Biosorption of Co (II) from aqueous solution using algal biochar: Kinetics and isotherm studies

The present investigation deals with the utilization of biochar derived from the pyrolysis of microalgae Scenedesmus dimorphus as an adsorbent for the removal of cobalt (II) ion (Co) from aqueous solution. A series of experiments were conducted in a batch system to evaluate the performance of the biochar for Co removal. The effect of contact time on adsorption of Co (II) onto surface of the biochar was investigated. The equilibrium sorption data were analyzed by using Langmuir, Freundlich, Temkin, Harkins-Jura and Dubinin-Radushkevich (D-R) isotherms and were found to be adequate in describing the Co adsorption onto the biochar. Equilibrium data were well fitted for Freundlich, Temkin and D-R isotherms. The kinetic study of Co (II) adsorption on microalgae biochar were described by applying pseudo-first-order and pseudo-second-order rate equations. The surface of adsorbent before and after the removal of Co (II) was characterized by using SEM, EDX and XRD analysis.