469370 Comparison of Performance Between Laboratory Scale and Industrial Scale Membranes
Cellulose acetate (CA) membranes are among the most researched polymers for separation and barrier applications because of their many useful characteristics including relative low cost, good toughness, high biocompatibility, good desalting, high potential flux. There are different methods used to fabricate porous polymeric membranes, and these can lead to irreproducible results, especially during scale up. The performance of the membrane is greatly influenced by not only the material but also the processing methods and conditions, because they affect the morphology of the membrane. Generally, a laboratory scale approach, such as knife over blade or solution casting, is used to cast a thin sheet of the polymeric membrane solution. Then, the final form of the membrane is prepared by sintering, stretching, or phase inversion. In many studies, the primary film casting process has been limited to doctor blade extrusion, however, this method is not always the most suitable for the industrial scale, because the solution exposed to the environment during the processing phase. Alternatively, slot die extrusion is a well-developed pre-metered approach that allows for continues casting of liquid film in a controlled environment, which also minimizes changes in liquid properties, such as rheology. The slot die coating process is a commonly used process for the manufacturing of plastics and polymer films, as well as coatings and optical films for liquid crystal displays in industry. For the scale up fabrication of hollow fiber CA membranes, a hollow fiber spin-line was used. The feasibility of processing cellulose acetate using a laboratory-scale doctor’s blade versus a scale up slot die extrusion vs hollow fiber membrane was examined. The effects of processing methods, conditions, and substrate on the morphology and on the flux of CA membranes were studied. CA membranes were tested for their performance under the same operational conditions of pressure, feed volume, and feed concentration.