Recent progresses in polymeric hollow fiber membrane preparation, characterization and applications (original) (raw)
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DESALINATION AND WATER TREATMENT, 2017
Preparation and properties of polyetherimide (PEI) hollow fiber membrane are described in a paper. PEI hollow fibers were produced on the spinning machine by phase inversion process. Experiments were designed with the aim to optimize the process parameters for the production of asymmetric polyetherimide hollow fibers. These parameters include polymer solution flow through the nozzle, bore liquid flow, air-gap distance, and the fiber take-up speed. CO 2 /CH 4 gas mixture permeation experiments were performed on produced membranes as well as the morphology studies by optical microscopy and scanning electron microscopy (SEM). The impact of the process parameters on the hollow fiber morphology and mixed gas transport and separation properties was investigated. Results show the critical influence of the bore liquid flow and the take-up speed on the fiber structure. With higher values of these parameters the membranes exhibited higher CO 2 /CH 4 selectivities. Tubular aspects of the fiber were obtained without deformations when high bore liquid flows were used. Smaller fiber diameters were achieved when the fiber take-up speed was higher.
Chemical engineering transactions, 2019
Currently, membrane unit operations are widely applied at industrial level, replacing conventional separation systems. Membrane gas separation represents a successful case, with an increasing number of installed plants in chemical processes, petrochemical plants and refineries for the production of nitrogen from air, the hydrogen separation and recovery and the carbon dioxide separation from natural gas. Owing to the low space footprint and low energy consumption, membrane separation is an environmental friendly technique that meets the Process Intensification requirements.The present study concentrates on the hollow fiber (HF) configuration that is the most used in applications of industrial interest. HF modules, having a high membrane packing density, are compact devices with thousands of square meters of membrane area per unit of volume.The required membranes have an asymmetric structure, in which a thin dense layer performs the separation and a porous substructure provides the n...
A review - The development of hollow fibre membranes for gas separation processes
International Journal of Greenhouse Gas Control, 2021
Gas separation is an important separation process to many industries, and membrane separation using hollow fibre membranes (HFMs) has become one of the emerging technologies. In this article, the gas separation concepts, gas transport mechanism, and the fabrication and gas separation performance of HFMs including asymmetric HFMs, thin film composite hollow fibre membranes (TFC-HFMs), and mixed matrix hollow fibre membranes (MM-HFMs), are reviewed and discussed. Dope composition and spinning parameters directly influence the structure of HFMs and subsequently the gas separation performance of HFMs. The gas separation performance of TFC-HFMs can be improved by the design of the coating solution, surface modification, and the addition of both a gutter layer and a protective layer. Mixed matrix membranes (MMMs) have been intensively investigated in flat sheet membranes and the inspiring gas separation results have been obtained. Therefore, the incorporation of nanoparticles into hollow fibre membranes is a desirable solution to increase the gas permeability and selectivity simultaneously. The functionalization of nanoparticles and fabrication methods of MM-HFMs are also presented.
A Comparison between Several Commercial Polymer Hollow Fiber Membranes for Gas Separation
Journal of Membrane and Separation Technology, 2017
Polyethersulfone (PES), polyetherimide (Ultem ® 1000), and polyimide (Matrimid ® 5218) are common commercial polymers used to produce hollow fiber membranes for different gas separation applications. In this work, asymmetric hollow fiber membranes were prepared using these polymers by a phase inversion technique. The effects of spinning parameters (composition of the dope and bore solution, bore flow rate, air gap distance, temperature of the spinneret and coagulation bath, as well as take-up speed) on the membrane structure and gas permeation properties were investigated. The membrane separation performances were characterized by measuring their gas permeation properties (permeance and selectivity) for different gases (H2, CO2, O2, N2, and CH4) and by their cross-sectional morphology using scanning electron microscopy (SEM). The relationships between the gas separation performance of the hollow fibers and the intrinsic gas properties of the dense flat membranes made of the same materials were also studied. A comparison between the average apparent skin layer thickness calculated from O2 permeability/permeance, and the results based on SEM images was made and good agreement was obtained between both results.
Macromolecular Research, 2015
Poly(vinylidene fluoride) (PVDF) dual-layer hollow fiber membranes with porous layers were successfully prepared by simultaneous spinning of thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS) through a triple orifice spinneret (TOS). The support layer was produced using a TIPS system from PVDF, with γ-butyrolactone (GBL) as the diluent. The prepared membranes were evaluated by analysis of their morphology, water flux, and tensile strength. The NIPS dope solution plays an important role in suppressing the formation of the dense top layer and forms a porous coating layer on the TIPS support layer. In addition, the effect of various non-solvent additives (polyvinylpyrrolidone (PVP), lithium chloride (LiCl), ethylene glycol (EG), and glycerol (Gly)) employed in the TIPS process was investigated. A specific morphology, namely, micro-sized holes in the spherulite structure, was observed on addition of specific mixtures of the non-solvent additives PVP, LiCl, and glycerol. Controlling the amount of added glycerol can help tune the dimensions of the holes. Because of this structure, the water flux of the membrane significantly increased, while a slight decrease in the tensile strength was observed. The specific morphology (hole structure) was very effective in controlling the porosity of the support layer on PVDF dual-layer hollow fiber membranes.
Journal of Membrane Science, 2005
Polymeric membranes have been well established in many separation processes since the introduction of a preparation technique generating asymmetric morphologies by Loeb and Sourirajan. If the separation layer of an asymmetric membrane is highly permeable, the support layer resistance can become significant. A highly asymmetric structure over the entire cross-section of a membrane is a prerequisite for the restriction of this resistance. With regard to hollow fiber membranes, a very open pore structure on the membrane surface opposite to the active layer is required.
Journal of Membrane Science, 2004
Hollow fibers were spun from a polyetherimide (PEI) solution in n-methylpyrrolidone (NMP) and γ-butyrolactone (GBL) by using the dry–wet spinning method at different air-gaps. The ultrafiltration performance of hollow fibers was studied using aqueous solutions of polyethylene glycol of different molecular weights. The pure water permeation flux increased with an increase in the air-gap. Molecular weight cut off (MWCO) also increased with an increase in the air-gap. Significant difference between the inner and outer surface of the hollow fibers was observed by atomic force microscopy (AFM). Alignment of nodule aggregates in the direction of bore fluid (water) was observed at the inner surface. The roughness parameters decreased both at the inner and outer surface with an increase in the air-gap but the changing pattern was quite different. On both surfaces, the size of nodule aggregates decreased with an increase in the air-gap. As the roughness parameter decreases, the pore size increases. A plausible explanation has been made.
Desalination, 2009
Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP) hollow fiber membranes were prepared by the dry/wet spinning technique at different copolymer concentrations from 17 to 24 wt%. All the spinning parameters were kept constant except the copolymer concentration. The temperature of both the internal and external coagulants was maintained at 40ºC. The effects of the copolymer concentration on the morphological properties of the hollow fibers were studied in terms of external and internal diameter and scanning electron microscopy (SEM). It was found that the thickness of all tested hollow fibers did not change significantly. An evolution of the cross-section structure with the increase of the copolymer concentration was detected. The cross-section of the hollow fiber prepared with the lowest copolymer concentration exhibited a finger-like structure in both the external and internal layers disappearing in the internal layer as the copolymer concentration increases. Finally, a sponge-like structure is formed through all cross-section of the hollow fiber prepared with the highest concentration. This may be explained based on the decrease of the coagulation rate with the increase of the copolymer concentration in the dope solution.
Journal of Membrane Science, 2003
Asymmetric blend polyethersulfone-polyimide (PES-PI) hollow fiber membranes prepared at different air gap and used for gas separation are characterized by atomic force microscopy (inside and out side surfaces) and by measuring the contact angle of out side surface. The outer surface was entirely different than the inner surface, as expected. On the inner surface nodule aggregates were aligned in rows, may be towards the direction of the bore fluid flow. On the outer surface, alignment of nodular aggregates in one direction was not observed. The average mean roughness parameter of the inner surface increased with the increase in the air gap used for the preparation of hollow fiber. On the other hand, it was opposite for the outer surface. From the gas separation experiments it was observed that gas permeation rate increased with the increase in air-gap. An attempt was made to find relationships between the surface morphology observed by AFM and permeability and selectivity of the studied hollow fiber membranes.From the contact angle measurement it was observed that the contact angle is directly related to the outside surface roughness. A plausible mechanism has been discussed.
Polymer hollow fiber membranes for gas separation: A comparison between three commercial resins
PROCEEDINGS OF PPS-33 : The 33rd International Conference of the Polymer Processing Society – Conference Papers, 2019
Polymer hollow fibre membranes are becoming more and more used for gas separation. In this work, asymmetric hollow fibre membranes were prepared by a phase inversion technique with three commonly used commercial polymers: polyethersulfone (PES), polyetherimide (Ultem® 1000), and polyimides (Matrimid® 5218). The effect of spinning parameters (composition of the dope and bore solution, bore flow rate, air gap distance, temperature of the spinneret and coagulation bath, as well as take-up speed) on the membrane morphology and gas permeation properties was investigated. The membrane separation performances were characterized in terms of gas transport properties (perméance/selectivity) for different gases (H2, CO2, O2, N2, CH4) to relate this information with their morphology studied by scanning electron microscopy (SEM). Furthermore, dense flat membranes from the same materials were prepared by solvent casting to investigate the relationships between the gas separation performance and membrane configuration (hollow fibers vs. compact flat membrane). Finally, a comparison between the apparent skin layer thickness from O2 permeability/permeance and SEM image gave good agreement.