Selective and multicycle removal of Cr(VI) by graphene oxide-EDTA composite: Insight into the removal mechanism and ionic interference in binary and ternary associations

Graphene-based composite has demonstrated great potential in environmental remediation and wastewater treatment. Herein, graphene oxide was modified with ethylenediaminetetraacetic acid aimed to augment heterogeneous functional groups on the composite i.e., EDTA@GO for aqueous Cr(VI) adsorption. The characterization materials revealed that EDTA linked with GO through an amide bond, and N, O, and C are present in EDTA@GO in 3.25, 19.98, and 76.77%, respectively, and the specific surface area of 100.93 m(2)/g. Tts maximum adsorption capacity of EDTA@GO towards C(VI) was 36.59 mg/g, at pH 1.8. The classical isotherm and kinetic models were best correlated with the Freundlich isotherm and pseudo-second-order kinetics, respectively. The electrostatic interaction was the predominant force involved Cr(VI) adsorption onto EDTA@GO, followed by the reduction into Cr(VI) and its complexation. The adsorption of Cr(VI) in binary and ternary association with Pb2+, Cd2+, and Cl-, seemed unaffected. However, the presence of S-2(-) has a profound effect on Cr(VI) adsorption. More interestingly, the presence of Cl- with S-2(-) in the ternary association (Cr(VI) + Cl- + S-2(-)) suppresses the antagonistic behavior of S-2(-) up to a certain extent that leads to enhance Cr(VI) removal. Overall, the thermodynamics and reusability study advocate the potential of EDTA@GO for multiple cycle Cr(VI) removal - pave the way for its application in wastewater treatment. (c) 2020 Elsevier B.V. All rights reserved.