酸碱指示剂在氨氮在线测量中的应用研究

Research and application of acid-base indicator in online measurement of ammonia nitrogen

常用的在线测量氨氮的方法有纳氏试剂比色法[1]、水杨酸分光光度法[2]。纳氏试剂本身具有毒性,配置与使用中都要小心,并且容易造成水的二次污染;水杨酸分光光度法试剂配置过程比较复杂,其中次氯酸钠在使用前需要标定其有效氯浓度和游离碱浓度,并且在常温下难以保存,因此这两种方法在应用过程中给用户带来许多麻烦。本文对酸碱指示剂在氨氮在线测量中的应用进行了研究。在酸碱指示剂中,加入定量的酸碱缓冲溶液,能够拓宽氨氮的测量范围,并提高测量结果的精度和分辨率。

Commonly used online methods for measuring ammonia nitrogen include Nessler＇s reagent colorimetric method and salicylic acid spectrophotometry method. It has to be careful when Nessler＇s reagent is used due to its toxicity, and it is likely to cause secondary pollution of water. Reagent preparation process is relatively complex for salicylic acid spectrophotometry as available chlorine concentration and free alkali concentration should be calibrated before the use of sodium hypochlorite, which is difficult to be stored at room temperature. Therefore, both of the methods above bring much trouble to users. Acid-base indicators were studied on ammonia nitrogen online measurement in this paper. The measurement range of ammonia nitrogen can he widened and the precision and resolution capacity of measurement results can be improved when quantitative buffer solution is added into the acid-base indicators.