Removal of acetylsalicylate and methyl-theobromine from aqueous environment using nano-photocatalyst WO3-TiO2 @g-C3N4 composite.

Highly efficient, visible light-driven and a novel ternary hybrid photocatalyst WO3-TiO2-g-C3N4 with robust stabilities and versatile properties has been synthesized through facile hydrothermal method. This study considers the photo-degradation of aspirin (acetylsalicylate) and caffeine (methyl-theobromine) via photocatalysts (WO3, WO3/TiO2, and WO3/TiO2/g-C3N4 (WTCN) composite) under visible-light irradiation. The SEM and TEM images show the formation of WO3 nanoparticles with orthorhombic structure and average particle size of 65 nm. The photocatalyst WTCN composite possesses higher-catalytic activity when compared to that of WO3 and WO3/TiO2 for degradation of aspirin and caffeine. The incorporation of g-C3N4 in WO3/TiO2 composite exhibited significant influence on the photocatalytic performance for both pollutants. Excellent photocatalytic performance of WTCN composite was observed owing to hydroxyl radical (OH) and superoxide radical (O2-) as main active species. The enhanced photocatalytic activity of WTCN composite can be attributed to following three reasons: (1) extended visible-light absorption; (2) extended surface area; (3) efficient charge-separation due to synergistic effects between g- and WO3/TiO2 composite. The removal efficiency of aspirin and caffeine (Methyl theobromine) could be achieved as much as 98% and 97% for acetylsalicylate and methyl-theobromine using WTCN composite material, respectively. This study could provide new insights into the synthesis of novel WO3-based materials for environmental and energy applications.