Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , P. R. China.
College of Environmental Science and Engineering , Dalian Maritime University , Dalian 116024 , P. R. China.
Environ Sci Technol. 2019 May 7;53(9):5195-5201. doi: 10.1021/acs.est.8b06130. Epub 2019 Apr 12.
Electrochemical oxidation based on SO and OH generated from sulfate electrolyte is a cost-effective method for degradation of persistent organic pollutants (POPs). However, sulfate activation remains a great challenge due to lack of active and robust electrodes. Herein, a B/N codoped diamond (BND) electrode is designed for electrochemical degradation of POPs via sulfate activation. It is efficient and stable for perfluorooctanoic acid (PFOA) oxidation with first-order kinetic constants of 2.4 h and total organic carbon removal efficiency of 77.4% (3 h) at relatively low current density of 4 mA cm. The good activity of BND mainly originates from a B and N codoping effect. The PFOA oxidation rate at sulfate electrolyte is significantly enhanced (2.3-3.4 times) compared with those at nitrate and perchlorate electrolytes. At sulfate, PFOA oxidation rate decreases slightly in the presence of OH quencher while it declines significantly with SO and OH quenchers, indicate both SO and OH contribute to PFOA oxidation but SO contribution is more significant. On the basis of intermediates analysis, a proposed mechanism for PFOA degradation is that PFOA is oxidized to shorter chain perfluorocarboxylic acids gradually by SO and OH until it is mineralized.
基于硫酸盐电解液中生成的 SO 和 OH 的电化学氧化是降解持久性有机污染物（POPs）的一种具有成本效益的方法。然而，由于缺乏活性和稳定的电极，硫酸盐的活化仍然是一个巨大的挑战。在此，设计了一种 B/N 共掺杂金刚石（BND）电极，通过硫酸盐活化来电化学降解 POPs。该电极对于全氟辛酸（PFOA）的氧化具有高效和稳定的性能，在较低的电流密度 4 mA cm 下，其一级动力学常数为 2.4 h，总有机碳去除效率为 77.4%（3 h）。BND 的良好活性主要源于 B 和 N 的共掺杂效应。与硝酸盐和高氯酸盐电解液相比，硫酸盐电解液中 PFOA 的氧化速率显著提高（2.3-3.4 倍）。在硫酸盐存在的情况下，OH 猝灭剂会略微降低 PFOA 的氧化速率，但在 SO 和 OH 猝灭剂存在的情况下，其下降幅度显著，表明 SO 和 OH 都有助于 PFOA 的氧化，但 SO 的贡献更为显著。基于中间产物分析，提出了一种 PFOA 降解的机理，即 PFOA 逐渐被 SO 和 OH 氧化为短链全氟羧酸，直到其被矿化为无机物。
