Copper adsorptive removal from aqueous solution by orange peel residue carbon nanoparticles synthesized by combustion method using response surface methodology

Abstract

In the present study, new and low-cost orange peel residue carbon nanoparticles as an adsorbent for the removal of copper ions was prepared. The orange peel residue carbon nanoparticles were synthesized by combustion technique by urea as fuel, and characteristics were analysed with BET, FESEM, and FTIR tests. FESEM and BET analysis display smaller particle size (100% below 30 nm), regular and narrow particle size distribution and higher specific surface area for combustion synthesized sample. The central composite design (CCD) under response surface methodology (RSM) by Design Expert software was employed to evaluate the effect of solution pH, initial copper concentration, contact time, and the ratio of fuel to adsorbent (F/A) on the removal efficiency of copper ions. Results of analysis of variance (ANOVA) showed that the initial copper concentration and pH were the most significant parameters for Cu2+ removal. The optimization of Cu2+ removal was carried out by four parameters (pH, the initial concentration of the Cu2+ solution, contact time and F/A) that were chosen in five surfaces. The numerical optimization showed that the optimum removal (94%) obtained at pH = 5, initial Cu2+ concentration = 36 ppm, contact time = 75 min, and F/A = 0.96. The experimental isotherm data were analysed using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D–R) isotherms. The Temkin equation was found to be in good accordance with equilibrium data for Cu2+ adsorption onto OPCM. The results indicated that the orange peel nanoparticle is efficient and economical for Cu2+ ions removal from aqueous solution.