Uranium capture from aqueous solution using Palm-waste based activated carbon: sorption kinetics and equilibrium

Abstract

In this research, we examined the effectiveness of adsorbents derived from commercially available palm kernel shell bio-char (PBC), as well as palm shell carbon that was activated through treatment with H2SO4 (PBC-SA) and ZnCl2 (PBC-Zn). Our primary objective was to enhance the adsorption capabilities of carbon materials and develop efficient sorbents for the removal of uranium ions from aqueous solutions. To gain insight into the characteristics of these materials, we employed various analytical techniques, including SEM, EXD, BET, FTIR, and Zeta potential. The optimization of the adsorption process involved the careful consideration of key parameters such as pH, contact time, adsorbent dosage, and initial metal ion concentration. Under specific conditions, including a pH level of 4.5, a contact time of 60 minutes, an adsorbent dosage of 10.0 g/L, and an initial metal concentration of 50 mg/L, the adsorbent materials PBC, PBC-SA, and PBC-Zn demonstrated uranium ion sorption capacities of 9.89 mg/g, 16.81 mg/g, and 21.93 mg/g, respectively. The kinetics of the adsorption process were analyzed using three models: the pseudo first-order model, the pseudo second-order model, and the intraparticle diffusion model. Our findings indicated that the pseudo second-order kinetics model provided the most suitable description of the uranium adsorption onto the prepared materials. Furthermore, the adsorption isotherm data were consistent with the Langmuir model, suggesting that the adsorption of uranium ions onto all materials followed a monolayer adsorption mechanism. Lastly, thermodynamic analysis revealed that the adsorption process was spontaneous and exothermic in nature.