Photocatalytic digestion of total phosphorus utilising nanotitanium dioxide photocatalyst
Thermal-assisted ultraviolet (UV) and H2O2-assisted UV photocatalytic oxidation methods utilizing nano-TiO2 photocatalyst are presented for the digestion of total phosphorus (TP) in water. The photocatalytic experiments for TP digestion were conducted using a 365 nm wavelength UV light, and TiO2 nanoparticles immobilized on a silicon wafer as the photocatalyst. The effects of H2O2 and temperature on the UV photocatalytic oxidation process are explained. The pseudo-first-order rate constants k of two phosphorus compounds for the UV digestion processes were obtained according to the pseudo-first-order equation. Both H2O2 and heating could improve the efficiency of the UV photocatalytic oxidation method. But by comparison, the enhancement of heating on the UV photocatalysis process is more distinctly than H2O2. In addition, the thermal-assisted UV digestion process will not lead to secondary pollution since no oxidant is needed in this digestion process, which makes it more compatible with electrochemical detection of TP. The thermal-assisted UV digestion method was employed for the digestion of real water samples. Compared with the conventional thermal digestion method for TP detection, this thermal-assisted UV digestion process decreased the digestion temperature from 120°C to 60°C within the same time, which enable the digestion process work at normal pressure.