In the present study

two biochars derived from Platanus orientalis Linn branches and leaves respectively were prepared by pyrolysis at the temperature of 500℃ under the oxygen-limited condition. The batch equilibration method was used to determine the effects of different factors

such as contact time

initial Pb

2+

concentration and initial solution pH on Pb

2+

adsorption capacity on the biochars. The characteristics of adsorption isotherms and adsorption kinetics were analyzed to reveal associated mechanisms. The results showed that the mineral elements and functional groups were more abundant in the leaf biochar than those in the branch biochar. The maximum adsorption of Pb

2+

on both biochars occurred at the initial pH 5 after

24 hours

and the adsorption capacity of the leaf biochar was 25.6% greater than that of the branch biochar. The adsorption of Pb

2+

could be described well by the pseudo-second-order kinetics

indicating that the adsorption process was mainly controlled by precipitation. The adsorption isotherms demonstrated that the adsorption of Pb

2+

to the biochars fitted Langmuir model better than Freundlich model. Therefore

monolayer adsorption was proposed as the dominant adsorption process

although the multilayer adsorption was also present. In conclusion

both biochars had good capacity for adsorption of Pb

2+

in water

and the leaf biochar was more effective than the branch biochar.