Photoelectrocatalytic digestion of total phosphorous utilizing TiO₂ nanotubes fabricated by anodic oxidation

Total phosphorous (TP) is one of the important indicators of water pollution and eutrophication, and the detection of total phosphorus is of important significance. Many digestion methods have been used for the detection of TP. TiO2/UV photocatalytic method, as an effective way to degrade organic substances, has been applied to TP digestion due to the advantages of low power consumption, reagent-free. However, due to the recombination of electron-hole pairs in the digestion process, a higher efficiency of conversion is desired. This paper introduces a photoelectrocatalytic digestion method for TP detection by applying an appropriate potential between the TiO2 working electrode and counter electrode to prevent the recombination of electron-hole pairs. The characterization of TiO2 nanotubes (NTs), which were prepared by anodic oxidation and used as the photocatalyst for TP digestion based on photoelectrocatalysis, was carried out by FESEM and XRD. The digestion rate of TP was evaluated by the concentration of phosphate which was measured by analyzer. The corresponding digestion rate for 1 mg/L (phosphorus meter) sodium polyphosphate solution is 4.1%, 44.7% and 65.4% in the electrocatalytic process, photocatalytic process and photoelectrocatalytic process, respectively. The results show that the photoelectrocatalytic digestion process is more efficient than the other two processes, and it has the potential to be applied to the pretreatment of TP detection.