Determination of Henry's law constants of ammonia and primary aliphatic amines by purge-and-trap system

• Main Author: 李昕穎
• Other Authors: 吳劍侯
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/10550804764175108751

碩士 === 國立清華大學 === 生醫工程與環境科學系 === 98 === The Henry’s law constant (KH; M atm-1) plays an important role on the study of the distribution and the fate of chemicals in the environment. In principle ammonium ion (NH4+) becomes gaseous ammonia (NH3(g)) in aqueous solutions at alkaline environment. The Henry’s law constant of ammonia in 1 M sodium hydroxide (NaOH) over a temperature range of 283?{323 K can be precisely determined using a homemade purge-and-trap system with ion chromatography and o-phthaldialdehyde (OPA) derivatization fluorescence as analysis method. The results were also compared with KH previously measured in 0.1 and 10 M NaOH and showed that the values of KH of ammonia decreased with increased ionic strengths of solution as a result of salting-out effect. The corrected experimental KH in deionized water was 50 M atm-1 at 298 K and 19 M atm-1 at 313 K by using Setschenow equation. The relation of KH with temperature was described by the equation: log KH= -6.36+2352.7/T, T= 283?{323K. This system could also be applied to measure KH of C2-C9 primary amines simultaneously by using OPA derivatization HPLC with fluorescence detection.