Low-frequency ultrasound to improve dead-end ultrafiltration performance

Low-frequency ultrasound (20 kHz) has been used to facilitate dead-end ultr afiltration of polymer solutions. The influence of ultrasonic irradiation o n permeate fluxes and retention ratios was investigated and compared with c onventional stirred and unstirred operations. In addition, the effect of th e ultrasonic field on the membrane permeability and on the polymer solution was examined. The efficiency of ultrasound in enhancing ultrafiltration pe rformance was demonstrated. This improvement is due to a decrease of the bo undary layer resistance against permeation flow, which may be attributed to disturbance induced within the cell and at the membrane surface by physica l effects associated with ultrasonic waves propagation.