Intensification of thorium biosorption onto protonated orange peel using the response surface methodology

Abstract

Abstract In this research work, intensifying the possibility of protonated orange peel to uptake thorium (IV) ions from aqueous solutions in a batch system was investigated and optimized using the response surface methodology. The effect of three independent process variables including thorium initial concentration, pH, and biosorbent dosage was assessed based on the central composite design. The validity of the quadratic model was verified by the coefficient of determination. The optimization results showed that the rate of thorium (IV) uptake under optimal conditions is 183.95 mg/g. The modeling results showed that the experimental data of thorium biosorption kinetics are fitted well by the pseudo-second-order model. According to the results, the biosorption process reached equilibrium after around 4 h of contact. The Langmuir isotherm describes the experimental biosorption equilibrium data well. The maximum absorption capacity of protonated orange peel for thorium adsorption was estimated by the Langmuir isotherm at 236.97 mg/g. Thermodynamic studies show that thorium adsorption on protonated orange peel is thermodynamically feasible, spontaneous, and endothermic.