无汞分光光度法快速测定含氯废水化学需氧量

建立无汞分光光度法快速测定含氯废水的化学需氧量。氯离子在测定化学需氧量反应中会增大重铬酸钾的消耗量,进而影响测定的准确性。传统的化学需氧量测定需要使用硫酸汞掩蔽氯化物。通过添加过量硫酸银以减少汞的使用,建立化学需氧量的无汞测定法。研究表明添加硫酸银含量1.03%的Ag2SO4-H2SO4试剂可以掩蔽500 mg/L及以下浓度氯离子的干扰。运用传统的测定方法和无汞测定法对理论化学需氧量为100 mg/L的邻苯二甲酸氢钾溶液进行测定,无汞测定法测定值略高于传统方法测定值。在氯离子浓度低于500 mg/L时,无汞方法测定值的准确度优于传统方法。另外,化学需氧量无汞测定法将化学药品的单位样本使用成本从0.61元降至0.47元。无汞分光光度法适用于含氯废水化学需氧量的快速测定。

Rapid determination of chemical oxygen demand in chlorine-containing sewage by mercury-free spectrophotometry

Mercury-free spectrophotometry was established for determining chemical oxygen demand(COD)in chlorine-containing sewage.Chloride ion would increase the consumption of potassium dichromate in the determination of COD,which might affect the accuracy of the determination.Conventional COD measurements required mercury sulfate to mask chloride.A new method of mercury-free spectrophotometry was established by adding excessive silver sulfate and reduced the dosage of mercury.It showed that Ag2SO4 dose in sulfuric acid reagent with the content not less than 1.03%successfully masked Cl-with the mass concentration not more than 500 mg/L.The conventional method and mercury-free method were used to determine the theoretical potassium hydroxide phthalate solution with COD of 100 mg/L,and the result data by the mercury-free determination method was slightly higher than that by the conventional method.However,when the Cl-concentration was lower than 500 mg/L,the average accuracy of the mercury-free method was better than the conventional method.Therefore,it was considered that when mercury concentration did not exceed 500 mg/L,the method for determining COD without mercury was feasible.Hg-free COD test successfully cut off the chemical cost for each sample from 0.61¥to 0.47¥.Mercury-free spectrophotometry is suitable for fast detection of COD in chlorine-containing sewage.