微波/过碳酸钠修复邻苯二甲酸酯污染场地的作用机理与调控研究

Phthalate acid esters (PAEs) are the main plasticizers that are widely used in many industries. PAEs are toxic to animals and human, and they can accumulate in the soils and result in the soil pollution. It has been found that the soils in solid waste dismantling areas and abandoned plastic industrial areas had been polluted heavily by PAEs. Until now, no treatment has shown efficacy. To understand the synergistic mechanisms of microwave and sodium percarbonate process, the reactive species and concentrations, the reaction rate constant and the activation energy of PAEs degradation in the three systems(microwave/sodium percarbonate system, conventional heating/sodium percarbonate system and single sodium percarbonate) will be comparatively studied. The kinetics of degradation reaction of PAEs in microwave/sodium percarbonate system will be studied at different temperatures，and the attack mechanism of active ingredient will be deduced．The reaction mechanism will be proposed based on the analysis of the degradation products by LC-MS and reactive species by ESR．The desorption and immobilized processes of PAEs and their degradation products will also be explored to reveal the remediation mechanism. Furthermore, the effects of absorbing material (water, activated carbon, iron powder) on the soil microwave heating enhancement effect, pH value on the active ingredient, moisture on PAEs removal ways will be studied to reveal the process and mechanism of main exogenous controllable factors remediating PAEs-contaminated sites. Based on which, microwave/sodium percarbonate oxidation will be built up to treat PAEs-contaminated sites. We wish to promote the development of microwave- sodium percarbonate oxidation technology by applying this project. It is also significant for reasonable use of the contaminated vegetable soil in the future.

固废拆解区、塑料化工搬迁场地甚至部分城市土壤邻苯二甲酸酯(PAEs)污染严重，目前尚无有效修复方法。通过对比三种体系条件下（微波（MW）/过碳酸钠（SPC）体系、传统加热/ SPC体系、单一SPC）活性成分与浓度、PAEs的降解反应活化能与降解反应速率，从MW对SPC的活化效应、MW非热效应和MW热效应三方面推导MW与SPC协同作用机制；分析PAEs在MW/SPC体系下的挥发与降解过程，监测降解产物，研究降解途径和降解动力学，揭示活性成分进攻机理；探索PAEs及其降解产物的MW解吸与固定化机制，揭示MW/SPC体系修复PAEs污染场地的作用机理；在此基础上，研究外源吸波物质（水、活性炭、铁粉）对土壤微波加热增强效果的影响、pH值对活性成分的影响、水分对PAEs去除途径的影响，探索制约MW/SPC体系修复PAEs污染场地的主要外源可控因子与调控机理，为有机污染场地化学修复的应用提供科学依据。

固废拆解区、 塑料化工搬迁场地甚至部分城市土壤邻苯二甲酸酯（PAEs）污染严重，目前尚无有效修复方法。本项目首先采集不同土地使用功能的土壤样品，分析土壤受PAEs的污染特征，挑选具有代表性的PAEs（DBP和DEHP）为目标污染物，通过正交试验和单因素试验探索微波强化过碳酸钠（SPC）降解DBP和DEHP的最佳反应条件（pH值、SPC投加量、催化剂投加量、反应温度、反应时间、底物浓度等）；在最佳反应条件下，研究了不同活性氧物种对DBP和DEHP氧化效率的贡献，对比分析了单独微波、水浴-SPC/FeSO4、微波-SPC/FeSO4对DBP和DEHP的降解效率，探索了MW-FeSO4-SPC催化氧化有机物的协同作用机理，结合降解产物分析了降解途径；同时，以土壤中的铁锰化物和水分为微波敏化剂，探讨了过碳酸钠（SPC）投加量、土壤含水率、初始pH、反应温度、反应时间对DBP去除效果的影响；在最佳反应条件下，探索土壤中常见的3种阴离子对反应体系的影响，研究了不同活性氧化物种对DBP氧化效率的贡献，对比分析了单独MW辐射、MW/SPC和水浴SPC对DBP的去除效率，探明了MW对SPC活性成分、PAEs降解反应活化能及降解反应速率常数的影响，探索了MW/SPC催化氧化土壤有机物的协同作用机理，结合DBP降解产物分析了DBP的降解机制，揭示了MW/SPC体系对PAEs污染场地的修复机理，明确制约MW/SPC体系修复PAEs污染场地的主要外源可控因子及调控机理，为MW/SPC协同应用提供理论依据，为PAEs污染场地原位修复提供新思路。.研究表明：影响微波/SPC体系氧化效率的主要因素有SPC投加量、土壤含水率、反应时间、初始pH和反应温度，微波能降低反应所需的活化能，PAEs降解符合Langmuir- Hinshelwood 动力学模型；体系中主要的活性物种是•OH和O2.-，HCO3-对体系氧化效率有明显抑制，Cl-表现为轻度抑制, PAEs降解先后历经了脂肪链断裂、苯环羟基化开环分解成小分子物质并被彻底矿化等过程；土壤微观结构未发生破坏，PAEs降解是主要去除途径。相关研究成果已发表学术论文20篇（SCI录用7篇），申请专利12件，培养研究生6名。