Date seed derived biochar for Ni(II) removal from aqueous solutions

School of Engineering, Griffith University, 170 Kessels Road, Brisbane, Australia

^* Corresponding author: a.elhanandeh@griffith.edu.au

Abstract

The purpose of this study was to investigate the adsorption characteristic of biochars derived from date seed for Ni²⁺ 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 Ni²⁺ 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 Ni²⁺ from aqueous solution than biochar prepared at lower temperature (DBS450). Adsorption efficiency of Ni²⁺ 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 Ni²⁺ by DSB550 was best fit to Langmuir isotherm with (R² = 0.94). The maximum adsorption capacity of Ni²⁺ 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 (R² = 0.99). The results of the study indicated that biochar derived from date seed biomass is a suitable material for adsorption of Ni²⁺ ion from aqueous solution.