Analysis of membrane pore blocking models applied to the ultrafiltration of PEG

In this work Hermia's models [J. Hermia, Constant pressure blocking filtration laws-application to powerlaw non-newtonian fluids, Trans. Inst. Chem. Eng. 60 (1982) 183-187] were used to investigate the fouling mechanisms involved in the ultrafiltration of polyethylene glycol (PEG). Ultrafiltration experiments were performed at different feed flow rates (1, 2 and 3 m/s) and transmembrane pressures (0.1, 0.2, 0.3, and 0.4 MPa). Feed concentration and temperature were kept constant at 5 g/L and 25 degrees C, respectively. The results showed that the best fit to experimental data corresponded to the cake layer formation model followed by the intermediate blocking model for all the experimental conditions tested. A more detailed analysis of the fouling mechanisms consisted in dividing the filtration curves in different regions that corresponded to the different fouling mechanisms. Complete blocking, intermediate blocking and cake layer formation or a combination of them were found to occur during the ultrafiltration experiments depending on the operating conditions tested. (c) 2008 Elsevier B.V. All rights reserved.