碳量子点修饰有序介孔碳-二氧化钛光催化剂的酚类污染物可见光催化降解机理研究

Xinjiang is located in inland areas with shortage of water resources. It is of important significance to carry out research on phenol removal in water pollutants due to phenolic pollutants in the wastewater produced by coal chemistry would lead to a major threat to the environmental problem of Xinjiang. The project intends to design a novel carbon quantum dot modified ordered mesoporous C-TiO2 composite photocatalytic materials with the ordered mesoporous structure and large specific surface area of the catalyst, by which could be more effective adsorption of organic pollutants as well as easy separation. The modification of carbon quantum dots enables it to have more efficiency in separation of photo-generated charge carriers. Additionally, its unique property of upconversion luminescence could improve its photo quantum efficiency and utilization of solar energy.Moreover,the adsorption as well as the activity of photodegradation of simulated waste water containing phenolic pollutants under visible light over the as-prepared material will be investigated. The influence of the content of carbon quantum dot on the catalyst and the location of carbon quantum dot in the catalyst will be analyzed. The adsorption law, photoelectro-catalytic degradation and mineralization mechanism will be revealed..The essence and mechanism of promoting charge separation, adsorption of pollutant, and catalytic degradation of pollutants by modification of carbon quantum dot will be explored. This project will not only offer a theoretical basis on guiding the design of efficient low-cost visible light photocatalyst, but also provide a new solution to depth purification on waste water containing phenol in Xinjiang's coal chemical industry.

新疆地处内陆地区，水资源匮乏，煤化工废水中的酚类污染物对新疆水体资源构成重大威胁，开展水中酚类污染物的去除研究对于新疆环境保护具有重要意义。本项目拟设计合成一种新型碳量子点修饰的有序介孔碳-二氧化钛光催化材料，使其具有有序的介孔孔道和大的比表面积，能更有效吸附有机污染物和易于分离；碳量子点的修饰及独特的上转换发光特性,使其加快表面电荷分离，有效提高光催化降解效率和太阳能的利用率.开展对水中酚类污染物的吸附、可见光催化降解的系统研究，揭示碳量子点在催化剂中的含量及所在活性中心的位置对催化剂结构的影响，探究该催化体系对酚类污染物的吸附规律、光催化降解规律和污染物矿化规律，揭示碳量子点修饰后对污染物的吸附作用、对电荷的加速迁移作用以及催化降解矿化作用的本质和机理，为指导设计高效低成本可见光催化剂提供理论依据，为新疆煤化工含酚废水的深度净化提供可借鉴的方法。

有机废水中的酚类和染料污染物对新疆水体资源构成重大威胁，开展水中酚类和染料污染物的去除研究对于新疆环境保护具有重要意义。以三聚氰胺和尿素混合热聚的方法合成了石墨相氮化碳，钛酸丁酯做前驱体，采用无水乙醇为溶剂合成了溶胶，在溶胶中加入g-C3N4，水热反应合成了TiO2-C3N4复合的具有层状结构的纳米异质结材料；以葡萄糖和壳聚糖为碳源水热法制备了碳量子点（CQDS），利用浸渍法将CQDS负载到TiO2-C3N4复合氧化物，制备了CQDS/TiO2-C3N4新型复合光催化剂。以苯酚和罗丹明 B(RhB) 为探针反应，在可见光照射下考查了催化剂的光催化活性。研究表明葡萄糖为碳源制备的CQDS/TiO2-C3N4复合材料的可见光活性都要好于TiO2、g-C3N4, 壳聚糖为碳源制备的碳量子点负载的样品在降解苯酚有较好的光催化效果。其可见光高活性的原因在于CQDS/ TiO2-C3N4复合的样品能有效吸收可见光，CQDS和TiO2-C3N4之间存在的协同效应有助于提高光催化活性。. 以双氰胺和硫酸氧钛为原料采用热聚合法合成具有良好结晶性的Ti掺杂g-C3N4光催化剂，利用XRD、BET、FT-IR和DRS、XPS、EXAFS、ESR等技术对材料的结构、晶相和表面化学成分等进行了表征。研究发现Ti是以[TiO4]4-的形式存在，没有形成聚合TiO2。[TiO4]4-进入入了g-C3N4的三嗪环中，影响了g-C3N4的表面电子结构。以罗丹明B（RhB）为模拟污染物评价了过渡金属Ti掺杂的g-C3N4材料液相光催化氧化性能。过渡金属Ti掺杂的g-C3N4在可见光激发下可以有效的降解RhB，活性远高于未掺杂的g-C3N4。在焙烧过程中Ti4+被双氰胺分解释放的NH3还原成Ti3+，Ti3+表面缺陷位促进生成·OH，有助于提高光催化活性。这两种新型催化剂在染料废水和含酚的煤化工废水处理方面将具有潜在的应用价值。