腐殖质/环糊精/农药三元体系主客体包结和光化学研究

In the view of the unclear mechanism for the participation of organic pollutants between dissolved organic matters and flushing agents, and the difficult in reusing flushing agents etc., this project plans to investigate the inclusion complex and photochemistry properties of dissolved organic matter (humus)-flushing agents (cyclodextrins)-organic pollutants (pesticide) ternary system. NMR titration, steady fluorescence and time-correlated single photo counting are applied to study the inclusion complex in the ternary system. Mechanism for the degradation of pesticides in cyclodextrin solution is proposed based on the structure change of pesticide after forming supermolecule with cyclodextrin and the analysis of transition species and intermediates formed during degradation. The practicability of reusing cyclodextrin by using UV photolysis is evaluated based on the effect of humus on the degradation of cyclodextrin. The remediation of simulated contaminated soil by using cyclodextrin flushing followed by UV photolysis are carried out in order to prove the proposed mechanism. The work performed in this project could provide new research idea for explanation and prediction of flushing agents' performance in remediation of soils with various contents of organic matter. The work also gives new theoretical support for the establishment of efficient, safe and economic soil remediation technology.

针对目前土壤淋洗液中污染物在淋洗剂和溶解性有机质两相间分配机制不明，难以实现淋洗剂的循环利用等问题，拟开展溶解性有机质(腐殖质)、淋洗剂(环糊精)和有机污染物(农药)三元体系的主客体包结和光化学研究工作。结合核磁滴定、稳态光谱与时间分辨荧光光谱法研究三元体系中的主客体包结作用。结合农药分子在形成超分子前后结构变化、光化学反应过程中产生的瞬态物质和中间产物的分析，研究农药分子在环糊精淋洗液中的降解机制。研究腐殖质对环糊精光降解行为的影响，探讨紫外光直接光解技术对实现环糊精循环利用的可行性。采用环糊精淋洗－紫外光降解联用技术修复模拟污染土壤，验证上述机制。本项目研究工作的开展可以为解释和预测淋洗剂对具有不同有机质含量土壤的修复效果提供新的研究思路。为建立高效、安全和经济的污染土壤修复工艺提供新的理论支撑。

针对土壤淋洗液中有机污染物/土壤溶解性有机质/淋洗剂三元体系中污染物的分配机制不明、淋洗剂再生困难等问题，首先利用稳态和瞬态荧光光谱法研究了有机污染物在土壤溶解性有机质（腐植酸等）和淋洗剂（环糊精，表面活性剂胶束等）两相间的分配问题。研究发现有机污染物在两相间的分配受污染物/环糊精包结作用强弱影响较大。环糊精的存在并没有影响腐植酸溶液中活性物种的生成和反应活性。考察了溶解性有机质对有机污染物和有机污染物/淋洗剂超分子直接紫外光解的影响。结果表明直接紫外光解（UV 254nm）可以有效去除模拟土壤淋洗液中的双酚A，并且可以很好的再生环糊精的洗脱能力，腐植酸的加入并没有影响环糊精的再生。最后利用增溶淋洗 紫外光解联用技术处理了菲污染土壤。结果表明，该技术具有良好的使用效果。综上，利用紫外光解技术可以实现去除土壤淋洗液中有机污染物的同时再生淋洗剂的洗脱能力的目的。为建立高效、环保、低成本的污染土壤修复技术提供了理论依据和实验支撑。