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抗生素被广泛应用于医疗和畜牧业,其可随人类或动物的尿液或粪便排出,进入土壤、地表水、市政管网及污水处理设施,甚至地下水中[1]. 抗生素不仅具有一定的毒性,还会诱导微生物产生抗性基因. 因此,会造成生态环境和健康风险[2].
目前,处理抗生素废水的传统方法包括吸附法、臭氧氧化、电化学氧化以及生物法等[3]. 近年来,生物电化学系统(Bioelectrochemical systems, BES) 也被用于降解抗生素. 例如,Chen[4]等在MFC中,利用石墨烯修饰生物电极来降解土霉素,8 d后降解率达95%[5]. Liang[6]等报道,改良的BES在24 h内对氯霉素的去除率达96%. Wu[7]等报道,在基于碳棒和泡沫铜电极的BES中,可在36 h内对CAP(初始浓度为32 mg·L−1)完全去除. 然而,在BES中,难降解有机物在降解过程中产生的一些有毒且难以矿化中间体,使微生物活性降低. 为解决该问题,有研究者将BES与人工湿地[8]或光催化技术耦合起来以强化污染物的矿化. 其中,BES与光催化过程耦合,既可提高污染物的矿化效率,又可提高能源回收[9-10],因而备受关注. 本课题组前期的研究工作证实,通过构建基于生物阳极和光电阴极的生物光电化学系统(Biophotoelectro- chemical system, BPES)可促进染料、2,4-二氯苯酚以及抗生素的降解[10-13]. 然而,BPES中高效光电极材料的研发以及抗生素降解过程机理仍需进一步深入研究.
在BPES中,光电极的催化性能对体系降解污染物的影响很大,因此,设计和构筑性能优异的光催化剂至关重要. 溴氧化铋(BiOBr)是一种层状半导体,因其独特的电子结构、适中的能带位置和良好的光学特性而受关注[14]. 但是,BiOBr的禁带宽度较宽 (Eg≈2.90 eV),且其光生电子空穴对极易复合,导致光催化效率较低[15]. 研究表明,通过金属离子Cu掺杂可提高催化剂的光催化活性[16]. 因此,本文的研究目的是通过Cu离子掺杂优化BiOBr光阴极,分析其理化性质和光电化学特性,并将其与生物阳极耦合构建BPES,考察其对盐酸四环素(TC)、磺胺甲恶唑(SMX)和阿莫西林(AMX)的降解性能. 此外,考察不同操作条件对BPES降解抗生素性能的影响,推断AMX的降解路径,并解析BPES生物阳极上微生物群落结构的演变规律,为BPES处理抗生素废水提供一定的理论依据.
基于Cu掺杂BiOBr光阴极的生物光电化学系统降解典型抗生素的特性及微生物群落响应
Degradation of typical antibiotics and microbial community response in a biophotoelectrochemical system with a Cu-doped BiOBr photocathode
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摘要: 抗生素难以生物降解且会诱导产生抗性基因,对生态环境和人体健康均造成威胁,因此,抗生素废水的高效处理意义重大. 本研究制备了Cu掺杂的BiOBr光阴极,并与生物阳极耦合,构建生物光电化学系统(biophotoelectrochemical system,BPES),用于降解抗生素. 结果表明,Cu-BiOBr较BiOBr具有更优异的光电化学性能. 光照条件下的BPES在48 h内对初始浓度为20 mg·L−1的阿莫西林(AMX)的去除率达91.38%. 此外,适当曝气可提高BPES对AMX的去除. 当AMX与盐酸四环素(TC),磺胺甲恶唑(SMX)在BPES中共降解时,降解过程均受到不同程度的抑制. 根据鉴定的AMX的降解中间产物,推断了AMX的降解路径. BPES的阳极生物膜上的微生物主要以电活性细菌Geobacter为主,其对抗生素具有较高耐受性以及降解能力.
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关键词:
- 生物光电化学系统 /
- Cu-BiOBr光阴极 /
- 抗生素 /
- 降解路径 /
- 微生物群落.
Abstract: Antibiotics are difficult to be biodegraded, and they can induce resistance genes; therefore, efficient treatment of antibiotics wastewater is of great significance. In this study, the Cu-doped BiOBr (Cu-BiOBr) photocathode was prepared and coupled with a bioanode to constructed a biophotoelectrochemical system (BPES) for antibiotics degradation. Results showed that the Cu-BiOBr exhibited superior photochemical performance as compared with the BiOBr. In the light-illuminated BPES, the removal of amoxicillin (AMX, initial concentrationof 20 mg·L−1) reached 91.38% within 48 h. In addition, providing suitable aeration in the BPES could promote AMX removal. When AMX, tetracycline hydrochloride (TC), and sulfamethoxazole (SMX) were co-existed in the BPES, degradation process of each antibiotic was inhibited to some extent. Possible degradation pathways of AMX in BPES were proposed according to the identified degradation intermediates. The dominated microorganisms on the anodic biofilm of the BPESs treating different antibiotic wastewater were electro-active bacteria--Geobacter, which showed relatively high resistance towards antibiotics and certain degradation ability. -
表 1 拟合不同光电阴极的EIS数据
Table 1. EIS data fitted by different photocathodes
光电阴极
PhotocathodesR0/Ω R1/Ω R2/Ω BiOBr 4.24 6.16×10−3 1.60×10−6 5-Cu-BiOBr 4.55 4.92×10−3 1.95×10−6 15-Cu-BiOBr 4.30 3.62×10−3 1.19×10−6 25-Cu-BiOBr 4.51 5.33×10−3 8.45×10−5 -
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