Study on adsorption coupling photodegradation on hierarchical nanostructured g-C 3 N 4 /TiO 2 /activated carbon fiber composites for toluene removal

The hierarchical nanostructured g-C3N4/TiO2/activated carbon fiber (ACF) composites are fabricated by simple ultrasonic assisted sol–gel method to removal toluene gas. The results show g-C3N4/TiO2 is evenly loaded onto the ACF surface in the form of a smooth film. The g-C3N4/TiO2/ACF possess strong photocatalytic activity, and its removal efficiency is twice as high as that of TiO2. Compared with TiO2, photoluminescence fluorescence (PL) intensity of g-C3N4/TiO2/ACF decreases nearly 10 times. Interestingly, the significantly enhanced removal efficiency is due to the synergetic effects of adsorption coupling photodegradation and the formation of Ti–O–C bonds between g-C3N4/TiO2 and ACF. The chemical bonding interaction accelerates the separation efficiency of photogenerated charge carriers. The removal efficiency and adsorption amount can be up to 94% and 140.55 mg/g for toluene concentration of 400 mg/m3 and space velocity of 1000 h−1 with 6% g-C3N4/TiO2/ACF. The space-time-yield of g-C3N4/TiO2/ACF reaches 141.06 g h−1 L−1 much higher than that of ACF (73.29 g h−1 L−1) and g-C3N4/TiO2 (64 g h−1 L−1). The possible photodegradation pathway and mechanisms are proposed. Therefore, the g-C3N4/TiO2/ACFs porous composites possess excellent application potential for elimination volatile organic compounds from atmospheric environment.