A novel Fe(III) crosslinked poly (vinyl alcohol) (PVA)/chitin nanofiber composites were prepared for dye adsorption from water. The adsorbents were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis. The effects of Fe(III) content and chitin nanofibers (NFs) incorporation on the dye removal efficiency of adsorbents were investigated. The adsorption influencing parameters such as solution pH, contact time and initial dye concentration were optimized for maximum methyl orange (MO) adsorption. With loading of chitin NFs, the dye removal efficiency of PVA/Fe(III) adsorbents was noticeable increased. In addition, the dye removal efficiency did not show significant decline in alkaline solution in the presence of chitin NFs. Kinetics, isotherms and thermodynamics of dye adsorption process were also thoroughly studied. The adsorption data were better fitted with the pseudo-second-order kinetics and Freundlich isotherm model. PVA-chitin NFs-Fe(III) adsorbent exhibited a high maximum adsorption capacity of 810.4 mg/g for MO adsorption. Furthermore, reuse experiments revealed that the adsorption efficiency remained almost constant during five cycles of adsorption/desorption. At last, the possible mechanism for dye adsorption-desorption was proposed. The obtained results revealed that the developed bionanocomposites could be considered as promising recyclable adsorbents for wastewater treatment.
