Understanding precipitation in amino acid salt systems at process conditions

Abstract

Rapid screening experiment has been used to acquire first-hand information on the precipitation characteristics of 14 aqueous amino acid salt systems. Absorption tests at 40o C have shown that at high concentrations, amino acid salt systems forms precipitate in the presence of CO2 resulting to 2 or 3 solid-liquid phase formation. Potassium salt of the amino acid salts generally showed better reaction kinetics than their sodium salt counterparts. 5m' KSar and 4.3m' KPro showed significantly higher reaction kinetics while 5m' KSar, 5m' KAla, 4.5m' KSer, 5m' KL-Ala were observed to have an upward shift in absorption rate at some point during absorption resulting to increased loading. Application of the conventional stripping process in the screening test, i.e. heating up the absorption solution to 80o C showed poor desorption characteristics for the precipitating amino acid salt solutions. Qualitative 13C NMR studies was used to identify the chemical species in the phases, 3-phase in 5m' KSar and 2-phase in 4.5m' KSer. The NMR results show that each phase contains HCO3 - /CO3 2- and carbamate fractions at varying degree.