Rh₂O₃/Ti electrode preparation using laser anneal and its application to the determination of chemical oxygen demand

The method of preparation of a Rh₂O₃/Ti electrode by using laser calcination and the characterization by x-ray diffractometer were proposed. The electrode, which could develop organic electrocatalytical oxidation, was employed as an amperometric sensor, together with a flow injection analysis, to measure chemical oxygen demand (COD) of waste water in a speedy way. The measuring principle was based on the current responses on the modified electrode which were proportional to the COD value. Under the optimized experimental condition, the linear range was 50-2000 mg l^-1, and the detection limit was 20.0 mg l^-1 (S/N ≤ 3). This method was successfully applied to determine the COD in samples without pretreatment. It was characterized by short analysis time, simplicity, low environmental impact, limited reagent consumption, easy automation and long lifetime of the sensor. Additionally, the COD values obtained by using the proposed method were within 5% of those given by the conventional COD method.