Experimental study of CO2 absorption in aqueous MEA and MDEA solutions enhanced by nanoparticles

The nanofluids based on MEA and MDEA solutions were prepared using ultrasonic dispersion method without any surfactant addition to study the influence of nanoparticles on the CO2 absorption by MEA and MDEA in the bubbling reactor. The influences of various factors including solid loading of nanoparticles, nanoparticle size, nanoparticle type, total volume flow rate of mixed gas and initial CO2 volume fraction on the CO2 absorption were investigated. Although the reaction rates of MEA-CO2 and MDEA-CO2 were different, the findings about the influence of nanoparticles based on MDEA solution were similar to that based on MEA solution. Most of tested nanoparticles could remarkably improve the gas-liquid mass transfer during the CO2 absorption process. The CO2 absorption enhancement factor increased with the increase of the solid loading of nanoparticles up to a maximum value and then decreased. The CO2 absorption enhancement factor based on the MEA solution for larger nanoparticles was greater than that for smaller nanoparticles. On the other hand, the absorption enhancement effect of nanoparticles based on the MDEA solution depends highly on the type of nanoparticle. It is also found that the enhancement factor based on the MDEA solution increased with the increase of the total volume flow rate of mixed gas or the initial CO2 volume fraction.