【摘要】 消解酸度、滴定酸度、还原性离子、消解时间等是影响重铬酸钾滴定法测定水中化学需氧量(COD)的重要因素。本文对这些影响因素开展研究，结果表明，消解酸度从50%(v/v)减少至30%,COD的测定值降低了35%～57%。氯离子的氧化产物为氯气，但采取0.025 mol/L的重铬酸盐时不能被完全氧化；铵离子单独存在时对测定COD值无贡献，但与氯离子共存时有贡献；碘离子则无此现象。更多还原

【Abstract】 In this paper, the performance of digestion acidity, titratable acidity, reducing ion and digestion time were investigated on the determination of chemical oxygen demand(COD) in water by potassium dichromate titration. The results show that the value of COD was reduced by 35%～57% as the acidity of digestion dropted from 50%(v/v) to 30%. Chloride can be oxidized to Chlorine gas, but not be completely oxidized by dichromate with the concentration of 0.025 mol/L. The reducing ion ammonium did not contribute to the determination of COD, but contributed with the coexistence of chloride ions. In addition, iodide did not have the phenomenon.更多还原