Removal of Lead (II) Ions from Wastewater Using Eggplant Peels

Abstract

In this study, three methods have been tested for the production of eggplant peel activated charcoal (EPPAC) from eggplant peel charcoal (EPPC). A new method has also been devised which does not include continuous involvement of inert gas stream from any external source. Activation parameters used for the production of activated charcoal such as activation temperature, activation time have been optimized. Based upon the maximum removal efficiency of 70% for lead (II) from wastewater, EPPAC-2 (prepared by physical mixing of grinded KOH and EPPC) has been considered most efficient as compared to EPPAC-1 (prepared by the physical mixing of KOH lentils and EPPC) and EPPAC-3 (impregnation). The surface area of EPPAC-2 is 739m2/g. Surface characterization of EPPAC-2 involves the determination of physical and chemical properties such as surface structure, pH, surface area, and surface functional groups. Adsorption of lead (II) ions has been confirmed by energy dispersive X-ray spectrometry (EDS) analysis on lead (II) loaded EPPAC-2. Adsorption experiments have also been conducted for the removal of lead (II) ions from wastewater by using EPPAC-2 as adsorbent. Optimum pH, adsorbent dose and equilibrium time are 5.1, 0.32g and 24h respectively. Adsorption kinetics of lead (II) has been best described by pseudo-second-order kinetic model. The adsorption equilibrium data has been fitted by using different models such as Langmuir, Freundlich, Duninin-Radushkevich, Temkin, Toth and Langmuir-Freundlich isotherm models. Langmuir adsorption model suits best for the equilibrium data. Maximum adsorption capacity of 140.84 mg/g has been given by Langmuir isotherm model. This study demonstrates that EPPAC-2 can be used as a low cost adsorbent for the removal of lead (II) ions in water treatment. Keywords: Eggplant peel activated charcoal; Adsorption; Isotherm; Low cost adsorbent; Wastewater treatment; Heavy metals