The relationship between chloride ion concentration, COD, and potassium dichromate concentration
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Dear fellow sailors, we deal with wastewater from rare earth processing. I have measured the chloride ion concentration in the water at the total discharge outlet, and it is around 12,000 mg/l. The rapid digestion spectrophotometry method (COD automatic detector) was used for this measurement; the COD value ranges from over 30 to almost 60 at times. I would like to ask you all how to determine the concentration of potassium dichromate and how to prepare each reagent. The method is: HJ/T 399-2007.
Adding mercuric sulfate can eliminate the interference of chloride ions
Doesn’t this method require chloride ions to be less than 2000?
This post was last edited by defender on 2015-12-16 09:31: 1/10 cod using the consumption feedback method
For wastewater from rare earth smelting, the actual level of organic pollution may not be very high, but since hydrochloric acid is used as an acidifying agent, the chloride ion content in the wastewater is extremely high. For this type of wastewater, it is recommended to use TOC as the detection method; in the COD detection method, chlorine has a significant impact on the test results.
The last edit to this post was made by qier5421 on 2015-12-28 at 16:10. If chloride ions come from salts and acids, why not try acidifying with sulfuric acid to avoid the interference caused by chloride ions? The concentration of chloride ions you mentioned is too high, and it’s difficult for masking agents to resolve this issue