铁-碳纳米复合物活化过硫酸盐氧化土壤多环芳烃的化学机制

The remediation of polycyclic aromatic hydrocarbons (PAHs) in soils is one of the most challenging topics in environmental engineering. Currently, in situ chemical oxidation based on activated persulfate is a promising technology, however, its efficiency is limited by the performance of activators employed in the reaction. The proposed research is directed towards the innovative design and preparation of spherical iron-carbon nano-composites as the activators for the in situ persulfate activation, followed by the mechanism studies on their application in the remediation of PAHs. The highly uniform spherical iron-carbon nano-composites, synthesized by an aerosol-assisted method in molecular level, achieved effective underground transportation in comparison to the bare zero-valent iron nanoparticles. In the meantime, the slow release process of the ferrous iron was efficiently controlled by the porous carbon support and thus enhanced the activation function. Moreover, the adsorption of organic pollutants by the spherical carbons contributed to the targeted pollutant contact of the oxidation system, resulting in the synergistic function of absorption and reaction which highly improved the PAHs removal efficiency. The distinction of the proposed research from earlier work is that all essential functions including effective delivery, targeted pollutant contact and high activity retention, of the constructed oxidation system are concurrently achieved. Therefore, the proposal, well suited for the urgent needs of the environmental restoration of the soil, not only has valid theoretical background also has broad application prospects.

多环芳烃（PAHs）污染土壤的治理是当前环境领域最具挑战性的课题之一。目前，基于活化过硫酸盐的原位化学氧化技术展现了一定的前景，但受限于活化剂的应用效果。本项目拟构建新型氧化体系铁-碳纳米复合物活化过硫酸盐，并考察其原位修复土壤PAHs的性能，重点研究活化机理、传递性能、吸收-氧化协同作用、土壤性质的影响以及降解路径等化学机制。项目采用气溶胶法合成球形铁-碳纳米复合物，克服了以往非均相活化剂不能在土壤中有效扩散的缺点；同时，多孔碳球对纳米零价铁的包覆实现了Fe2+的缓释，从而避免硫酸根自由基的淬灭；再者，碳球对PAHs的吸收有助于整个氧化体系对污染物PAHs的靶向接触，在吸收-反应的协同作用下去除效率得到提高。项目的特色在于构建的氧化体系同时具备在地下的有效传输、成功靶向接触污染区以及保持高活性处理污染物等必需功能。因此，项目兼具理论意义和应用前景，适合我国当前土壤修复的紧迫需求。

原位化学氧化修复技术被认为是一种快速、有效且普适性强的土壤污染治理的方法。如何保证氧化体系在土壤及地下水中的有效迁移扩散、成功靶向接触污染物以及进一步提高有效物种自由基的浓度是其中的关键。本项目构建了新型铁-碳纳米复合物活化过硫酸盐氧化体系，并将其用于多环芳烃（PAHs）污染土壤的治理。研究成功制备了新型活化剂球形Fe-C纳米复合物，其具有地下传输性优良、高效活化类芬顿体系以及靶向接触污染物等三个典型的优点及特征；同时项目构建了适合我国当前土壤修复的球形Fe-C纳米复合物活化过硫酸盐氧化体系，揭示了其原位修复土壤多环芳烃过程中的地下传输性能、吸收及氧化反应特性，修复效率影响因素。另外，项目还弄清了所构建的球形Fe-C纳米复合物活化过硫酸盐氧化体系对典型PAHs的去除机理，从而为研究该体系在修复土壤及地下水中更多污染物奠定理论基础。同时，项目将自行设计的材料制备方法拓展到其它热门环境纳米材料（二氧化钛以及钴酸锂）的制备上，应用场景也从多环芳烃延伸到土壤及地下水中广泛存在的硝酸盐和三氯乙烯。在此期间，发表与项目内容相关的文章10篇（含中文核心期刊2篇，英文SCI8篇）。