Solute-Membrane Fouling Interactions During the Ultrafiltration of Black Tea Liquor

This paper reports experimental results concerning the ultrafiltration of hot tea extract reconstituted from tea powder. The filters studied [fluoropolymer (FP) and regenerated cellulose (RC)] were effective at reducing the degree of haze from the tea solutions tested.Results are presented indicating that fluoropolymer, the more hydrophobic of the two materials examined, became fouled with hydrophilic tea species which were not totally removed during cleaning. These deposits became modified on the membrane, producing a more hydrophilic surface than the original membrane. This observation demonstrates an advantage in using moderately hydrophobic membranes for tea filtration, providing the potential for increased permeate flux following multiple fouling and cleaning cycles.