Leaching remediation of heavy metal contaminated fluvio-aquatic soil with tea-saponin

For the purpose of investigating the possibility of tea-saponin on leaching remediation of heavy metal contaminated soil, the effect of tea-saponin on the removal of heavy metals from contaminated soil were analyzed by oscillation and soil leaching methods. The results showed that the concentrations of tea-saponin and the soil pH value had obvious effects on the removal efficiency of heavy metals. In the soil leaching experiment, 7% tea-saponin solution was used as flushing agents, the optimum conditions were as follows: pH value was 5.0±0.1, the ratio of soil to solution was 1:4. Then the removal efficiency could reach 6.74%, 42.38%, 13.07% and 8.75% for Pb, Cd, Zn and Cu, respectively. The removal efficiency of heavy metals was in a sequence of Cd＞Zn＞Cu＞Pb. After soil leaching by tea-saponin, heavy metals in acid-soluble fraction and oxide fraction were effectively removed, and the environment risk of heavy metals was decreased. It also shows that tea-saponin has great potentiality in leaching remediation of heavy metal contaminated soil.