Adsorption of cadmium and copper using biochar obtained from the residue of the second-generation ethanol production: kinetics and equilibrium study

Abstract

The disposal of industrial effluents containing cadmium and copper ions is a significant environmental concern. This study aims to address this issue by evaluating the adsorption capacity of adsorbents derived from residual biomass from second-generation ethanol production. The objective is to effectively remove cadmium and copper ions from aqueous solutions. The biochar utilized in the study was characterized as microporous and exhibited characteristic bands associated with carboxyls and hydroxyls. The pHPZC (point of zero charge) was determined to be 8.0. The kinetic study revealed that the PSO (pseudo-second-order) model provided the best fit, indicating that the adsorption rate depends on the amount of solute adsorbed onto the adsorbent’s surface. In the equilibrium study, it was observed that adsorption occurred in a monolayer, as evidenced by the superior fit of the Langmuir model. Furthermore, the equilibrium experimental data for the bicomponent system was more accurately represented by the empirical models of Extended Freundlich and Modified Redlich-Peterson. These findings demonstrate the potential of biochar derived from the residue of second-generation ethanol production, a novel application, in effectively removing cadmium and copper ions from aqueous solutions.