Desorption of carbon dioxide from monoethanolamine solution via calcium chloride addition under ultrasound irradiation and evaluation of the characteristics of generated calcium carbonate

Abstract

We report the desorption of carbon dioxide [CO2(g)] from monoethanolamine (MEA) solution via the addition of calcium chloride (CaCl2) into a CO2-Absorbed MEA solution (0.2 M, pH 8.2) under ultrasound treatment (28 kHz, 200 kHz) and stirring (1500 rpm). Ultrasound at 28 kHz had a higher CO2(g) desorption ratio than either ultrasound at 200 kHz or stirring after 1 min [9.2% (28 kHz), 6.2% (stirring), and 5.8% (200 kHz)]. Treatment with ultrasound at 28 kHz resulted in the highest Ca recovery ratio, 89.1%, at 1 min treatment time. The desorption of CO2(g) from the MEA solution using 28 kHz ultrasound started immediately after the initiation of CaCO3 formation. Furthermore, it was found that the average particle size of CaCO3 obtained by ultrasound treatment at 28 kHz and a treatment time of 1 min was 0.91 μm, with a narrow particle size distribution.