CROSS-FLOW FILTRATION OF GUAR GUM SOLUTIONS - EXPERIMENTAL RESULTS

Experimental results of cross-flow filtration of pseudo-plastic guar g um solutions are presented. We studied the variation in the rheologica l properties of a guar gum solution during a filtration run by recover ing the layer remaining on the tubular membrane wall at the end of the run and by calculating the concentration at the membrane wall using t he film theory model. The steady state fluxes were found to depend mai nly on concentration and cross-flow velocity, while transmembrane pres sure and pore size had very little effect. This is in agreement with t he concentration polarisation mechanism, and the filtration rate seeme d to be controlled by the dynamic membrane formed at the membrane wall . Besides, the flux rise with temperature was lower than expected from the permeate viscosity reduction. Finally, a first approximation of t he boundary layer thickness, mass transfer coefficients and diffusion coefficient is given. (C) 1998 Elsevier Science B.V. All rights reserv ed.