Modeling of adsorption behavior of the amine-rich GOPEI aerogel for the removal of As(iii) and As(v) from aqueous media

Abstract

In the present study, a PEI cross-linked graphene oxide aerogel (GOPEI) was prepared. The interaction of GO and PEI was investigated by FT-IR and XPS analysis and after that further characterization was conducted using SEM, EDX, XRD, Raman spectroscopy and BET surface area measurement. The prepared GOPEI aerogel was utilized for the treatment of As(V) and As(III) contaminated water. The maximum uptake capacity, 4.80 ± 0.27 mg g⁻¹ for As(V) and 4.26 ± 0.24 mg g⁻¹ for As(III), was obtained at an initial As(V)/As(III) concentration of 3 mg L⁻¹, GOPEI dose 0.6 g L⁻¹, and ambient temperature (30 °C). The adsorption process was found to be pH sensitive where the optimum pH was 4 for As(V) and 7 for As(III) whereas at pH 6 significant uptake capacity was observed for both As(V) and As(III), which is close to the pH of drinking water. Therefore, GOPEI can be used for the adsorption of As(V) as well as As(III) at a common pH and ambient temperature without much changing the pH of drinking water. In order to use the GOPEI aerogel as an adsorbent in a continuous column for the treatment of arsenic contaminated water, the practicability was tested by conducting detailed kinetics, isotherm and thermodynamics studies. The adsorption, which occurs on a monolayer on the heterogeneous surface of the GOPEI aerogel, was found to be thermodynamically feasible and follows pseudo-second-order kinetics.