磷酸盐材料用于可见光光催化降解农药污染物的研究

Persistent organic pollutants (POPs), most of which are pesticides, are highly toxic, widely distributed, and particularly persistent in the environment. They have significant potential impacts on human health. It is very desirable to develop novel treatment methods for transforming organic contaminants into non-hazardous compounds. Among the wide varieties of advanced oxidation processes (AOPs), semiconductor photocatalysis has emerged as one of the most promising technologies because it is inexpensive, environmentally friendly, no secondary pollution, and represents an efficient way to utilize the energy of natural sunlight. Organic phosphorus and Organochlorine are most widely distributed in nature. The development of visible-light-active photocatalytic systems is the key to their chemical transformation into non-hazardous compounds based on their chemical properties. In this proposal, novel catalytic techniques for the degradation of pesticide pollutants will be approached by developing heterogeneous photoactive catalysts with high stability, molecular tunability, and facile recyclability. Based on the preliminary studies, doped Ag3PO4 catalysts will be firstly prepared under mild conditions. Then, the experiments on photocatalytic degradation of organic phosphorus and organochlorine will be carried out to further understand the high stability of doped Ag3PO4 catalysts. Under optimized conditions, new phosphate-based visible light photocatalysts with good performance but low-cost will be prepared by using environmentally friendly materials (hydroxyapatite, etc.) as supports. Lastly, new photocatalytic technologies will be developed to eliminate pesticides pollutants.

如何把残留农药低成本高效地转化成CO2、H2O以及无机物等无毒、无害物质是当前国际上环境化学领域最具挑战性的课题之一。有机氯和有机磷是当前最为常见的两类环境污染物，发展针对性消除这两类污染物的新方法、新技术具有重要的科学意义和实用价值。基于课题组前期预研，根据两类农药污染物氧化降解产物的特性，本项目提出在温和条件下制备Ag3PO4类可见光光催化剂，并通过元素掺杂、负载等技术提高催化剂的稳定性、降低制备成本，在揭示元素掺杂提高Ag3PO4光催化剂稳定性"内在机制"的基础上，深入探讨农药类有机污染物光催化降解的动力学过程及机理，进而以环境友好材料（羟基磷灰石等）作为催化剂载体，在最优化条件下构筑成本低廉、催化活性好、稳定性高的新型磷酸盐类可见光光催化剂，建立消除、治理有机氯和有机磷这两类环境污染物的新方法。

基于半导体光催化反应建立的高级氧化技术有可能成为去除农药类有机污染物的新手段，其相关研究具有重要的科学意义和实用价值。本项目研究表明，通过简单的沉淀法或共沉淀法可以制备Mo-Ag3PO4、MoS2/Ag3PO4、Au NRs/Ag3PO4、HAP/Ag3PO4等复合型光催化剂，利用SEM、XRD、XPS、IR、Raman、BET等技术对其结构和表面特性进行分析，证实MoS2/Ag3PO4、Au NRs/Ag3PO4、HAP/Ag3PO4为两相复合结构，Mo-Ag3PO4为掺杂模式。相对于纯Ag3PO4本身，在相同的条件下上述复合材料光催化降解有机染料罗丹明B的活性均有明显增加。进一步结合紫外漫反射及电化学表征，我们对每种复合型光催化剂的增强机制进行了探索。对HAP/Ag3PO4而言，光催化活性的增强机制在于HAP的载体效应改变Ag3PO4的分散性能及其对污染物的吸附作用。对Mo-Ag3PO4而言，光催化活性的增强机制在于钼酸根窄化了Ag3PO4的带隙，促进光生电荷分离，减少光腐蚀，增强稳定性。对MoS2/Ag3PO4而言，光催化活性的增强机制同样在于有效促进光生电荷的分离，但MoS2和Ag3PO4的带隙特征决定该复合型光催化剂发生光生电荷转移的方式是光生空穴由Ag3PO4转移到MoS2。由于MoS2/Ag3PO4光生电子发生后续反应的路径与纯Ag3PO4类似，光腐蚀作用使其稳定性与纯Ag3PO4相当。由于Ag3PO4在可见光区具有光响应、Au NRs在近红外区具有光吸收，Au NRs/Ag3PO4复合型光催化剂显示了宽光谱响应的特性，其与罗丹明B构成的光反应体系在420纳米以上的光谱区间内均显示了优于纯Ag3PO4的反应活性，并对其增强机理进行了探讨。基于上述研究我们用Au NRs/Ag3PO4、Mo-Ag3PO4对阿特拉津等农药污染物进行了降解，建立了降解有机污染物的新方法。