电导率可调控粉煤灰基地质聚合物的自组装及光催化染料降解机理研究

It is a new idea to carry out the effective separation of photoporduction electrons-hole pairs by assiociation the synthesis of regulable conductivity fly ash-based geopolymer with self-assembly of nanoscale semiconductors, and a novel photocatalyst of fly ash-based geopolymer can be synthesized. It is critical to explore the influences of the content of graphene, the types of activators and dosages, the ratio of alkali activator to fly ash, the ratio of water to fly ash, the curing conditions on mechanical properties, pore structures and electric conductivity of fly ash-based geopolymer. The great efforts have focused on the solutions of scientific problems about the energy band matching, the band gap controlling and coupling in the process of assembled nanoscale semiconductors, as well as the overlap of graphene and semiconductor each other to form conductive path. The photocatalytic activation is evaluated by degradation of organic pollutant, and several major factors including pollutant concentration, dose of photocatalyst, light source and irradiation time are investigated in detail. It is important for us to establish the kinetic models both adsorption and degradation by the characterizations of hydroxyl radicals, intermediate products and degradation mechanism in situ. Once the fundamental scientific problems both the effective separation of photoporduction electrons-hole pairs and the degradation mechanism of dye are resolved, it is able to provide the reliable theoretical support for the engineering applications of this new type of photocatalyst in the field of pollutant treatments. It has significant values of theoretical research and the practical prospect for the value-added utilization of fly ash, sustainable development of coal, and printing and dyeing industry.

将电导率可调控粉煤灰基地质聚合物的制备与纳米半导体的自组装相耦合，合成一种新型的电导率可调控粉煤灰基地质聚合物半导体自组装光催化剂，是实现光生电子-空穴对高效分离的新思路。通过考察石墨烯掺量、激发剂种类与用量、碱灰比、水灰比、养护制度等对粉煤灰基地质聚合物力学性能、孔结构以及导电性能的影响，阐明纳米半导体自组装过程中的能带匹配、带隙调控耦合、导电石墨烯与半导体相互搭接形成电子传输通道的科学问题。以光催化染料降解为研究对象，考察染料结构及浓度、催化剂用量、pH值、光源种类等因素对染料降解率的影响；通过对染料降解过程中羟基自由基的示踪、中间产物的原位表征、反应动力学模型的构建，解决催化剂光生电子-空穴对的高效分离以及染料降解机理的科学问题,为把该催化剂应用于处理印染废水的工程化应用提供可靠的理论支撑。这对于粉煤灰的高附加值利用，煤炭及印染行业的可持续发展，具有重要的基础研究意义和实际应用前景。

光生电子-空穴对的有效分离是光催化过程中的瓶颈问题，将电导率可调控粉煤灰基地质聚合物的制备与纳米半导体的自组装相耦合，形成一种新型的、低成本、髙活性的电导率可调控粉煤灰基地质聚合物半导体光催化剂，是实现光生电子-空穴对高效分离的新思路。项目深入系统地研究了电导率可调控石墨烯-粉煤灰基地质聚合物纳米半导体光催化剂的制备，电导率可调控炭黑-粉煤灰基纳米半导体地质聚合物光催化剂的制备，导电粉煤灰基地质聚合物固化重金属及光催化性能等相关内容。结果表明：当石墨烯掺量为1.0wt%时，试样180 d的电导率从未掺石墨烯的0.00071 S/m提高到0.27 S/m；当炭黑的掺量为4.5wt%时，试样180 d的电导率增加到0.63 S/m。在光催化染料降解反应体系中，研究发现催化剂的电导率与染料的降解率成正相关规律,表明石墨烯及导电炭黑在光催化降解过程中起到了传输光生电子的重要作用，促进了光生电子-空穴对的髙效分离，从而提高了催化剂的光催化活性。通过对染料降解过程中中间产物的示踪，解决了羟基自由基(•OH)及超氧自由基(O2• -)是染料氧化降解的主要活性物种的科学问题，为该类催化剂处理印染废水的工程化应用提供了可靠的实验及理论支撑。项目对于粉煤灰的高附加值利用，煤炭及印染行业的可持续发展，对于开发以废（粉煤灰）治废（印染废水），治理过程无三废排放的绿色化工过程，具有重要的基础研究意义和实际应用价值。