The effect of Fe3O4 nanoparticles on the mass transfer of CO2 absorption into aqueous ammonia solutions

Fe3O4 nanoparticle has been developed as an effective mass transfer promotor for CO2 absorption into aqueous ammonia solutions. The overall volumetric mass transfer coefficients (K(G)(CO)(2)A) were determined for various nanoparticle loadings, nanoparticle sizes, ammonia concentrations, inlet CO2 concentrations and gas flow rates in a bubbling reactor. Results showed that K(G)(CO)(2)A increased with the increase of nanoparticle loadings up to a maximum value and then decreased. With 0.3 g/l nanoparticles, the value of K(G)(CO)(2)A for an ammonia concentration of 4 wt % reached 5.6 x 10(-5) mol /(m(3)s Pa), 14.5 % higher than that achieved without nanoparticles. Results also showed that K(G)(CO)(2)A had upward trend with the increasing of ammonia concentration, downward trend with the increasing of CO2 inlet concentration, and first increased and then decreased with the increasing of gas flow rate. The mass transfer enhancement by Fe3O4 nanoparticles was mainly attributable to coalescence inhibition as well as micro-convection induced by the Brownian motion.