摘要：

从物理化学角度讨论采用氨气敏电极的氨氮在线监测仪的监测过程及原理，得出水中离子总量、溶解性物质总量、表面活性剂类物质及pH是干扰氨氮在线监测仪监测精度和稳定性的主要因素；缓冲液中足够高的EDTA二钠盐和NaOH的浓度是此类仪表稳定监测的前提条件。结合氨氮含量低、电导率及碱度高的水源水的监测，采用了氨气敏电极A1000氨氮在线监测仪。为了掩蔽水中大部分离子和溶解性物质，消除碱度影响及提高pH，需调整缓冲液EDTA二钠盐及NaOH的浓度使仪表排出废液的电导率和pH满足电导率≤10μS/cm、pH≥12。在此条件下，不仅可根据样品水的特点自配缓冲液及标液，经济合理，且监测值与人工分光光度法测定值平均偏差小于10%。

关键词: 在线监测, 氨气敏电极, 干扰因素, 缓冲液

Abstract:

From the point of physical chemistry, the procedure and principle of using an ammonia electrode for the ammonia-nitrogen on-line process monitor are systemically discussed. The major interferring factors are the total inos in water, total dissolved substances, surface active agents and pH. The premise conditions are that the concentrations of EDTA-Na₂and NaOH in the buffer solution are high enough. When the source water sample having low NH⁴⁺-N content and high conductivity and basicity is monitored, the ammonia electrode A1000 on-line process monitor is used. In order to shelter most of the ions and dissolved substances of water, lower basicity and raise its pH value, it is necessary to adjust the concentrations of EDTA-Na₂ and NaOH in the buffer solution until the discharge water gets to EC≤1 μS/cm, pH≥12. Under these conditions, the buffer solution and standard solution can be self-made economically according to water samples. In addition, the average deviation between the monitored value and the artificial spectrophotometric monitored value is less than 10%.

Key words: on-line process monitor, ammonia electrode, interferring factors, buffer solution

中图分类号: 

• X703.1