COD对硝酸盐氮分析结果的影响

The Influence of COD on the Analysis Results of Nitrate Nitrogen

[目的]研究不同COD浓度下硝酸盐氮吸光度的变化。[方法]利用紫外分光光度法测定标准溶液中的硝酸盐氮,分析7种有机物在不同COD下对硝酸盐氮吸光度的影响。[结果]COD浓度分别为15 000、20 000和15 000 mg/L时,葡萄糖、甲醇和乙醚(带有单键)对硝酸盐氮吸光度无明显影响;COD浓度分别为7 500、16 000和7 500 mg/L时,甲醛、苯和乙酸(带双键)使得硝酸盐氮吸光度分别增加约5倍、1倍和8倍;COD为10 000 mg/L时,丙酮使得硝酸盐氮吸光度减少约14倍。因此,利用紫外分光光度法测定含有机物的硝酸盐氮水样时,虽然该法简便、快速,但有一定的适应范围和局限性。[结论]该研究为采用紫外分光光度法测定硝酸盐氮浓度的可行性分析提供了依据。

[Objective] The aim was to study the changes of absorbance of nitrate nitrogen under different concentrations of COD.[Method] The concentration of nitrate nitrogen in the standard solution was measured by using ultraviolet spectrophotometry,and the effects of seven organic substances with various COD concentrations on the absorbance of nitrate nitrogen were analysed.[Result] When the COD concentration of glucose,methanol and ether reached 15 000,20 000 and 15 000 mg/L respectively,there was no obvious influence on the absorbance of nitrate nitrogen.Meanwhile,while the COD concentration of formaldehyde,benzene and acetic acid reached 75 000,16 000 and 7 500 mg/L respectively,the absorbance of nitrate nitrogen increased by five times,one times and eight times respectively.In addition,when the COD concentration of acetone was up to 10 000 mg/L,the absorbance of nitrate nitrogen decreased by 14 times.Therefore,ultraviolet spectrophotometry,used in the detection of nitrate nitrogen in water sample with organic matter,was simple and rapid,but this method had a certain rang and limitation.[Conclusion] The study could provide references for the discussion on the feasibility of ultraviolet spectrophotometry in the determination of nitrate nitrogen concentration.