Abstract: Two inorganic eluents,HCl and CaCl₂,were tested in an experiment to elute Pb and Cd from heavy metal contaminated soil in a mining area for comparison of their efficiencies and for investigation of factors, such as eluent concentration, timing, temperature, solid-liquid ratio and frequency of elution, affecting elution efficiency. It was found that HCl was better than CaCl₂ in removing Pb and their Pb removal rate was 26.0%-68.2% and 14.6%-48.7%,respectively,but CaCl₂ was better than HCl in removing Cd and their Cd removal rate was 30.7%-54.6% and 24.2%-42.6%, respectively. Among the factors studied,eluent concentration had a significant effect on Pb removal rate,while elution frequency had on Cd removal rate. No significant impact was observed from other factors.The optimal elution conditions for Pb from soil are: HCl 200 mmol·L^-1 in concentration; 240 min in duration; 20 ℃ in temperature; 1∶15 in m (solid)∶ V( liquid) ratio and 2 in frequency; whereas the conditions for Cd from soil are: CaCl₂ 50 mmol·L^-1 in concentration; 240 min in duration; 35 ℃ in temperature; 1∶20 in m (solid)∶ V(liquid) ratio and 4 in frequency.

Key words: inorganic eluent, contaminated soil, heavy metal, Pb, Cd, removal