Communication Dans Un Congrès Année : 2022

Ultrasound-assisted crossflow ultrafiltration of cellulose nanocrystal suspensions: multiscale approach by SAXS and MicroPIV.

Résumé

In the field of biorefinery, ultra and microfiltration techniques may be relevant for the valorization of high value-added wood-based products. Regarding cellulose nanocrystals (CNC), the different production methods lead to heterogeneous mixtures in size, containing both CNC and micrometric particles. In this context, membrane separation would solve this problem by isolating the CNC from the larger particles. However, this process is limited by the accumulation of particles on the membrane surface (fouling and concentration polarization phenomena). The strategy chosen in this study is to control clogging and improve mass transfer, by coupling ultrasonic fields with shear and pressure flow fields acting during crossflow ultrafiltration [1]. The objectives of this work are to provide an understanding of the mechanisms involved in the formation of concentration polarization layers with/without ultrasound using a multiscale approach combining, i) small angle X-ray scattering (SAXS) and ii) particle image velocimetry (micro-PIV) measurements during tangential ultrafiltration. SAXS measurements allow the determination of concentration profiles at the nanoscale [2] while micro-PIV gives information on the velocity fields in the vicinity of the membrane surface and during filtration on scales of a few hundred micrometers [3]. A crossflow filtration cell coupled to ultrasound has been developed to apply the ultrasonic waves close to the plane membrane and to obtain an in-situ characterization of the colloidal organization, concentration profiles and velocity fields in the polarization layer. Ultrasound induces a decrease in the thickness of the concentration polarization layer, associated with its reduction of concentration, as well as a modification of the anisotropic organization in the vicinity of the membrane, enhancing the filtration performances. These results reveal an equilibrium between the rheological behavior of the suspension at the membrane surface and various external forces due to pressure, shear flow and local shear stress induced by ultrasonic waves.

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Dates et versions

hal-04904054 , version 1 (21-01-2025)

Identifiants

  • HAL Id : hal-04904054 , version 1

Citer

Mathilde Challamel, Veronica Avalos, Stéphane Baup, Nicolas Hengl, Henda Djeridi, et al.. Ultrasound-assisted crossflow ultrafiltration of cellulose nanocrystal suspensions: multiscale approach by SAXS and MicroPIV.. Euromembrane 2022, Sorrento, 20 - 24 November 2022, Sorrento (Naples, Italie, Nov 2022, Sorrento (Naples), Italy. ⟨hal-04904054⟩
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