Synthesis of amine group polymerized magnetic graphene oxide nanocomposites for chromium removal using response surface methodology

Chromium exists usually in both trivalent and hexavalent forms in aqueous systems. The two-oxidation states of chromium have different chemical, biological and environmental characteristics. Chromium is used in a variety of industrial applications; hence, large quantities of chromium are discharged into the environment. In this study, a magnetic graphene oxide nanocomposite polymerized with a 5-Aminoisophthalic acid amine group was used to remove chromium metal from aqueous media using the Central Composite Design for Response Surface method to optimize the adsorption process. To identify functional groups of synthesized nanoadsorbents use of the Fourier transform infrared spectroscopy (FTIR), the scanning electron microscopy (SEM) and the thermal gravimetric analysis (TGA). The optimization results based on the response surface model showed that the optimum value of the pH variable was 3.5, the initial concentration of the metal in solution was 55 mg / l, the adsorbent amount was 25 mg and the adsorbent contact time was 37.5 minutes. Also, the results of the adsorption isotherm models showed that the Langmuir model with a value of R2, 0.99 is more suitable with the adsorption process of chromium by the synthesized adsorbent and the maximum adsorption capacity based on the Langmuir model was 90.90 mg/g. Examination of the adsorption thermodynamic process indicates that the adsorption process has been endothermic and the adsorption capacity increases with increasing temperature. Overall, the results obtained in this study illustrate that the magnetic graphene oxide nanocomposite polymerized with amine group is expected to be an effective and economically viable adsorbent for Cr(VI) removal from aqueous system.