Study on photocatalytic oxidation for determination of the low chemical oxygen demand using a nano-TiO2–Ce(SO4)2 coexisted system

A new photocatalytic system, nano-TiO2–Ce(SO4)2 coexisted system, which can be used to determine the low chemical oxygen demand (COD) is described. Nano-TiO2 powders is used as photocatalyst in this system. The measuring method is based on direct determination of the concentration change of Ce(IV) resulting from photocatalytic oxidation of organic compounds. The mechanism of the photocatalytic oxidation for COD determination was discussed and the optimum experimental conditions were investigated. Under the optimum conditions, a good calibration graph for COD values between 1.0 and 12 mg l−1 was obtained and the LOD value was achieved as low as 0.4 mg l−1. When determining the real samples, the results were in good agreement with those from the conventional methods.