电辅助微生物还原降解偶氮染料的过程及机理研究

发布时间：2018-05-03 00:14

本文选题：水处理 + 电辅助微生物　；参考：《天津工业大学》2017年硕士论文

【摘要】：由于偶氮染料在印染、造纸等工业生产中的广泛使用,造成全世界染料废水大部分都是偶氮染料废水,并且其废水具有高毒性、高色度、成分复杂等特点对环境危害极大,成为公认的难处理废水。研究发现,单纯的物理、化学或生物方法,虽然对偶氮染料有一定的降解,但使用任一种处理手段都不太理想。本文将电化学和微生物体系相结合,组成电辅助微生物体系还原污染物。前期研究发现电辅助微生物对氯酚类难降解污染物有良好的去除效果,但是否对偶氮染料也能达到较好的去除,以及降解过程和机理,目前较少,需要进行深入研究。本文选取偶氮染料活性艳红X-3B为处理对象,首先对比研究了电辅助微生物体系(EAMS)、电化学体系(ECS)和微生物体系(MS)厌氧条件下对活性艳红X-3B的降解性能。其次在EAMS中研究关键影响因素,包括外电压、温度、硫酸根以及硝酸根对降解活性艳红X-3B的影响,确定最佳电压以及反应的活化能,并通过紫外-可见分光光度计、GC-MS对降解产物进行分析,推测EAMS对活性艳红X-3B降解机理。最后,在EAMS中加入氧化还原介体蒽醌-2-磺酸盐(AQS),研究AQS对偶氮染料降解的强化效果以及反应体系的电流变化,并对其强化机理进行分析。研究结果表明:与ECS和MS相比,EAMS中电化学催化和微生物降解技术对染料降解存在协同作用,大大提升了活性艳红X-3B的降解率。不同电压下染料的降解符合一级动力学特征,且0.4V电压下染料降解最快。在一定温度范围内,温度升高有助于染料的降解,由阿伦尼乌斯方程估算得EAMS降解活性艳红X-3B的活化能为60.526kJ/mol,说明染料降解主要依靠微生物的氧化还原,而不是生物吸附。硫酸根对染料还原影响不大,只有当浓度高达600mg/L后,染料降解率略微降低。硝酸根对染料还原影响较大,加入任何浓度的硝酸盐,前6h染料降解速率均下降,主要原因是反硝化菌夺电子能力较强,硝酸根优先被还原。在EAMS中,活性艳红X-3B中偶氮键首先断裂,三嗪结构以及萘环结构也可被降解,苯环部分被降解为烷烃,并且有新的苯类物质产生。对EAMS和MS中活性艳红X-3B的产物进行GC-MS分析,发现EAMS中主要产物为无毒的烷烃类物质,而MS中主要产物为有毒的苯类物质。当c(AQS)为0.050mmo1/L时,染料降解最快,一级动力学常数为1.962 h-1,是未添加AQS的(0.2644 h-1)7.42倍。加入AQS后,体系中电流升高,说明AQS加快了降解过程中电子传递速率。研究显示,AQS的加入实现了电极-远离电极的微生物-染料之间多相反应界面远程电子传递过程,使整个体系的微生物都可以快速发挥作用,达到强化降解偶氮染料。
[Abstract]:Due to the widespread use of azo dyes in printing and dyeing, papermaking and other industries, most of the world's dye wastewater is azo dye wastewater, and its wastewater has the characteristics of high toxicity, high chromaticity and complex composition, which is harmful to the environment. Become a recognized refractory wastewater. It is found that only physical, chemical or biological methods are not ideal for the degradation of azo dyes. In this paper, electrochemistry and microbial system are combined to form electroassisted microbial system to reduce pollutants. Previous studies have found that electroassisted microbes have a good removal effect on chlorophenol refractory pollutants, but whether to achieve better removal of azo dyes, as well as the degradation process and mechanism, is less, so it needs to be further studied. In this paper, the reactive brilliant red X-3B of azo dyes was selected as the treatment object. Firstly, the biodegradability of reactive brilliant red X-3B was studied under the anaerobic conditions of electroassisted microbial system (EAMSG), electrochemical system (ECS) and microbial system (MSS). Secondly, the key influencing factors were studied in EAMS, including external voltage, temperature, the influence of sulfate and nitrate on the degradation of reactive brilliant red X-3B, and the optimum voltage and the activation energy of the reaction were determined. The degradation products were analyzed by GC-MS with UV-Vis spectrophotometer, and the degradation mechanism of reactive brilliant red X-3B was inferred by EAMS. Finally, the enhancement effect of AQS on the degradation of azo dyes and the current change of the reaction system were studied by adding the redox medium, anthraquinone -2-sulfonate, to EAMS, and the strengthening mechanism was analyzed. The results showed that compared with ECS and MS, the degradation rate of reactive brilliant red X-3B was greatly enhanced by the synergistic effect of electrochemical catalysis and microbial degradation on the degradation of dyes. The degradation of dyes at different voltages accords with the first-order kinetic characteristics, and the degradation of dyes is the fastest at 0.4 V voltage. The activation energy of reactive brilliant red X-3B degraded by EAMS was estimated to be 60.526kJ / mol from Arrhenius equation, which indicated that the degradation of dyes mainly depended on the redox of microorganisms, not on biosorption. Sulfate had little effect on the reduction of dyes, but the degradation rate of dyes decreased slightly when the concentration was as high as 600mg/L. Nitrate had a great effect on the reduction of dyes. The degradation rate of dyes decreased 6 hours before adding nitrate at any concentration. The main reason was that denitrifying bacteria had strong electron capture ability and nitrate was reduced preferentially. In EAMS, the azo bond in reactive brilliant red X-3B breaks first, the triazine structure and naphthalene ring structure can also be degraded, the benzene ring is partially degraded to alkane, and new benzenes are produced. The products of reactive brilliant red X-3B in EAMS and MS were analyzed by GC-MS. It was found that the main products of EAMS were nontoxic alkanes, while the main products of MS were toxic benzenes. When 0.050mmo1/L was 0.050mmo1/L, the dye degradation was the fastest, and the first-order kinetic constant was 1.962 h-1, which was 7.42 times as high as 0.2644h-1H ~ (-1) without AQS. After the addition of AQS, the current in the system increased, which indicated that AQS accelerated the electron transfer rate in the degradation process. The results show that the addition of AQS can realize the long-distance electron transfer process between the electrode and the microorganism far away from the electrode and the multiphase reaction interface, so that the microorganism of the whole system can play a rapid role to enhance the degradation of azo dyes.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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