Assessment of soil washing for Zn contaminated soils using various washing solutions

Bench-scale soil washing experiments were conducted to remove Zn from contaminated soils. Various washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sodium hydroxide (NaOH), oxalic acid (HOOCCOOH·2H2O), sulfuric acid (H2SO4), phosphoric acid (H3PO4), and tartaric acid (C4H6O6) were used. The concentration of the washing solutions used in this study ranged from 0.1 M to 2 M with a liquid to solid ratio of 10. The soil washing results showed the following order of washing solution decreasing effectiveness for the removal of Zn: HCl > HNO3 > H2SO4 > H3PO4 > C4H6O6 > HOOCCOOH·2H2O > NaOH.