硼掺杂金刚石薄膜电极电催化降解双酚A

Electrochemical degradation of bisphenol A at boron-doped diamond electrodes

摘要:

针对水环境中环境激素双酚A (bisphenol A, BPA)的污染,采用直流等离子体化学气相沉积方法制备了硼掺杂金刚石(boron-doped diamond,BDD)薄膜电极,利用高效液相色谱法和液相色谱质谱联用的方法,对BPA在BDD电极上的降解规律及降解历程进行研究．结果表明：不同初始质量浓度的BPA在电极上均能被完全降解,降解规律符合准一级反应动力学,初始质量浓度100和10 mg·L-1时的表观反应速率常数分别为0.494和0.700 h-1；电流密度从10 mA·cm-2提高到40 mA·cm-2时,表观反应速率常数增大50.61％,去除率提高11.26 ％．BPA的降解过程检测到7种中间产物,降解主要分为两个途径：一是BPA的一侧苯环先开环降解,最后完全矿化;二是BPA的两个苯环同时开环,然后逐级降解直至矿化．

Abstract:

To solve the pollution of bisphenol A (BPA) which was considered as an environmental endocrine, boron-doped diamond (BDD) electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) system. Mechanisms and reaction pathways of electrochemical degradation of bisphenol A (BPA) at BDD electrode was investigated by high performance liquid chromatography(HPLC) and liquid chromatography-mass spectrometer(LC-MS). The results showed that BPA with different initial concentrations were completely mineralized to CO₂ at BDD electrode, following the pseudo-first-order rate kinetics. The apparent reaction rate constant for BPA with initial concentrations of 100 and 10 mg·L-1 were 0.494 and 0.700 h-1, respectively. When the current density was increased from 10 to 40 mA·cm-2, the apparent reaction rate constant and the removal rate were increased by 50.61％ and 11.26％, respectively. Seven intermediate products were detected in the degradation process, and two different degradation pathways were discovered. One pathway was that BPA was decomposed readily into one-ring aromatic compounds first and eventually mineralized by electrolysis to CO₂, another was that both of the aromatic rings in BPA molecular structure underwent ring breakage simultaneously and then continuously oxidized to CO₂ till the end of the reaction.