A fixed bed column study for the removal of Pb2+ ions by watermelon rind

Abstract

The present study reports the feasibility of removing Pb²⁺ ions from aqueous solution using watermelon rind (WR) as a low cost adsorbent. Fixed bed column studies were employed to study the removal efficiency of Pb²⁺ ions by varying the column parameters such as flow rate, bed height and initial metal ion concentration. The results showed that breakthrough and exhaustion time increases with a decrease in flow rate, inlet concentration, and an increasing bed height. The breakthrough curves obtained were analyzed with Adams–Bohart, Thomas and Yoon–Nelson models. On comparison of the R² values, both the Thomas and Yoon–Nelson models were found to have a better fit than the Adams–Bohart model and these two models can be used to predict the adsorption of Pb²⁺ ions in a fixed bed column. Desorption of Pb²⁺ ions on WR was repeated for three cycles in 0.1 M HCl solution. The loading capacity of WR was compared with other adsorbents and was found to be high. These results show that watermelon rind, a non-hazardous agro waste, can be successfully employed for the elimination of Pb²⁺ ions from aqueous solution.