Abstract
Ion chromatography (IC) is widely used for the quantification of ammonium ion at the mg/L level. However, it is extremely difficult to analyze samples of very dissimilar concentration ratios of Na+/NH4+, such as seawater. P&T system utilized the characteristics of ammonium ion under alkaline environment can further convert ammonium to ammonia and prevent from the interference of high concentration of salt. In this study, we improve the stability and efficiency of the P&T system. To better understand the kinetic of ammonia in the P&T system, a theoretical model is developed based on the mass balance and two film theory. System parameters, including the height of liquid in the purging bottle, temperature, N2 flow rate, purge time, concentration of sodium hydroxide were discussed. To increase the system stability by reducing the temperature variation, concentrated NaOH solution was used instead of solid particle of NaOH. The system efficiency was enhanced by increasing the height of purge tube.