Effect of 2-mercaptoethanoic acid treatment of fluted pumpkin waste (<i style="">Telfairia occidentalis </i>Hook. f.) on the sorption of Ni²⁺ ions from aqueous solution

Abstract

Differential sorption behaviour of pure and acid treated pumpkin waste biomass on the sorption of Ni²⁺ion from aqueous solution was assessed by an ensemble of sorption techniques. Biomass was chemically treated by 0.50 <i style="">N</i> and 1.00 <i style="">N</i> 2-mercaptoethanoic acid solutions. Sorption capacity calculations from Langmuir isotherm model reveals the following amounts of Ni²⁺ions bound per gram of biomass: pure, 12.69; 0.5 <i style="">N</i> acid treated, 40.0; and 1.0 <i style="">N</i> acid treated, 42.19 mg/g. The sorption probabilities for Ni²⁺onto pure and differentially acid treated biomass were 0.19, 0.22 and 0.31 respectively. Acid treatment significantly enhanced the adsorption potential, adsorption density and sorption probability of biomass towards the metal ion. The negative values of E_a suggest that sorption process is exothermic. This study demonstrates that fluted pumpkin waste could be utilized as low cost, environment friendly biosorbent for the removal of Ni²⁺ and other trace metals from aqueous solution.