Description
The COD online analyzer uses potassium dichromate open reflux colorimetric method to oxidize the sample. Under the control of a microcomputer, the water sample is mixed with potassium dichromate solution and concentrated sulfuric acid, and silver sulfate is added as a catalyst to chelate chloride ions in the mercury sulfate solution. The mixed liquid undergoes a certain period of reflux at 165 ℃, and the reducing substances in the water react with the oxidant. The Cr6+in the oxidant is reduced to Cr3+, and the color of the mixture will change. Convert the increase in Cr3+into voltage change through photoelectric colorimetry. By measuring the changed voltage and calculating the COD value through curve lookup.