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

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.


Direct measurement of molecular stiffness and damping in confined water layers
We present direct and linear measurements of the normal stiffness and damping of a confined, few molecule thick water layer. The measurements were obtained by use of a small amplitude (0.36 Angstrom), off-resonance atomic force microscopy technique. We measured stiffness and damping oscillations revealing up to seven molecular layers separated by 2.526+/-0.482 Angstrom. Relaxation times could also be calculated and were found to indicate a significant slow-down of the dynamics of the system as the confining...
Enhanced vaterite and aragonite crystallization at controlled ethylene glycol concentrations
Oral, Çağatay Mert; Kapusuz, Derya; Ercan, Batur (Sakarya Üniversitesi, 2019-04-01)
Calcium carbonate (CaCO3) has three distinct anhydrous polymorphs, namely vaterite, aragonite and calcite. Although there is a high demand for aragonite and vaterite polymorphs for biomedical use, their unstable nature makes it challenging to synthesize them compared to calcite, which is the most stable form of CaCO3. Despite the remarkable effort on stabilizing vaterite and aragonite polymorphs in aqueous solutions, phase-pure vaterite and aragonite polymorphs have not been synthesized yet, without referri...
Electrical Characterization of ZnInSe2/Cu0.5Ag0.5InSe2 Thin-Film Heterojunction
Gullu, H. H.; Parlak, Mehmet (Springer Science and Business Media LLC, 2019-05-01)
ZnInSe2/Cu0.5Ag0.5InSe2 diode structures have been fabricated by thermal evaporation of stacked layers on indium tin oxide-coated glass substrates. Temperature-dependent dark current-voltage measurements were carried out to extract the diode parameters and to determine the dominant conduction mechanisms in the forward- and reverse-bias regions. The heterostructure showed three order of magnitude rectifying behavior with a barrier height of 0.72 eV and ideality factor of 2.16 at room temperature. In the high...
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Sludge characteristics of a full-scale vacuum rotation membrane (VRM) bioreactor having plate-type membranes with 0.038 m nominal pore size and 540 m(2) surface area were investigated. The VRM plant is composed of an aeration tank and a filtration chamber. The sludge floc size distribution, as determined microscopically, was mainly between 0 and 100 m in the filter chamber with very little difference in size distribution between summer (20-25 degrees C) and winter (10-15 degrees C) seasons. Small floc size ...
Controlled release of vancomycin from biodegradable microcapsules
Ozalp, Y; Ozdemir, N; Kocagoz, S; Hasırcı, Vasıf Nejat (2001-01-01)
Poly D,L-lactic acid (PLA) and its copolymers with glycolide PLGA 90:10 and 70:30 were polymerized under various conditions to yield polymers in the molecular weight range 12 000-40 000 daltons, as determined by gel permeation chromatography. Vancomycin hydrochloride was the hydrophilic drug of choice for the treatment of methicillin resistant Staphyloccoccal infections. It was microencapsulated in the synthesized polymers using water-oil-water (w/o/w) double emulsion and solvent evaporation. The influence ...
Citation Formats
C. Kocaman, E. Büküşoğlu, and P. Z. Çulfaz Emecen, “Controlling Ultrafiltration Membrane Rejection via Shear-Aligned Deposition of Cellulose Nanocrystals from Aqueous Suspensions,” ACS APPLIED MATERIALS & INTERFACES, vol. 13, no. 30, pp. 36548–36557, 2021, Accessed: 00, 2021. [Online]. Available: