强吸附性的铁改性粘土光催化剂的制备及其降解硫丹的机理研究

A new adsorption-photocatalytic oxidation system for the disposal of new persistent organic pollutant - organochlorine endosulfan is suggested on the basis of a bifunctional material both as adsorbent and catalyst. The structure-activity relationship of adsorption and catalysis, the reaction process and mechanism of endosulfan degradation are discussed. The sorptive iron-supported clay catalyst can be fabricated by the method of polymeric hydroxy cationic sol pillaring and ion-exchange & in-situ hydrolysis with lamellar clay as support and iron or iron oxide as catalyst seeds. The mechanism of adsorption of endosulfan onto the iron-supported rectorite is to be discussed, and then the adsorption- photocatalytic oxidation system is constructed with oxygen or hydrogen peroxide as oxidant and endosulfan as target pollutant under the visible irradiation to discuss the structure-activity relationship between the adsorption ability and catalytic characteristics. GC-MS, electron spin resonance (ESR) and in situ infrared are employed to track the intermediates and reactive oxygen species (ROS) to clarify the degradation reaction process and mechanism of endosulfan from scientific point of view. The implementation and completion of this project will provide new ideas for the design and fabrication of heterogeneous catalyst, meanwhile the application of new endosulfan pollution disposal method can produce prominent environmental and economic benefits.

本项目针对新型的持久性有机污染物--有机氯杀虫剂硫丹提出一种基于吸附-催化双功能材料构建的吸附-光催化氧化体系，研究吸附与催化之间的构效关系，探讨硫丹催化氧化降解反应过程和机理。首先，以层状粘土为基体、铁离子或铁氧化物为催化剂、通过聚合羟基阳离子溶胶纳米微粒柱撑、离子交换-原位水解沉淀法制备强吸附性的铁改性粘土催化剂；然后，以硫丹为对象，研究它在材料上的吸附行为特征及机理，以氧气/过氧化氢为氧化剂，辅以可见光照作用，构筑吸附-光催化氧化降解硫丹体系，研究材料吸附性能与催化性能之间的构效关系；并采用GC-MS、顺磁共振和原位红外等手段分析降解过程的中间产物及氧化物种的来源和迁移，阐明硫丹降解反应过程和机理，具有重要的科学意义。本项目的实施与完成可为负载型多相催化剂的设计与构筑提供新观点，同时硫丹污染末端治理新方法的应用可产生重要的环境效益和经济效益。

现代农业生产中有机氯类农药的广泛使用乃至滥用导致环境中有大量农药残留，这些农药残留物对人类健康与生态系统功能带来不同程度威胁，为了减轻这种环境压力，本项目主要针对以硫丹和高效氯氰菊酯为代表的有机氯农药之类的持久性有机污染物为研究对象，展开了粘土负载类催化材料、合成溴氧化铋、石墨烯材料、合成的多孔纳米管等系列研制工作，并将其用于探讨同时具备吸附和光催化功能的新型负载型光催化剂体系和电催化体系的作用原理，研究了吸附作用与光电催化之间的构效关系，探讨有机污染物光电催化氧化降解反应过程和机理。结果发现，材料的比表面积和吸附性能对材料的光催化性能有重要影响，巨大的比表面积及良好的吸附性能是材料自身具有高的光催化活性的重要原因；光电催化氧化降解持久性有机污染物的主要作用机理均为羟基自由基氧化机制。本项目研究结果为负载型多相催化剂材料的设计与构筑提供了新的思路。