Effect of organic diluents on separation of heat stable salts (HSS) generated during carbon dioxide absorption using amine solution

Abstract

Organic diluents, i.e. 2-ethyl-1-hexanol, 1-octanol, 1-heptanol, 1-hexanol, and 1-pentanol, were used in the liquid-liquid extraction of heat stable salts (HSSs) in a monoethanolamine (MEA) solution used in the carbon dioxide absorption process. The HSSs aqueous solution consisted of 1,000 ppm of formate, acetate, oxalate, and glycolate. An equal volume of 1 M of extractant in different diluents to HSSs solution was mixed for complete separation. Analyses of the concentrations of HSSs in aqueous solutions were completed by using high performance liquid chromatography with an ultra violet detector. The extraction of HSSs without MEA solution revealed that, for the same carbon chain length, the extraction efficiency of 2-ethyl-1-hexanol was better than 1-octanol. The extraction efficiency decreased with decreasing of carbon chain length for formate, acetate, and glycolate. In the presence of MEA solution, the HSS extraction efficiency in every diluent at room temperature decreased with a small variation. The extraction of HSSs with MEA was independent of carbon numbers of diluents. The extraction efficiency does not change with increasing in extraction temperature.