Competitive adsorption of Cu2+ in Cu2+, Co2+ and Ni2+ mixed multi–metal solution onto graphene oxide (GO)–based hybrid membranes

Abstract

Graphene oxide (GO)–based hybrid membranes (GHMs) were synthesized by sol–gel reaction of GO with N-[3-(trimethoxysilyl)propyl] ethylene diamine (KH792). Some methods including XRD, TGA and DSC thermal measurements, surface FE–SEM and EDS images, FTIR, and XPS are applied to characterize their performance properties. Especially, competitive adsorption of Cu2+ onto these GHMs in Cu2+, Co2+ and Ni2+ mixed multi–metal aqueous solution was considered to inspect the selectivity of Cu2+ adsorption in mixed multi–metal system. Typical theoretical equations are modelled to search the adsorption mechanism. Both TGA and DSC curves showed that the thermal stability of these GHMs could exceed 500 °C. XPS spectra confirm the formation of hybrid matrix in GHMs. Competitive adsorption of Cu2+ in mixed multi–metal solution proves that Cu2+ adsorption onto these GHMs had better selectivity. Adsorption mechanism suggests that the adsorption of Cu2+, Co2+ and Ni2+ ions followed Lagergren pseudo 2nd–order kinetic model and diffusion–chemisorption model, respectively. Moreover, Langmuir isotherm model indicates that the adsorption of metals on the surface of GHMs was monolayer process and the Qm values can be arrived at 4.338, 3.339, and 3.160 mg/g for Cu2+, Co2+ and Ni2+, respectively. These results unveil that these GHMs have prospective applications in the separation and recycle of Cu2+ from Cu2+, Co2+ and Ni2+ ternary mixed multi–metal wastewater by stepwise separation technique. As a practical application, the adsorption separation of metals from synthetic laterite leach solution was examined. The outcome demonstrates that Cu2+ can be removed preferentially from the synthetic laterite leach solution by these GHMs, exhibiting potential usages in the removal of metals from industrial wastewater by multistage operation method.