赤泥基类Fenton催化剂的制备及其性能研究

发布时间：2018-01-15 08:13

本文关键词：赤泥基类Fenton催化剂的制备及其性能研究　出处：《广西大学》2017年硕士论文　论文类型：学位论文

更多相关文章：赤泥 Fenton α-Fe_2O_3 ZnO 橙黄 Ⅱ

【摘要】：随着我国工业化进程的加快,工业废水大量排放,对自然环境及人类健康造成了严重的危害,其中有机废水由于具有水质复杂、COD高、毒性大、难降解等特点,其处理一直是环保领域的热点话题,高级氧化法被认为是处理有机废水比较可行的方法之一。其中,Fenton氧化法因具有高效、稳定、污染物降解相对彻底等优势而被广泛应用。但是均相Fenton法存在铁离子难回收,容易造成二次污染等缺点,限制了其工业化应用。为此,国内外学者利用天然铁矿或将催化活性铁组分固定在载体上,制备出不溶于水的非均相催化剂,以解决催化剂难回收等问题。赤泥是制铝工业提取氧化铝时排出的污染性废渣,根据氧化铝不同生产方法可分为拜耳法赤泥、烧结法赤泥和联合法赤泥。赤泥呈强碱性(pH 10.0-12.5),主要的化学成分包括Fe203、Si02、A1203、Ti02、Na2O、CaO等,其中拜耳法赤泥通常铁含量高,铁氧化物含量高达30%以上,这一特性为拜耳法赤泥制备非均相类Fenton催化剂提供了可能。本研究工作,从循环经济的角度出发,同时立足于广西区域发展,以广西制铝行业大量排放的拜耳法赤泥为基础材料,通过无机酸酸化对赤泥进行预处理,再经高温焙烧过程制备出酸化/焙烧赤泥;通过引入糖蜜酒精废液协同无机酸酸化对赤泥进行预处理,再经高温焙烧过程制备出糖蜜酒精废液-硫酸酸化/焙烧赤泥;通过对赤泥进行焙烧预处理,充分释放赤泥的碱性物质,然后将预处理后的赤泥制成浆液,并向浆液中投加锌盐,利用赤泥自身碱源,沉淀水相中的锌离子,得到前驱体,再经焙烧处理,将具有光催化活性的半导体材料ZnO固载于赤泥基体上,制备出赤泥基ZnO/α-Fe2O3复合材料。并以黄药和橙黄Ⅱ模拟有机废水,研究酸化/焙烧赤泥、糖蜜酒精废液-硫酸酸化/焙烧赤泥、赤泥基ZnO/α-Fe2O3复合材料的类Fenton催化性能,确定其最佳制备工艺及部分应用工艺条件。借助XRD、SEM、EDS以及N2吸附与脱附等技术对催化剂进行表征分析,研究所制备催化剂的结构特点。研究成果可为赤泥的资源化利用提供参考,主要研究结果如下:(1)酸化/焙烧赤泥制备过程中关键控制步骤的最佳工艺条件包括:硫酸酸化至泥浆的pH=3、焙烧温度673K、焙烧时间1 h。催化剂的表征显示,酸化/焙烧赤泥中的铁相主要是α-Fe203,并且该催化剂是一种多孔的材料,具有粗糙的表面。在上述条件下所制备出的酸化/焙烧赤泥具有优良的类Fenton催化性能,在催化剂投加量0.2g.L-1 H202初始浓度5mmol·L-1的条件下,对于50 mg.L-1的丁基黄药溶液在反应进行到40 min时,黄药去除率达到90.2%,并且所制备的催化剂在Fenton过程中性能稳定。另外酸化/焙烧赤泥催化类Fenton过程中羟基自由基的产生以及丁基黄药的降解机理被探究。(2)糖蜜酒精废液-硫酸酸化/焙烧赤泥制备过程中关键控制步骤的最佳工艺条件包括:对于3 g赤泥,9 mL浓度为0.7 mol·L-1 H2S04配以2 g糖蜜酒精废液作为酸化试剂,焙烧温度573K,焙烧时间1h。催化剂的表征显示,糖蜜酒精废液-硫酸酸化/焙烧赤泥中的铁相主要是α-Fe203,有微量的炭生成,并且该催化剂是一种多孔的材料,表面粗糙。另外,糖蜜酒精废液的加入,节省了H2SO4的用量,同时也显著增强了所制备催化剂的物化性能。催化剂近中性的微环境、优良的孔结构、炭的生成都促使糖蜜酒精废液-硫酸酸化/焙烧赤泥的催化性能显著提高。其中,炭的生成以及优良的孔结构完全归因于催化剂制备过程中糖蜜酒精废液的加入。在上述条件下所制备出的催化材料具有优良的类Fenton催化性能,在初始溶液pH 3、H202投加量50mmol·L-1、橙黄Ⅱ质量浓度40mg.L-L、反应时间6h的条件下,橙黄Ⅱ去除率达到86.79%;该催化降解过程符合一级动力学模型。并且,所制备的催化剂在Fenton过程中具有优良的沉降性能以及较好的稳定性,反应溶液中总铁离子质量浓度在5次重复使用过程中均远低于10 mg.L-1的国家标准。(3)赤泥基ZnO/α-Fe2O3复合材料制备过程中关键控制步骤的最佳工艺条件包括:预处理温度973K、预处理时间1 h、赤泥与Zn(N03)2质量比2:1、焙烧温度623K、焙烧时间2 h。催化剂的表征显示,赤泥基ZnO/α-Fe2O3复合材料中的铁相主要是α-Fe2O3,ZnO成功固载于赤泥基体上,并且该催化剂是一种多孔的材料,具有粗糙的表面和良好的孔隙结构,而且对紫外光和可见光具有较好的吸收能力。在上述条件下所制备出的赤泥基ZnO/α-Fe2O3复合材料具有优良的光助Fenton催化性能,在催化剂投加量0.1g·L-1、反应温度303K、H2O2初始浓度20mmol·L-1条件下,40 mg·L-1的橙黄Ⅱ溶液在荧光高压汞灯持续照射4 h时,去除率达到74.75%。
[Abstract]:With the acceleration of China's industrialization, industrial wastewater emissions caused serious damage to the natural environment and human health, including organic wastewater with a complex quality, high COD, high toxicity, refractory and other characteristics, it has been a hot topic in the field of environmental protection, advanced oxidation method is considered to be one of the methods for treatment of organic the waste water is feasible. The oxidation of Fenton method is efficient, stable, relatively complete degradation of pollutants advantages and is widely used. But all phase Fenton iron ions difficult to recycle, easy to cause two pollution and other shortcomings, limiting its industrial application. Therefore, the scholars at home and abroad by natural or catalytic activity of iron ore component fixed on the carrier, the preparation of a water insoluble heterogeneous catalyst, to solve the problem of catalyst. The red mud is difficult to recycle aluminum industry pollution discharged waste when extracting alumina According to different production methods of alumina slag can be divided into the Bayer process, sintering red mud and combined method of red mud is strongly alkaline (pH 10.0-12.5), the main chemical composition including Fe203, Si02, A1203, Ti02, Na2O, CaO and so on, which is usually the Bayer red mud high iron content, iron oxide content is as high as 30% above, this characteristic for Bayer red mud preparation of heterogeneous Fenton catalyst may be provided. In this paper, from the perspective of circular economy, and based on regional development in Guangxi, Bayer red mud emissions in Guangxi aluminum industry as the basic materials, the inorganic acid of red mud pretreatment after the calcination process was prepared by acidification / roasting red mud; molasses alcohol wastewater by introducing inorganic acid coordination of red mud was pretreated by high temperature roasting process of preparation of molasses alcohol wastewater - sulfur acid / red mud through roasting; After roasting pretreatment of red mud, alkaline substances released in full of red mud, and red mud after pretreatment into slurry into the slurry, and adding zinc salt and its utilization of red mud alkali source, precipitation of zinc ion in aqueous phase. The obtained precursor, followed by calcination, ZnO semiconductor materials with photocatalytic activity immobilized on red mud substrate prepared by red mud ZnO/ alpha -Fe2O3 composites. With xanthate and orange simulated organic wastewater, acidification / roasting red mud, molasses alcohol waste sulfuric acid roasting / red mud, the catalytic properties of red mud based ZnO/ alpha -Fe2O3 composite Fenton, determine the process and part of the application process the best preparation conditions. With the help of XRD, SEM, EDS and N2 adsorption and desorption technique to characterize the catalyst, study its structure characteristics of the catalyst. The research results can provide reference for the resource utilization of red mud, the main The results are as follows: (1) acidification / roasting red mud preparation including optimum conditions of key steps in the process: sulfuric acid to mud pH=3, 673K calcination temperature, calcination time characterization of 1 h. catalyst showed that the acidification / roasting in the red mud iron phase is mainly alpha -Fe203, and this is a kind of porous catalyst the material has a rough surface. Under these conditions, the acidification / prepared roasting Fenton red mud has excellent catalytic performance, the catalyst dosage and the initial concentration of H202 0.2g.L-1 5mmol L-1, the Ding Ji xanthate solution of 50 mg.L-1 to 40 min in the reaction, the removal rate of xanthate 90.2%, and the catalyst stability in the process of Fenton. In addition, acidification / hydroxyl radical activated red mud generated in the process of catalytic Fenton and Ding Ji xanthate degradation mechanism was explored. (2) - molasses alcohol wastewater Roasting sulfuric acid / red mud preparation including the optimum conditions of key steps in the process: for 3 G red mud, 9 mL concentration of 0.7 mol L-1 H2S04 with 2 g of molasses alcohol wastewater as acidifying reagent, 573K calcination temperature, calcination time characterization of 1h. catalyst showed that the molasses alcohol waste sulfuric acid / roasting in the red mud iron phase is mainly alpha -Fe203, a carbon trace, and the catalyst is a porous material, surface roughness. In addition, addition of molasses alcohol waste, saving the amount of H2SO4, but also significantly enhance the physicochemical properties of the catalyst for preparing the catalyst. The micro environment of nearly neutral the pore structure, excellent carbon, Chengdu to molasses alcohol waste sulfuric acid roasting / catalytic performance of red mud increased significantly. The carbon formation and fine pores completely due to the catalyst preparation process of honey alcohol wastewater Join. Under these conditions, the catalytic material prepared with Fenton excellent catalytic performance in the initial solution, pH 3, H202 dosage of 50mmol, L-1, orange 40mg.L-L concentration, reaction time 6h, orange removal rate reached 86.79%; the degradation process meets the first grade dynamic model. And the catalyst in the Fenton process has good stability and excellent settleability, total iron ion concentration in the reaction solution after 5 times of repeated use process are far lower than the national standard of 10 mg.L-1. (3) the optimum conditions including key control steps of red mud ZnO/ alpha -Fe2O3 composite material preparation process: pretreatment temperature 973K, pretreatment time of 1 h, red mud and Zn (N03) 2 623K mass ratio 2:1, calcination temperature, calcination time characterization of 2 h. catalyst showed that the red mud ZnO/ alpha -Fe2O3 composite iron phase in the main If a -Fe2O3 ZnO was successfully immobilized on red mud substrate, and the catalyst is a porous material with rough surface and good pore structure, but also has better absorption ability of UV and visible light. Under these conditions the asorbent ZnO/ alpha -Fe2O3 composites prepared with photo Fenton excellent catalytic performance, the dosage of the catalyst is 0.1g L-1 303K H2O2, reaction temperature, initial concentration of 20mmol and L-1 under the condition of orange solution 40 mg - L-1 in high-pressure mercury lamp continuous irradiation of 4 h, the removal rate reached 74.75%.

【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;O643.36

【参考文献】