Flow-Field Flow Fractionation (Fl-FFF) is an idealization of the cross flow membrane filtration process in that, (1) the filtration flux and crossflow velocity are constant from beginning to end of the device, (2) the process is a relatively well-defined laminar-flow hydrodynamic condition, and (3) the solutes are introduced as a pulse-input that spreads due to interactions with each other and the membrane in the dilute-solution limit. We have investigated the potential for relating Fl-FFF measurements to membrane fouling. An advection-dispersion transport model was used to provide ‘ideal’ (defined as spherical, non-interacting solutes) solute residence time distributions (RTDs) for comparison with ‘real’ RTDs obtained experimentally at different cross-field velocities and solution ionic strength. An RTD moment analysis based on a particle diameter probability density function was used to extract “effective” characteristic properties, rather than uniquely defined characteristics, of the standard solute mixture. A semi-empirical unsteady-state, flux decline model was developed that uses solute property parameters. Three modes of flux decline are included: (1) concentration polarization, (2) cake buildup, and (3) adsorption on/in pores, We have used this model to test the hypothesis—that an analysis of a residence time distribution using Fl-FFF can describe ‘effective’ solute properties or indices that can be related to membrane flux decline in crossflow membrane filtration. Constant flux filtration studies included the changes of transport hydrodynamics (solvent flux to solute back diffusion (J/k) ratios), solution ionic strength, and feed water composition for filtration using a regenerated cellulose ultrafiltration membrane. Tests of the modeling hypothesis were compared with experimental results from the filtration measurements using several correction parameters based on the mean and variance of the solute RTDs. The corrections used to modify the boundary layer mass transfer coefficient and the specific resistance of cake or adsorption layers demonstrated that RTD analysis is potentially useful technique to describe colloid properties but requires improvements.
Skip Nav Destination
Article navigation
Research Article|
March 01 2005
Predicting membrane flux decline from complex mixtures using flow-field flow fractionation measurements and semi-empirical theory
J. Pellegrino;
J. Pellegrino
*University of Colorado, Department of Civil, Environmental, and Architectural Engineering, Boulder, CO 80309-0428, USA
Search for other works by this author on:
S. Wright;
S. Wright
**US Army, NORAD-USNORTHCOM Command Surgeon's Office, Colorado Springs, CO, USA
Search for other works by this author on:
J. Ranvill;
***Colorado School of Mines, Dept. of Chemistry and Geochemistry, Golden CO, 80401 USA
E-mail: john.pellegrino@colorado.edu
Search for other works by this author on:
G. Amy
G. Amy
*University of Colorado, Department of Civil, Environmental, and Architectural Engineering, Boulder, CO 80309-0428, USA
Search for other works by this author on:
Water Sci Technol (2005) 51 (6-7): 85–92.
Citation
J. Pellegrino, S. Wright, J. Ranvill, G. Amy; Predicting membrane flux decline from complex mixtures using flow-field flow fractionation measurements and semi-empirical theory. Water Sci Technol 1 March 2005; 51 (6-7): 85–92. doi: https://doi.org/10.2166/wst.2005.0625
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
eBook
Pay-Per-View Access
$38.00