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

Abstract

The present study reports the feasibility of removing Pb 2+ 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 Pb 2+ 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 R 2 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 Pb 2+ ions in a fixed bed column. Desorption of Pb 2+ 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 Pb 2+ ions from aqueous solution.244 | Environ. Sci.: Water Res. Technol., 2015, 1, 244-250 This journal isThe majority of adsorption studies have been carried out in batch modes which are limited to a laboratory process and generally not applicable to most of the long term treatment processes. Continuous column studies are the most valuable and economical treatment processes used in practice for the removal of heavy metal ions from industrial effluents. Activated carbon is a commonly used sorbent for the removal of inorganic and organic pollutants from waste water. In spite of its effectiveness in the removal of pollutants, high activation cost limits its use as an economical adsorbent. Hence, the present study reports the use of a low cost adsorbent such as watermelon rind for the removal of Pb 2+ ions from aqueous solution.

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