Papers by Keyword: Asymmetric Membrane

Abstract: Membrane technology in gas separation application was commercialized approximately 30 years ago because of a number of advantages offered compare to the conventional technique. The use of poly (lactic acid) (PLA), a biodegradable polymer, as a membrane material would assist the reduction of depending to petroleum-based polymer. This study investigated the effect of evaporation time to the gas separation performance of PLA membrane. Membrane prepared from polymer solution consist of PLA and dicholoremethane (DCM) as solvent was fabricated using pneumatically controlled casting system with dry/wet phase inversion method. Permeation test was conducted using pure carbon dioxide and methane gas. The results revealed that as the evaporation time increased, the pore size and surface porosity decreased, while the skin layer thickness increased. Although the morphology of the prepared membranes showed the desirable structure, the gas separation performance of the membrane prepared with polymer concentration of 15wt% and 60s evaporation time was found to be promising but not yet commercially ready.

Abstract: Ceramic materials have been widely utilized due to its attractive properties including high resistance to extremely harsh environments; chemical and heat, and its durability to the remarkable mechanical strength. Inorganic flat sheet films in this study were prepared by dry-wet phase inversion process followed by sintering method, which expected to produce very unique micro-structures leading to improvement in performance for various applications including catalytic reactions and filtration processes. Aluminium oxide was chosen as the main material due its known capability in filtration processes, membrane reactors and membrane catalysis applications. Polyethersulfone (PES) was used as an organic binder in the membrane dope formulation. Besides alumina and PES, the dope solution was consisted of N-methyl-2-pyrrolidone (NMP) and arlacel as solvent and additive, respectively. The main aim of this study is to investigate the effect of sintering temperature on the morphology and structure of the prepared membranes. Scanning electron microscope (SEM) was used to examine the membrane structure. Since the morphology of a membrane highly influences its mechanical properties, the membrane strength was measured using tensile test. From the SEM, preliminary cast membrane structure displayed a long finger-like near the outer and inner walls sandwiched a sponge-like structure that provided the membrane strength.

Abstract: Symmetric and asymmetric polysulfone membranes were fabricated using different of solvents; N-methyl-pyrrolidone (NMP), Tetrahydrofuran (THF) and Dimethylacetamide (DMAC) at different polymer concentration (15 and 20%) to study the influence of varying type of solvents and polymer concentration in membrane fabrication. The membranes were characterized using Field Emission Scanning Electron Microscopy (FESEM), Thermogravimetric Analyzer (TGA), Universal Testing Machine (UTM) and Fourier Transform Infra-Red (FTIR).The results disclosed that the symmetric, higher polymer concentration membrane contributed to better thermal and mechanical stabilities. PSF/THF membrane showed good mechanical strength while PSF/DMAC membrane illustrated great thermal stability. 20% of polymer concentration and PSF/THF membrane led to the thicker skin layer and dense structure formation.

Abstract: The prevention of undesired abdominal wall adhesion after surgery was investigated using asymmetric polysaccharide composite membranes as physical barriers. The hyaluronate (HA) and chitosan (CS) based asymmetric composite membranes were prepared with one smooth surface to inhibit fibroblasts and one porous surface to improve the tissue cells. With adaption of the reaction temperature, pH and component ratios, a series crosslinked membranes were processed with different appearance, mechanical strength and swelling ratios. Cell culture results showed the fibroblasts were inhibited on the composite membranes with comparison of that on petri dish. The osteoblasts proliferated obviously on the porous surface. The composite membranes resulted in less post-operative adhesion of the peritoneum and cecum than shown by non-treated rats without physical barriers, which could be used as a physical barrier to prevent abdominal post-operative adhesion during healing.

Abstract: A mathematical model for facilitated transport in asymmetric membranes with fixed site carriers was derived by assuming concentration fluctuation and an analogy between electron transport in resistor-capacitor circuit and mass transport in an asymmetric membrane of facilitated transport. In order to examine the validity of the model, bovine serum albumin fixed membranes were fabricated and experiment of facilitated transport of bilirubin was carried out in diffusion cell. The agreement between the theoretical and experimental results is exceptional.

Abstract: An asymmetric polysulfone membrane with reactive group of –OH was obtained by hydrolyzing the chloromethylated polysulfone membrane, and the albumin molecules were immobilized into the membrane with a crosslinking reagent of 1,4-butanediol diglycidyl ether. The albumin-fixed membrane was used to remove lipophilic toxins, bilirubin, from the bilirubin-albumin solution. The experiment results showed that the transfer rate of bilirubin was clearly enhanced after fixing albumin into the hydroxylated polysulfone membranes. The clearance of bilirubin was 49.3%. In addition, the effect of membrane thickness on the removal of bilirubin is discussed.