Laminar Flow Dissolution and Diffusion in Non-Newtonian Fluid

Abstract

Dissolution rates of benzoic acid from the inner surface of cast benzoic acid tubes to water and aqueous carboxymethyl cellulose (CMC) solution under laminar flow conditions have been studied. The measured dissolution rates have been used to calculate diffusivity. In the range investigated, the diffusivity in the polymer solution has been found to be independent of shear rate and lower than that in water.

The structure‐breaking effect on oxygen diffusion coefficients in electrolyte and polyelectrolyte solutions

“…Nevertheless, these small differences in the normalized steady-state readings do not significantly affect the assessed values of Dl. A similar behavior of solute diffusion in aqueous CMC solutions has been observed by many other researchers (Clough et al, 1962;Luikov et al, 1969;Wasan et al, 1972;Mashelkar and Soylu, 1974;Deo and Vasudeva, 1977;Kumar and Upadhyay, 1980). Only a 1.4% deviation has been found in this case.…”

“…In CMC solutions, however, oxygen diffusion coefficients first increase slightly in the low concentration range, then decrease when the polyelectrolyte solutions become more concentrate. A similar behavior of solute diffusion in aqueous CMC solutions has been observed by many other researchers (Clough et al, 1962;Luikov et al, 1969;Wasan et al, 1972;Mashelkar and Soylu, 1974;Deo and Vasudeva, 1977;Kumar and Upadhyay, 1980). For aqueous xanthan solutions, oxygen diffusion coefficients show a slight decrease when the xanthan concentration is lower than 0.5 wt% and a monotonic increase in more concentrate solutions of up to 2 wt%, which is the highest concentration investigated in this study.…”

Residence time distribution of the liquid in two‐phase cocurrent downflow in packed beds: Air/newtonian and non‐newtonian liquid systems

“…The effects of the liquid-side shear stress and bed permeability reduction are small at low CMC concentrations and low gas flow rates and the influence of the diffusion phenomena in the particles is approximately the same as in the case of the air-water system due to the low decrease of the tracer diffusivity in the polymer solutions (Osmers and Metzner, 1972;Kumar and Upadhyay, 1980). Thls may be due to the fact that for air-CMC the effect of the driving force (two-phase pressure drop) in the balance of the forces is more important than in the case of air-water system.…”

“…The decrease of the molecular diffusivity of the tracer in the CMC solutions with increasing CMC concentration (Osmers and Metzner, 1972;Kumar and Upadhyay, 1980) can explain the decrease of the mass transfer coefficients between the stagnant and dynamic zones. The decrease of the molecular diffusivity of the tracer in the CMC solutions with increasing CMC concentration (Osmers and Metzner, 1972;Kumar and Upadhyay, 1980) can explain the decrease of the mass transfer coefficients between the stagnant and dynamic zones.…”

Hydrodynamics and Mass Transfer in Heterogeneous Systems

“…Since the weight loss of benzoic acid Δm is small, bulk concentration is negligible so equilibrium concentration c* was taken as a driving force Δc. The benzoic acid solubility and diffusivity in water were taken from the literature (Kumar, et al, 1978;Kumar & Upadhyay, 1980 …”