Adsorption coupling photocatalytic removal of gaseous n-hexane by phosphorus-doped g-C₃N₄/TiO₂/Zn(OAc)₂-ACF...

VOCs emission reduction in the petroleum and petrochemical industry is a hot and difficult topic at present. The single method may not be able to meet the actual treatment status. Therefore, the adsorption coupled photocatalytic degradation technology was used to remove VOCs. Phosphorus-doped carbon nitride (PCN) and PCN/TiO₂ were prepared by hydrothermal synthesis and sol-gel method, and then PCN/TiO₂/Zn(OAc)₂-ACF composites were prepared by ultrasonic impregnation on zinc acetate modified activated carbon fibers (Zn(OAc)₂-ACF). The removal efficiency of n-hexane by composite materials was explored in a self-made reactor, and the factors affecting removal efficiency, removal mechanism, and possible ways of degradation were investigated. The results showed that under the optimum reaction conditions (initial concentration of n-hexane 200 mg/m³, space velocity 1000 h^-1, light intensity 24 W, mass fraction of doped PCN 6%, loading twice, calcination temperature 450 °C), PCN/TiO₂/Zn(OAc)₂-ACF composite has the highest removal efficiency of n-hexane (90.2%). The adsorption capacity of the composites after doping the P element was 215.3 mg/g, which did not enhance the adsorption performance compared with that before doping, but the removal rate of n-hexane was higher. This showed that doping P element was helpful to enhance the photocatalytic activity of the composites.