Effect of polyacrylamide on absorption rate of carbon dioxide in aqueous polyacrylamide solution containing monoethanolamine

Abstract

Carbon dioxide was absorbed into aqueous polyacrylamide (PAM) solution containing monoethanolamine (MEA) in a flat-stirred vessel to investigate the effect of the non-Newtonian rheological behavior of PAM on the rate of chemical absorption of CO2, where the reaction between CO2 and MEA was assumed to be a first-order reaction with respect to the molar concentrations of CO2 and MEA, respectively. The Deborah number, which reflects the viscoelastic properties of the non-Newtonian liquid, was obtained from the relationship between the measured shear stress and the primary normal stress difference against the shear rate of the aqueous PAM solution. A unified correlation is proposed for the volumetric liquid-side mass transfer coefficient (kLa) of carbon dioxide in water, as well as aqueous PAA solutions, by introducing the Deborah number. The elastic properties of PAM reduced or accelerated the absorption rate of CO2 relative to that of a Newtonian liquid based on the same values of viscosity according to the PAM concentration.