276125 Modeling Permeate Flux in Ultrafiltration of Non-Newtonian Polysaccharide Solutions

Tuesday, October 30, 2012: 9:14 AM
402 (Convention Center )
Michelle C. Almendrala, Philippine Sugar Research Institute Foundation, Makati City, Philippines

Modeling permeate flux in ultrafiltration of non-Newtonian polysaccharide solutions

Michelle C. Almendrala*, 1,  Shang-Tian Yang2, Jonathan L. Salvacion3

1School of Chemical Engineering and Chemistry, Intramuros, Manila, Philippines 1002

2Department of Chemical and Biomolecular Engineering, Columbus, Ohio, USA 43210

3Department of Chemical Engineering, University of the Philippines, Diliman, QC, Philippines*e-mail: michael.almendrala@yahoo.com

Abstract

           

The development of mathematical  models for permeate flux behavior  of non-Newtonian polysaccharide solutions in ultrafiltration has been studied using hollow fiber membrane modules. The gel polarization model was modified to express the permeate flux as function of the operating parameters. The modified gel model integrating the average wall shear stress per unit length of the membrane (gW /L) has been proposed to predict permeate flux. Two empirical equations based on the modified gel polarization model were also developed to express the dependence of the resulting permeate flux on the properties of the solution and operational variables. These correlations were able to predict the permeate flux behavior on the assumptions made for the constant and variable gel layer concentrations. An empirical model was also developed incorporating the factors affecting flux. The developed model is capable of predicting the dependence of the permeate flux on operating conditions and solution properties. It was demonstrated in this model that the effects of temperature, concentration, transmembrane pressure, shear rate and pH on permeate rate are interdependent. For all these models, the resulting permeate fluxes have been shown to be controlled primarily by the wall shear rate or the feed flowrate. Achievement of high fluxes depends therefore, upon operating at flow conditions that maximize the rate of mass transfer from the membrane surface. In laminar flow systems, this is achieved by operating at high fluid velocities across the membrane surface.The predicted results based from the mathematical models were similar and found to be in good agreement with the experimental data.

Keywords: ultrafiltration; permeate flux; gel polarization



Extended Abstract: File Not Uploaded
See more of this Session: Modeling Transport in Membrane Processes
See more of this Group/Topical: Separations Division