Influence of the properties and characteristics of sugar-beet pulp extract on its fouling and rejection behaviour during membrane filtration

摘要

In the present work, some of the factors that influence the rejection and fouling patterns observed during sugar-beet pulp extract ultrafiltration were examined. This material contained pectins, exhibiting a wide molecular weight distribution and a high tendency for aggregation. A dual pattern in the variation of the observed rej ection coefficient with permeate flux was observed depending on the molecular weight: decreasing with increasing permeate flux for molecular weight fractions higher than 10 kD and the opposite for fractions less than 3 kD. Pectins were mainly responsible for the fouling properties of the pulp extract as ultrafiltration of purified beet-pectin solutions demonstrated. Efforts to alter the aggregation patterns in the extract both by changing the solutions' pH and by adding a reducing agent showed that the interaction between different components of the extract, rather than between pectins only, had a positive effect on the fouling behaviour.