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Hemodialysis Membranes for Treatment of Chronic Kidney Disease: State-of-the-Art and Future Prospects
Published in Sundergopal Sridhar, Membrane Technology, 2018
N.L. Gayatri, N. Shiva Prasad, Sundergopal Sridhar
The technology to spin dialysis-grade fibers is a challenging problem. The basic physics of the hollow fiber membrane formation involve the polymer solution coming into contact with the bore fluid, and then undergoing phase inversion to form the hollow core. The inner and outer diameters of the spinneret determine the diameter and thickness of the resultant hollow fiber membranes. The HD grade hollow fiber spinning technology poses a twofold challenge. The first set of issues are the composition of the dope solution and the spinning conditions like viscosity, thermodynamics of the solution, along with operating conditions like temperature, humidity, take-up speed and post-treatment methodologies. The second challenge is the design of the extruder. These two aspects in tandem helped to successfully design the spinning process for dialysis grade hollow fibers.
Current Trends in Membrane Science
Published in Mihir Kumar Purkait, Randeep Singh, Membrane Technology in Separation Science, 2018
Mihir Kumar Purkait, Randeep Singh
The development of an artificial pancreas can be brought to fruition by grouping or integrating pancreatic islets (contains insulin producing β-cells) into a membrane. The idea behind this concept is that the membrane, whether flat or hollow fiber, separates the pancreatic islets from the blood stream with the membrane having permeabilities for glucose and insulin. In addition, the membrane will be completely impermeable to the immunoglobulins and lymphocytes. This concept was first tested in the 1970s–1980s, when a polyacrylonitirle-vinyl chloride copolymer hollow fiber membrane with molecular weight cut off of 80 kDa was used to protect the transplanted pancreatic islets from the blood stream in a dog [9]. Similarly, an acrylic coiled tubular membrane was used to house pancreatic islets having a 50 kDa molecular weight cut-off and 60 cm2 surface area. This membrane was tested both in vitro and in vivo in diabetic dogs. Since then, the artificial pancreas has seen lots of development and many devices have been proposed using flat sheet and hollow fiber membranes. For hollow fiber membranes, the pancreatic islets were either loaded inside the lumen of the membrane or on the outer surface and the blood stream is allowed to pass through the outer or inside the lumen, respectively. The high surface area makes the hollow fiber membrane a more attractive option as compared to flat sheet membranes. Depending upon the place of the pancreatic islets’ integration into the membrane, the artificial pancreas can be of three types:
Membrane Contactor Device Designs – History and Advancements
Published in Anil K. Pabby, S. Ranil Wickramasinghe, Kamalesh K. Sirkar, Ana-Maria Sastre, Hollow Fiber Membrane Contactors, 2020
Membrane contactors can be made from flat sheet membranes, and there are some commercial applications of this type of device. However, most common commercial membrane contactors are made from small-diameter, microporous hollow fiber (or capillary) membranes with fine pores that span the hollow fiber wall from the fiber inside surface to the fiber outside surface. Figure 3.1 illustrates a single hollow fiber microporous membrane separating two phases – a ‘shell side’ and a ‘lumen side’, meaning outside and inside of the hollow fiber, respectively. The hollow fiber membrane is typically made of hydrophobic materials such as polypropylene, polyethylene, PTFE, PFA, PVDF, PMP, etc.
Preparation and characterization of nanoclay loaded polyacrylonitrile hollow fiber membranes
Published in The Journal of The Textile Institute, 2025
Mahdi Nouri, Marjan Abbasi, Tara Aghebati, Mahsa Shirzadkhan
Asymmetric hollow fiber membranes have been widely applied to a separation process owing to possessing many advantageous characteristics compared to flat sheet membranes. Some of the hollow fiber membranes advantages are their semipermeability, high surface area to volume ratio (high membrane packing densities), no requirement of feed and permeate spacers, less demand for pretreatment and maintenance, excellent mass transfer properties, simple configuration of the module compared to spiral modules, ease of handling during module fabrication, modest energy requirement, flexibility and low operation cost. Therefore, the scientists focused their attention on the development of hollow fiber membranes for a wide range of applications such as treatment of the wastewater of textile dyeing processes. In addition, hollow fiber membrane modules are almost involved in all of the polymer membrane separation processes such as reverse osmosis (RO), micro/nano/ultra-filtration (MF, NF, UF), dialysis, gas separation, pervaporation in which, the key technology is development of proper hollow fiber membranes (Ahmad et al., 2019; Lin et al., 2020; Peng et al., 2012; Yu et al., 2012). It is well known that the morphology, separation performance and mechanical properties of the polymeric membranes depend upon various factors such as polymer type and composition, design of the spinneret, type, composition and temperature of the internal and external coagulants, bore liquid flow rate, gas gap type and length, dope flow rate and fiber take-up velocity and so on (Alsalhy, 2007; Alsalhy et al., 2014).
Interface treatment and performance study on fiber tube reinforced polyvinylidene fluoride hollow fiber membranes
Published in The Journal of The Textile Institute, 2020
Liyan Liu, Hongdou Shen, Ting Li, Yongliang Han
To overcome the disadvantages of low interfacial bonding properties, many methods were applied to modify fiber tubes and cast solutions. One method is to prepare homogeneous material reinforced hollow fiber membranes, such as polyacrylonitrile (PAN) braided tube reinforced homogeneous hollow fiber membranes, which indicated that the interfacial bonding state of the homogeneous reinforced hollow fiber membranes were better than that of the heterogeneous reinforced hollow fiber membranes and showed similar performance with the commercial PVDF hollow fiber membrane (Zhang, Xiao, Hu, & Bai, 2013; Quan et al., 2015; Fan et al., 2015; Bai et al., 2013). However, there are limitations in actual production because the homogeneous hollow fiber membrane was in higher cost than commercial hollow fiber membrane.
Progress in pretreatment of methadone: an update since 2015
Published in Preparative Biochemistry & Biotechnology, 2023
The hollow fiber membrane can be specially designed for the purpose of increasing the extraction efficiency and decreasing the organic solvent used. Also, a chiral selector can be added to the membrane to enhance the selectivity of the particular analyte. Hadjmohammadi and Hashemi[16] established an HF-LPME method to extract and separate racemic methadone from prepared solution employing sheep leather as the membrane and chiral (2-hydroxypropyl)-β-cyclodextrin (OHP-β-CD) as a versatile chiral selector. Combined with the HPLC-UV system, this method successfully provided an enantioselectivity value of 12.1 at last.