Facile preparation of methionine-functionalized graphene oxide/chitosan polymer nanocomposite aerogel for the efficient removal of dyes and metal ions from aqueous solutions

Abstract

Heavy metal ions and organic compounds are often discharged together with the industrial and textile wastewaters. These effluents often cause severe toxicological impacts on the human health and environment. In this study, we propose a simple and an efficient approach to obtain methionine-functionalized graphene oxide/ chitosan polymer nanocomposite aerogel (Meth-GO/CH) to be used for the removal of dyes and metal ions from aqueous solutions through batch adsorption. Characterization of Meth-GO/CH nanocomposites was performed to determine the morphology of the prepared material. The elimination of dyes and metal ions from aqueous solutions by the adsorbent material was studied under different influencing factors. The adsorption process followed the Langmuir model for monolayer adsorption. Maximum adsorption capacities were: 46.511 mg/g for Rhodamine B, 243.902 mg/g for Crystal Violet, 66.225 mg/g for Ni(II) and 149.253 mg/g for Cu(II), respectively, at room temperature. The kinetic results revealed good fitting for the pseudo-second-order kinetic model, which showed the highest linear regression coefficient and lowest values for error functions. These results suggest that the chemical adsorption is the rate determining step, which involves sharing of electrons between the adsorbent and the adsorbate. Moreover, the thermodynamic parameters revealed the feasibility, spontaneity, and the endothermic nature of the adsorption process. The as-prepared Meth-GO/CH could be successfully reused up to five cycles of consecutive adsorption–desorption experiments, where 80 % of the original adsorption value was still achieved in the 5th cycle. Overall, the short-time adsorption process, high adsorption capacity and good regenerability of the safe, biodegradable and cost-effective Meth-GO/CH aerogel material makes it as an advantageous reusable promising tool for wastewater treatment.