This trend could be due to the high availability of free active sites at the beginning of the adsorption process, whereas after a specific period of time active siteswill be gradually occupiedwhichwill make the process
of adsorption slower [60]. As showninFig. 2(A), it took almost 45min to reach the equilibrium stage for the ACW while it took almost 90 min to reach equilibrium for the ACP. This could be an indication of the higher
availability of adsorption sites on ACW.