Questions about COD
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Why do alkalis and solvents cause an increase in COD?
What alkalis and solvents are used, and what method is employed to determine COD?
Alkaline solutions do not increase COD; however, if the solvent is an organic one, it will definitely increase COD. Everyone should understand what COD stands for: it is Chemical Oxygen Demand. It is a substance that can be oxidized by potassium dichromate (under strong acidic conditions).
Chemical oxygen demand (COD) is the amount of oxidizing agent consumed when a water sample is treated with a certain strong oxidizer under specific conditions. It is an indicator of the amount of reducing substances in water. Reducing substances in water include various organic compounds, nitrites, sulfides, ferrous salts, etc. But the main component is organic matter. Therefore, Chemical Oxygen Demand (COD) is often used as an indicator to measure the amount of organic matter in water. Therefore, the increase in COD is not related to the alkaline solution; it is likely due to the effect of organic solvents.
Any substance that can be oxidized by potassium dichromate will cause the COD to increase upon addition.
Alkaline solutions do not increase COD; if the solvent is an organic solvent, it will definitely increase COD