Study of synergistic effect among photo-, electro-, and sonoprocesses in photocatalyst degradation of phenol on tungsten-loaded titania nanotubes composite electrode

The degradation of 4-nitrophenol (4-NP) in aqueous solution with different processes was investigated. Tungsten-loaded titania nanotubes (WT-NTs) were used as electrode in photocatalytic (PC), sonophotocatalytic (SPC), photoelectrocatalytic (PEC), and sonophotoelectrocatalytic (SPEC) processes. WT-NTs electrode was fabricated by in situ anodization of titanium in a single-step process using sodium tungstate as the tungsten source. The morphology and structure were characterized by FE-SEM, XRD, and EDX. Experimental results showed that the hybrid processes could efficiently enhance the degradation efficiency of 4-NP and followed pseudo-first-order kinetics. At the optimized experimental conditions, the rate constants of degradation of 4-NP were 0.0594 min −1 for SPEC process, 0.0293 min −1 for PEC process, 0.0211 min −1 for SPC process, and 0.0116 min −1 for PC process. The rate constants indicated that there existed synergistic effect in the ultrasonic, electro-assisted, and photocatalytic processes.