多孔介质中膨润土悬浮液携带负载型纳米零价铁的强化传输

Enhanced transport of K-nZVI by bentonite suspensions in porous media

为强化纳米零价铁(nZVI)在多孔介质中的传输,采用膨润土悬浮液携带高岭土负载纳米零价铁(K-nZVI)。通过沉降试验和流变性试验确定了修复剂中膨润土和K-nZVI掺量最佳配比;开展模拟柱试验,探讨了不同注入压力下K-nZVI在多孔介质中的迁移特性;结合数值模拟,分析了修复剂配比和注入压力对K-nZVI扩散半径的影响规律。试验结果表明,膨润土悬浮液能显著提高K-nZVI的稳定性和分散性;膨润土和K-nZVI最佳掺量分别为5%和0.4%;膨润土悬浮液携带K-nZVI修复剂注入多孔介质中时存在临界注入压力。数值模拟结果表明,K-nZVI扩散半径与注入压力呈正相关,与修复剂黏度呈负相关。本文研究结果可为有色冶炼场地重金属污染修复工程提供理论指导。

Due to high reactivity and relatively low cost,nano zero-valent iron(nZVI)has become an alternative material for in-situ remediation of contaminated sites.However,factors such as short transport distance and easy deposition in porous media also seriously restrict its injection remediation effect.The optimum ratio of bentonite and kaolin supported nano zero-valent iron(K-nZVI)in the remediation agent was determined by sedimentation and rheological tests.The transport characteristics of deionized water and bentonite suspensions carrying K-nZVI in porous media under different injection pressures were investigated using simulating column tests.The results show that bentonite suspensions could significantly improve the stability and dispersibility of K-nZVI.The proportion of bentonite and K-nZVI are 5%and 0.4%,respectively,which is the best ratio of the remediation agent.The transport capability of K-nZVI carried by deionized water increases with the increase of injection pressure,while there is a critical injection pressure for bentonite suspensions carrying K-nZVI remediation agent.The numerical simulation results show that the diffusion radius of K-nZVI is positively correlated with the injection pressure and negatively correlated with the viscosity of the remediation agent.The results provide theoretical guidance for the remediation project of heavy metal pollution in non-ferrous smelting sites.