硼掺杂金刚石薄膜电极降解青霉素G钠废水机制

针对抗生素废水中青霉素类物质难于生化降解的问题,采用直流等离子体化学气相沉积方法制备硼掺杂金刚石(boron-doped diamond, BDD)薄膜电极,以典型的青霉素G钠为目标污染物,对BDD电极降解青霉素的规律及降解历程进行研究.结果表明,不同质量浓度的青霉素G钠在电极上均能够被完全降解,发生电化学燃烧.青霉素G钠和化学需氧量(chemical oxygen demand, COD)的降解符合一级反应动力学,电流密度从10 mA/cm²提高到20 mA/cm²时,青霉素G钠和COD的反应速率常数分别增加了51.3%和29.1%.BDD电极上青霉素G钠的降解主要受液相传质过程控制,电流效率(current efficiency, E_C)与青霉素G钠的质量浓度和电流密度有关.得到了青霉素G钠在BDD电极上的降解历程,主要的中间产物有青霉酸、异构青霉酸、青霉烯酸和青霉噻唑酸.

Degradation mechanism of penicillin G sodium wastewater at boron-doped diamond electrodes

To deal with the bio-refractory substances of penicillin in antibiotic wastewater, boron-doped diamond (BDD) electrodes prepared by direct current plasma chemical vapor deposition system were used to investigate the degradation rule and pathway of penicillin wastewater with penicillin G sodium as target pollutant. Results show that penicillin G sodium with different concentrations could be completely degraded at BDD electrodes by electrochemical combustion reaction. The degradation of penicillin G sodium and chemical oxygen demand (COD) accorded with the pseudo-first-order rate kinetics. When the current density was increased from 10 mA/cm² to 20 mA/cm², the apparent reaction rate constant of penicillin G sodium and COD increased by 51.3% and 29.1%, respectively. The degradation of penicillin G sodium at BDD electrodes was controlled by mass transfer in liquid phase. The concentration of penicillin G sodium and current density greatly influenced the current efficient (E_C). Major intermediate products of the degradation pathway of penicillin G sodium at BDD electrodes were penillic acid, isopenillic acid, penicillenic acid, and penicilloic acid.