Acid-treated Bentonite as filler in the development of novel composite PVA hydrogels

In this study, novel eco-friendly hydrogel adsorbents were synthesized based on poly(vinyl alcohol) (PVA) and different contents of an acid-treated bentonite (1-5 wt %). The hydrogels were prepared by freezing-thawing, which is a simple and nontoxic method. The materials were morphologically and thermally characterized by means of swelling assays, X-ray diffraction, scanning electron microscopy, dynamic scanning calorimetry, and thermogravimetric analysis in order to evaluate the effect of acid-treated bentonite loading. The composite hydrogels showed very distinct porous structure and thermal features in comparison to neat PVA as a consequence of the addition of the clay. Moreover, the performance of the obtained composite hydrogels was tested toward the adsorption of cationic (methylene blue) and anionic dyes (methyl red and methyl orange) from aqueous media. The presence of acid bentonite seems to be beneficial for improving the removal capacity of PVA-based hydrogels. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47663.