Removal of Cd(II) from aqueous solutions using plant-derived biochar: Kinetics, isotherm and characterization

Abstract

As a carbon-rich, microporous solid produced from biomass pyrolysis, biochar derived from plant materials has been gaining research attention for their potential application as adsorbents in removal of toxic heavy metals. The study aimed to investigate the efficiency of biochars derived from oil seed rape (OSR), Miscanthus (MSP) and wheat (WSP) in the removal of Cd(II) in aqueous solution and compare the Cd(II) adsorption capacity of biochars produced at two pyrolysis temperatures of 550 °C and 700 °C. Batch Cd(II) adsorption experiments revealed that biochars derived from OSR and MSP that prepared at pyrolysis temperature of 550 °C performed better in Cd(II) removal than those at 700 °C. The pseudo-first kinetic model and the Sips isotherm model provided the best simulation of the kinetic and equilibrium data, respectively for all biochars tested. Desorption of Cd(II) from all biochars was achieved with nearly complete Cd(II) recovery using HNO3 as the desorbing agent.