Characterization of Adsorptive Capacity and Investigation of Mechanism of Cu²⁺, Ni²⁺and Zn²⁺Adsorption on Mango Peel Waste from Constituted Metal Solution and Genuine Electroplating Effluent

Abstract The present study reports the potential of mango peel waste (MPW) as an adsorbent material to remove Cu2+, Ni2+, and Zn2+ from constituted metal solutions and genuine electroplating industry wastewater. Heavy metal ions were noted to be efficiently removed from the constituted solution with the selectivity order of Cu2+ > Ni2+ > Zn2+. The adsorption process was pH-dependent, while the maximum adsorption was observed to occur at pH 5 to 6. Adsorption was fast as the equilibrium was established within 60 min. Maximum adsorption of the heavy metal ions at equilibrium was 46.09, 39.75, and 28.21 mg g for Cu2+, Ni2+, and Zn2+, respectively. Adsorption data of all the three metals fit well the Langmuir adsorption isotherm model with 0.99 regression coefficient. Release of alkali and alkaline earth metal cations (Na+, K+, Ca2+, Mg2+) and protons H+ from MPW, during the uptake of Cu2+, Ni2+, and Zn2+, and EDX analysis of MPW, before and after the metal sorption process, revealed that ion exchange was the main mechanism of sorption. FTIR analysis showed that carboxyl and hydroxyl functional groups were involved in the sorption of Cu2+, Ni2+, and Zn2+. MPW was also shown to be highly effective in removing metal ions from the genuine electroplating industry effluent samples as it removed all the three metal ions to the permissible levels of discharge legislated by environment protection agencies. This study indicates that MPW has the potential to effectively remove metal ions from industrial effluents.