Enhancement of Cr(VI) removal efficiency via adsorption/photocatalysis synergy using electrospun chitosan/g-C3N4/TiO2 nanofibers.

Chitosan/g-C3N4/TiO2 (CS/CNT) nanofibers were fabricated by electrospinning technique for Cr(VI) removal through the adsorption and photocatalytic processes. The effects of crucial factors in the adsorption process including contact time (0-1440 min), pH (1-7), initial concentration of Cr(VI) (20-800 mg/L) were investigated. The photocatalytic experiment was executed in a photochemical reactor with an 800 W xenon lamp to simulate visible light. In adsorption process, at pH = 2, the adsorption capacities of chitosan (CS) nanofibers, CS/CNT10:1 (CS : g-C3N4/TiO2 = 10:1) nanofibers and CS/CNT5:1 nanofibers were 20.8, 165.3 and 68.9 mg/g, respectively, suggesting the addition of g-C3N4/TiO2 (CNT) could notably enhance the acid resistance of CS and widen its practical application. Under visible-light irradiation, the removal efficiency of Cr(VI) using CS/CNT nanofibers was appreciably improved, which was about 50 % higher than that of pure adsorption, indicating that the CS/CNT nanofibers exhibited the effective synergistic effect of adsorption and photocatalysis.