超声强化铁碳微电解耦合Fenton法降解硝基苯废水

发布时间：2018-04-26 15:12

本文选题：超声波 + 铁碳微电解　；参考：《中北大学》2017年硕士论文

【摘要】：铁碳微电解还原法是一种处理硝基苯废水的有效方法。该法将硝基苯苯环上的硝基还原为胺基,活化苯环,使其更易于氧化或生化处理。然而铁碳微电解床在处理有机废水的长期运行过程中,常存在铁碳填料易钝化、难连续可用的问题,造成该法需周期性停止,进行填料清洗再生,从而增加废水处理成本且致使铁碳微电解工艺难以连续长期高效运行。针对铁碳微电解存在的问题,本文提出超声强化铁碳微电解降解硝基苯的思路:将超声与铁碳微电解联用降解硝基苯废水,利用超声的空化作用强化铁碳微电解降解硝基苯废水,旨在提高铁碳填料的连续使用性。此外,本研究针对超声/铁碳微电解对硝基苯废水的低矿化度,将超声/铁碳微电解法与Fenton法耦合处理硝基苯废水,优化有机废水迁移转化的工艺条件。首先,采用超声/铁碳微电解法还原降解硝基苯废水,考察了零价铁(Fe~0)剂量、活性炭(GAC)剂量、废水初始pH值、超声功率对超声/铁碳微电解法降解硝基苯的影响规律。结果表明:不更换填料时,超声/铁碳微电解法连续处理4批相同废水的硝基苯去除率均在90%左右;而在铁碳微电解法处理下,4次硝基苯去除率依次为52.01%、36.19%、25.16%、17.38%。采用SEM和EDS检测分析反应过程中铁碳填料表面形貌及元素组分,考察超声对铁碳微电解反应的强化机制。在超声的作用下,铁碳填料表面反应活性位点在反应过程中可连续再生,从而使铁碳微电解法能连续高效运行。本研究采用单因素法得到了降解硝基苯的适宜操作条件:Fe~0剂量20 g·L~(-1),GAC剂量10 g·L~(-1),废水初始pH为4,超声功率为192 W。在此条件下,反应80 min,硝基苯的去除率可达93%。其次,在超声/铁碳微电解单因素实验基础上,采用响应面法建立了超声/铁碳微电解法对硝基苯去除率预测的工艺参数数学模型,且检验结果表明该模型拟合程度及准确度较高。实验因素贡献率为Fe~0剂量≈废水初始pH值超声功率GAC剂量,且Fe~0剂量与废水初始pH值之间,以及废水初始pH值与超声功率之间交互作用明显。再次,本研究将超声/铁碳微电解与Fenton法耦合深度降解硝基苯废水。结果表明:铁碳微电解-Fenton法连续处理4批硝基苯废水时,硝基苯最终去除率从69.4%降至31.66%,TOC去除率也从48.11%降至19.2%;而超声/铁碳微电解-Fenton法处理4批硝基苯废水时,硝基苯去除率均达到100%左右,TOC去除率均稳定至60%以上。与单纯铁碳微电解-Fenton法相比,超声不仅整体上强化了铁碳微电解-Fenton法降解硝基苯废水的效率,而且也提高了其对硝基苯废水矿化度。得到的适宜操作条件为:H2O2总投加量为4 mL并分五次添加,超声/铁碳微电解的出水pH调为4,反应30 min,最终硝基苯去除率达到100%,TOC去除率可达75%。最后,采用高效液相色谱及气相色谱-质谱联用仪对超声强化降解废水的中间产物进行了分析,并对其降解途径进行了推测。在超声/铁碳微电解作用下硝基苯的降解途径为:硝基苯先加氢还原为亚硝基苯,继而被还原为苯胲,最终转化为苯胺。苯胺在Fenton法作用下,先被氧化为对亚胺醌,继而氧化脱胺生成化学性质较不稳定的对苯醌;此外,超声/铁碳微电解处理后的废水中残留的硝基苯在Fenton法作用下,经氧化生成对硝基酚,再经脱硝也转化为对苯醌;对苯醌经氧化后分解生成草酸、丙二酸、丁二酸、反式丁烯二酸等小分子物质,最后彻底氧化分解为二氧化碳和水。
[Abstract]:Iron carbon micro electrolysis reduction is an effective method for the treatment of nitrobenzene wastewater. This method reduces nitrobenzene on nitrobenzene ring to amines, activates benzene ring and makes it easier to oxidize or biochemical treatment. However, iron carbon micro electrolysis bed is often passivated and difficult to be readily available in the long operation process of organic wastewater treatment. It is necessary to stop the method periodically and carry out the cleaning and regeneration of the packing, thus increasing the cost of the wastewater treatment and causing the iron carbon micro electrolysis process to be difficult to run continuously for a long time. Water, using the cavitation effect of ultrasound to strengthen the degradation of Nitrobenzene Wastewater by iron carbon micro electrolysis, aiming at improving the continuous use of iron and carbon filler. In addition, this study is aimed at the treatment of Nitrobenzene Wastewater by ultrasonic / iron carbon microelectrolysis and Fenton method to optimize the transfer and transformation of organic wastewater. First, the reduction and degradation of Nitrobenzene Wastewater by ultrasonic / iron carbon micro electrolysis was used to investigate the effect of zero valent iron (Fe~0) dose, active carbon (GAC) dose, initial pH value of wastewater and ultrasonic power on the degradation of nitrobenzene by ultrasonic / iron carbon micro electrolysis. The results showed that the ultrasonic / iron carbon micro electrolysis process was continuously treated for 4 batches of the same waste when the filler was not replaced. The removal rate of nitrobenzene in water is about 90%, and the removal rate of 4 nitrobenzene is 52.01%, 36.19% and 25.16% in the process of iron carbon micro electrolysis. 17.38%. and EDS are used to detect the surface morphology and element composition of iron carbon filler in the reaction process by SEM and EDS. The reactive sites in the surface of the material can be regenerated continuously during the reaction process, so that the iron carbon micro electrolysis process can run continuously and efficiently. The suitable operating conditions for the degradation of nitrobenzene are obtained by the single factor method: Fe~0 dose 20 g. L~ (-1), GAC dose 10 g L~ (-1), initial pH of wastewater 4, and ultrasonic power of 192 W. in this condition, 80 min, The removal rate of nitrobenzene can reach 93%. next. On the basis of single factor experiment of ultrasonic / iron carbon micro electrolysis, a mathematical model for predicting the removal rate of nitrobenzene by ultrasonic / iron carbon micro electrolysis is established by the response surface method. The test results show that the model has a high degree of fitting and accuracy. The contribution rate of the experimental factor is Fe~0 dose wastewater. The initial pH value of ultrasonic power is GAC, the Fe~0 dose and the initial pH value of wastewater, and the interaction between the initial pH value of the wastewater and the ultrasonic power are obvious. Thirdly, the ultrasonic / Fe carbon micro electrolysis and Fenton method are coupled to the degradation of nitrobenzene wastewater. The results show that the iron carbon micro electrolysis -Fenton method is used to treat 4 batches of nitrobenzene wastewater continuously. The final removal rate of benzene to benzene is reduced from 69.4% to 31.66%, and the removal rate of TOC is also reduced from 48.11% to 19.2%, while the removal rate of nitrobenzene is about 100% and the removal rate of TOC is stable to more than 60% when treating 4 batches of Nitrobenzene Wastewater by ultrasonic / iron carbon micro electrolysis -Fenton method. Compared with the pure iron carbon micro electrolysis -Fenton method, ultrasound not only strengthens the iron carbon microelectricity on the whole. The efficiency of -Fenton degradation of nitrobenzene wastewater and the mineralization of nitrobenzene wastewater have been improved. The suitable operation conditions are as follows: the total dosage of H2O2 is 4 mL and is added five times. The effluent pH of ultrasonic / iron carbon micro electrolysis is 4, the reaction is 30 min, the removal rate of nitrobenzene is 100%, the TOC removal rate can reach 75%. and the high performance liquid is used. The intermediate products of ultrasonic enhanced degradation wastewater were analyzed by chromatography and gas chromatography-mass spectrometry, and the degradation pathway was speculated. The degradation pathway of Nitrobenzene Under the action of ultrasonic / iron carbon micro electrolysis was that nitrobenzene was hydrogenated to nitroso first, and then returned to aniline at Fenton. Under the action of the method, it is oxidized to imide quinone first and then oxidizing deamine to produce quinone. In addition, the residual nitrobenzene in the wastewater after ultrasonic / iron carbon micro electrolysis is oxidized to p-nitrophenol by oxidation and then converted to quinone by denitrification, and oxalic acid is decomposed to produce oxalic acid after oxidation. Dicarboxylic acid, succinic acid, trans maleic acid and other small molecules, finally completely oxidized to carbon dioxide and water.

【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X78

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