The removal of methylene blue and maxilon blue dyes using a polyvinyl alcohol/poly(acrylic acid-co-acrylamide) composite hydrogel from water

Purpose In this study, polyvinyl alcohol (PVA)/poly[acrylic acid (AAc)-co-acrylamide (AM)] composite hydrogel was prepared by radical copolymerization in the presence of Fe 3+ freezing-thawing method. The swelling behavior of the hydrogel was investigated. The novel synthesized hydrogel was used as an adsorbent for the removal of dyes from aqueous solutions. In this paper, methylene blue and maxilon blue 5G were selected as representative cationic dyes. In addition, adsorption isotherm models were used to describe the dye adsorption process. Design/methodology/approach The prepared composite hydrogel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy and UV–visible. Findings The prepared hydrogel exhibited excellent adsorption ability for both dyes. Various experimental conditions affecting the dye adsorption were explored to achieve maximum removal of both dyes. In addition, adsorption isotherm models were used to describe the dye adsorption process. Originality/value To the best of the author’s knowledge, synthesis of PVA/poly(AAc-co-AM) composite hydrogel in the presence of Fe 3+ and investigation of the removal of methylene blue and maxilon blue 5G dyes is done for the first time successfully.