A Novel Agricultural Waste Adsorbent, Watermelon Shell for the Removal of Copper from Aqueous Solutions

Abstract

The present study deals with the application of Watermelon Shell, an agricultural waste, for the adsorptive removal of Cu(II) from its aqueous solutions. This paper incorporates the effects of time, dose, temperature, concentration, particle size, agitation speed and pH. Analytical techniques have been employed to find pore properties and characteristics of adsorbent materials. Batch kinetic and isotherm studies have also been performed to understand the ability of the adsorbents. The adsorption behavior of the Cu(II) has been studied using Freundlich, Langmuir and Tempkin adsorption isotherm models. The monolayer adsorption capacity determined from the Langmuir adsorption equation has been found as 111.1 mg/g. Kinetic measurements suggest the involvement of pseudo-second-order kinetics in adsorptions and is controlled by a particle diffusion process. Adsorption of Cu(II) on adsorbents was found to increase on decreasing initial concentration, increasing pH up to 8, increasing temperature, increasing agitation speed and decreasing particle size. Overall, the present findings suggest that watermelon outer shell is environmentally friendly, efficient and low-cost biosorbent which is useful for the removal of Cu(II) from aqueous media.