The purpose of this study was to investigate the adsorption
characteristic of biochars derived from date seed for Ni 2+ ions removal
from aqueous solutions. Two biochars were prepared by slow pyrolysis of date seed for 3 h at 450 °C (DSB450) and 550 °C (DSB550). The
adsorption of Ni 2+ was carried out by batch experiments at room
temperature. The effects of pyrolysis temperature, contact time, initial
metal concentration, and solution pH were investigated. The results
showed that biochar prepared at higher temperature (DSB550) had higher
adsorption capacity of Ni 2+ from aqueous solution than biochar prepared at lower temperature (DBS450). Adsorption efficiency of Ni 2+ ions was pH
dependent and the maximum adsorption was found to occur at pH around 6.0. To describe the equilibrium isotherms, the experimental results were analyzed by the Langmuir, and Freundlich isotherms. The adsorption
isotherm for Ni 2+ by DSB550 was best fit to Langmuir isotherm with (R 2

0.94). The maximum adsorption capacity of Ni 2+ of DSB550 biochar was
0.609 mmol g 1 . Pseudo-first order, pseudo-second order, and intraparticle diffusion models were used to model the kinetic parameters and
mechanism of adsorption process. The results showed that the adsorption
kinetics of these biochars are well described by a pseudo-second order
kinetic model with correlation coefficient (R 2 = 0.99). The results of the
study indicated that biochar derived from date seed biomass is a suitable
material for adsorption of Ni 2+ ion from aqueous solution