Synthesis and performance characterization of poly(vinyl alcohol)-xanthan gum composite hydrogel

Abstract Poly(vinyl alcohol) (PVA)-xanthan gum (XG) hydrogel, which possesses good reusable absorption properties, has been prepared by the freezing–thawing method. Hydrogels prepared with different ratios compositions are characterized using Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscope (SEM), and examined in terms of their swelling behavior, mechanical, rheological and adsorption properties. The results show that a shift in the major signals of FTIR for OH absorption, and with varied intensities in the FTIR spectra andmore and more wrinkles observed in SEM indicated cross-linked interaction by the polymers. All the features of the PVA-XG hydrogel are closely related to its rheological properties. The presence of XG visibly improves the swelling ratio of PVA-XG and reduces the compression properties of PVA-XG due to the formation of hydrogen bonds between the PVA and XG. PVA-XG-4 had the best adsorption of methylene blue (MB) dye, such enhancement in adsorption can be attributed to strong electrostatic attraction between XG and MB. The adsorption conformed to the second-order kinetic model and the adsorption process conformed to the Langmuir isotherm model. In addition, PVA-XG-4 exhibits a promising cycling absorption performance. The 1st and 5th cycle of dye removal for PVA-XG-4 reached to 92 and 80%, respectively. Provides basis for application in water treatment.