Kinetics and equilibrium study of adsorptive removal of cadmium ions from aqueous solutions by utilizing lime peel as a biosorbent

This work investigates the potential of utilizing lime peel wastes as a low-cost adsorbent for the adsorption of cadmium ions from aquatic media. The batch system was employed for determining the adsorption performance and optimum operating conditions and parameter values such as feed concentration, adsorbent concentration, the adsorbent particle size, contact time, and initial pH for the feed. The Langmuir, Freundlich, Dubinin-Radushkevich, and Sips isotherm models were examined to evaluate the adsorption results. Regression analysis indicates that the adsorption data is well-fitted to the Freundlich isotherm. Moreover, kinetic analysis of obtained data was carried out using three models including pseudo-first-order, pseudo-second-order, and, Weber-Morris intraparticle diffusion. The pseudo-second-order model fitted the experimental data better than the others. According to thermodynamic analysis, the adsorption of cadmium on lime peel was found to be spontaneous and endothermic. The removal percentage of cadmium reached 90% which proves that lime peel wastes have great potential to be employed as biosorbent for cadmium separation from aqueous media. The regeneration of the loaded adsorbent showed that 77.8% & PLUSMN; 1.6% of the cadmium adsorbed on the adsorbent could be recovered by contacting the adsorbent with a 0.1 M HCl solution after four adsorption-desorption cycle.

Automated summary

This study examined the potential of using lime peel wastes as a low-cost adsorbent for removing cadmium ions from water. The adsorption performance and optimum operating conditions were determined using a batch system. The Freundlich isotherm and pseudo-second-order model were found to fit the adsorption data well. Thermodynamic analysis showed that the adsorption of cadmium on lime peel was spontaneous and endothermic. The results suggest that lime peel wastes have great potential as a biosorbent for cadmium separation from water.