Controlling Ultrafiltration Membrane Rejection via Shear-Aligned Deposition of Cellulose Nanocrystals from Aqueous Suspensions

Kocaman C., Büküşoğlu E., Çulfaz Emecen P. Z.

ACS APPLIED MATERIALS & INTERFACES, vol.13, no.30, pp.36548-36557, 2021 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 13 Issue: 30
  • Publication Date: 2021
  • Doi Number: 10.1021/acsami.1c09815
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, EMBASE, INSPEC, MEDLINE
  • Page Numbers: pp.36548-36557
  • Keywords: cellulose nanocrystals, ultrafiltration, tangential flow filtration, shear alignment, limiting flux, LIQUID-CRYSTALLINE, RHEOLOGY, NANOPAPERS, ALIGNMENT, FILMS
  • Middle East Technical University Affiliated: Yes


Cellulose nanocrystals (CNCs) of 180 nm length and 8 nm diameter were deposited on porous supports by tangential flow filtration followed by salt permeation to form ultrafiltration membranes. At a high enough shear rate on the support surface, CNCs aligned in the direction of flow, showing a nematic order. The shear rates for transition to the nematic phase determined from rheology analysis, polarized optical microscopy, and membrane performance were consistent with one another, at ca. 10 s(-1). Permeating an AlCl3 solution through the shear-aligned CNC deposit stabilized the CNC layer by screening repulsive electrostatic interactions, and the stable CNC layer was obtained. On changing the surface shear rate from 10 to 50 s(-1), the order parameter of CNCs increased from 0.17 to 0.7 and the rejection for Blue Dextran (5 kDa) increased from 80.4 to 92.7% and that for beta-lactoglobulin (18 kDa) increased from 89.6 to 95.4%. Hence, a simple and scalable method for controlling rejection properties of ultrafiltration membranes is developed, which uses aqueous CNC suspensions to form the selective layer.