硅藻土负载型非均相芬顿催化剂的制备及其降解染料研究

发布时间：2018-06-19 18:06

  本文选题：芬顿 + 亚甲基蓝　； 参考：《成都理工大学》2017年硕士论文

【摘要】：据统计,1吨染料废水的排放,将造成20吨水体的污染,染料废水因生物难降解性和“三致”毒性,会对湖泊、江河等水体造成巨大危害。针对该类废水的处理,芬顿技术是目前研究最为集中且极具前景的高级氧化技术之一。芬顿氧化法具有高降解率、化学反应过程友好、成本低和应用广泛等特点,但传统芬顿体系存在出水色度高、铁流失量大,反应体系呈酸性等缺点。研究发现,制备不溶于水的催化剂,能改善传统芬顿的缺点。本文以硅藻土为载体,采用直接蒸发法制备一种新型负载型非均相催化剂,优化了D-Fe_2O_3的制备条件,并对其进行了SEM、XRD等表征;考察了各反应因素对催化降解的影响;初步探讨了氧化亚甲基蓝的过程以及各因素的反应动力学;分析了D-Fe_2O_3的稳定性,并利用非均相芬顿流化床对D-Fe_2O_3的实用性进行评价。经实验可知制备过程中铁离子浓度和固液比对D-Fe_2O_3的催化性能存在影响,其制备的最优铁离子浓度和固液比分别为0.5 mol/L和1:15;SEM、EDS和XRD的结果表明,在改性硅藻土表面上负载了致密的、不定型的Fe_2O_3。又建立了非均相芬顿体系(D-Fe_2O_3/H2O2),在相同的反应条件下,该体系相较于传统芬顿体系对亚甲基蓝的脱色速率提升了3.5倍。通过正交实验可知各因素对脱色效果的影响程度各不相同,其中初始pH反应温度D-Fe_2O_3投加量双氧水投加量。经过单因子实验结果表明,当双氧水投加量120 mmol/L、D-Fe_2O_3投加量12 g/L、反应温度55℃、初始pH 3和初始浓度50 mg/L时对亚甲基蓝的脱色效果最佳,反应20 min脱色率可达99%以上。通过UV-vis分析和文献可知,在降解过程中显色基团(巯基,-S-)的N,S双烯环及其两侧连接的苯环发生分解,中间产物不断地进行脱甲基化和脱氨基化,直至降解为CO2、H2O和无机盐离子(Cl-、NO3-和SO42-)。降解反应符合一级反应,其线性相关度均达到0.950以上。对D-Fe_2O_3稳定性分析可知,在强酸和强碱环境中溶出铁量分别为5.31 mg/L和0.05 mg/L,耐酸碱性能良好;D-Fe_2O_3经过5次连续重复使用后,仍能保持在90 min内达到99%以上的脱色率;在非均相芬顿流化床小试实验中,反应器出水澄清,色度能达到污水排放标准;反应器出水COD、脱色率和溶出铁量分别达到50 mg/L、99%和18 mg/L以上。因此D-Fe_2O_3有运用于实际的可能性,是一种很有潜力的非均相芬顿催化剂。
[Abstract]:According to statistics, the discharge of 1 ton dye wastewater will cause 20 tons of water pollution. Because of biodegradability and "three causes" toxicity, dye wastewater will cause great harm to lakes, rivers and other water bodies. Fenton technology is one of the most concentrated and promising advanced oxidation technologies for the treatment of this kind of wastewater. Fenton oxidation is characterized by high degradation rate, friendly chemical reaction process, low cost and wide application. However, the traditional Fenton system has the disadvantages of high chroma of effluent, large amount of iron loss and acidic reaction system. It has been found that the preparation of insoluble catalysts can improve the shortcomings of traditional Fenton. In this paper, a novel supported heterogeneous catalyst was prepared by direct evaporation with diatomite as the carrier. The preparation conditions of D-Fe2O3 were optimized and characterized by SEMMA-XRD, and the effects of various reaction factors on the catalytic degradation were investigated. The process of methylene blue oxidation and the reaction kinetics of various factors were discussed, the stability of D-Fe2O3 was analyzed, and the practicability of D-Fe2O3 was evaluated by using a non-homogeneous Fenton fluidized bed. The experimental results show that the concentration of iron ion and the ratio of solid to liquid have influence on the catalytic performance of D-Fe2O3. The optimum concentration of iron ion and the ratio of solid to liquid are 0.5 mol / L and 1: 15% SEMEDS and XRD, respectively. The results show that the modified diatomite is loaded on the surface of the modified diatomite, and the results of XRD show that the optimum concentration of iron ion and the ratio of solid to liquid are 0.5 mol / L and 1: 15 respectively. Unshaped Fe2O3s. Furthermore, a heterogeneous Fenton system was established. Under the same reaction conditions, the decolorization rate of methylene blue in this system was 3.5 times higher than that in the traditional Fenton system. The orthogonal experiment shows that the influence of various factors on the decolorization effect is different, among which the initial pH reaction temperature D-Fe2O3 dosage of hydrogen peroxide is different. The results of single factor experiment show that the decolorization efficiency of methylene blue is the best when the dosage of hydrogen peroxide is 120 mmol / L, the dosage of D-Fe2O3 is 12 g / L, the reaction temperature is 55 鈩，

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