Investigation of the Efficiency of Peanut Shells as a Biosorbent for the Removal of Ni (II) Ions from the Galvanic Wastewater in Accordance with Circular Economy Principles

Abstract

Water pollution by heavy metal ions poses a significant environmental problem due to their toxicity, persistence, and potential for accumulation in living organisms. Nickel requires particular attention, as it can occur at elevated concentrations in galvanic industry wastewater. Therefore, the aim of this study was to investigate the efficiency of peanut shells as a natural and readily available biosorbent for the removal of Ni(II) ions from galvanic wastewater within the context of circular economy principles. As an agricultural residue, peanut shells represent a potentially economically and environmentally acceptable alternative to conventional adsorbents. The experimental study examined the influence of key process parameters on adsorption efficiency, primarily wastewater pH, initial Ni(II) concentration, and biosorbent mass. Based on the obtained results, optimal process conditions were determined and adsorption efficiency was evaluated. The adsorption equilibrium was analysed using the Freundlich and Langmuir isotherm models. The results demonstrated that peanut shells can serve as low-cost biosorbents for the efficient removal of Ni(II) ions from galvanic wastewater. For both samples, the highest removal efficiency was achieved at pH 6 and an initial Ni(II) concentration of 1000 mg L-1. The Freundlich adsorption isotherm model showed good agreement with the experimental data, with R2>0.9 for Sample 1 and R2>0.8 for Sample 2. The comparable adsorption performance of the two samples indicates that peanut-shell residue previously used can be further valorised as a biosorbent for Ni(II) removal. The multiple use of the same biomass residue contributes to waste reduction and improved resource utilisation, supporting the potential application of peanut shells within a circular economy approach.