常温常压纳米零价铁活化分子氧矿化三嗪类除草剂新策略及机理研究

The destruction and mineralization of the s-triazine ring is the final and key step for the complete removal of environmental s-triazine herbicide pollutants. Advanced oxidation technologies can not break down the s-triazine ring when degradation of s-triazine herbicides at mild conditions and the final oxidation product is cyanuric acid with s-triazine ring. This project aims to develop a novel molecular oxygen activation system for the breaking and minerazation of s-triazine herbicide with the utilization of nanometer zero-valent iron. In the novel system, nickel ions with catalytic activity of hydrogen will be introduced in order to adjust the types and quantities of active species and avoid generating stable cyanuric acid through reaction between hydroxoy radicals and s-triazine herbicide, leading to breaking and mineralization of s-triazine herbicide via non-cyanuric acid pathway, thus total destruction of s-triazine herbicide at room temperature and pressure over zero-valent iron could be obtained. The pathway of interfacial electron transfer, active species generatation, active species types and their formation will be investigated systematically. The characteristics of herbicide pollutants degradation and the mechanism of C-N and C-Cl bonds breaking for the s-triazine by kinds of active species in the process will be studies in detail to reveal the interaction mechanism of reaction of different active species and typical s-triazine herbicide. This project could provide theoretical support for the development of green and efficient pollution control technology.

三嗪环的开环及矿化是三嗪类除草剂在环境中彻底消除的必要步骤。温和条件下高级氧化技术氧化三嗪类除草剂的最终产物是三聚氰酸，无法实现其开环矿化。本项目旨在通过在纳米零价铁活化分子氧氧化体系引入镍离子，促进氢自由基产生，调控体系中活性物种种类，诱导三嗪类除草剂加氢脱氯，避免脱氯上羟基生成极其稳定的三聚氰酸中间产物，优化三嗪类除草剂的降解途径，实现常温常压下纳米零价铁活化分子氧矿化三嗪类除草剂。本项目将系统考察体系中界面电子转移途径、分子氧活化机理、溶剂水的作用、活性物种的种类，深入分析活性物种生成和消亡途径；研究除草剂的降解特性以及各活性物种在三嗪类除草剂C-Cl和C-N键断裂过程中的作用，揭示不同活性物种与典型三嗪类除草剂的相互作用规律，阐明三嗪类除草剂降解和三嗪环开环等机理，为发展绿色高效农药污染控制技术提供理论支持。

本项目系统表征了纳米零价铁活化分子氧前后材料形貌、晶体结构、表面状态。分析镍离子与纳米零价铁界面作用机理。分析考察了体系中界面电子转移途径、氢自由基和活性氧物种的产生及消亡的规律及影响因素，研究了分子氧和溶剂水在该体系的还原活化分子机制。研究了除草剂污染物在该体系中降解途径、速率、稳定性、动力学及机理，研究了不同活性物种与典型三嗪类除草剂农药污染物的相互作用规律及除草剂的降解特性，研究了导致除草剂C-Cl键和三嗪环C-N键的断裂过程中各类活性物种的作用及反应路径等机理。构建了DFT理论计算模型，模拟自由基与三嗪研究环境条件体系活性物种种类及数量的影响，进一步研究了在模拟自然环境和条件下西玛津、阿特拉津在体系中的降解速率、稳定性、动力学及机理。内容包括：一、研究了纳米铁镍双金属/空气体系降解阿特拉津特性。二、研究了铜离子促进核壳结构Fe@Fe2O3活化分子氧高效降解阿特拉津效率及机理。三、构建了磷酸二氢钾增强零价铁活化分子氧降解阿特拉津体系并研究了相关机理。四、研究了亚硫酸盐促进光化学降解阿特拉津致三嗪环断裂、硫代硫酸钠高效脱氯去除三嗪类除草剂机理。项目的完成为发展绿色高效农药污染控制技术提供理论支持。