磁性过渡金属氧化物催化类芬顿反应降解有机染料

发布时间：2018-05-25 04:07

本文选题：铁酸镍 + 硫修饰改性铁酸钴　；参考：《西北师范大学》2015年硕士论文

【摘要】：近年来,随着工业废水的排放量不断增加以及淡水资源的不断减少,越来越多的化学工作者致力于工业废水的净化与再生的研究。其中,以类芬顿反应为基础的高级氧化技术(AOPs)由于其高效的反应性能以及较好的可行性受到了更多的关注。本研究以活性金属氧化物催化H_2O_2产生羟基自由基进行氧化的类芬顿反应体系降解水溶液中的有机染料为目的,分别通过溶胶-凝胶法和共沉淀法制备了NiFe_2O_4和CoFe_2O_4两种非均相反应催化剂,并对后者进行了硫元素的修饰。研究过程中分别选定了孔雀石绿(MG)和酸性橙II(AOII)两种有机染料为降解目标底物,通过控制变量法考察了煅烧温度、初始pH值、参加反应的各成分用量等一系列因素对催化效果的影响。此外,对于催化剂的稳定性和反应机理也进行了较为深入的讨论。通过研究得到了以下结论:(1)溶胶-凝胶法制得的NiFe_2O_4催化剂经过XRD、BET、SEM的测试表明其尺寸较小,分散均匀,属于纳米颗粒;以其在温度298 K、催化剂用量1.0 g·L-1、H_2O_2浓度20 mM、初始pH=7的条件下对25 mg/L的孔雀石绿水溶液进行降解,反应40 min后降解脱色率可达99%以上。(2)通过共沉淀法制得CoFe_2O_4颗粒并用0.5 M稀硫酸进行修饰进而在高温下煅烧得到S-CoFe_2O_4催化剂。经过XRD、BET、SEM、FT-IR、VSM表征证实了该催化剂是分散性较好并且粒度均匀的磁性纳米颗粒。(3)以其在温度298 K、催化剂用量0.1 g·L-1、H_2O_2浓度6 mM、初始pH=6的条件下对50 mg/L的酸性橙II水溶液进行降解,反应30 min后降解脱色率可达98%以上,同时总有机碳(TOC)的去除率也达到了40%。在后续的催化剂回收重复试验过程中,发现回收过程对两种催化剂的性能均有一定的影响,通过XRD、BET以及EDS的表征对后者催化性能的下降进行了较为深入的讨论。
[Abstract]:In recent years, with the increasing discharge of industrial wastewater and the decreasing of fresh water resources, more and more chemical workers devote themselves to the study of purification and regeneration of industrial wastewater. Among them, advanced oxidation technology based on Fenton reaction (AOPs) has attracted more and more attention because of its high efficiency and good feasibility. The purpose of this study was to degrade organic dyes in aqueous solution by a Fenton-like reaction system catalyzed by active metal oxides to produce hydroxyl radical from H_2O_2. Two heterogeneous catalysts, NiFe_2O_4 and CoFe_2O_4, were prepared by sol-gel method and co-precipitation method, respectively, and the latter was modified by sulfur element. Two kinds of organic dyes, malachite green (MG) and acidic orange (IIAOII), were selected as the target substrate in the study. The calcination temperature and initial pH value were investigated by means of variable control method. The effect of a series of factors, such as the amount of each component involved in the reaction, on the catalytic effect. In addition, the stability and reaction mechanism of the catalyst were also discussed. The following conclusions are obtained: (1) the NiFe_2O_4 catalyst prepared by sol-gel method has been tested by XRDX BETSEM. The results show that the catalyst is small in size, uniform in dispersion and belongs to nanometer particles. The malachite green aqueous solution of 25 mg/L was degraded at 298K temperature, 1.0 g L-1 H2O2 concentration of 20mm, initial pH=7, and the amount of catalyst was 1.0 g / L ~ (-1) H _ 2O _ 2. After 40 min reaction, the decolorization rate can reach over 99%. The CoFe_2O_4 particles were prepared by coprecipitation method and modified with 0.5M dilute sulfuric acid, and then calcined at high temperature to obtain S-CoFe_2O_4 catalyst. It was confirmed by the characterization of XRDD-BETSE-SEMT-IRT-IRSM that the catalyst was a magnetic nanoparticles with good dispersion and uniform particle size. At 298K, the amount of catalyst 0.1 g / L ~ (-1) H _ 2O _ 2 was 6 mm, and the acid orange II solution of 50 mg/L was degraded under the initial pH=6 condition. The decolorization rate was over 98% after 30 min reaction, and the removal rate of total organic carbon (TOC) was 40%. In the subsequent repeated experiments of catalyst recovery, it was found that the recovery process had a certain effect on the performance of the two catalysts. The degradation of the catalytic performance of the latter was discussed through the characterization of XRD-BET and EDS.
【学位授予单位】：西北师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;X703

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