Experimental Study of Carbon Dioxide Absorption Using Aqueous Potassium Hydroxide Solutions

The chemical absorption technology is widely used in the industry to remove carbon dioxide post-combustion. It is necessary to develop and identify optimal chemical solutions to absorb more and reduce the absorption energy. The aqueous solutions of alkali metal hydroxides are considered by the researchers due to their low energy requirement and their compatibility with the environment in comparison with amine absorbers. In this research, hydroxide solutions, especially potassium hydroxide, have been used to absorb carbon dioxide. In absorption experiments, the effect of stirring and temperature on the absorption of carbon dioxide by aqueous hydroxide potassium in a laboratory-scale reactor has been studied. The results showed that with increasing stirring of the mixer from 50rpm to 150 rpm, the loading, absorption, and mass transfer flux of carbon dioxide increased 33%, 32%, and 36 respectively but the increase in the agitator over this amount would not have an effect on the absorption rate. The temperature increase was carried out in the range of 25-65°C with a 6 bar pressure, a concentration of 1.5 mol/L, and a stirring speed of 150 rpm. It was observed that increasing the temperature to half the absorption process increased the loading, absorption rate, and absorption flux of carbon dioxide, but the equilibrium parameters decreased slightly with increasing temperature. In fact, with temperature increasing from 22°C to 65°C, the equilibrium loading, adsorption rate and absorption flux of carbon dioxide decreased 15%, 2.4%, and 13%, respectively.