Adsorption of Cr(III) and Cu(II) on Hydrothermally Synthesized Graphene Oxide–Calcium–Zinc Nanocomposite

Abstract

This work deals with the synthesis and application of graphene oxide–calcium–zinc (GO@CZ) nanocomposite for the adsorption of Cr(III) and Cu(II) from aqueous solutions. The adsorption was studied using various parameters such as initial metal ion concentrations, contact time, effects of pH, and adsorbent dose. The batch experiments were conducted to demonstrate maximum adsorption capacity at pH 7, and it was found to be 285.71 mg g–1, and 270.27 mg g–1 for Cr(III) and Cu(II), respectively. The pseudo-second-order kinetic model was best fitted to kinetic data of adsorption having the regression values (R2) > 0.9989 and > 0.9979 for Cr(III) and Cu(II), respectively. The Langmuir isotherm model was best fitted with the adsorption data having R2 values for Cr(III) and Cu(II) as > 0.9990 and > 0.9971, respectively. The chemisorption primarily through surface complexation of GO sheets on Ca–Zn(OH)2CO3 nanograins as well as adsorption of metal ions onto the GO@CZ nanocomposite was further confirmed using XPS stu...