【作者】 姜文风；

【导师】 蒋景阳；

【作者基本信息】 大连理工大学 ， 应用化学， 2013， 博士

【摘要】 多硝基酚和染料类化合物是一类毒性大、难生化降解的有机污染物,这些有机污染物随着人类生产和生活活动进入环境,对水质、土壤以及自然生态系统造成严重危害。因此,研究多硝基酚和染料废水的处理方法和技术具有重要的理论和现实意义。利用TiO2光催化氧化技术处理有机废水是近20年发展起来的新兴水处理技术。TiO2光催化剂由于具有廉价无毒、化学稳定性好、光催化活性高、降解有机污染物彻底等特点而日益受到人们的关注。但是,TiO2光催化也存在可见光利用率低、光量子效率低、与有机污染物界面相容性差,在溶液中易团聚、分离回收困难等缺陷,这些缺陷成为制约TiO2光催化技术进一步发展的瓶颈问题。为了解决上述问题,人们通常对TiO2光催化进行改性,使其具有可见光响应、高催化活性、对有机污染物吸附性强、稳定性良好且易于分离回收。本文采用掺杂、敏化、智能载体负载以及表面修饰等方法制备多种改性TiO2复合光催化剂,有效提高了Ti02光催化剂的可见光响应范围、有机污染物吸附性能与光催化活性。在此基础上,以模拟太阳光为光源,以复合光催化材料在可见光照射下催化降解二硝基酚和染料类化合物为探针反应,系统研究考察了所制备复合光催化剂的催化活性及其影响因素,考察了复合光催化剂的降解机理。主要研究结果如下：1、利用掺杂改性的方法,通过溶胶-凝胶法制备了石墨烯掺杂改性的TiO2-GO复合光催化剂。利用XRD、SEM、TEM、FT-IR、UV-vis、TG-DTA等分析测试方法对所制备的光催化剂进行了结构表征。结果显示,GO的加入使复合光催化剂的吸收带较纯TiO2发生了明显红移。GO提高了TiO2纳米粒子的分散度和对有机污染物的吸附性能。以模拟太阳光为光源,研究所制备的TiO2-GO复合光催化剂对2-仲丁基-4,6-二硝基苯酚(DNBP)的光催化降解行为。系统考察了溶液pH值、光催化剂用量、溶液初始浓度、光照时间等不同因素对复合光催化剂的催化活性影响。可见光照射下TiO2-GO复合光催化剂可以有效降解DNBP, TiO2-GO复合光催化剂对DNBP的吸附和光催化降解能力明显高于纯Ti02样品。根据Langmuir-Hinshelwood方程,在低浓度下光催化降解反应符合一级反应动力学。借助GC-MS及离子色谱分析仪器对降解过程中间产物的分析,提出了合理的DNBP光催化降解反应途径。2、利用导电聚合物敏化的方法,通过紫外光引发制备了聚邻苯二胺(PoPD)敏化的PoPD-TiO2-GO复合光催化剂。利用XRD、SEM、TEM、FT-IR、UV-vis等分析测试方法对所制备的光催化剂进行了结构表征。结果显示,在PoPD-TiO2-GO复合光催化剂中,Ti02粒子表面形成了厚度适中的致密PoPD层,增强了Ti02催化剂对有机污染物的吸附作用和对可见光的使用效率。考察了PoPD-TiO2-GO复合光催化剂在模拟太阳光下对亚甲基蓝(MB)染料废水的降解脱色作用及其影响因素。在最佳的降解条件下,复合光催化剂对染料的吸附和光降解脱色率明显高于纯TiO2样品。在低浓度下光催化降解脱色反应符合准一级反应动力学方程。PoPD-TiO2-GO具有良好的循环使用性。3、利用染料光敏化和智能水凝胶聚合物负载的方法,通过自由基聚合首次合成出具有可见光响应、温度及pH敏感型复合光催化剂Poly(NIPAM-co-AAc-co-CoMPc)/(TiO2-GO)。利用XRD、TEM、FT-IR、UV-vis等分析测试方法对所制备的复合光催化剂进行了表征。对所制备的复合光催化剂的温度及pH敏感性进行了研究。结果表明,Ti02粒子成功负载在智能载体Poly(NIPAM-co-AAc-co-CoMPc)上。Poly(NIPAM-co-AAc-co-CoMPc)/(TiO2-GO)复合光催化剂在可见光区域有较强的吸收,复合光催化剂中TiO2-GO纳米粒子分散均匀,与聚合物结合紧密。以模拟太阳光为光源,研究了所制备的复合光催化剂在可见光作用下对DNBP的光催化降解性能及影响因素。研究显示,所合成的复合光催化剂不但具有可见光响应,有效提高了Ti02光量子效率,而且催化剂具有的温度及pH敏感性质可以实现催化剂的方便回收和循环利用。4、以三聚氯氰和苯甲醚为原料,合成出2,4-双(2,4-二羟基苯基)-6-(4-甲氧基苯基)-1,3,5-三嗪等系列紫外吸收化合物。应用表面修饰方法,制备了三嗪修饰的TiO2-GO光催化剂。研究表明,三嗪化合物修饰TiO2-GO光催化剂对DNBP有良好的吸附性能。更多还原

【Abstract】 Environmental pollution by toxic compounds can be detrimental to human health and the environment. Dinitrophenolic compounds and dyestuffs are widely avknowledged to be two types of hazardous compounds. These hazardous compounds are introduced into environment from its manufacturing and application processes. Although much benefits is obtained from their uses, dinitrophenolic compounds and dyestuffs have some undesirable side effects, such as toxicity and carcinogenity, and these hazardous compounds can be hardly destroyed by using conventional wastewater treatment methods. Therefore, the removal of dinitrophenolic compounds and dyestuffs from aqueous solution is necessary and very important. The direct photocatalytic reaction by using semiconductor particles as photocatalyst has attracted much attention as a promising method to degrade organic pollitants in recent20years. Among these semiconductor materials, TiO2as photocatalyst has been widely used to photodegrade organic pollutants for its relatively high catalytic reactivity, nontoxicity, physical and chemical stability, avirulence and cost-effectiveness. However, uses of TiO2nanoparticles in applications such as wastewater treatment have been limited because there are major bottleneck drawbacks associated with TiO2photocatalysts, namely, low photo-quantum efficiency arising from the fast recombination of photo-generated electrons and holes, low efficiency for utilizing solar light due to its large band gap, low capacity for the adsorption of organic pollutants and the problem of separation and recovery of nanometer sized TiO2particles from water. The preparation of TiO2composite photocatalysts by using doping, sensitizing, intelligent polymeric hydrogel supporting and surface modification methods are reported in this work. The application of these TiO2composite photocatalysts in the photocatalytic degradation of dinitrophenols and dyes containing wastewater is also investigated thoroughly in the thesis. The main results are as follows:1. The TiO2-GO composite photocatalyst was prepared by doping graphene oxide (GO) into the nanosized TiO2particles. The microstructure and morphology of the photocatalyst were characterized by XRD, SEM, TEM, FT-IR, UV-vis and TG-DTA techniques. The results showed that the addition of GO can enhance the degree of dispersion and adsorption capacity of TiO2particles can be enhanced significantly by doping TiO2with GO. The TiO2-GO composite photocatalyst can cause an obvious red shift of UV-vis spectra compared with pure TiO2. The photocatalytic degradation of2-.sec-butyl-4,6-dinitrophenol (DNBP) was studied with TiO2-GO composite photocatalyst under visible light illumination. The effect of experimental parameters such as pH values, initial concentration of DNBP, catalyst dosage, irradiation time, etc. on the photocatalytic degradation efficiency of DNBP were systematically studied in the work. The results indicated that the TiO2-GO composite photocatalyst showed much higher adsorption capacity and photocatalytic degradation efficiency than the pure TiO2catalyst. The photocatalytic reaction was discussed in terms of Langmuir-Hinshelwood model and followed pseudo-first order kinetics in low concentration of DNBP. A plausible DNBP degradation pathway was also suggested on the basis of analysis of degradation products.2. Poly-o-phenylenediamine (PoPD) sensitized TiO2-GO composite photocatalyst (PoPD-TiO2-GO) was successfully synthesized by’in situ’polymerization ofPoPD in the presence of TiO2-GO particles with ultraviolet light photoinitiating method. The prepared PoPD-TiO2-GO composite photocatalyst was characterized by XRD, SEM, TEM, FT-IR, UV-vis techniques. The results demonstrated that a dense conductive PoPD layer with reasonable thickness deposited on the surface of TiO2-GO composite particles, which can enhance adsorption of organic pollutants and make more use of visible light. The photocatalytic decolorizadation of methylene blue (MB) was evaluated with PoPD-TiO2-GO composite photocatalyst under visible light irradiation. The effect of experimental parameters such as pH values, initial concentration of DNBP, catalyst dosage, irradiation time, etc. on the photocatalytic decolorizadation of MB were systematically investigated. In terms of Langmuir-Hinshelwood model the photocatalytic decolorization reaction followed pseudo-first order kinetics in low concentration. The PoPD-TiO2-GO composite photocatalyst showed much higher adsorption capacity and photocatalytic degradation efficiency than the pure TiO2catalyst. Moreover, the composite photocatalyst has high reusable ability.3. A novel composite photocatalyst of Poly(N-isopropylacrylamide-co-acrylic acid-co-cobalt tetra(N-carbonylacrylic) aminephthalocyanine)/(titanium dioxide-graphene oxide)(Poly(NIPAM-co-AAc-co-CoMPc)/(TiO2-GO)) was successfully prepared via free radical polymerization method. The microstructure and morphology of the photocatalyst were characterized by XRD, TEM, FT-IR, UV-vis techniques. The results show that TiO2particles were successfully encapsulated in the copolymer carrier in spherical shapes and the composite photocatalyst was activated by visible light. The thermo-and pH-responsive properties of the composites were investigated by using swelling ratio measurements. The photocatalytic activity of obtained Poly(NIPAM-co-AAc-co-CoMPc)/(TiO2-GO) composite catalyst in visible light was estimated by measuring the degradation efficiency of DNBP in an aqueous solution. The effect of pH of the solution, catalyst concentration, irradiation time and initial DNBP concentration were examined as operational parameters. The thermo and pH sensitive composite photocatalysts exhibited easy separation and less deactivation after several runs. The results showed the feasible and potential use of the multisensitive composites in photodegradation of organic pollutants by controlling temperature and pH simply.4. A series of triazine. compounds such as2,4-bis(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine were successfully synthesized by using anisole and cyanuric chloride as raw materials. The synthesized triazine compounds can be used as ultraviolet absorbers. TiO2-GO composite photocatalyst modified with the synthesized triazine compounds showed much higher adsorption capacity than the pure TiO2catalyst.更多还原