Preparation of a core-double shell chitosan-graphene oxide composite and investigation of Pb (II) absorption.

The need for new and impactful materials to address the global problem of water pollution continues to be driving force in chemical research. This report presents the preparation of a core-double shell composite consisting of sand base substrate onto which sequential layers of chitosan and graphene oxide (GO) are deposited. The adsorption characteristics of this material for Pb (II) from aqueous solutions is investigated. Specifically, different initial lead concentrations are allowed to reach equilibrium with the chitosan-graphene oxide composites, after which the remaining abundance of lead in the aqueous phase is analyzed by atomic emission spectrometry. In many cases, the resulting equilibrium lead concentration of the treated water reached below the detection limit of the method used (<15 ppb) in less than three hours. Furthermore, the data from the adsorption experiments are plotted for comparison against two different isotherm models. This study suggests that the interaction between lead and the GO-chitosan composite more closely resembles characteristics anticipated by the Freundlich adsorption isotherm than that expected by Langmuir-like properties.