Photoelectrocatalytic COD determination method using highly ordered TiO 2 nanotube array

Abstract

This work focuses on the experimental studies of a photoelectrocatalytic method for COD determination in a thin-cell reactor based on a highly effective TiO 2 nanotube array electrode. The effect of preparation parameters on the photoelectrocatalytic performance of TiO 2 nanotube array electrodes including the electrolyte, anodic potential, anodic time, solution pH, calcination temperature and time was examined. The TiO 2 nanotube array electrode prepared in preparation parameters at 1% HF electrolyte solution, anodic potential 20 V, anodic time 5 min, calcination temperature 450 °C with highly photoelectrocatalytic performance was chosen as the working electrode. When it is used in a thin-cell photoeletrocatalytic reactor for COD determination, it requires about 1–5 min to complete the oxidation of organics without further titration, much faster than the standard K 2Cr 2O 7 method (2–4 h). It consumes very limited harmless and inexpensive supporting electrolyte, free from secondary pollution. A wide dynamic working range of 0–850 mg/L can be achieved by this method, much wider than any other photoeletrocatalytic methods using TiO 2 nanoparticles or nanofilms in the reported literature. The effects of the water components were studied to propose the TiO 2 nanotube array method. Real sample analyses were also carried out and the COD value of real samples determined by this method agreed well with the standard dichromate method, and it shows good accuracy, stability and reproducibility.