Remediation of heavy metals-contaminated soil using CaCl_2 and MgCl_2 coupled with a dissolved organic carbon solution

摘要

Dissolved organic carbon (DOC) washing has been proved that it could remove heavy metals effectively from contaminated soil. Addition of Ca or Mg into an acid aqueous solution was known promoting the removal for heavy metals. The object of this study was employing mixture solutions prepared using CaCl_(2(aq)), MgCl_(2(aq)), and the liquid fertilizer for remediation of a soil severely contaminated with Cr (918 ppm), Cu (1015 ppm), Zn (1105 ppm), and Ni (529 ppm). Effect of Ca and Mg additions on the removal was examined. When soil washings were conducted using the Ca/Mg solutions, only content of Zn remained in soil favored the level of control standard. The DOC substantially elevated removal efficiency of metal during the washing. Two soil washes using a 4000 ppm DOC/0.1M CaCl_2/0.1M MgCl_2 solution with a of pH 2.0 at 25°C removed approximately 68%, 70%, 69%, and 9% of Cu, Ni, Zn, and Cr respectively. Combined action from the Ca~(2+), Mg~(2+), and proton replacements as well as the organic complexation brought the removal of metals to a maximum level.