Fast Electrochemical COD (eCOD) Measurement on Polluted Water

Abstract

COD is one of the main parameters for assessment of water quality. There are many procedures to determine COD but most of them are time expensive because a digestion step is included to complete the oxidation of organic matter by chemical reactants. The proposed method uses the same technology as for preparative electrochemical oxidation of pollutants but here with an analytical purpose. A flow-cell with laminar path is designed to circulate the water and it was tested with standard solutions in a continuous amperometric technique. A single analysis takes only 4 minutes and no reactants are consumed, only electrical energy. The range of electrochemical-COD (eCOD) that can be detected goes from 0.1 to 1200 ppm, and a LOD of 0.03 ppm and an RSD% below 0.3 are calculated. Similar results were found by checking for different organic pollutants. These results are compared with those obtained by using the dichromate standard method (COD-Cr) and no significative differences are observed.