The use of titanium dioxide particles embedded in anionic hydrogel composite for photocatalytic degradation of methylene blue

Abstract

AbstractPoly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) (p(AMPS)) anionic hydrogels with 1, 5 and 10 wt% TiO2 particles were prepared by a simultaneous free radical polymerization and crosslinking reaction. The hydrogel composites were tested as photo‐catalysts for the degradation of methylene blue (MB) in water. Since MB dye is positively charged, MB should be readily absorbed by the anionic p(AMPS) hydrogel and then degraded by the entrapped TiO2 nanoparticle photocatalysts within the p(AMPS) matrix. Photocatalytic degradation of MB was promoted using a UV lamp (300 W) to activate TiO2 particles and was monitored by UV–Vis spectrometer. Interestingly, the activation energy of 20.58 kJ.mol−1 was found to be one of the lowest reported in the literature. The reusability and regeneration efficiency studies of the composite catalyst showed that the p(AMPS)‐TiO2 composite catalyst possessed 90% activity even after five repetitive use and maintained above 85% activity even after the second regeneration. Using different organic scavengers such as ascorbic acid, dimethylsulfoxide and methanol, it was determined that the main reactive species in the photodegradation of MB dye are electrons and superoxide ions. p(AMPS)‐TiO2 composite hydrogel has potential to be used as a good photocatalyst in degradation of toxic dyes and some organic pollutants.