Fabrication and evaluation of polyacrylic acid/TiO۲ nanocomposite hydrogels for removing methylene blue pigment from aqueous solution

Polyacrylic acid/guar gum/Titanium dioxide (PAA/GG/TiO۲) hydrogels were fabricated according to the central composite design of response surface methodology by Design-Expert software. The results of methylene blue (MB) removal with UV or without radiation and the swelling ratio were analyzed as three experimental design responses. The effects of cross-linking agents, gum, nanoparticles, and pH of the medium on responses are interpreted. The absorption percentages of methylene blue were ۸۸.۲-۹۶.۹% and ۸۹.۶-۹۹.۲% in visible light and ultraviolet radiation, respectively. Although the absorption of hydrogels required inflation, there was no evident relation between absorption and swelling. Nevertheless, increasing the pH boosted swelling and absorption significantly.