This paper reports the efficiency of a biosurfactant tea-saponin on removing heavy metal from contaminated soils.Batch experiments were performed to test the influence of tea-saponin concentration

pH and ionic strength on the removal efficiency.The results showed that the removal efficiency of heavy metals could be enhanced with the increase of the added tea-saponin concentrations.By adding 7% of tea-saponin

the removal efficiency of heavy metals in the tested soil samples can reach the maximum and could finally reach 96.36%

71.73%

43.71% and 20.56% for Cd

Zn

Pb and Cu respectively.The removal efficiency gradually decreased with the increase of pH values.The suitable pH scope should about 5.0.The ionic strength slightly had a negative influence on the removal efficiency of Zn

Cd

but no efforts on Pb

Cu.Comparing the transformation of heavy metals' chemical forms before and after tea-saponin treatment by BCR method

it was found that heavy metals in acetic acid extractable fraction are more easily to remove

the second is hydroxide-bound fraction

heavy metals in organically-bound fraction and residual fraction are difficult to remove.