污染土壤原位高效修复中的界面化学关键机制研究

Heavy metal and organic pollution of soil is one of the significant environment issues attracting much more attention all over the world, which is also very serious in our country. Remediation of the polluted soil, especially the development of the on-site techniques, is of very urgent demand for the secure of the society, while the current remediation technologies could not meet the actual requirement because of the diverse disadvantages. The interfacial chemical mechanisms play very important role on the efficient application of the diverse remediation techniques, so the related theoretical researches are very significant for the innovation of the techniques. This project plans to study the principle of the micro adsorption states and the transference principle of the heavy metal elements and the organic pollutants in soil, investigate the interaction principles between the heavy metal cations and organic pollutant molecules with the selected green surfactants, and explore the novel remediation technique which might completely remove the heavy metal and organic pollutants from the soil through the multi-phase foam flow. The interfacial adsorption and solubilization properties of the surfactants would drive the movement of the heavy metal and organic pollutions from soil surface to the gas/water interface of the foam films, and the transportation of the foam flow in soil medium could be swept thoroughly, the heavy metal and the organic pollutants atrapped in the foam films would be floated with the gas bubbles and be removed completely, thereby efficient on-site remediation of polluted soil could be achieved, while little residue would be left over. The project plans to explore the key interfacial chemical principles in the soil remediation, investigate the discipline of the transference of substances driven by foam flow in the porous soil media, which provide fundamental direction for the innovation of the progress of the ecofriendly efficient on-situ soil remediation technique, has important theoretical significance and also social environmental meaning.

土壤污染是当前全球瞩目的重大环境问题之一，我国的土壤重金属和有机污染均日益严重，治理修复迫在眉睫。国内外对污染土壤修复的探索方兴未艾，现有技术不能满足需要，相关理论研究和高效修复技术的创新亟待进行。界面化学机制在污染土壤治理修复中的作用举足轻重，进行相关研究对推动技术创新意义重大。本项目研究重金属和有机污染物在土壤中的微观状态和迁移规律，考察在土壤界面绿色表面活性剂与污染物的相互作用机制，探索通过向土壤中注入泡沫流体，利用绿色表面活性剂的性质将重金属离子和有机污染物迁移至气液界面和泡沫液膜内，利用泡沫流体均匀波及的特性实现对土壤孔隙介质的全面渗透，保障污染物彻底脱出，从而实现对重金属、有机复合污染土壤的原位快速高效修复，并可避免处理剂残留。本项目探索污染土壤治理中的界面化学关键机制，研究土壤孔隙介质中多相流体的迁移规律，创新绿色高效原位土壤修复技术，理论意义、社会意义和环境意义均十分重大。

针对当前污染土壤治理这一全球范围内的重大环境问题，特别是我国大量城市地块因重金属和有机物污染亟待快速修复所面临的极大挑战，本项目提出了采用水基泡沫原位高效修复治理复合污染土壤的创新技术路线，经系统的性能研究和机制探讨，完成了体系设计，而且对技术进行了完善和优化，不仅为治理修复污染土壤提供新技术和新材料，同时针对界面超分子相互作用微观机制研究所取得的认识对于指导构建可持续功能性胶体分散体系具有重要的理论意义。本项目以分子模拟和实验研究相结合，考察了多种新型绿色表面活性剂的界面分子行为和泡沫性能，研究了发泡气体和发泡方法对分散体系微结构和泡沫稳定性的影响，为根据土壤特性因地制宜制备适宜的泡沫体系提供指导；探讨了重金属离子和有机小分子与表面活性剂在界面的相互作用，证实了气液分散体系携带重金属和有机物的性能优势和理论机制。在此基础上，通过考察表面活性剂间的复配协同、水溶性聚合物和纳米颗粒与表面活性剂的相互作用及对泡沫性能的影响规律与机制，优选绿色表面活性剂和环境友好聚合物或纳米颗粒构建了一系列具有优异泡沫性能和界面活性的水基泡沫体系，且在高盐、高温、含油及高强度剪切等苛刻条件下保持良好稳定性和携液能力，为利用水基泡沫治理土壤污染打下了坚实基础。通过考察水基泡沫对水中以及土壤中重金属离子和有机污染物的处理能力和相关机制，建立和完善了以水基泡沫结合多相抽提高效修复治理污染土壤的技术途径，可一次性高效修复复合污染土壤并避免处理剂残留。针对土壤修复过程中产生的含有重金属和有机污染物的污水，构建了氧化石墨烯气凝胶、纤维素气凝胶以及天然多糖绿色水凝胶等，不仅对重金属具有优异吸附性能，还可通过原位转化或预先搭载具有优异光催化性能的纳米颗粒实现对有机污染物的光催化降解，从本质上杜绝二次污染。项目研发的绿色水基泡沫体系和水凝胶/气凝胶材料不仅在环境领域并且在油田化学、日化等领域也具有十分重要的应用前景。