，优化工艺参数，形成了一套完整的电催化降解工艺。本项目的研究将为工业废水中难降解典型毒害有机物污染物的控制提供理论基础与技术支撑。