Synthesis of graphene oxide-choline chloride in order to remove phosphate ion from aqueous samples: study of mechanism, isotherm and adsorption kinetics

Abstract

In this study, a graphene oxide-choline chloride adsorbent was used as a highly efficient and environmentally friendly material for removing phosphate ions from aqueous samples. Graphene oxide was synthesized using the Hummers method and then modified with choline chloride to create the graphene oxide-choline chloride adsorbent. The synthesized adsorbent was characterized using Fourier transform infrared spectrophotometry (FT-IR), Field Effect Scanning Electron Microscopy (FESEM), and Energy-dispersive X-ray spectroscopy (EDX). It was then applied to remove phosphate ions at different pH levels and stirring times. The results of this study showed that the maximum removal efficiency of phosphate ions was achieved at pH 5, with an adsorbent amount of 0.015 g and a stirring time of 30 minutes. Furthermore, it was observed that the adsorption of phosphate ions on the adsorbent surface followed the Langmuir isotherm (monolayer adsorption), with a maximum adsorption capacity of 217.4 mg/g. The examination of absorption kinetics also revealed that the absorption of phosphate ions followed pseudo-second-order kinetics, and an increase in temperature favored the progress of the reaction.