Dialysis experiments with asymmetric cellulose acetate membranes

1988 ◽  
Vol 53 (6) ◽  
pp. 1247-1259
Author(s):  
Hans-Hartmut Schwarz ◽  
Jaromír Lukáš ◽  
Jiří Vacík
Keyword(s):  
Cellulose Acetate ◽  
Cross Section ◽  
Membrane Structure ◽  
Phase Inversion ◽  
Solution Concentration ◽  
Diffusion Permeability ◽  
Asymmetric Structure ◽  
Cellulose Acetate Membranes ◽  
The Asymmetry ◽  
Dialysis Time

Cellulose acetate membranes for ultrafiltration produced by phase inversion have an asymmetric structure in the cross-section. In spite of this assymetry it is possible to characterize such membranes by dialysis. The asymmetry has no influence on the permeability for solute poly(oxyethylene). The membrane structure was varied systematically by annealing. The influence of solution concentration, dialysis time and temperature was also investigated. Statements are made on the annealing influence. A relationship between diffusion permeability and the true rejection is discussed.

scholarly journals Synthesis and Characterization of Novel Integral Asymmetric Monophasic Cellulose–Acetate/Silica/Titania and Cellulose–Acetate/Titania Membranes

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 195 ◽  
Author(s):  
Inês Peixoto ◽  
Mónica Faria ◽  
M. Clara Gonçalves
Keyword(s):  
Cellulose Acetate ◽  
Phase Inversion ◽  
Sol Gel ◽  
Asymmetric Structure ◽  
Hydraulic Permeability ◽  
Icp Oes ◽  
Phase Inversion Technique ◽  
In Series ◽  
Covalently Bound

Two series of novel integral asymmetric monophasic hybrid membranes, cellulose acetate/silica/titania (CA/SiO2/TiO2—series 1) and cellulose acetate/titania (CA/TiO2—series 2), were developed by the coupling of sol-gel technology and a modified version of the phase inversion technique. SEM micrographs confirmed the integral asymmetric structure of all membranes. ATR-FTIR and ICP-OES results showed that, for the membranes in series 1, TiO2 is covalently bound to SiO2, which, in turn, is covalently bound to CA, while for the membranes in series 2, TiO2 is directly and covalently bound to the CA matrix. Permeation experiments revealed that the permeation performance of the membranes in series 1 is unaffected by the introduction of TiO2. In contrast, the introduction of TiO2 in the series 2 membranes increased the hydraulic permeability by a factor of at least 2 when compared to the pristine CA membrane and that incremental additions of TiO2 further increased the Lp.

scholarly journals Synthesis and Characterization of Blended Cellulose Acetate Membranes

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 4
Author(s):  
Abdullah M. Asiri ◽  
Francesco Petrosino ◽  
Valerio Pugliese ◽  
Sher Bahadar Khan ◽  
Khalid Ahmad Alamry ◽  
...  
Keyword(s):  
Contact Angle ◽  
Cellulose Acetate ◽  
Cross Sections ◽  
Mechanical Stability ◽  
Polymer Chains ◽  
Asymmetric Structure ◽  
Cellulose Acetate Membrane ◽  
Average Pore ◽  
Average Pore Radius ◽  
Cellulose Acetate Membranes

The casting and preparation of ultrafiltration ZnO modified cellulose acetate membrane (CA/ZnO) were investigated in this work. CA membranes were fabricated by phase inversion using dimethylformamide (DMF) as a solvent and ZnO as nanostructures materials. Ultrafiltration (UF) performance, mechanical stability, morphology, contact angle, and porosity were evaluated on both CA- and ZnO-modified CA samples. Scanning electron microscopy (SEM) was used to determine the morphology of the membranes, showing different pore sizes either on rough surfaces and cross-sections of the samples, an asymmetric structure and ultra-scale pores with an average pore radius 0.0261 to 0.045 µm. Contact angle measurements showed the highest hydrophobicity values for the samples with no ZnO addition, ranging between 48° and 82.7° on their airside. The permeability values decreased with the increasing CA concentration in the casting solution, as expected; however, ZnO-modified membranes produced lower flux than the pure CA ones. Nevertheless, ZnO modified CA membranes have higher surface pore size, pore density and porosity, and improved surface hydrophilicity compared with pure CA membranes. The results indicated that the incorporated nano-ZnO tends to limit the packing of the polymer chains onto the membrane structure while showing antifouling properties leading to better hydrophilicity and permeation with consistent UF applications.

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