Potential of Activated Groundnut Shells as a Natural Adsorbent for Removal of Lead (II) Ions Metals from Aqueous Solution

Abstract

Lead (Pb) present in water at high levels causes a serious problem in many places all over the world. Activated carbon (AC) is employed as a low- cost alternative adsorbent in wastewater treatment for removal of heavy metals, acid dyes and even odour.  The objective of this study was to assess the potential of activated groundnut shell as an adsorbent for removal of Lead from aqueous Lead (II) Chloride solutions using batch experiments. The groundnut shells were impregnated with activating reagents and subsequently heated to obtain activated groundnut shells. From the results the adsorption of Lead was optimal at contact time of 65 minutes, pH of 5, an adsorbent dose of 0.6 g, initial metal ion concentration of 50 ppm, and temperature of 65ºC with an adsorption removal of 18.425%. Langmuir isotherm is the best adsorption isotherm with R2= 0.9601. From FTIR experiment, there was a participation of –OH, and –NH groups in the uptake of metals. The Gibbs free energy value of –13,391.800 J·mol⁻¹ confirms that the adsorption process is spontaneous. Furthermore, analysis of the Dubinin–Radushkevich (D–R) isotherm revealed mean free energy values (E < 8 kJ·mol⁻¹), which are characteristic of physisorption, thereby indicating that the adsorption mechanism proceeds predominantly through physical interactions rather than chemical bonding. This study advances a simple and low-cost alternative adsorbent for removal of lead from waste waters.