Nanoscale zero-valent iron (nZVI)has the characteristics of small size,large specific surface,high reactivity and degradation with various contaminations,whereas it is limited in remediation of contaminated groundwater because of the lack of dispersibility and inoxi-dizability. Modified nZVI can improve the dispersibility and stability. The following characteristics of modified nZVI had be studied:nZVI modified in porous media needed lower cost,but fewer materials could be used;nZVI modified with various polymers could promote the reac-tivity towards NAPL,but it might cause secondary pollution without appropriate choice;Bimetallic nano-particles had the character of faster response speed and lower possibility to corrode,however,it would need high cost,and transition metal might be harmful to the environment. nZVI could degrade different heavy metal contaminates in groundwater,there different reaction mechanisms based the relative size between Fe2+ and standard electrode potential of heavy metal contaminates:adsorption/surface complexing,dual adsorption and reduction and redu-ation. However,modified nZVI had several disadvantages such as high cost and environmental toxicity.%纳米零价铁（nZVI）粒径小、比表面积大、反应活性高，可降解多种污染物，但nZVI分散性差、抗氧化性弱的特点使其在地下水修复中的应用受到限制。改性nZVI可以提高nZVI的分散性及稳定性，研究了现有改性nZVI的特点：多孔材料负载改性nZVI成本较低，但可选择的材料相对较少；有机物包覆分散改性nZVI的改性材料较多，可以促进非水相液体污染物与nZVI的接触反应，但选择不当容易引起二次污染；双金属改性纳米材料的反应速度较快，不易形成腐蚀产物，但成本较高，且过渡金属可能对环境有害。nZVI可以处理多种地下水重金属污染物，根据Fe2＋和目标重金属离子污染物的标准电极电位的相对大小，降解方式分为表面吸附—配合作用、表面吸附—还原作用和表面还原作用，但是改性nZVI存在价格高、有环境毒性等问题。
展开▼
