Study of CO2 capture by seawater and its reinforcement

Numerous coal-fired power plants, cement plants and steel mills are concentrated in coastal areas of China, and are three major CO2 emitters. Seawater may be a potential resource to capture CO2 in coastal areas. In this study, we used seawater as a CO2 absorbent to capture CO2. An online chromatography apparatus was used to determine CO2 solubility in seawater with different temperatures, pressures and salinities. Then, the thermodynamics and kinetics were studied for the influences of temperature and salinity on CO2 capture in seawater. The experimental results show that increasing temperature and salinity were adverse to CO2 capture by seawater because of an increase in Henry's constant from a thermodynamics aspect. The kinetic results show that high temperature and low salinity can increase the CO2 absorption rate. In order to improve the CO2 absorption ability of seawater and promote CO2 fixation in carbonate precipitation, we added CaO as major components of industrial alkaline substances to enhance the seawater absorption of CO2. CO2 solubility in seawater with 0.4% CaO increased by 79.25%. It shows that the addition of CaO can enhance greatly seawater capture of CO2. The seawater and its reinforcement with CaO is a potential method to capture CO2.