Investigation of photocatalytic oxidation for determination of chemical oxygen demand of the ground water

A photocatalytic oxidation method for the detection of the chemical oxygen demand (COD) of the ground water using sol-gel-based nano-TiO₂ film, which was coated onto the quartz tube, was proposed. In this method, the photo-exited conduction band electrons released from illuminated nano-TiO ₂ film could be easily accepted by Ce(IV) to enhance the activity of photocatalytic degradation of organic compounds. Therefore, the COD of a given sample can be assessed by determination of the change of the concentration of Ce(IV). Under the optimum operation conditions, the determination range of COD was 1.0-12 mg·L^-1 and the limit of detection was 0.4 mg·L^-1. This method was also applied to the determination of the COD of ground water samples. The results were in good agreement with those from the conventional (i.e., permanganate) COD methods.