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研究报告

Degradation of chloramphenicol by electron beam irradiation in aqueous solution

基金项目：北京市产学研项目（No.51900265005）；国家水体污染控制与治理科技重大专项（No.2009ZX07207-008，2009ZX07419-002，2009ZX07207-001，2015ZX07406005-001）；中央高校基本科研业务费专项资金（No.2652013101，2652013086，2652013087）；国家重大科学仪器设备开发专项（No.2012YQ060115）

聂明华
1. 江西师范大学地理与环境学院, 鄱阳湖湿地与流域研究教育部重点实验室, 南昌 330022;2. 复旦大学环境科学与工程系, 上海市大气颗粒物污染与防治重点实验室, 上海 200433

摘要：本研究对氯霉素（CAP）在不同条件下的电子束辐照降解进行了研究.结果表明，电子束辐照可有效去除水中CAP，低浓度CAP在酸性条件下的辐照降解更为显著，且降解过程符合准一级动力学模型.通过添加不同的自由基清除剂，发现HO·在CAP降解中起关键作用，此外，CAP分子也会吸收辐照而发生分解.水中共存的阴离子和腐殖酸（HA）对CAP辐照降解均有抑制作用，这跟其与HO·的反应速率常数大小有关，并且反应速率越大，其抑制能力越强.CAP在去离子水中的去除率高于其他实际水体，但辐照剂量为4 kGy时，污水厂污水过滤水和胶体浓缩液中的CAP也可分别去除89.1%和81.7%.利用GC-MS检测到辐照后溶液中有6种中间产物，主要是通过脱水、不对称中心断键和脱酰胺作用形成.此外，IC检测有Cl^-、NO₃^-和NO₂^-的产生，并且TOC在一定程度上降低，说明部分CAP被矿化.

Abstract：Electron beam irradiation-induced degradation of chloramphenicol (CAP) under different conditions was investigated. The results show that CAP can be effectively removed by electron beam irradiation. The degradation efficiencies of low initial concentration CAP can be remarkably improved in an acidic condition, and CAP removal followed the pseudo-first-order reaction kinetics. Results of Scavenging tests suggest that the degradation of CAP might be mainly ascribed to HO·oxidation and the direct decay of CAP molecules induced by irradiation. The removal efficiency of CAP was influenced by the additives (such as inorganic anions and HA) of aqueous solution, in the order of NO₂^- > I^- > Br^- > HA > CO₃^2-/HCO₃^- > NO₃^- > Cl^- > SO₄^2-,largely due to their competition with CAP for the reactive radicals generated, especially HO·. The degradation rate of CAP in deionized water was the highest among different water matrices. Up to 89.1% and 81.7% of CAP were removed from the filtrate and retentate phase of wastewater at an absorbed dose of 4 kGy, respectively. Six intermediates were identified by using GC-MS during CAP degradation, and some anions (Cl^-, NO₃^-and NO₂^-) were detected with IC. The CAP degradation pathway was proposed according to the intermediates.

Key words：electron beam irradiation chloramphenicol degradation coexisting substances degradation pathway