Removal of Hexavalent Chromium in Industrial Wastewater Using Poly[Allylamine‐(N,N‐Dimethylacrylamide)] Grafted onto Magnetic Nanoparticles

Abstract

ABSTRACTThe present study proposes a new method for the use of functionalized magnetite nanoparticles (MNPs) for adsorption of chromium ions in industrial wastewater. Free radical copolymerization of N,N‐dimethylacrylamide and allylamine forms a functional chelating group, which is grafted onto MNPs using (3‐mercaptopropyl)trimethoxysilane as the novel adsorbent. The grafted MNPs were characterized by Fourier transform infrared spectrometer, elemental analysis, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscopy. The optimum pH for sorption of the metal ion was 4. The sorption capacity of the functionalized MNPs was 38.61 mg/g. The chelating sorbent was reused for 11 cycles of sorption–desorption without a significant change in sorption capacity. The functionalized MNPs showed good adsorption of Cr(VI) as evidenced by the dimensionless separation factor of 0.529. The equilibrium sorption data for Cr(VI) onto the polymeric sorbent was analyzed using the Langmuir, Freundlich, and Redlich–Peterson models. The equilibrium adsorption data indicated that the Langmuir and Freundlich constants were 0.01 and 0.486, respectively, at pH 4 and 25°C. In the Redlich–Peterson model, g equaled 0.98, indicating that the Langmuir isotherm is the best model. Removal from the industrial wastewater sample in the presence of other metal ions was successful with an average removal of 82.22% of hexavalent chromium.