典型β-内酰胺类抗生素在臭氧氧化降解过程中毒性变化规律研究

Study on the toxicity variation of typicalβ-Lactam antibiotics during ozonation degradation

β-内酰胺类抗生素应用广泛,近些年来在各类水体中频繁检出,其在水处理工艺过程中的毒性控制越来越受到重视.本文以4种典型β-内酰胺类抗生素为目标污染物,采用臭氧氧化和急性毒性试验等研究其在臭氧氧化过程中急性生物毒性变化规律,采用毒性预测软件T.E.S.T.评估了4种抗生素及其氧化降解中间产物的生态毒性,并分析了中间产物(TP)结构与生物毒性之间的定量构效关系.结果表明,青霉素钠(PG)和头孢曲松钠(CS)在臭氧氧化过程中急性毒性升高,阿莫西林(AMX)和头孢氨苄(CLX)毒性变化未呈明显规律性;随着溶液pH值的升高,臭氧氧化PG和CS反应速率加快且生成更多高毒性中间产物,导致反应体系毒性增强.毒性评估结果表明,4种抗生素被认定为大鼠LD_(50)的“有毒”、非发育性毒物和致突变阴性,多数产物被认定为大鼠LD_(50)的“非常有毒”、发育毒物和致突变阳性.综合急性毒性试验和T.E.S.T.预测结果表明,反应终点毒性增强的主要原因是母体污染物分解但生成的高毒性中间产物并未被矿化,需通过加大臭氧剂量或延长反应时间以降低体系毒性.

β-Lactam antibiotics are widely used and have been frequently detected in various water bodies in recent years.Their toxicity control in water treatment processes has received increasing attention.In this paper,fourβ-lactam antibiotics were used as target pollutants to analyze the changes in their acute biotoxicity during ozonation.Toxicity prediction software T.E.S.T.was used to evaluate the ecotoxicity of the antibiotics and their ozonation intermediates.The acute biotoxicity evolution during the ozonation process was studied,and the quantitative relationships between the structures and biotoxicities of the intermediate were analyzed.Results showed that the acute toxicity of sodium penicillin G(PG)and sodium ceftriaxone(CS)increased during the ozonation treatment.The toxicity of amoxicillin(AMX)and cephalexin(CLX)changed irregularly.As the increase in pH,the reaction rate of PG and CS increased and generated more highly toxic intermediates,resulting in increased toxicity.The results of the toxicity assessment showed that four antibiotics were identified as"toxic",non-developmental toxicants and mutagenic negative in rat LD_(50).Most intermediates were identified as"very toxic",developmental toxicants and mutagenic positive in rat LD_(50).Combining the results of the acute toxicity test and T.E.S.T.prediction,a main reason for the increased toxicity after the reaction was the generation of highly toxic intermediates during the decomposition of the parent pollutant,which were not completely mineralized.The toxicity of the system can be reduced by increasing the ozone dose or increasing the reaction time.