A new way to apply ultrasound in cross-flow ultrafiltration: Application to colloidal suspensions

• Published in: Ultrasonics sonochemistry 2014-05, Vol.21 (3), p.1018-1025
• Main Authors: Hengl, N., Jin, Y., Pignon, F., Baup, S., Mollard, R., Gondrexon, N., Magnin, A., Michot, L., Paineau, E.
• Format: Article
• Language: English
• Subjects: Acoustics; Chemical and Process Engineering; Chemical Sciences; Chemistry; Colloidal state and disperse state; Concentration polarization; Engineering Sciences; Exact sciences and technology; Fouling; General and physical chemistry; Mechanics; Membranes; Membranes, Artificial; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Physics; Polymers - chemistry; Process enhancement; Reactive fluid environment; Silicates - chemistry; Sulfones - chemistry; Suspensions - chemistry; Ultrafiltration; Ultrafiltration - methods; Ultrasonic chemistry; Ultrasonics - methods; Ultrasound
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2013.11.008

A new coupling of ultrasound device with membrane process has been developed in order to enhance cross-flow ultrafiltration of colloidal suspensions usually involved in several industrial applications included bio and agro industries, water and sludge treatment. In order to reduce mass transfer resistances induced by fouling and concentration polarization, which both are main limitations in membrane separation process continuous ultrasound is applied with the help of a vibrating blade (20kHz) located in the feed channel all over the membrane surface (8mm between membrane surface and the blade). Hydrodynamic aspects were also taking into account by the control of the rectangular geometry of the feed channel. Three colloidal suspensions with different kinds of colloidal interaction (attractive, repulsive) were chosen to evaluate the effect of their physico-chemical properties on the filtration. For a 90W power (20.5Wcm−2) and a continuous flow rate, permeation fluxes are increased for each studied colloidal suspension, without damaging the membrane. The results show that the flux increase depends on the initial structural properties of filtered dispersion in terms of colloidal interaction and spatial organizations. For instance, a Montmorillonite Wyoming–Na clay suspension was filtered at 1.5×105Pa transmembrane pressure. Its permeation flux is increased by a factor 7.1, from 13.6Lm−2h−1 without ultrasound to 97Lm−2h−1 with ultrasound.