三嗪类农药在天然和微孔矿物上的吸附及其在矿物微孔内的微波诱导降解

The s-triazines are among the most widely used herbicides in the world and in China, and widespread contamination of surface water and groundwater has resulted from their applications. This proposed project is going to investigate the sorption of atrazine and three other major s-triazine herbicides (metamitron, metribuzin, and ametryne) on a range of natural and microporous minerals, and study their degradation when sorbed in mineral micropores (<2 nm) under microwave irradiation, with the objectives of obtaining better understanding on the subsurface transport of these herbicides, and developing a novel treatment method for removing them from aqueous environment. The sorption isotherms and kinetic parameters of the four s-triazines on natural and microporous minerals will be measured to study the influence of surface chemistry, pore size, and surface morphology of minerals on their sorption capacities and the sorption rates of the s-triazines. Mass spectrometry and infrared spectroscopy techniques will be employed to evaluate the degradation kinetics of the s-triazines sorbed on the microporous minerals under microwave irradiation, and to elucidate the degradation mechanism. The influence of dissolved organic matter (DOM) and cations, which often co-exist with the s-trazines in contaminated surface water and groundwater, as well as solution pH and temperature, on the sorption of the s-triazines will be studied, while the impact of DOM and cations on their microwave-induced degradation in the mineral micropores will also be quantified. Mechanistic understanding on the roles of DOM and cations in the sorption and microwave-induced degradation of s-triazines will be obtained, and counter-measures will also be developed to eliminate the potential interference effects from DOM and cations when necessary. Based on the experimental results, a novel treatment method based on sorption by microporous mineral sorbents coupled with microwave-induced degradation will be developed, and the its effectiveness for the treatment of s-triazines and other organic nitrogen pesticides in contaminated surface water and groundwater will be evaluated. The results of this proposed project are expected to enhance our understanding on the fundamental interactions of s-triazines with natural and microporous minerals and help better predicting their transport behavoir in deep soils and groundwater aquifers, where organic carbon is essentially absent on the porous media and the transport of organic contaminants is controlled by their interactions with the mineral matrices. The novel treatment technology developed in this study is also expected to have important practical applications in water pollution control.

三嗪类农药是施用最为广泛的除草剂之一，已经造成了大范围的地表和地下水体污染。本项目拟研究4种典型三嗪类农药在天然和微孔矿物上的吸附，及它们在微孔(<2 nm)内的微波诱导降解，掌握和预测该类污染物的环境迁移行为规律，并研发利用矿物材料将其从环境水体中去除的新方法。通过测量典型三嗪类农药在矿物介质上的吸附等温线和动力学参数，研究微孔的表面化学性质和孔道尺寸及形貌对吸附性能和速率的影响；通过质谱、红外光谱等手段解析微孔中三嗪类农药在微波辐射下的降解动力学和机理；考察溶解性有机质（DOM）、阳离子、pH及温度对三嗪类农药在微孔中吸附的影响，以及DOM和阳离子对它们微波诱导降解的影响，解析相关机理并在必要时建立干扰控制措施；开发基于微孔矿物吸附-微波诱导降解的新型处理方法，并验证其对于三嗪类农药等的处理效果。研究成果将具有污染物环境迁移规律方面的理论意义和水体污染处理的应用价值。

三嗪类农药是施用最为广泛的除草剂之一，已经造成了大范围的地表和地下水体污染。研究这类化合物在天然多孔矿物上的吸附机理对于认识其在深层土壤和地下水环境中的迁移具有重要的意义。同时，因其在天然水体中的广泛检出，建立相应的污染控制方法对于保护环境和人体健康也非常重要。本项目以认识典型三嗪类农药在天然和微孔矿物上的吸附机理，以及研发利用矿物材料将其从环境水体中去除的污染控制新方法为目标。通过过去四年的研究工作基本上实现了预期目标，并在对三嗪类农药在多孔矿物上吸附与微波诱导降解机理研究的基础上，扩展考察了其它类型的有机污染物，包括亚硝胺化合物、氯酚类化合物、氟喹诺酮类化合物等在多孔矿物上的吸附与微波诱导降解行为，进一步验证了相关的微孔吸附机理和微波诱导降解机制，并拓展了微孔矿物吸附-微波诱导降解方法处理有机污染物的应用范围。在保证完成项目目标的前提下，探索成果在解决其它重要环境问题方面的可行性，体现了创新从解决实际问题入手。项目执行过程中侧重研究了有机物与微孔矿物相互作用的微观机理以及吸附于矿物微孔中的有机物在微波辐照下的降解机制，主要成果包括：(i) 解析了多孔矿物的孔道结构和表面化学性质对三嗪类农药等有机物吸附的影响机制；(ii) 解析了微波照射过程中矿物微孔中三嗪类农药等有机物的降解机理并考察了影响污染物降解的主要因素；(iii) 系统考察了环境水体组分对三嗪类农药等有机物在微孔中吸附及微波诱导下降解的影响，并建立了微孔矿物吸附-微波诱导降解耦合的污染控制方法。通过本项目研究，阐明了三嗪类农药等有机污染物与多孔矿物相互作用的部分重要机制，建立了微孔矿物吸附-微波诱导降解耦合的污染控制新方法，为认识极性有机污染物在地下环境中的迁移行为以及污染控制提供了理论基础和技术支持。本项目执行期间共发表标注项目资助号国际SCI论文29篇，获美国授权发明专利1项；培养毕业博士人5人，毕业硕士生3人，指导出站博士后1人。