Removal of Pb²⁺ And Zn²⁺ from aqueous solution using eggshell powder as adsorbent: kinetics and equilibrium studies

Abstract

Pollution caused by human activity is a growing concern in today's world. Several contaminants from various companies are emitted into the environment. Heavy metals are non-biodegradable, poisonous, and persistent pollutants that have negative impacts on the ecological niche of all life forms, including humans. Therefore, the objective of this study was to use locally produced chicken eggshell powder to remove metal ions (Pb²⁺ and Zn²⁺) from aqueous solutions using an adsorption technique. The sorption process is influenced by pH, contact time, initial metal ion concentration, and sorbent dose. The pH of 7.0 and contact time of 60 minutes is ideal for the uptake of metal ions. Pseudo-first order and pseudo-second order rate measures were utilized to examine the adsorption kinetics. Langmuir and Freundlich models were employed for the adsorption isotherm study. Equilibrium adsorption data of Pb²⁺ and Zn²⁺ followed the Langmuir and Freundlich isotherms with R² of 0.834 and 0.993 respectively. The kinetics data revealed pseudo-second order rate model to best describe the reaction while Freundlich isotherm model was a better model that best fit for Pb²⁺ and Zn²⁺ adsorption onto eggshells adsorbent. In conclusion, chicken eggshell powder may be employed as alternative, low cost and effective local adsorbent for Pb²⁺ and Zn²⁺ removal from aqueous solution.