Effects of solvent sort, PES and PVP concentration on the properties and morphology of PVDF/PES blend hollow fiber membranes

Abstract

Poly (vinylidene fluoride) (PVDF)/polyethersulfone (PES) hollow-fiber membranes were spun by dry-wet spinning setup. PVDF and PES were employed as base polymers. Four different solvents including dimethyl sulphoxide, dimethyl formamide, 1-methyl-2-pyrrolidone, and dimethyl acetamide (DMAc) were used as the solvents. Polyvinylpyrrolidone (PVP) was used as pore-forming additive. The preparation variables in this work are sort of solvents, content ratio of PVDF/PES, and concentration of PVP. The membranes prepared by phase inversion were characterized by using scanning electron microscopy. Membrane performance was evaluated by shrinkage ratio, pure water flux and retention to bovine serum albumin (BSA). The shrinkage ratio of PVDF/PES blend hollow fiber membrane decreases when DMAc was used as a solvent. The pure water flux of blend membranes reaches the maximum and the retention to BSA reaches the minimum when the casting solution contains 1.5 wt % PES. The pure water flux reaches the maximum when the concentration of PVP is 5 wt %. The retention to BSA decreases and the shrinkage ratio increases with PVP concentration increasing. V C 2010 Wiley Periodicals, Inc. J Appl

Tailoring the molecular weight cut off values of polyacrylonitrile based hollow fibre ultrafiltration membranes with improved fouling resistance by chemical modification

“…7) of PANMA fibres clearly show the presence of an asymmetric structure consisting of thin skin layer on both the outer and inner surfaces and the sublayer containing many longer and regular finger-like macrovoids and porous structure, as reported by several other authors for different types of hollow fibres [2][3][4][5][6][7][8][9][10]. Furthermore, the finger-like macrovoids that were originating from just below the inner and outer surfaces were interdicted in the middle of the fibre.…”

“…Several parameters such as spinning dope composition (concentrations of the polymer and additive, molecular weight and chemical nature of the additive, type of the solvent) and spinning process parameters (air gap, polymer dope extrusion rate, draw ratio, bore fluid flow rate, and gelation bath composition and temperature) exert a great effect on morphology of the fibres and hence on their separation properties [2][3][4][5][6]. Polyvinylpyrrolidone (PVP), which is compatible with many membrane forming polymers, is the most widely used additive in the casting/spinning dope to control the ultrafiltration membrane morphology and thus the membrane separation properties [7][8][9][10][11][12]. Nonsolvent additives like water, ethylene glycol, diethylene glycol, diethylene glycol dimethyl ether, glycerol, ethanol and tetrahydrofuran were also employed in the spinning dope to alter the separation profile of the membranes [13][14][15][16].…”

Parameter Screening of PVDF/PVP Multi-Channel Capillary Membranes

“…A three-level fractional factorial linear screening design with three centre points was generated with the software package MODDE (v12.1, Sartorius Stedim Data Analytics AB, Umea, Sweden [62]). The range of the process variables was derived from literature [50,51,52,53,54,55,56,57,58], delimiting the design space with 4 variables set to quantitative (concentration of PVDF in spinning dope c PVDF 12–18 wt.%, concentration of PVP in spinning dope c PVP 4–6 wt.%, temperature of spinning dope T Dope 20 ∘normalC to 50 ∘normalC, and temperature of coagulation bath T H 2 O 20 ∘normalC to 50 ∘normalC) and 2 factors set to multilevel (MW PVDF 390, 585, 685 kDa and MW PVP 10, 55, 360 kDa). The generated screening design with 21 possible dope solutions is tabulated in Table 1.…”

“…In this study, we aim to produce and characterize seven-channel capillary membranes for MF/UF in a NIPS spinning process from the system PVDF—main polymer with high chemical resistance/PVP—hydrophilic and pore-forming additive [50]/ N , N -dimethylacetamide (DMAc)—solvent. As numerous factors control and influence the spinning process and final membrane characteristics (concentration of PVDF in spinning dope c PVDF [50,51], concentration of PVP in spinning dope c PVP [50,52,53,54], temperature of spinning dope T Dope [55,56], temperature of coagulation bath T H 2 O [55,56], PVDF molecular weight MW PVDF [57,58], and PVP molecular weight MW PVP [50]), we used a fractional factorial design generated via Design of Experiments (DoE) to reduce the number of spinning assays. The chosen screening design allows the study of linear relations, but is not suitable for optimization purposes.…”

Fabrication of hollow fiber membranes using amphiphilic block copolymers as pore-forming additives

“…In general, the hollow fiber membranes need to be highly permeable, highly selective, resistant to chemical, thermal, and mechanical stresses, and less susceptible to fouling. A large number of studies have been carried out to prepare hollow fibers with these desired properties through various means such as exploring various materials (Sun et al 2010, Wu et al 2010, adding additives (Zhao et al 2007, Carlos Mierzwa et al 2012, changing fabrication conditions (Yang et al 2007, Tang et al 2012, and carrying-out post-treatments (Qin et al 2005a, Khulbe et al 2010. Among these, the choice of membrane materials is crucial for actual applications because it determines the chemical and thermal resistance of resultant membranes.…”