Helical hollow fibers via rope coiling: Effect of spinning conditions on geometry and membrane morphology

Helical hollow fiber membranes from poly(ether sulfone) were spun via dry-wet spinning, making use of the liquid rope coiling phenomenon. The polymer solution composition was changed by varying the coagulation value and adding PEG400 as pore former. The bore liquid composition, outer coagulation bath temperature, air gap, polymer dope and bore liquid flowrates were varied to map the conditions where helical fibers form. It was observed that increasing air gap changed fiber geometry from straight to helical. Increasing the outer coagulation bath temperature caused helical geometries to become irregular or straight under identical spinning conditions, possibly due to the higher water vapour absorption in the air gap. Regularly helical fibers could, however, be spun with a coagulation bath at 50 degrees C under a variety of conditions. Comparing fibers spun under the same conditions with different solutions, it was observed that as the solution's viscosity increased, the geometry shifted towards helical. Increasing the bore liquid solvent strength so as to form the skin on the bore side yielded straight fibers due to the fast solidification of the fibers before curling and all helical fibers fabricated had a denser skin on the shell side. During filtrations of yeast suspensions, the helical fibers experienced less fouling with the feed on either the bore or the shell side of the membrane, which shows that using liquid rope coiling to spin helical fibers is a promising, practical method of alleviating fouling in membrane filtrations.


Fouling behavior of microstructured hollow fibers in cross-flow filtrations: Critical flux determination and direct visual observation of particle deposition
Çulfaz Emecen, Pınar Zeynep; Wessling, M.; Lammertink, R.G.H. (Elsevier BV, 2011-04-15)
The fouling behavior of microstructured hollow fiber membranes was investigated in cross-flow filtrations of colloidal silica and yeast. In addition to the as-fabricated microstructured fibers, twisted fibers made by twisting the microstructured fibers around their own axes were tested and compared to round fibers. In silica filtrations, the three different fibers showed similar behavior and increasing Reynolds number increased the critical fluxes significantly. In yeast filtrations, the twisted fiber perfo...
Polycarbonate-polypyrrole mixed matrix gas separation membranes
Hacarlioglu, P; Toppare, Levent Kamil; Yılmaz, Levent (Elsevier BV, 2003-11-01)
The gas separation properties of the polycarbonate-polypyrrole mixed matrix membranes were evaluated based on the introduction of conducting polymer as powder fillers. The electrically conductive fillers are obtained from two main synthesis routes namely electrochemical and chemical methods. The permeation properties of polycarbonate-polypyrrole systems are highly dependent on the synthesis method (electrochemical or chemical) and also the membrane casting conditions (casting solvent type). The introduction...
Pervaporation of organic/water mixtures through B-ZSM-5 zeolite membranes on monolith supports
Bowen, TC; Kalıpçılar, Halil; Falconer, JL; Noble, RD (Elsevier BV, 2003-04-15)
High-quality, boron-substituted ZSM-5 zeolite membranes were prepared on Al2O3-coated SiC multi-channel monolith supports. Monoliths have larger surface to volume ratios than tubular supports and are more practical for large-scale applications. Two types of supports with 66 channels (2 mm x 2 mm, 10.6 cm(2) surface area cm(-3)) and 22 channels (4 mm x 4 mm, 7.2 cm(2) cm(-3)) were used. The membranes effectively removed alcohols and acetone from 5 wt.% organic/water binary feeds by pervaporation over a tempe...
Active carbon/graphene hydrogel nanocomposites as a symmetric device for supercapacitors
ATEŞ, MURAT; Cinar, Damla; Caliskan, Sinan; GEÇGEL, ÜNAL; ÜNER, OSMAN; BAYRAK, YÜKSEL; Candan, Idris (Informa UK Limited, 2016-01-01)
Activated carbons (ACs) are successfully synthesized from Elaeagnus grain by a simple chemical synthesis methodology and demonstrated as novel, suitable supercapacitor electrode materials for graphene hydrogel (GH)/AC nanocomposites. GH/AC nanocomposites are synthesized via hydrothermal process at temperature of 180 degrees C. The low-temperature thermal exfoliation approach is convenient for mass production of graphene hydrogel (GH) at low cost and it can be used as electrode material for energy storage ap...
Thermally stimulated current measurements in undoped Ga3InSe4 single crystals
IŞIK, MEHMET; Hasanlı, Nızamı (Elsevier BV, 2011-06-01)
The trap levels in nominally undoped Ga3InSe4 crystals were investigated in the temperature range of 10-300 K using the thermally stimulated currents technique. The study of trap levels was accomplished by the measurements of current flowing along the c-axis of the crystal. During the experiments we utilized a constant heating rate of 0.8 K/s. Experimental evidence is found for one hole trapping center in the crystal with activation energy of 62 meV. The analysis of the experimental TSC curve gave reasonabl...
Citation Formats
H. Yucel and P. Z. Çulfaz Emecen, “Helical hollow fibers via rope coiling: Effect of spinning conditions on geometry and membrane morphology,” JOURNAL OF MEMBRANE SCIENCE, pp. 54–62, 2018, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/34691.