差异性活化过硫酸盐对水中结合态残留抗生素微界面去除与迁转机制

The residual of antibiotics in natural waters has raised extensive concern on the risk of drinking water safety. Compared to the free residue, binding with the co-existing dissolved organic matters (DOM) is also the normalized form for the antibiotic residuals in the water. However, the in-situ identification and the removal behavior by chemical oxidation concerning “bound residue” have been rarely reported. This proposal is to construct the system for quantitative identification and analysis of bound antibiotics using charge-based response on the mico-surface, by establishing the response model between the microcharge index of DOM and concentrations of bound residual antibiotics. Through the differential activation of persulfate (radical and non-radical mechanism), the oxidation performance of featured reactive oxygen species (radicals or singlet oxygen) for the bound antibiotics on the micro-interface was investigated, whose involving mechanism on the binding/detaching between DOM and the targets was also discussed. The fates and pathways were advanced, concerning the detaching-degrading process of bound antibiotics and the synchronous specific transitions of DOM. This project aims at achieving the accurate concentration identification of the trace bound antibiotics, elucidating the entire components removal performance and transferring mechanism for bound antibiotics on the micro-interface of DOM, using differentially activated persulfate, and promoting the efficient removal of typical residual antibiotics in natural water. The results will provide theoretical support for the development and optimization of the decontamination of bound residual antibiotics in drinking water.

天然水中抗生素残留所引起的饮用水安全风险已引起广泛关注。与自由态残留相比，同水中共存溶解性有机物（DOM）结合亦是该类物质残留的常态化形式，针对该类“结合态”残留的原位检测及化学氧化去除行为目前几乎未见报道。本课题拟通过DOM微观电荷特性指标与结合态抗生素浓度响应模型的建立，构建基于微界面电荷响应的结合态抗生素定量识别与检测体系；研究在差异性活化过硫酸盐（自由基/非自由基机理）作用下，特征氧活性物质（自由基或单线态氧）在结合微界面处对抗生素的氧化效能及对目标物与DOM结合/解离过程的动态介入机制；解析结合态抗生素的解离-降解与DOM同步特异性转变的归趋路径。课题拟实现痕量结合态残留抗生素精准浓度检测，明晰过硫酸盐差异性活化方式对典型结合态抗生素在DOM微界面的全组分去除效能与迁移转化机制，促进天然水中特征残留抗生素高效量化去除，为饮用水中结合态残留抗生素去除工艺开发和优化提供理论支持。

抗生素类物质在水环境中的广泛残留，在世界范围内已引起了人们对长期暴露于该环境中的水生物种所面临的生态毒性以及相关衍生耐药性的重点关注。由于抗生素类物质的双电离结构特性使其能够与水中的溶解性有机质(DOM)和金属离子(Mn+)发生相互作用，导致抗生素在水环境中同时存在自由态和结合态两种状态。DOM和Mn+与抗生素的结合作用对其在水环境中的迁移、转化和降解等均会产生显著影响，相关结合作用对其化学转化的影响研究较少。本研究系统性分析了结合态四环素(TET)分别在DOM和三价铁离子背景水体下的赋存和界面去除机制。.研究选取水环境中四种典型的溶解性有机质，考察其在不同离子强度IS和pH值条件下与TET的结合作用。并通过UV-vis光谱、总有机碳(TOC)、三维荧光光谱(EEM)、zeta电位和分子尺寸分布等技术以分析IS和pH对结合性能的影响。结果表明，羧基和酚羟基是DOM结合TET的主要位点，结合Donnan模型和多元线性回归分析，研究重建了修饰的Karickhoff模型，有效预测了不同IS和pH条件下DOM的结合性能。.研究考察了HA-TET配合物体系在UV、UV/H2O2、UV/PS和UV/PMS氧化工艺中自由态和结合态TET的化学转换。FTIR和核磁共振氢谱(1H NMR)分析表明，HA中的羧基和酚羟基，以及TET分子的-N(CH3)2)基团是参与结合的主要位点。基于原位荧光时间扫描和紫外差分吸收光谱分析结果在除UV/PS体系外，自由态TET优先于结合态TET被氧化降解。.通过理论计算与质谱分析，研究确定了自由态、混合态和结合态TET在不同体系中降解途径，共鉴定出TET33种降解产物。毒性评估和统计分析表明，中等分子量(230≤m/z≤380)的中间产物毒性相对较高，产物毒性由大到小分别为双环>>三环>单环/四环结构产物。研究构建了毒性累积模型(PTAM)以计算氧化过程中整体毒性变换。.研究证实TET与Fe3+的结合作用会显著抑制Fe3+的水解作用。通过差分光谱分析表明，Fe3+-TET配合物的摩尔比为1:1，而含两个-N(CH3)2官能团的二甲胺四环素(MC)分子与Fe3+的配合摩尔比为1:2。Fe3+与TET通过结合作用形成了Fe3+-TET配合物，会在紫外辐射条件下快速生成•OH，从而实现TET的快速降解。