Application of the Response Surface Methodology in the Removal of Cu2+ and Pb2+ from Aqueous Solutions Using Orange Peels

ABSTRACT: Increasing industrialization and urbanization has led to increased wastewater effluents, which affect the environment if not properly treated before discharge into water bodies. Hence, it is important to adopt an efficient technique for treating wastewater before discharge into water bodies. This study investigated the interaction of initial concentration, pH, adsorbent dosage, and particle size with orange peels for the biosorption of Cu2+ and Pb2+ from aqueous solution using the response surface methodology (RSM) with the central composite design (CCD). The regression model ascertained the validity of the second-order polynomial equation for the biosorption of Cu2+ and Pb2+ using orange peels. The coefficient of determination (R2) obtained from the analysis of variance (ANOVA) for Cu2+ and Pb2+ are 0.9852 and 0.9433, respectively. The maximum adsorption uptakes of Cu2+ and Pb2+ were 54.94 mg/g and 65.14 mg/g respectively, which suggests that orange peels have a higher affinity for Pb2+ than for Cu2+. The maximum efficiencies of Cu2+ and Pb2+ under the optimum conditions of the process variables are 88% and 90%, respectively. The agreement between the experimental and predicted values shows that the quadratic model developed can be used to adequately determine the interaction between process parameters in the bio-sorption of Cu2+ and Pb2+ onto orange peels. The study contributes to the search for eco-friendly and sustainable solutions to the treatment of water contaminated with low concentrations of Cu2+ and Pb2+ metal ions.