Study on the difference in adsorption performance of graphene oxide and carboxylated graphene oxide for Cu(II), Pb(II) respectively and mechanism analysis

Abstract

Graphene oxide has been widely studied as a new type of adsorbent due to its strong affinity for heavy metal ions. However, limited by the number of oxygen-containing functional groups on its surface, there are still some defects in the field of heavy metal ion adsorption. In this paper, graphene oxide (GO) was prepared by modified Hummers method, and carboxylated graphene oxide (GO-COOH) was further synthesized by the derivatization reaction of bromoacetic acid with hydroxyl group under strong alkali conditions. The physical and chemical properties of the material were characterized by XRD, SEM, TEM, XPS and FT-IR. Taking copper and lead ion solutions as pollution models, the adsorption behaviors of the two heavy metal ions solutions on GO were investigated through batch adsorption experiments, adsorption kinetic model, adsorption isotherm model and Van't Hoff equation. The experimental results showed that the maximum adsorption capacity of GO for Cu(II) after carboxyl group treatment increased from 55.47 mg/g to 62.02 mg/g, and the maximum adsorption capacity of GO-COOH for Pb(II) increased from 85.17 mg/g to 96.21 mg/g. In this paper, the reasons for the difference in the adsorption capacity of GO for Cu(II) and Pb(II) and the significant enhancement of the adsorption performance of GO-COOH were discussed, and the possible adsorption mechanism was proposed. The research in this paper provides a new way to realize the efficient utilization of graphene oxide materials in the purification process of water environment and the development of modern materials science.