Cadmium and chromium adsorption from water using Fe3O4@SiO2@ nano-chitosan/graphene oxide composite

Heavy metals are the most toxic pollutants which enter the environment by diffusion through various industries and considered as a serious threat to human health due to the indissolubility and carcinogenic properties [1]. During past years, some techniques have been developed to remove heavy metal ions from water and wastewater such as ion-exchange, reverse osmosis, adsorption, photocatalytic degradation, membrane filtration, etc. The adsorption technique is used as a cost-effective and high-efficiency method. In recent decades, a variety of adsorbents including different polymers such as cellulose, chitosan, and carbonaceous matters like graphene oxide, as well as minerals as metal oxides, have attracted particular attention because of their unique properties [2,3]. In this study, we synthesized Fe3O4@SiO2@ nano-chitosan/graphene oxide composite to remove Cr3+ and Cd2+ ions from contaminated waters. Chemical and morphological features of the prepared adsorbent were analyzed by Fourier transform infrared and Raman spectroscopies, scanning and transmission electron microscopies and X-ray powder diffraction technique. The results showed that the adsorption kinetic and isotherm data well fitted the pseudo-second-order and Freundlich models, respectively for cadmium ions with a maximum adsorption capacity of ca. 314.44 mg/g. Initial investigation was also carried out for the chromium adsorption which confirmed the high efficiency of the removal process for Cr3+ ions; the experiments will be completed. It is believed that the nanocomposite with surface functional groups such as OH, COOH, and NH2 representing superior chemical properties, can be utilized as a promising candidate to remove toxic heavy metal ions especially cadmium and chromium from water.