Synergetic adsorption-photocatalysis process of titania-silica photocatalysts and their immobilization on PEEK nonwoven filter for VOC removal

Studying the synergistic mechanisms of removing volatile organic compounds (VOCs) in an adsorption-photocatalytic oxidation process, remains a major challenge. This study explores the synergistic effects of SiO2 nanoparticles and anatase TiO2 nanocomposites in removing ethyl acetate, as a VOC test model, under solar irradiation in a photo-reactor. The physiochemical properties of the synthesized TiO2/SiO2 nanocomposites (70/30 and 50/50, molar ratio) and pure TiO2 nanoparticles were systematically characterized. It was found that the TiO2/SiO2 nanocomposite with 30% SiO2 showed the best synergistic adsorption and photocatalytic activity for the elimination of ethyl acetate among the tested samples. The integrated adsorption-photocatalytic mechanisms of TiO2/SiO2 nanocomposites were revealed by inverse gas chromatography (IGC), electron paramagnetic resonance (EPR), photoluminescence (PL) techniques and kinetic analysis. Moreover, a facile ambient-temperature immobilization method was successfully developed to load photocatalysts onto poly-ether ether-ketone (PEEK) nonwoven. In addition, the photo-induced chemiluminescence (PICL) analysis confirmed that the TiO2/SiO2 coating prevented the photodegradation of PEEK substrate under UVA radiation and improved its photostability. These results provided new understanding on designing highly adsorptive photocatalysts which are commercially applicable on filter materials for efficient VOC removal and air purification.