Reduced graphene oxide supported Zn/Al double layered hydroxide for adsorptive removal of lead, arsenic and cadmium: Experimental and statistical analysis

Abstract

For environmental sustainability, the effective elimination of heavy metal ions from aqueous solutions is of utmost significance. Use of graphene oxide for removing toxic metal ions like lead, arsenic, and cadmium is regarded as an efficient and practical method. However, its effectiveness is limited by GO aggregation, leading to decreased performance. In this study, a composite material (rGO-Zn/Al LDH) combining reduced graphene oxide and zinc-aluminium double-layered hydroxide was successfully synthesized using a simple co-precipitation technique. The layered structure of rGO-Zn/Al LDH was confirmed by the structural and morphological characterization. This composite was employed for Pb(II), As(V), and Cd(II) remediation from water. A comprehensive evaluation was conducted through a series of batch adsorption studies to thoroughly comprehend the influence of different parameters on the rGO-Zn/Al LDH removal efficiency. To optimize the adsorption process under different variables, the RSM-CCD approach was also employed. The results of isotherm and kinetic studies revealed that the adsorption process adheres to the Langmuir isotherm model and follows second-order kinetics. rGO-Zn/Al LDH maximum adsorption capacity was determined to be 280.11 for Pb(II), 227.27 for As(V) and 178.25 mg/g for Cd(II), respectively. The co-existence of different ions in the solution didn't greatly affect the metal ions removal, demonstrating the potential of rGO-Zn/Al LDH as a promising material for decontamination of Pb(II), As(V), and Cd(II).