基于含水层介质中铁的类芬顿氧化技术由于其“经济有效、环境友好”被广泛用于难降解有机污染地下水的修复中。但过氧化氢在地下环境中的不稳定性使该技术的修复效率受到较大影响，注入的大量过氧化氢直接分解成水和氧气而没有参与类芬顿反应生成羟基自由基，导致其利用率较低；且大量生成的氧气占据介质孔隙降低渗透性，还促使污染物挥发扩大污染范围。本课题拟使用过氧化钙作为过氧化氢缓释剂，并将其制成纳米颗粒注入地下形成反应带，以提高过氧化氢利用率，改善修复效果。通过批次实验，柱、槽模拟实验，拟研究不同地层环境下过氧化钙的水溶及分解特性；揭示硝基苯在反应带中的降解机理及主要控制因素；掌握纳米过氧化钙在含水层中运移分布的时空变化特征；建立过氧化钙浆液注入浓度、污染物水力停留时间、修复效率之间的响应关系；综合分析评估纳米过氧化钙化学反应带的修复效能和机理。研究成果可为难降解有机污染场地的高效修复治理提供理论依据。

Fenton-like technology based on iron in aquifer materials, known as "cost-effective, environmentally friendly", was widely applied in remediation of groundwater contaminated by recalcitrant organic pollutants. However, the instability of hydrogen peroxide in subsurface severely affect the remediation efficiency. Large amount of injected hydrogen peroxide directly decompose into water and oxygen, without the participation of fenton-like reaction to generate hydroxyl radicals, resulting in lower utilization of hydrogen peroxide. Besides, the release oxygen gas clogs pores around injection wells and promotes contaminant volatilization which leads to the spreading of contaminated zone. This project intends to use calcium peroxide as slow-released agent of hydrogen peroxide, and then, the slow-released agent is synthesized into nano particles, which can be injected into subsurface to form reactive zone. This approach can improve the utilization of the hydrogen peroxide and remediation performance. Batch experiments, column/tank experiments will be carried out to study: the dissolution and decomposition characteristics of calcium peroxide in different geological formations; nitrobenzene degradation mechanisms in the reactive zone and the main controlling factor; the calcium peroxide migration and distribution characteristics in aquifer; the functional relationship among the concentration of injected calcium peroxide slurry, hydraulic retention time, and remediation efficiency. Then, the remediation performance and mechanisms on the chemical reactive zone of nano calcium peroxide will be comprehensively analyzed and evaluated. The findings of this project can serve as theoretical bases for efficient remediation of sites contaminated by recalcitrant organic pollutants.