Chitosan-polyvinylpyrrolidone composite as an efficient adsorbent for eosin Y dye from aqueous solution

In this study, eco-friendly chitosan-polyvinylpyrrolidone composite (CS-PVP) was synthesized from a facile one-pot reaction at room temperature and characterized using Fourier transform Infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and elemental mapping. Characterization results confirmed the successful synthesis of CS-PVP with rough surface morphology, good crystallinity and good thermal stability with the Tpeak of the first decomposition at 330 °C. Therefore, a batch experiment was carried out in order to remove eosin Y (EY) dye from the aqueous solution using CS-PVP. The effect of initial pH solution, sorbent dose and contact time on the removal efficiency of EY were considered. Result predicted that the adsorption capacity increased with the solution pH decreased from 5 to 3. The maximum adsorption capacity was 77.24 mg/g (98%) at pH solution of 3, adsorbent dose of 0.02 g and 180 min contact time. In addition, the adsorption process of EY was well fitted by the pseudo-first order (PFO) kinetic model and the Freundlich isotherm. The adsorption mechanism of EY using CS-PVP composite can be attributed to the different electrostatic attractions, hydrogen bonding and n–π interaction. The desorption studies of EY dye from the surface of PVP-CS showed that it is reusable. The thermodynamic parameters for adsorption of EY using CS-PVP were calculated and results confirmed that the adsorption is endothermic and spontaneous. This process is simple, low-cost and high effective in organic dye remove using the as-prepared CS-PVP composites.