有机酸对重金属污染耕地土壤的修复研究

The Repairing Study of Heavy Metal-contaminated Farmland Soil by Organic Acids

利用水、柠檬酸溶液和醋酸溶液依次淋洗受重金属严重污染的耕地土壤,再利用石灰水溶液淋洗调节土壤pH值。分析柠檬酸溶液、醋酸溶液在0.2mol/L、0.5mol/L、0.7mol/L、11mol/L等不同浓度下其淋洗液中的重金属含量,从而找出对重金属淋洗效果好的酸种类及其相应的浓度。实验结果表明,随着柠檬酸、醋酸溶液浓度的增大,其对重金属的淋洗能力呈增强趋势;在同等浓度条件下,柠檬酸对Cu、Pb、Cd的淋洗效果比醋酸的好,而对Zn的淋洗,醋酸的淋洗效果比柠檬酸的好;对Cu、Zn、Pb、Cd的淋洗上,选择柠檬酸的最佳浓度分别为11mol/L、11mol/L、0.71mol/L、11mol/L,选择醋酸的最佳浓度均为11mol/L。经检测可知,污染土壤经过柠檬酸、醋酸处理后,重金属含量已经大大减少,其重金属残量值已达到国家环境质量标准的相关限量要求,说明有机酸对重金属污染耕地土壤有较好的改良作用。

Water, citric acid solution and acetate solution were used to wash heavy metal-contaminated farmland soil successively, then calcium hydroxide solution was utilized to adjust soil pH value. The heavy metal content of the eluent was analyzed under different concentrations of citric acid and acetate solution, as 0.2 mol/L, 0.5 mol/L, 0.7 mol/L and 1 mol/L, thus better effective acid kinds and its corresponding concentrations were found.The experimental results showed that elute ability were improving with the increase of citric acid and acetate solution concentrations, under the same concentration, the elute effect of citric acid solution on Cu, Pb,Cd was better than that of acetate solution, the elute effect of acetate solution on Zn was better than that of citric acid solution, for the four elements, the optimum concentration of citric acid solution was lmol/L, lmol/L, 0.7mol/L, lmol/L respectively, the optimum concentration of acetate solution was lmol/L. The heavy metal content of contaminated soil treated by citric acid and acetate solution reduced greatly, heavy metal residual value had attained the related requirement of national standards for environment quality, this indicated that organic acids has good improving effect on heavy metal-contaminated farmland soil.