Photocatalytic Degradation of Anionic Azo Dyes Acid Orange ۷ and Acid Red ۸۸ in Aqueous Solutions Using TiO۲-containing Hydrogel

The photocatalytic degradation of two anionic azo dyes Acid Red۸۸ (AR ۸۸) and Acid Orange ۷ (AO۷) was investigated in aqueous solution using a TiO۲-containing hydrogel and UV light. The pH-sensitive hydrogel poly (styrene-alt-maleic anhydride) (PSMA), was synthesized and crosslinked in the presence of melamine and TiO۲ nanoparticles which results in entrapment of TiO ۲ into the melamine-grafted PSMA (M-g-PSMA) hydrogel. Potential application of this nanocomposite for removal of azo dyes from wastewater was studied and the effective parameters on degradation process including time, initial pH value of the solutions, temperature and amount of added nanocomposite were optimized. The optimized values for effective parameters are as follows: time: ۳۰ min, initial pH of the solutions: ۵.۲۳ for AO۷ and ۵.۳ for AR۸۸, temperature: ۲۴ ºC and amount of added nanocomposite: ۲۵۰ mg. Results showed that in optimum experimental conditions the removal percentages are about %۹۴ for AR۸۸ and %۷۱ for AO۷ indicating good removal performance toward the method whilst pH-sensitivity of the nanocomposite facilitates retrieval of nanocatalyst at the end of the reaction.

Keywords:

Photocatalytic degradation , Hydrogel , TiO۲ , Azo dye , Acid Red ۸۸ , Acid Orange ۷