【作者】 于凌；

【导师】 张凤君；

【作者基本信息】 吉林大学 ， 环境工程， 2011， 硕士

【摘要】 硝基苯废水的污染问题已经成为全球关注的环境问题,地下水中的硝基苯的污染问题日益严重,已经越来越多的受到了国内外学者的关注与重视。硝基苯具有毒性强,化学性质稳定,污染性强,难被生物降解.并且对水体的污染持续时间长等特点。无论是进入水体还是空气中,都将对环境及人类造成很大的伤害。所以我们必须重视地下水体中的硝基苯污染问题。目前.国内外对地下水中硝基苯污染问题的研究还处于起步阶段.硝基苯对地下水的污染问题还有待进一步的深入研究。本研究运用纳滤技术、化学氧化及活性炭吸附的方法,旨在对去除地下水中含有的高浓度硝基苯,以期为硝基苯污染的地下水治理研究提供理论依据。实验利用纳滤技术将硝基苯废水分离成高浓度的浓缩液和浓度较低的透过液,探讨了4个环境因素对整个纳滤过程的影响。纳滤过程对硝基苯的截留的最佳条件为进水浓度600mg/L、流量60L/h、pH值8、温度50℃。采用一级一段循环模式,以污染地下水的实际情况运行.截留率为64.15%。结果表明,纳滤技术对硝基苯有较好的截留效果,为进一步处理硝基苯提供了必要的条件。对于高浓度的浓缩液采用化学氧化的方法处理。首先是利用正交实验确定了Fenton试剂氧化硝基苯的最佳水平组合为反应时间60min、pH值3、H2O2浓度800mg/L、Fe2+浓度160mg/L。在最佳水平组合条件下进行实验,在反应初始阶段.硝基苯的转化率不高,随后转化率逐渐上升：当反应进行超过60min后,硝基苯的转化率变化不大，但均达97%以上。结果表明.Fenton试剂能很好的氧化去除硝基苯。与Fenton试剂氧化法相比,还可以采用臭氧氧化的方法来处理纳滤过程的浓缩液,确定最佳影响因素为pH值10、水浴温度50℃、O3流量400h/L。在最佳条件下进行实验.随着反应的进行,硝基苯的转化率逐渐升高,最高时的转化率可以达到40.06%。反应进行10min后.转化率继续升高的趋势不大,但均达到37%以上。为了提高臭氧对硝基苯浓缩液的处理效果,将H2O2作为催化剂引入臭氧氧化工艺,确定最佳影响因素的为pH值10、水体温度50℃、臭氧流量300h/L、H2O2的投加量15mg/L。在最佳条件下进行实验,硝基苯的转化率逐渐升高,反应进行25min.转化率可以达到91.94%。可见.以H2O2作为催化剂的臭氧氧化过程使硝基苯的转化率明显增加,H2O2和臭氧联合使用要比单独臭氧氧化处理硝基苯的效果更好。对于相对浓度比较低的透过液,利用活性炭较强的吸附能力和巨大的比表面积的特点进行吸附去除。随着活性炭投加量的增加,水体中剩余硝基苯的浓度越来越小,硝基苯的去除率逐渐升高。活性炭投加量为100g/L时,活性炭对硝基苯的吸附效果最好.去除率可以达到99.31%,硝基苯的浓度为1.3188mg/L。活性炭投加量为50g/L时,硝基苯的去除率可达98.87%,浓度为2.1783mg/L。从处理后溶液的浓度以及经济上的考虑,采用活性炭投加量为50g/L。活性炭对硝基苯的吸附容量随着反应时间的延长而增加,吸附主要发生在60min内。准二级反应动力学方程的拟合程度是最好的,R2可以达到0.9999,所以可以用准二级反应动力学方程来描述整个活性炭吸附硝基苯的过程。结果表明,活性炭对硝基苯有很强的吸附能力,对硝基苯废水的治理具有一定的实际意义和工程意义。本研究将纳滤技术、化学氧化法、活性炭吸附法结合,很好的处理含有硝基苯的地下水.整个实验过程硝基苯的去除率很高。实验为地下水中硝基苯的去除研究提供了理论依据,具有一定的工程意义。更多还原

【Abstract】 Nitrobenzene wastewater pollution has already become a global environmental problem. The groundwater pollution by nitrobenzene has become increasingly serious, and already been the concern and attention to domestic and foreign scholars at present. Nitrobenzene has the following characteristics such as:highly toxicity, stable chemical properties, highly polluting,difficult to be biodegradable, and the pollution has lasted for a long time. Whether nitrobenzene into water or air. it could cause large damage to environment and human. Therefore, we must pay more attention to groundwater pollution problems by nitrobenzene. At present, the research of groundwater pollution by nitrobenzene is still in the initial stage. So the problem of groundwater pollution by nitrobenzene still needs to be further studied.The purpose of this study was expected to remove the high nitrobenzene of groundwater. with the methods of NF. Chemical oxidation and Activated carbon adsorption. Besides, the research was also investigated, looking forward to providing theory basis in groundwater pollution by nitrobenzene. Permeate and concentrated liquid had been separated and the effects of four main factors including influent concentration, flow, pH and temperature were studied by using NF process. Selection of optimum condition for NF process, which was the influent.600mg/L: concentration.60L/h:pH.8:temperature.50℃. The rejection could reach 64.15% with the actual polluted groundwater by the cyclical NF process. The results showed that NF could reject nitrobenzene effectively, and could provide necessary condition for removing nitrobenzene.Chemical oxidation had been used to treat the concentrated liquid of nitrobenzene. The effect of main factors on oxidization of Fenton reagent was observed by orthogonal experiment. The optimal condition was the reaction time. 60min; pH.3;concentrate of H2O3.800mg/L:concentrate of Fe2+,160mg/L. in which the conversion rate was relatively low at the beginning, and then increased gradually. The conversion rate could reach 97% and could stay a stabile level after 60 minutes. The results showed that it had good treatment efficiency of nitrobenzene with the method of Fenton reagent.Comparison of Fenton reagent. ozone oxidation had been used to treat the concentrated liquid of nitrobenzene. The optimal condition of main factors was pH. 10;temperature,50℃:flow of O3,400h/L, in which the conversion rate increased gradually. The highest conversion rate could reach 40.06% and could stay a stabile level after 10 minutes with the conversion rate of more than 37%. In order to improve the treatment effect of concentrated liquid of nitrobenzene, H2O2 had been used as the catalyst in the ozone oxidation process. The optimal condition of main factors was pH. 10:temperature,50℃;flow of O3,300h/L; dosage of H2O2,15mg/L, in which the conversion rate increased gradually and could reach 91.94% after 25 minutes. The conversion rate was increased obviously with the ozone oxidation process when the H2O2 was the catalyst. H2O2 and ozone oxidation in combination could remove nitrobenzene better than ozone oxidation process.Activated carbon adsorption had been used to treat the permeate liquid of nitrobenzene because of the large adsorption capacity and specific surface area. With the increasing dosage of activated carbon, the removal rate had become lower. The removal rate of nitrobenzene was 99.31% and the concentration was 1.3188mg/L when the dosage was 100mg/L. The removal rate of nitrobenzene was 98.87% and the concentration was 2.1783mg/L when the dosage was 50mg/L. The optimum dosage was 50mg/L because of the rest concentration of nitrobenzene and economic considerations. The main adsorption occurred in 60 minutes, and the adsorption capacity had increased with the reaction time. The data were fitted to pseudo-second order kinetic model. and R2 was 0.9999. So the adsorption process could be described with the pseudo-second order kinetic model. The results showed that nitrobenzene had been adsorbed very well by activated carbon adsorption, and it had certain practical significance and engineering significance for the governance of nitrobenzene wastewater.In a word, the method of NF-Chemical oxidation-Activated carbon adsorption was ssuccessfully used to treat nitrobenzene of groundwater and had high removal rate by this experiment. It will have big engineering significance in wastewater treatment in the future.更多还原