Improved Cd (II) ions removal performance from aqueous solution using cerium doped activated carbon

Abstract

The present work deals with the removal of Cd (II) ions in aqueous solution using modified activated carbon based palm kernel shells. The activated carbon surface was modified by incorporating cerium atoms. The experiments were performed in batch mode by varying the initial pH solution, adsorbent dose, contact time and initial concentration of Cd (II) ions. The experimental results analysis revealed that the Cd (II) ions removal percentage increased with the increase of the contact time and reached adsorption equilibrium within 150 min with a removal percentage of 51.24%. The adsorbed quantities were strongly linked to the ionic radius and hydration energy of oxides with optimal pH values ranging between 5 and 7 for optimal adsorbent dose of 0.03 g. Six isotherms models were investigated to explain the adsorption equilibrium. The Freundlich and Hasley isotherms models gave the best fit according to their correlation coefficient values R2 > 0.9. Moreover, the value of (1/n) was less than unity indicating the heterogeneity of Ce-doped activated carbon surface. The surface heterogeneity and material porosity were confirmed by scanning electron microscopy. Four kinetics models were used to identify the mechanisms that governed the Cd (II) ions adsorption. The pseudo second order and intraparticle diffusion kinetics models fitted well the experimental data. Both chemisorption and physisorption mechanisms of Cd (II) ions removal were controlled by hydrated radius and the diffusion process into AC-Ce network. Thus, the Ce-doped activated carbon obtained by carbonization/activation of palm kernel shells is an alternative and low-cost adsorbent which can be useful for the remediation of heavy metal contamination resulting from the migration from phosphogypsum production sites to water resources.