Photocatalytic efficiency of TiO2/poly[acrylamide-co-(acrylic acid)] composite for textile dye degradation

A novel photocatalytically degradable TiO₂/polyacrylamide-co-(acrylic acid)] composite hydrogel (TiO₂/polyAAm-co-AAc]) was synthesized by polymerization in an aqueous solution with N,N’-methylenebisacrylamide as the crosslinker and ammonium persulphate and TEMED as the initiator pair. The combined and separate effects of photodegradation and adsorption processes for dye removal were evaluated using methylene blue (MB) as the model dye for a photodegradation target, and compared with those of the neat polyAAm-co-AAc], and a commercially available TiO₂ photocatalyst (Degussa P-25). Without photodegradation (i.e. in the dark), the TiO₂/polyAAm-co-AAc] composite adsorbed up to 85% of the MB from a 5 mg L⁻¹ MB solution in 15 min compared to only 10% for the pristine TiO₂. The reproducibility in photodegradation of the reused polyAAm-co-AAc] composite was also investigated, where polyAAm-co-AAc] was found to be photocatalytically degraded under UV irradiation. Therefore, the TiO₂/polyAAm-co-AAc] composite hydrogel is a good dye adsorber with self-photodegradability and it also can easily be separated from the reaction by simple filtration. With these properties, the TiO₂/polyAAm-co-AAc] hydrogel can be called a green polymer for use in the photodegradation-adsorption process for the abatement of various pollutants.