二氧化钛纳米材料的制备及其对农药乐果的光催化性能研究

发布时间：2017-12-26 22:29

本文关键词：二氧化钛纳米材料的制备及其对农药乐果的光催化性能研究　出处：《北京化工大学》2015年硕士论文　论文类型：学位论文

【摘要】：当前水污染问题是一项非常复杂的系统工程,其中,农药废水是水污染治理的具有挑战性的课题之一,用于水处理的新材料和新技术的开发成为研究者们关注的焦点。光催化氧化技术作为一种新型的环境友好的技术,在农药废水处理领域具有良好的发展前景。光催化氧化技术降解农药的关键在于光催化剂的选择以及催化剂的结构和性能。Ti02纳米材料因其氧化能力强、化学稳定性和热稳定性良好、且不会造成二次污染,从而成为该领域的金牌催化材料。为此,本文以廉价且资源丰富的钛铁矿为原料,通过一系列单因素实验制得Ti02催化剂,得到了优化的制备条件。为了改善纯Ti02催化剂分散性差和比表面积小等不足,将其负载到SBA-15分子筛上,从而提高催化剂比表面积。同时以农药乐果为目标降解物,考察这两种催化剂的光催化性能,研究其相互关系和影响规律。1.以四川攀枝花钛铁矿为原料,采用液相法硫酸酸解钛铁矿制得TiOSO4溶液,然后TiOSO4经过水解制得不同晶型、不同形貌和不同颗粒大小的纳米TiO2。深入考察了酸解过程中硫酸摩尔体积、反应时间、反应温度和硫酸浓度对钛铁矿酸解率的影响和还原剂铁粉的用量,并探讨了水解过程中不同水解条件对产物结晶度、形貌、产率的影响以及不同煅烧温度对Ti02晶型和粒径的影响。结果表明,当硫酸浓度为13.5 mol·L-1,硫酸摩尔体积为0.32 mol,反应时间为120 min,反应温度为160℃时,钛铁矿酸解率高达95.21%,所得的钛液中Ti4+浓度为121 g.L-1,钛液稳定性良好。在不同水解条件下制得不同形貌的TiO2产物,最高产率达到92.18%。在600℃-950℃温度范围下煅烧得到不同晶型(锐钛矿型、金红石型、锐钛矿-金红石混晶型)和不同颗粒大小的纳米TiO2(40 nm-60 nm),TiO2产物纯度高于99%。2.用前期制得的TiOSO4溶液作为前驱体和自制的SBA-15介孔分子筛作为载体,通过后合成水解法制备了含有不同TiO2负载量的TiO2/SBA-15催化剂。在模拟太阳光下,考察了催化剂煅烧温度、溶液初始pH值、催化剂用量、不同TiO2负载量和不同反应温度对乐果降解的光催化活性的影响,并对所制得的TiO2/SBA-15催化剂的稳定性进行研究。此外,对光催化过程中产生的中间产物和光催化动力学规律也进行了分析。研究结果表明,负载后的催化剂仍能保持SBA-15介孔分子筛稳定有序的二维六方孔结构,且比表面积大,克服了常用光催化剂因比表面积小而导致光催化效率低的缺点。26%TiO2/SBA-15催化剂的比表面积为386m2·g-1,它对农药乐果的光催化活性最高,在7小时内乐果可完全降解,该催化剂比纯TiO2催化性能高约62%,且其稳定性良好,使用4个循环后催化性能没有明显降低。分析结果表明,光催化降解农药乐果的反应是一级反应。
[Abstract]:At present, water pollution is a very complex systematic project. Pesticide wastewater is one of the challenging problems in water pollution control. The development of new materials and technologies for water treatment has become the focus of researchers. As a new and environmentally friendly technology, photocatalytic oxidation technology has a good prospect in the field of pesticide wastewater treatment. The key of photocatalytic oxidation technology to degrade pesticides is the selection of photocatalyst and the structure and performance of the catalyst. Ti02 nanomaterials, due to their strong oxidizing ability, good chemical stability and thermal stability, will not cause two pollution, thus becoming the gold catalytic material in this field. Therefore, in this paper, the Ti02 catalyst was prepared by a series of single factor experiments with the cheap and rich ilmenite as raw material, and the optimum preparation conditions were obtained. In order to improve the poor dispersivity and small specific surface area of the pure Ti02 catalyst, the catalyst was loaded onto the SBA-15 molecular sieve to improve the specific surface area of the catalyst. At the same time, the photocatalytic properties of the two catalysts were investigated with the pesticide dimethoate as the target, and the relationship and influence law of these catalysts were studied. 1. the TiOSO4 solution was prepared from sulfuric acid and Ilmenite from Sichuan Panzhihua ilmenite by liquid phase method. Then TiOSO4 was hydrolyzed to prepare nano TiO2 with different crystal forms, different morphologies and different particle sizes. An in-depth study of the acid hydrolysis process of sulfuric acid molar volume, reaction time, reaction temperature and concentration of sulfuric acid hydrolysis rate of ilmenite and iron reducing agent dosage, and discusses the different hydrolysis conditions during the hydrolysis effect of crystallinity, morphology and yield of product and the effect of different calcination temperature on Ti02 crystal type and particle size. The results show that when the concentration of sulfuric acid is 13.5 mol? L-1, the molar volume of sulfuric acid is 0.32 mol, the reaction time is 120 min, and the reaction temperature is 160 degrees, the dissolution rate of ilmenite is as high as 95.21%. The Ti4+ concentration in the titanium solution is 121 g.L-1, and the stability of titanium liquid is good. TiO2 products with different morphologies were prepared under different hydrolysis conditions, with the highest yield of 92.18%. Different crystalline forms (anatase, Jin Hongshi type, anatase, Jin Hongshi mixed crystal type) and nano TiO2 (40 nm-60 nm) with different particle sizes were obtained at calcination temperature of 600 -950, and the purity of TiO2 product was higher than 99%. 2., using TiOSO4 solution as precursor and homemade SBA-15 mesoporous molecular sieve as carrier, TiO2/SBA-15 catalyst containing different TiO2 loading was prepared by post synthesis hydrolysis method. Under the simulated sunlight, the effects of calcination temperature, initial pH value, amount of catalyst, TiO2 loading and reaction temperature on photocatalytic activity of dimethoate degradation were investigated, and the stability of the TiO2/SBA-15 catalyst was studied. In addition, the intermediate products and the regularities of photocatalytic kinetics produced during the photocatalytic process are also analyzed. The results show that the immobilized catalyst can keep SBA-15 mesoporous molecular sieve stable six dimensional pore structure and large specific surface area, to overcome the common photocatalyst surface area than the resulting photocatalytic efficiency low. The specific surface area of 26%TiO2/SBA-15 catalyst is 386m2. G-1. It has the highest photocatalytic activity for pesticide dimethoate. In 7 hours, dimethoate can be completely degraded. The catalytic performance of the catalyst is about 62% higher than that of pure TiO2, and its stability is good. After 4 cycles, the catalytic performance is not significantly reduced. The results show that the reaction of photocatalytic degradation of pesticide dimethoate is a first-order reaction.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X592;TQ426

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