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US 5,683,914 AGranted
Method for chloride ion removal prior to chemical oxygen demand analysis
AssigneeHach Company
InventorsDonald G. Miller, Scott V. Brayton
Life of this patent
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Abstract
A method of pretreating aqueous chemical oxygen demand (COD) samples to remove the risk of potential chloride ion interference. The method comprises acidifying an aqueous COD test sample, and thereafter passing the acidified sample through a source of pentavalent bismuth (Bi.sup.5+) such as sodium bismuthate.
Claims12
A method of selective chloride ion removal from aqueous COD test samples by oxidation to chlorine, said method comprising:
- reacting an acidified aqueous COD test sample with pentavalent bismuth (Bi.sup.5+) anion at ambient temperature conditions, to oxidize chloride ion (Cl.sup.-) to free chlorine which escapes as a gas, said oxidation to chlorine occurring without also oxidizing organic materials that are present.
The method of claim 11 wherein the acid is sulfuric acid.
A method of pretreating aqueous COD samples to remove the risk of potential interference of chloride ions, said method comprising:
- acidifying an aqueous COD test sample, and thereafter under ambient temperature conditions passing the acidified test sample through a solid form source of pentavalent bismuth (Bi.sup.5+) to selectively oxidize chloride ion to free chlorine without also oxidizing organic materials that are present.
Dependencies are inferred from the claim text.