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

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 R-2 > 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. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study focuses on the removal of Cd (II) ions from aqueous solutions using modified activated carbon derived from palm kernel shells. The results showed that the removal percentage of Cd (II) ions increased with the contact time and reached equilibrium after 150 minutes, with a removal percentage of 51.24%. The optimal pH range for adsorption was found to be between 5 and 7, with an optimal adsorbent dose of 0.03 g. The Freundlich and Hasley isotherm models provided the best fit to the experimental data, indicating the heterogeneity of the Ce-doped activated carbon surface. Scanning electron microscopy confirmed the surface heterogeneity and material porosity. Kinetics studies revealed that both chemisorption and physisorption mechanisms were involved in the removal of Cd (II) ions, with hydrated radius and diffusion process playing a crucial role in controlling the adsorption process. Overall, the Ce-doped activated carbon derived from palm kernel shells is a cost-effective alternative adsorbent for the remediation of heavy metal contamination in water resources.