新型自偏压生物-光电化学系统降解典型抗生素的机理研究

The control and treatment of antibiotics polluted water is one of the hot environmental issues currently. Using bioelectrochemical system (BES) for antibiotics degradation through cathodic reduction has certain advantage over traditional physical, chemical and biological technologies. However, utilizing BES for antibiotics reductive degradation requires external electrical driving force (which is energy consuming), and it also suffers from incompletely degradation (toxic intermediates accumulation) and low degradation efficiency. To address these issues, the light-driven, self-biased bio-photoelectrochemical system（SB-BPES）based on g-C3N4 heterojunction photocathode is proposed for more efficient degradation of antibiotics. Metronidazole and nitrofurazone are chosen as the model antibiotics, and the experiments will be conducted as follows: examining antibiotics degradation kinetics, identifying the intermediates, tracking their further degradation behavior, and discussing the possible degradation; analyzing the microbial community and shedding light on microbial metabolic function, as well as their environmental evolution regulation; then revealing antibiotics degradation mechanism based on microbial structure and possible degradation pathways; besides, evaluating the effects of different heterojunction photocathodes, light intensities, substrate concentrations on the performance of antibiotics degradation and cell performance of the system, and exploring the relationship between photocathodes’ energy-band structure and antibiotics degradation; understanding those factors influencing mechanism for antibiotics degradations and SB-BPES electrical outputs, and thus establishing optimization strategy. From the above experiments, theoretical evidence of using SB-BPES for antibiotics degradation will be provided through system development, degradation mechanism discussion and system performance optimization, which is beneficial for advancing antibiotic wastewater treatment technologies.

抗生素水体污染控制与治理是当前热点环境问题之一。生物电化学系统（BES）阴极还原降解抗生素相对传统物理、化学及生物技术具有一定优势。然而，利用BES还原降解抗生素需电能驱动，且降解不彻底、效率较低。对此，本研究拟构建基于g-C3N4基异质结光阴极的光驱动自偏压生物光电化学系统（SB-BPES），实现节能、高效降解抗生素。以甲硝唑和呋喃西林为代表，考察抗生素降解动力学特性，鉴定中间产物并追踪其行为归趋，推断降解途径；分析微生物群落结构，明确微生物代谢功能及其环境演变规律；结合微生物生态结构及降解途径，揭示抗生素降解机理；探究不同异质结光阴极、光强及底物浓度等对抗生素降解的影响，挖掘异质结的能带结构与抗生素降解之间的关系理论，明确不同因素对SB-BPES综合性能的影响机制，确立调控优化策略。从体系构建、机理探讨及性能优化方面为SB-BPES处理抗生素废水提供依据，推动抗生素废水处理技术的发展。

抗生素对环境及人类具有危害作用，因此，开发高效的抗生素废水处理技术重要重大。本项目提出构建基于光阴极的生物光电化学系统（BPES），旨在高效、节能降解抗生素。本项目开展的工作如下：（1）优化制备了g-C3N4/CdS光阴极，并对其进行了表征和测试，系统研究了基于g-C3N4/CdS光阴极的BPES降解呋喃西林（NFZ）的特性、影响因素及机理；（2）探究了基于BiOBr光阴极的BPES降解氯霉素的特性及微生物群落结构；（3）优化制备了BiVO4/RGO光阴极，并探讨了其在BPES中去除金霉素的特性。结果表明：（1）g-C3N4/CdS（1:9，7.5 mg/cm2）光阴极具有最优的光响应能力及光生载流子分离效率，将其用于BPES中，4 h内对NFZ的去除率达83.1%，TOC去除率显著高于对照体系；微生物降解、电催化降解和光催化降解在BPES中协同促进NFZ的降解；NFZ降解主要包括硝基还原、C=N不饱和键还原以及C-N不饱和键和N-N键受到攻击等过程；BPES的阳极生物膜中产电菌占比最多，且在光驱动下，体系可自发产生约1.0 mA的电流，形成自偏压系统（SB-BPES），其对NFZ的TOC去除率达到63%。（2）光照条件下，BPES中BiOBr光阴极电势较低，有利于氯霉素脱氯；阳极生物膜的主导微生物为Geobacter 和Pseudomonas。（3）基于BiVO4/RGO-泡沫镍光阴极的BPES对金霉素的去除率达70%，且稳定性较好。自偏压生物光电化学系统的构建及运行，为难降解有机废水的零耗能高效处理提供了新思路，NFZ的降解路径和机理丰富了抗生素降解的理论体系。目前，本项目取得的研究成果在国际著名期刊如Journal of Hazardous Materials和Bioresource Technology等上面发表SCI论文9篇。

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