Reduction of nitrate to nitrite with cadmium metal

Abstract

The reduction of nitrate to nitrite by using cadmium coated with copper in a reductor column has been widely used on the determination of nitrate. The effects of the flow rate, pH and types of cadmium on the reduction have been investigated. However, the function of copper coated on cadmium has still not been elucidated. In this study, the reduction of nitrate by using cadmium without copper was investigated. Cadmium without copper reduced nitrate to nitrite the same way as cadmium coated with copper, if copper ion was added to a sample solution above 10 mg/l. It was presumed that the reduction of nitrate was affected by the copper ion in the sample solution, rather than copper coated on the cadmium. The effects of chloride ion and silicate on the reduction were smaller than that of cadmium coated with copper.