Removing heavy metals from Pb, Cr-contaminated soils with different extractants

EDTA, Dodecylbenzene sulfonate, HCl, Tartaric acid and CaCl₂ were used as extractants to remove Cr and Pb from Pb, Cr-contaminated soils. Batch equilibrium experiments were performed under variation of solid:liquid ratio and washing time. The results indicated that Citric acid, EDTA and Tartaric acid were effective for extracting Cr from the soils and EDTA, HCl and Tartaric acid were effective for extracting Pb. Heavy metals in the clay were more difficult to be extracted than those in the loam and the sand. The washing time and solid: liquid ratio had the great impact on removal efficiency. The optimum washing times of EDTA, Dodecylbenzene sulfonate, HCl, Citric acid,Tartaric acid and CaCl₂ were 16 h, 20 h, 16 h, 16 h, 16 h and 24 h, respectively. The optimum solid: liquid ratios of EDTA, Dodecylbenzene sulfonate, HCI, Citric acid, Tartaric acid and CaCl₂ were 1:10, 1:10, 1:10, 1:10, 1:10 and 1:14, respectively.