Facile Synthesis of Graphene Oxide for Multicycle Adsorption of Aqueous Pb2+ in the Presence of Divalent Cations and Polyatomic Anions

Abstract

This study reports a low-cost, NaNO3-free synthesis of graphene oxide (GO) at room temperature, for the purpose of Pb2+ adsorption in single, binary, and ternary association. The GO displays single layered sheets of ∼1 nm thickness with specific surface area of 195 m2/g. The removal of Pb2+ shows an equilibrium time of 15 min with maximum adsorption of 178.5 mg/g, which is best fitted to pseudo-second-order kinetic and Langmuir adsorption isotherm model. A reduction in adsorption efficiency of Pb2+ by 9.52% in Pb2+−Ni2+ and 10.88% in Pb2+−Cd2+ was observed with an increase in concentration of Ni2+ and Cd2+ from 10 to 50 mg/L. Similarly, 19.31% drop in overall efficiency of Pb2+ was observed with increase in the initial concentration of ternary solution (Pb2+ ̵ Ni2+ ̵ Cd2+) from 10 to 50 mg/L. The presence of SO42– and NO3– up to 800 mg/L has little effect on Pb2+ adsorption, compared to Ni2+ and Cd2+. The GO shows only 11.8% decrease in Pb2+ adsorption after five consecutive adsorption–desorption cycles. This study signifies the economic potential of GO toward selective removal of Pb2+ from wastewater in the presence of divalent cations and polyatomic anions on the basis of its multicycle performance.