国产过硫酸钾不能用于水样总氮测定的原因解析和对策
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摘要
碱性过硫酸钾消解-紫外分光光度法是测定总氮的国家标准方法,然而国产过硫酸钾试剂因纯度不够而无法满足分析要求,但具体原因尚未解明。采用各种参数对国产过硫酸钾试剂进行了详细分析,结果表明过硫酸钾的总氮含量为0.103%~0.236%,是其标注浓度的20.6~47.2倍,表明产品总氮超标严重是其不能用于分析的主要原因。在此基础上,用重结晶法对国产过硫酸钾进行了提纯,第一次重结晶后,总氮去除率高达95.6%~97.0%。随着重结晶次数的增加,国产过硫酸钾的总氮含量进一步降低。将重结晶后的过硫酸钾产品应用于水样总氮的分析表明,经重结晶1次或以上的国产过硫酸钾产品可满足水样总氮分析要求。
The Chinese national standard method for total nitrogen is the alkaline potassium persulfate digestion plus UV spectrophotometry. However,apart from the reason that the purity of domestic potassium persulfate cannot meet the quality standard,specific reason remains unknown. Therefore,the quality of several domestic potassium persulfate products was examined with total nitrogen,ammonia and blank absorbance values. Results showed that the total actual nitrogen contents were 0. 103%-0. 236%,which was 20. 6-47. 2 times of label contents in domestic potassium persulfate product. Our results clearly indicated that the excessive content of total nitrogenin domestic potassium persulfate products was the main reason which led to the failure of total nitrogen measurement. To purify the domestic potassium persulfate,recrystallization was used remove the excessive nitrogen. After once recrystallization,the total nitrogen removals were as high as 95. 6%-97%. With the increase of the recrystallization times,the total nitrogen contents in domestic potassium persulfate were further reduced. With application of recrystallization potassium persulfate for determination of nitrogen in campus lake water sample,it is indicated that recrystallization for one or more times could greatly improve product quality and the purified products were proven to be appropriate for the total nitrogen measurement in real water sample.
The Chinese national standard method for total nitrogen is the alkaline potassium persulfate digestion plus UV spectrophotometry. However,apart from the reason that the purity of domestic potassium persulfate cannot meet the quality standard,specific reason remains unknown. Therefore,the quality of several domestic potassium persulfate products was examined with total nitrogen,ammonia and blank absorbance values. Results showed that the total actual nitrogen contents were 0. 103%-0. 236%,which was 20. 6-47. 2 times of label contents in domestic potassium persulfate product. Our results clearly indicated that the excessive content of total nitrogenin domestic potassium persulfate products was the main reason which led to the failure of total nitrogen measurement. To purify the domestic potassium persulfate,recrystallization was used remove the excessive nitrogen. After once recrystallization,the total nitrogen removals were as high as 95. 6%-97%. With the increase of the recrystallization times,the total nitrogen contents in domestic potassium persulfate were further reduced. With application of recrystallization potassium persulfate for determination of nitrogen in campus lake water sample,it is indicated that recrystallization for one or more times could greatly improve product quality and the purified products were proven to be appropriate for the total nitrogen measurement in real water sample.
引文
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[9]任妍冰,曹雷,杨慧林,等.碱性过硫酸钾紫外光度法测定水中总氮时影响空白值的因素[J].江苏环境科技,2008,21(S1):48-50.
[2]Du R,Cao S,Li B,et al.Performance and microbial community and analysis of a novel DEAMOX based on partial-denitrification and anammox treating ammonia and nitrate wastewaters[J].Water Res,2017,108:46-56.
[3]王毛兰,胡春华,周文斌.碱性过硫酸钾法测定水质总氮的影响因素[J].光谱实验室,2006,23(5):1046-1049.
[4]周英杰,王淑梅,陈少华.影响总氮测定的关键影响因素研究[J].环境工程,2012,30(1):106-110.
[5]杨绒,赵满兴,周建斌.过硫酸钾氧化法测定溶液中全氮含量的影响条件研究[J].西北农林科技大学学报:自然科学版,2005,33(12):107-111.
[6]潘本锋,鲁雪生,李莉娜,等.紫外分光光度法测定总氮空白值过高原因分析[J].环境工程,2010,28(S1):326-328.
[7]郝冬亮.碱性过硫酸钾消解紫外分光光度法测定总氮的影响因素[J].中国给水排水,2014,30(12):148-150.
[8]潘忠成,李敏.HJ 636—2012测定总氮时影响空白值因素分析[J].环境工程,2016,34(1):126-129,167.
[9]任妍冰,曹雷,杨慧林,等.碱性过硫酸钾紫外光度法测定水中总氮时影响空白值的因素[J].江苏环境科技,2008,21(S1):48-50.