Removal of Nitrate in Aqueous Solution by Adsorption using Activated Carbon from Peanut (Arachis hypogaea) Shells Impregnated with Zn2+ from ZnCl2 Solution

Abstract

High levels of nitrate in water have negative impacts on human health and the environment. Among the various technologies used to remove nitrates, adsorption has been extensively studied and has demonstrated enhanced effectiveness, particularly with surface modifications. In this study, nitrate removal from aqueous solution was investigated using activated carbon from peanut shells (ACPS) and ACPS impregnated with Zn2+ (ACPS-Zn) from ZnCl2 solution. The surface morphology of the prepared adsorbents was observed using scanning electron microscopy (SEM) and the elemental analysis was determined by Energy-Dispersive X-ray Spectroscopy (EDX). The effect of increasing contact time and adsorbent dosage on the nitrate removal using ACPS and ACPS-Zn were investigated. The highest nitrate removal efficiency is attained using ACPS-Zn with 2.5 g/100 mL adsorbent dosage at 5 min of contact time. Langmuir and Freundlich adsorption isotherms were used to describe the experimental results. Isotherm studies revealed that ACPS was best fit to Langmuir adsorption isotherm and ACPS-Zn was best fit to Freundlich adsorption isotherm and kinetics studies showed that the adsorption mechanism adheres to the pseudo-second order kinetic model. Results of the study showed that impregnation with Zn2+ enhanced the efficiency of nitrate removal by the adsorbent.