钛基改性DSA电极氧化法去除水中全氟化合物

为了提高金属氧化物电极(DSA电极)的稳定性及催化活性,实现全氟化合物(PFCs)的高效降解,分别以溶胶涂覆法和电沉积法制备了改性DSA(Ti/SnO_2-ZnO)电极,并用于全氟辛酸(PFOA)和全氟辛烷磺酸(PFOS)的电化学降解过程研究.实验分别考察了电流密度、溶液初始pH、 PFOA与PFOS初始浓度对PFCs降解效果的影响.结果表明:两种方法制备的改性DSA电极表面均匀负载了SnO_2-ZnO复合涂层.在二维电极体系中,极板面积约为65.0 cm~2,电流密度为20.0 mA·cm~(-2),极板间距为15.0 mm,电解质为1.30 g·L~(-1)次氯酸钠溶液以及电解时间为150 min时,溶胶涂覆法和电沉积法所制备的Ti/SnO_2-ZnO电极对初始浓度为100 mg·L~(-1)的PFOA和PFOS分别在pH为3.50和6.50时去除效果最佳,分别达到了90.6%、94.6%和91.0%、93.7%;循环使用电极3次,其降解过程均符合准一级反应动力学,且电沉积法制备的电极效果优于溶胶涂敷法,表现出对PFCs类污染物稳定、高效的去除能力.

Removal of perfluorinated compounds (PFCs) in aqueous solution by electrochemical oxidation with titanium-based modified dimentional stable anode

In order to improve the stability and catalytic activity of dimentional stable anode (DSA) and realize the efficient degradation of perfluorocompounds (PFCs),the modified DSA electrode (Ti/SnO₂-ZnO) was prepared by using Sol-Gel and electrodeposition and used to degrade the perfluorooctane acid (PFOA) and perfluorooctane sulfonic acid (PFOS). The effects of current density, initial pH of solution, PFOA and PFOS concentrations on the degradation of PFCs were investigated. The results show that SnO₂-ZnO composite coatings were uniformly coated on the surface of the modified DSA electrodes prepared with two methods. When in the two-dimension electrode system, the plate area was about 65.0 cm²,the current density was 20.0 mA·cm^-2, the plate spacing was 15.0 mm, the electrolyte was 1.30 g·L^-1 sodium hypochlorite solution and the electrolysis time was 150 min, the PFOA and PFOS with initial concentration of 100 mg·L^-1 were optimally degraded at pH 3.50 and 6.50, reaching 90.6%, 94.6%, and 91.0%, 93.7%, respectively. The electrooxidation process of PFC is in accrodance with the pseudo-first-order kinetics after three times of recycling. The electrodes prepared by electrodeposition show stable and efficient removal ability for PFCs pollutants is better than the Sol-Gel method.