Preparation, degradation pathway and mechanism of Ag-TiO2/g-C3N4 photocatalyst for formaldehyde removal
Description
spherical Ag-TiO2/g-C3N4 composite photocatalysts were prepared on activated alumina carriers using thermal condensation synthesis and impregnation methods. The optimal preparation conditions were determined based on the formaldehyde degradation rate, with pH 2, roasting temperature of 525°C, Ag/TiO2 doping ratio of 1:3, 18 wt% Ag-TiO2 doping, and loading temperature of 500°C being preferred. Formaldehyde photocatalytic degradation experiments were conducted using the prepared photocatalysts in a homemade simulated photocatalytic experimental chamber under weak UV irradiation, with a catalyst usage of 4g, initial formaldehyde concentration of 0.8 mg/m3, and reaction time of 30 minutes. The obtained formaldehyde degradation rate was 28.56%. Structural, morphological, optical absorption, and photocatalytic active substance analyses were performed using various characterization methods. It was found that the enhancement in photocatalytic ability resulted from the formation of the tubular g-C3N4 carrier structure, which increased the catalyst loading area, exposing more active sites. Additionally, g-C3N4 promoted the generation of more active radicals, while the incorporation of silver nitrate and TiO2 facilitated photogenerated carrier separation, enhancing visible light absorption by the catalyst. The composite photocatalytic material exhibited only a 0.07% reduction in adsorption rate after three cycles of recycling, indicating its good stability in formaldehyde degradation. In conclusion, the advantages of Ag-TiO2/g-C3N4 photocatalytic degradation of formaldehyde lie in the generation of superoxide radicals and fewer electron-hole complexes.