Enhancement of CO2 mass transfer using SiO2 nanoparticles in an aqueous a-MDEA solution for CO2 absorption process

This study investigates the effect of adding SiO2 nanoparticles to the amine solution on the mass transfer coefficients with the aim to obtain effective solvent in the CO2 capturing process. An aqueous mixture of the methyl di-ethanol amine (MDEA), activated by blending with Piperazine (PZ) (a-MDEA), was considered as base absorption solvent. The addition of SiO2 nanoparticles with six different concentrations to the base absorption solvent was then studied. The absorption process took place in an agitated batch reactor at 40 ºC. Considering the gas pressure drop in the reactor the CO2 absorption and mass transfer rates were obtained for all types of the solvents and were compared with each other. Results revealed that two regimes of fast and slow were involved in the CO2 absorption process, where the overall mass transfer of the fast regime was more than 100 times that of the slow one. The results indicated that the liquid phase controlled the mass transfer in the CO2 absorption process. Furthermore, the maximum increase in the absorption rate was happenned when the concentration of SiO2 nanoparticles was set at 25 ppm in the solvent. In this regard, the enhancement was at least 85% increase in the overall mass transfer coefficient. The findings of this study can be used to design new nanoparticle-based solvents and reduce the cost of the CO2 capturing process.