Removal of Cd（Ⅱ） and Pb（Ⅱ） from soil through desorption using citric acid：Kinetic and equilibrium studies

The desorption test was conducted to evaluate the desorption behavior of Pb（Ⅱ）and Cd（Ⅱ）using citric acid.The influential factors that were considered included initial Pb（Ⅱ）,Cd（Ⅱ）contamination levels in soil,concentration of citric acid,reaction time,soil pH value and ionic strength.The test results indicated that the desorption was a rapid reaction（less than 6 h）,and the removal percentages of Cd（Ⅱ）and Pb（Ⅱ）increased with the increasing contamination levels,concentration of citric acid and the addition of Na^＋,Ca^2＋,Na^＋, Cl^– and the chelating of organic ligands.