Abstract
Organic solvents, 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 solvents 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 and for the different carbon chain length, the extraction efficiency was independent of carbon number from C8 to C5, for example, the extraction efficiency of formate and glycolate, with the extractant in 1-octanol was relatively close to that in 1-pentanol. In the presence of MEA in the aqueous solution, the extraction efficiency decreases related to that without MEA and was independent of carbon number in chain length of solvents. An increase of extraction temperature to 60 °C showed that the extraction efficiencies in all solvents and HSSs are independent of temperature elevation.
