【摘要】 通过实验室模拟研究将纯水提取与冷冻法相结合修复Cr（Ⅵ）污染土壤的可行性.结果表明，对于1 000 mg/kg Cr（Ⅵ）污染土壤，利用纯水进行提取，总铬的提取率约为35%,该结果与常规的草酸提取法相近.向纯水提取液中加入草酸，使其浓度为500μmol/L,冷冻结冰后，提取液中Cr（Ⅵ）的还原率达97%. NaCl, NaNO₃,Na₂SO₄对Cr（Ⅵ）的去除效果有微弱的抑制作用.紫外吸收光谱、 X射线光电子能谱、红外光谱和三维荧光光谱测试结果表明，该方法的作用原理为草酸提供H⁺,土壤中的溶解性有机质（DOM）作为还原剂，通过冷冻浓缩效应使土壤提取液中六价铬被还原.可见，纯水提取与草酸冷冻法相结合可用于异位修复Cr（Ⅵ）污染土壤，并可减少化学试剂的用量，有利于维护土壤理化性质的稳定.更多还原

【Abstract】 The feasibility of remediation of Cr（Ⅵ）-contaminated soil by combining pure water extraction and freezing method was studied through laboratory simulation. The results show that for 1 000 mg/kg Cr（Ⅵ）-contaminated soil, the extraction rate of total chromium is about 35% by using pure water for extraction, which is similar to the conventional oxalic acid extraction method. After freezing and icing, oxalic acid was added to the pure water, extraction solution at a 500 μmol/L, the reduction rate of Cr（Ⅵ） in the extraction solution reaches 97%. NaCl, NaNO₃, and Na₂SO₄ have a weak inhibitory effect on removal efficiency of Cr（Ⅵ）. The ultraviolet absorption spectrum, X-ray photoelectron spectroscopy, infrared spectra, and 3D fluorescence spectroscopy tests show that the working principle of the method is that oxalic acid provides H⁺, and dissolved organic matter（DOM） in the soil acts as a reducing agent, hexavalent chromium in the soil extract is reduced through the freeze-concentration effect. Therefore, the combination of pure water extraction and oxalic acid freezing method can be used for the ex-situ remediation of Cr（Ⅵ）-contaminated soil, and can decrease the usage of chemical reagents, which is conducive to maintaining the stability of soil physicochemical properties.更多还原