Dimensionless numbers for solubility and mass transfer rate of CO2 absorption in MEA in presence of additives

Abstract

This study aimed to compare the both solubility and mass transfer rate of CO2 in monoethanolamine (MEA) in the presence of various additives, including Titanium dioxide (TiO2) and Graphene oxide (GO) nanoparticles as well as two surfactants named Tetra-n-butylammonium bromide (TBAB) and Sodium dodecyl sulfate (SDS) using dimensionless numbers. Batch gas absorption experiments were performed at ambient temperature and various concentrations of additives from 0 to 0.1wt.% at an initial pressure of 20bar. By recording changes in the temperature and pressure of the gas in the loading tank, the number of CO2 moles consumed was obtained in terms of time. The mass transfer coefficient and solubility were then calculated by kinetic and thermodynamic analyses. The dimensionless numbers, namely ES and ER, were calculated to analyze the behavior of the system. ES represents the solubility in the presence of an additive to that in the base solvent, whereas ES shows the mass transfer coefficient in the additive-containing solvent to that in the base solvent. The new, useful dimensionless number Et was defined to investigate the mass transfer rate and solubility simultaneously. For the additives used in this study, the highest ES, ER and Et were 1.31(0.0375g of SDS), 1.25(0.075g of TBAB) and 1.57(0.075g of SDS), respectively. The results shows that surfactants have better effect on solubility and mass transfer rate of CO2 in MEA.