Anomalous Enhancement of Interphase Transport Rates by Nanoparticles: Effect of Magnetic Iron Oxide on Gas−Liquid Mass Transfer

In this paper, we examine the effect of magnetic iron oxide nanoparticles on gas-liquid mass transfer rates. Carbon dioxide and oxygen are the gases absorbed, into a variety of reactive and nonreactive liquids. Experiments have been carried out in a welted wall column (where the hydrodynamics can be rigorously modeled) and in a capillary tube (with the liquid phase being quiescent). In the case of absorption with reaction, Studies have been conducted in several absorption regimes, representing different levels of transport limitations. The experiments convincingly demonstrate that the liquid phase mass transfer coefficients are significantly enhanced in the presence of nanoparticles in the region of coil cent ration gradients, the extent of enhancement depending oil the Volume fraction of solid particles in the fluid, and oil the particle size scaled with respect to the depth of penetration of the diffusing solute. A modified Sherwood number has been identified, based oil the traditional theories of interphase mass transfer, as the dominant parameter which determines the magnitude of the mass transfer intensification effect tit a given particle holdup, and a correlation has been derived for the enhancement, which explains not only the data obtained in this work, but also data from the literature. The enhancement effect, having been observed in the presence and absence of reaction and flow, points to the fundamental molecular-level transport processes being influenced by the nanoparticles, but the exact mechanisms remain to be established.