生物电化学系统降解氟代硝基苯性能及机理研究

发布时间：2018-03-07 23:38

本文选题：氟代硝基苯　切入点：生物电化学系统　出处：《浙江工商大学》2017年硕士论文　论文类型：学位论文

【摘要】：氟代硝基苯类化合物是一种新型难降解有毒有机污染物,具有"三致性'"和"脂溶性"。相比于同等结构的氯代化合物,氟代化合物的化学稳定性更高,生物毒性更强。如果这类污染物直接排放到水体中将对人类和环境造成严重危害。因此,开发一种环保、高效、经济的有机氟废水处理新工艺迫在眉睫。本论文构建生物电化学系统(bioelectrochemical system,BES)来强化氟代硝基苯类废水的处理,同时比较BES对邻氟硝基(o-FNB)、间氟硝基(m-FNB)和对氟硝基苯(p-FNB)三种不同氟取代位的单氟硝基苯降解性能的差异。此外,还探讨了 BES中生物阴极对p-FNB的还原去除、生物阳极对p-FNB氧化脱氟和电子传递机理。获得主要结论如下:(1)以p-FNB为模拟污染物,在反应器驯化到运行稳定阶段,BES去除100%的p-FNB所需要的时间为18 d,相比于微生物系统(BS)(36 d)缩短了 50%。在运行稳定阶段,BES去除p-FNB的一级动力学常数达到0.078 h-1,是BS(0.048 h-1)中的1.625倍。GC-MS结果表明,p-FNB在BES中主要通过硝基的还原去除,而在BS中则主要通过微生物降解去除。此外,在BES中富集的主要功能微生物为 Anaerolineae(20.8%),Flavobacteriia(15.9%)和 Alphaproteobacteria(14.8%),在 BS 中则主要为 Flavobacteriia(32.8%),Clostridia(24.1%)和 Ignavibacteria(19.2%)。(2)BES对o-FNB、m-FNB和p-FNB的去除和脱氟性能表现出显著差异。BES去除三种不同氟取代位的单氟硝基苯的难度分别为o-FNBm-FNBp-FNB。其中p-FNB在BES中的母体去除率、脱氟率以及TOC去除率分别为99.7%、50.1%和84.8%。远高于o-FNB(22.6%、3.6%和 5.4%)和 m-FNB(50.2%、5.2%和 10.7%)。量子化学结果表明,o-FNB中N原子的电荷密度最强,m-FNB其次,p-FNB最弱。氟代硝基苯还原成相应的氟代苯胺后,间氟苯胺(m-FA)脱氟需克服的势垒最强(△Eb=47.69 kcal mol-1),对氟苯胺(o-FNB)(△Eb=15.68kcal mol-1)和对氟苯胺(p-FNB)(△Eb=18.19 kcal mol-1)则差异不显著。生物群落结构结果表明,以o-FNB富集的主要功能微生物为 Proteobacteria(58.0%),Firmicute(14.0%)和 Bacteroidetes(9.6%),以m-FNB富集的主要功能微生物为Proteobacteria(47.6%),Firmicutes(19.3%)和 Bacteroidetes(10.3%),而以p-FNB 富集的主要功能微生则为 Proteobacteria(26.49%),Bacteroidetes(24.5%)和Chloroflexi(13.0%)。(3)在厌氧单室BES中,p-FNB主要通过阴极表面将硝基还原成胺基进而转化为p-FA实现母体去除,然后在阳极表面通过氧化降解p-FA实现脱氟反应,因此p-FNB在BES中的的降解矿化是生物阴极的还原和生物阳极氧化的共同作用。微生物只能以氧气作为电子受体才能降解p-FNB,但不能利用硝酸盐或硫酸盐为电子受体来降解p-FNB;在仅提供电子供体的条件下p-FNB可以实现还原转化为p-FA,但无法实现脱氟。
[Abstract]:Fluoronitrobenzenes are a new type of refractory toxic organic pollutants, which are characterized by "tritoxicity" and "liposolubility". Compared with chlorinated compounds of the same structure, fluorinated compounds have higher chemical stability. If these pollutants are released directly into the water body, they will cause serious harm to human beings and the environment. Therefore, the development of a kind of environmental protection, high efficiency, In this paper, bioelectrochemical system BESs was constructed to enhance the treatment of fluorinated nitrobenzene wastewater. At the same time, the degradation performance of p-fluoronitrobenzene (p-fluoronitrobenzene) and p-fluoronitrobenzene (p-fluoronitrobenzene) (p-fluoronitrobenzene) by BES were compared. In addition, the reduction removal of p-FNB by the biological cathode in BES was also discussed. The mechanism of oxidation defluorination and electron transport of p-FNB by biological anode. The main conclusions are as follows: (1) p-FNB is used as a simulated pollutant. It takes 18 days to remove p-FNB of 100% from acclimation to stable operation of the reactor, which is 50 days shorter than that of microbial system. The first-order kinetic constant of removal of p-FNB is 0.078 h ~ (-1), which is BS(0.048 h-1). The results of GC-MS showed that p-FNB was mainly removed by reduction of nitro in BES. While in BS, it is mainly removed by microbial degradation. In addition, The main functional microbes enriched in BES are Anaerolineae 20.8i and Flavobacteriae 15.9) and Alphaproteobacteria 14.8, mainly Flavobacteria 32.8T in BS) and Ignavibacteria(19.2%).(2)BES in removing and defluorination of o-FNBm-FNB and p-FNB. It is difficult for BES to remove three kinds of monofluoronitrobenzene with different fluorine substituents. The degree of p-FNB is o-FNBm-FNBp-FNB.The parent removal rate of p-FNB in BES, The defluorination efficiency and the TOC removal efficiency were 99.70.1% and 84.8%, respectively, which were much higher than those of o-FNB22.6% and 5.4%) and m-FNBU 50.2% and 10.7%, respectively. The quantum chemical results showed that the charge density of N atom was the strongest in o-FNB, followed by p-FNB, and the corresponding fluoroaniline was reduced from fluorobenzene to corresponding fluoroaniline. There was no significant difference between m-FA-fluoroaniline and p-fluoroaniline p-FNB-1 (Eb=15.68kcal mol-1) and Eb=18.19 kcal mol-1 (p-fluoroaniline p-FNB-1). The main functional microorganisms enriched by o-FNB are Proteobacteriae 58.0 and Bacteroidetesi 9.6m, and the main functional microbes enriched by m-FNB are Proteobacteriae 47.6i) and Bacteroidetes10.3m) and the main functional microbes enriched by p-FNB are Proteobacteria 26.49s 24.5m) and Chloroflexithroides 13.0b in anaerobic single-chamber BES, mainly through the cathode surface. The main functional microbes enriched by p-FNB are Proteobacteria 26.49 Bacterodes 24.510) and Chloroflexius 13.0%. 3) in the anaerobic single chamber BES, the main functional microorganism enriched by p-FNB is Proteobacteria 26.49 Bacterodes 24.510) and Chloroflexie 13.0%. 3) in anaerobic single-chamber BES, the main functional microorganism enriched by p-FNB is Proteobacteria26.49TES 24.510) and Chloroflexius 13.0%. The nitro group was reduced to amine group and then converted to p-FA to remove the matrix. Then the defluorination reaction was realized by oxidation degradation of p-FA on the anode surface. Therefore, the degradation and mineralization of p-FNB in BES is the co-action of biological cathodic reduction and biological anodic oxidation. Microorganisms can only use oxygen as an electron receptor to degrade p-FNB, but can't use nitrate or sulfate as electron acceptor to degrade p-FNB. P-FNB was degraded and p-FNB was reduced to p-FAunder under the condition of only providing electron donor, but defluorination could not be realized.
【学位授予单位】：浙江工商大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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