生物阴极原位自固定负载纳米钯强化氯霉素还原降解机制及调控方法

The biocathode bioelectrochemical system (BES) is a promising technology for reductive degradation of antibiotic chloramphenicol (CAP), however, it often suffers from low dechlorination efficiency and incomplete dechlorination of CAP. Herein, in situ formation and self-immobilization of palladium nanoparticles (Pd-NPs) into biocathode is proposed that will improve the biocatalysis of biocathode and further integrate Pd-based catalysis to enhance CAP reduction with complete dechlorination. The enhanced CAP reduction strategy is also established through controlling the loading amounts of Pd-NPs on the biocathode and adding different hydrogen/electron donors into catholyte. The electron transfer mechanism that mediated by Pd-NPs from biocathode to microbes is verified using high-throughput sequencing and electrochemical technologies. The morphology and structure of the biocathode with Pd-NPs fabrication are characterized by scanning electron microscope, transmission electron microscope and atomic force microscope. The crystallinity and element valence state of Pd-NPs are characterized by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The cyclic voltammetry characterization and degradation pathway of CAP on the biocathode with Pd-NPs fabrication are investigated. Basing on these results, the reduction mechanism of CAP by the BES with Pd-NPs fabricated biocathode is proposed. The results of this project will have both theoretical and technical values for treating CAP containing wastewater using the biocathode BES.

生物阴极型生物电化学系统可还原降解氯霉素，但仍面临氯霉素脱氯不彻底、脱氯效率低等问题。为此，本研究拟利用生物阴极原位自固定负载纳米钯，通过提高阴极的生物催化性能并联合钯催化，强化氯霉素还原降解，实现完全脱氯；并探讨不同纳米钯负载量和多种氢/电子供体下的氯霉素还原降解效率及降解动力学，建立生物阴极负载纳米钯强化氯霉素还原降解的调控方法。同时，利用电化学技术、宏转录组及16S rDNA高通量测序技术等手段解析纳米钯介导的阴极与微生物间电子传递机制，借助材料学方法分析纳米钯的晶型组分及生物膜-纳米钯催化层的表面结构特征等，并结合氯霉素在载钯生物阴极上的循环伏安特征及其降解途径和转化历程，阐明生物阴极原位自固定负载纳米钯强化氯霉素还原降解的作用机制，为处理氯霉素废水提供理论依据和技术基础。

针对生物阴极型生物电化学系统去除以氯霉素代表的抗生素时存在脱氯不彻底、脱氯效率相对较低等问题，本项目进行了生物阴极原位负载纳米钯和纳米金，通过纳米金属颗粒提高生物膜导电性、降低电极与微生物间电子转移势垒、提高生物阴极生物电化学催化性能等，强化去除氯霉素类抗生素。结果表明，当生物阴极原位负载纳米钯时，与对照组相比，电荷转移内阻降低了673%，极限电流密度提高了4.3倍，氯霉素去除速率常数提高了44%，而且在反应4h内，去除效率提高了近71%。当生物阴极原位合成纳米金时，氯霉素去除效率是对照组生物阴极的1.8倍，并选择性富集了Dokdonella, Bosea, Achromobacter, Bacteroides 和Petrimonas等具备电子传递和污染物降解能力的微生物。该研究为设计高电活性生物膜和纳米金属材料修饰电极提供了重要的指导作用，也为绿色合成纳米材料在生物电化学领域的应用提供了更多可能性。