基于分子印迹型MOFs催化剂去除典型抗生素类污染物的研究

Wastewater treatment plants (WWTPs) are among the main sources of antibiotics' release into the environment worldwide. Therefore, a secondary removal process for removing the low-level antibiotics in the effluent from WWTPs is needed. In this project, using (metal) porphyrin as organic ligand and Fe (II), Co (II) or Ce (III) as metal ion, molecularly imprinted Metal-organic frameworks (MIP-MOFs) catalysts are prepared. During the synthesis, structural analogs or mixture antibiotics are selected as templates for the target sulfonamides or tetracyclines. The prepared MIP-MOFs catalysts are able to decompose the adsorbed antibiotics under visible light irradiation or by metal activated persulfate, leading to regeneration of surface active sites of the catalysts. During the degradation of the antibiotics, the imprinted cavities can enhance absorption of the target antibiotics and inhibit the highly toxic intermediates. For practical application, the stability of the MIP-MOFs is further investigated. Moreover, the thermodynamics and kinetics of the catalytic degradation are studied in a complex wastewater system containing low-level antibiotics. With these studies, we demonstrate the difference of the reaction mechanisms between the antibiotic degradation under visible light irradiation and that by metal activated persulfate, which further provides the practical way for selecting the advanced oxidation processes of the MIP-MOFs. We believe the project presents a safe and green route for catalytic degradation of low-level antibiotics in the effluent from WWTPs, and shows great potential in creating artificial enzymes for the purposes of removing other highly toxic organic pollutants.

针对污水处理厂出水中低浓度抗生素污染物的处置难题，本项目选择典型磺胺类、四环素类抗生素为目标污染物，采用模板类似物或者混合模板技术，以（金属）卟啉基配体为有机配体，以Fe(II)、Co(II)或者Ce(III)等为金属离子制备一种新型分子印迹型金属有机骨架催化剂（MIP-MOFs）。该催化剂具有特异性富集低浓度目标抗生素的能力，并且能够在可见光照射下或者活化过硫酸盐降解低浓度抗生素污染物。本项目将探索分子印迹孔穴对目标抗生素的吸附增强效应及其抑制降解过程中高毒性中间产物生成的机制，研究催化剂的稳定性及重复再利用能力，研究复杂环境条件下低浓度典型抗生素的降解热力学和动力学过程。重点研究两种高级氧化技术降解抗生素污染物的不同反应机理，阐明实际污水体系中催化剂氧化方式的选取规律，从而提出一种可深度处置污水处理厂出水中低浓度抗生素污染物的新方法。

针对污水处理厂出水中低浓度抗生素污染物难降解的难题，本项目采用原位模板自组装法制备了不同类型分子印迹型MOFs催化剂。实验数据表明，金属离子与目标抗生素污染物之间的配位作用在印迹孔穴形成过程中起主要作用。在优化条件下，分子印迹型MOFs催化剂对目标污染物的吸附容量高达295.2 mg g-1，远高于传统的分子印迹聚合物（MIPs）。不同的印迹体系测试表明，选用2-氨基对苯二甲酸为有机配体制备分子印迹型MOFs催化剂具有普适性。分子印迹型MOFs催化剂活化过硫酸盐、活化H2O2、可见光芬顿催化降解目标抗生素污染物的实验结果表明，可见光催化活化H2O2的光芬顿体系是目标抗生素降解的最佳高级氧化技术。与非印迹型MOFs催化剂相比，分子印迹型MOFs催化剂对目标污染物的降解能力提高了64%，光催化降解选择性提高了4.74倍。降解机理研究表明，分子印迹型MOFs催化剂上抗生素污染物的催化降解过程被限制在印迹孔穴之中，抗生素污染物在光催化过程中生成的降解产物种类简单且浓度较低。基于这种降解效率高、无高毒性中间产物生成的分子印迹型MOFs催化剂，本项目建立了一种深度处置污水处理厂出水中低浓度抗生素的新方法。该研究成果将为推进分子印迹光催化技术向低浓度抗生素污染物治理实用化发展提供理论依据，具有重要的科学意义。