【作者】 杨珂；

【导师】 李先宁； 蒋永伟；

【作者基本信息】 东南大学 ， 资源与环境（专业学位）， 2024， 硕士

【摘要】 随着工农业的快速发展,大量抗生素等难降解有机物进入水环境中,对水体造成严重污染。此外,抗生素在水体中积累还会诱导抗性基因产生,严重威胁水生态安全。内嵌中间电极的生物电化学系统是处理抗生素水体污染的有效手段之一。本研究采用双金属氧化物MnCo₂O₄和碳纳米管（Carbon Nano Tubes,CNTs）对生物电化学系统的中间电极改性,解决了普通碳纤维刷中间电极的电催化活性差、电子转移效率低等问题,提高了系统的电化学性能,促进了水体中抗生素磺胺甲噁唑（Sulfamethoxazole,SMX）的原位去除,抑制了抗性基因的水平转移,并初步解析了SMX的降解机理。主要的研究内容和结论如下:（1）分别采用水热法和化学气相沉积法对中间电极（CF）改性,制备MnCo₂O₄和CNTs改性中间电极（MN-C和CN-C）。电极的形貌、组成的表征结果证明两种改性中间电极成功制备。MN-C和CN-C表面分别附着大量的MnCo₂O₄纳米棒和碳纳米管,与CF相比,比表面积显著增加。MN-C中MnCo₂O₄尖晶石结构晶格缺陷能够催化氧化还原反应。CN-C表面含氧活性官能团可以增强电极的亲水性及电极反应活性位点。将CF、MN-C和CN-C嵌入生物电化学系统中,构建内嵌（改性）中间电极生物电化学系统（CF-B、MN-B和CN-B）,MN-B和CN-B的平均电流分别比CF-B提高了32.3%和31.1%,MN-B和CN-B的的比电容分别比CF-B提高了13.9倍和6.2倍。MN-B和CN-B的欧姆内阻基本相同,比CF-B下降了30.5%左右。说明MnCo₂O₄和CNTs对中间电极的改性显著提高了系统的电化学性能。其中MN-B的电化学性能优于CN-B,MN-B的比电容比CN-B提高了108.0%,并且其CV曲线中氧化还原峰的位置和形状较CN-B发生了明显的变化,说明过渡金属离子参与氧化还原反应,可以介导更多电子在中间电极上的转移。（2）在三个周期的运行期间,MN-B和CN-B中的SMX平均去除效率分别比CF-B高29.5%和15.0%。并且,MN-B对SMX的去除效率显著高于CN-B,比CN-B高12.59%。在研究系统内生物电化学作用等方式对SMX的去除贡献中发现生物电化学作用是系统中SMX的主要去除方式,CF-B、MN-B和CN-B中生物电化学作用分别贡献了66.9%、81.0%和71.8%。这是因为中间电极的改性改变了电极表面的微观结构,提升了电极的电化学性能,强化了电子的传递效率,促进了SMX的降解反应。MN-B中生物电化学作用对SMX的去除贡献率比CN-B高12.3%,因为过渡金属离子可以被细胞色素C识别,促进了细胞外电子转移到水体中的SMX中,实现高效降解。分别按照一级和二级两种反应动力学方程建立生物电化学作用降解SMX动力学模型。系统生物电化学作用降解SMX反应更为符合二级反应动力学,MN-B、CN-B的二级反应速率常数为0.195、0.119（mg/L）^-1·d^-1,比CF-B(0.085（mg/L）^-1·d^-1)分别提高了128.3%和39.0%。（3）对系统内中间产物进行测定,推测出SMX降解途径,初步探究了系统对SMX去除机理。从微生物群落结构和优势功能菌阐释内嵌改性电极生物电化学系统去除抗生素机理。MN-B、CN-B改性电极上微生物群落的丰富度和多样性显著大于CF-B,并且富集了Trichococcus等电活性功能菌,抑制了Romboutsiazhe等非电活性菌和非耐药微生物的生长。在运行周期中,MN-B、CN-B中的抗性基因sul1、sul2丰度均小于CF-B,说明电极材料改性可以在一定程度上抑制sul1、sul2的基因转移。更多还原

【Abstract】 With the rapid development of industry and agriculture,a large number of refractory organic substances such as antibiotics enter the water environment,causing serious pollution problems,and the excessive concentration of antibiotics in the environment will induce the generation of resistance genes,seriously threatening the ecological security of water environment.Bioelectrochemical System（BES）has a higher efficiency for antibiotic removal than conventional biological methods and has great potential for removing antibiotic resistance genes.This research group constructed a bioelectrochemical system with embedded intermediate electrodes to achieve in situ removal of antibiotics from overlying water.However,the bioelectrochemical performance of the common carbon fiber brush intermediate electrode is weak,and the antibiotic removal performance needs to be further improved.In this study,the electrode material was modified to explore an effective way to solve this problem.In this research,bimetallic oxide MnCo2O4 and Carbon Nano Tube（CNTs）were used to modify the intermediate electrode,and the effect and effect of the modified intermediate electrode on the electrochemical performance of the system and the removal of antibiotic Sulfamethoxazole（SMX）in water were analyzed.And the mechanism is analyzed preliminarily.The main research contents and conclusions are as follows:（1）The intermediate electrodes（carbon fiber,CF）were modified by hydrothermal method and chemical vapor deposition method respectively,and the intermediate electrodes modified by MnCo2O4 and CNTs（MN-C and CN-C）were prepared.The results showed that MnCo2O4was successfully modified on the surface of the intermediate electrode,and had a stronger ability to catalyze the REDOX reaction.CNTs were successfully modified on the surface of the intermediate electrode,which enhanced the electrocatalytic activity of the electrode material.By embedding CF,MN-C and CN-C into the bioelectrochemical system,the embedded（modified）intermediate electrode bioelectrochemical system（CF-B,MN-B and CN-B）was constructed,and the average current of MN-B and CN-B was increased by 32.3%and 31.1%compared with CF-B,respectively.The specific capacitance of the intermediate electrode was483.47 F/g（MN-B）>232.47 F/g（CN-B）>32.50 F/g（CF-B）.The ohmic resistance of MN-B and CN-B is basically the same,which is about 30.5%lower than that of CF-B.The electrochemical performance of MN-B is slightly better than that of CN-B.（2）During the operation period of three cycles,the average removal efficiency of SMX in MN-B and CN-B was 29.5%and 15.0%higher than that of CF-B,respectively.Moreover,the removal efficiency of MN-B for SMX is significantly higher than that of CN-B,which is 12.59%higher than that of CN-B.In the study of the contribution of bioelectrochemical action to SMX removal in the system,it was found that bioelectrochemical action was the main method of SMX removal in the system,and the bioelectrochemical action in CF-B,MN-B and CN-B contributed 60.60%,77.24%and 69.20%,respectively.The kinetic models of bioelectrochemical degradation of SMX were established according to the first and second order reaction kinetics equations respectively.The second order reaction rate constants of MN-B and CN-B were 0.195 and 0.119（mg/L）^-1·d^-1,which were 128.3%and 39.0%higher than that of CF-B(0.085（mg/L）^-1·d^-1),respectively.（3）The intermediate products in the system were determined,the SMX degradation pathway was inferred,and the SMX removal mechanism was preliminarily explored.The mechanism of antibiotic removal by modified electrode bioelectrochemical system was explained from the structure of microbial community and dominant functional bacteria.The richness and diversity of the microbial community on the modified electrodes of MN-B and CN were significantly greater than that of CF-B,and electroactive functional bacteria such as Trichococcus were enriched,while non-electroactive bacteria and non-drug-resistant microorganisms such as Romboutsiazhe were inhibited.During the operation cycle,the abundance of resistance genes sul1 and sul2 in MN-B and CN-B was smaller than that of CF-B,indicating that the modification of electrode materials could inhibit the gene transfer of sul1and sul2 to a certain extent.更多还原