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Membrane Flux (membrane + flux)
Selected AbstractsFlux enhancement in TFC RO membranesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2001Mark A. Kuehne The effects of varying processing conditions during fabrication of TFC RO membranes were systematically investigated. It was found that the membrane flux is greatly dependent on the processing steps that follow the synthesis of the thin film coating, such as washing, treatment with glycerol, and drying of the membrane. Glycerol is not simply a passive flux - p reserving agent, preventing loss of porosity during oven drying. In combination with a second oven drying step, glycerol actively enhances flux. Membrane flux can be similarly enhanced by treatment with solutions of organic salts, followed by oven drying. The effect of these treatments is quite large, increasing the flux by 30,70%, with no loss of salt rejection. Flux-enhancing additives were also used in the aqueous polyamine solution used to prepare the thin film coating. [source] Probing protein colloidal behavior in membrane-based separation processes using spectrofluorometric Rayleigh scattering dataBIOTECHNOLOGY PROGRESS, Issue 3 2010Rand Elshereef Abstract One of the primary problems in membrane-based protein separation is membrane fouling. In this study we explored the feasibility of employing Rayleigh light scattering data from fluorescence studies combined with chemometric techniques to determine whether a correlation could be established with membrane fouling phenomena. Membrane flux was measured in a dead-end UF filtration system and the effect of protein solution properties on the flux decline was systematically investigated. A variety of proteins were used as a test case in this study. In parallel, the colloidal behavior of the protein solutions was assessed by employing multiwavelength Rayleigh scattering measurements. To assess the usefulness of Rayleigh scattering measurements for probing the colloidal behavior of proteins, a protein solution of ,-lactoglobulin was used as a base-case scenario. The colloidal behavior of different ,-lactoglobulin solutions was inferred based on published data for this protein, under identical solution conditions, where techniques other than Rayleigh scattering had been used. Using this approach, good agreement was observed between scattering data and the colloidal behavior of this protein. To test the hypothesis that a high degree of aggregation will lead to increased membrane fouling, filtration data was used to find whether the Rayleigh scattering intensity correlated with permeate flux changes. It was found that for protein solutions which were stable and did not aggregate, fouling was reduced and these solutions exhibited reduced Rayleigh scattering. When the aggregation behavior of the solution was favored, significant flux declines occurred and were highly correlated with increased Rayleigh scattering. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Flux enhancement in TFC RO membranesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2001Mark A. Kuehne The effects of varying processing conditions during fabrication of TFC RO membranes were systematically investigated. It was found that the membrane flux is greatly dependent on the processing steps that follow the synthesis of the thin film coating, such as washing, treatment with glycerol, and drying of the membrane. Glycerol is not simply a passive flux - p reserving agent, preventing loss of porosity during oven drying. In combination with a second oven drying step, glycerol actively enhances flux. Membrane flux can be similarly enhanced by treatment with solutions of organic salts, followed by oven drying. The effect of these treatments is quite large, increasing the flux by 30,70%, with no loss of salt rejection. Flux-enhancing additives were also used in the aqueous polyamine solution used to prepare the thin film coating. [source] Beta-2-Microglobulin in nocturnal hemodialysis , A comparative study in low and high flux dialysersHEMODIALYSIS INTERNATIONAL, Issue 1 2005A.B. Reid In end-stage renal failure, impaired renal catabolism leads to retention of beta 2 microglobulin (ß2M), identified as the major constituent of hemodialysis (HD) related amyloidosis. It has been previously shown that, while using a high flux (HF) HD membrane, nocturnal hemodialysis (NHD) with its increased time and frequency provides a much higher clearance of ß2M compared to conventional HD. We compared serum ß2M levels between low flux (LF) and HF in a group of 9 NHD patients who dialyse 8 hours 6 nights/week. Fresenius polysulfone LF membrane size F6-F8 HPS dialyser were used for the first 15 months (mth) of NHD (SA 1.3,1.8 m2). Subsequently, polysulfone HF FX80 dialyzer were used (SA 1.8 m2). Blood flow and dialysate flow rates were unchanged throughout the study. ß2M levels were measured at 6, 12, 15 mth on LF and at 6, 12 mth on HF. Albumin, homocysteine (Hcy), and phosphate (Phos) levels were also recorded at these times. ß2M levels trended upwards during the 15 mth on LF (36.6 ± 10.57 at 6 mth vs 47.1 ± 11.7 at 15 mth). On introduction of HF, there was a significant fall in ß2M at 6 mth to 12.4 ± 3.5 (p < 0.003), while ß2M levels were unchanged at 12 mth of HF. A downward trend in Hcy levels with the use of HF was noted (12.9 ± 2.9 at 0 mth Vs 11.1 ± 3.7 at 12 mth). Plasma albumin and Phos levels remained unchanged as did the use of Phos supplementation. Levels of ß2M continued to rise on NHD with LF, indicating inadequate clearance. With the introduction of HF there was a significant fall in ß2M levels consistent with improved clearance. The implications of this are that ß2M clearance may be time and frequency dependent only if dialyser membrane flux is adequate. [source] L -Lysine Monohydrochloride Syrup Concentration using a Membrane Hybrid Process of Ultrafiltration and Vacuum Membrane DistillationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2008O. Bakhtiari Abstract The development of energy saving membrane separation processes is finding a unique position in process industries. One of the important areas where they are employed is the biotechnology industry. This industry has its own specifications and requirements, e.g., levels of diluteness, thermal, chemical and shear fragility. Membrane separation processes have the characteristics necessary to match these specifications and needs. In this research, the determination of the experimental concentration of L -Lysine monohydrochloride (L -lysine-HCl) syrup was investigated using ultrafiltration (UF) and vacuum membrane distillation (VMD) hybrid membrane processes. Four parameters that are known to have significant influence on the UF process were examined, i.e., pressure difference across the membrane, feed concentration of L -lysine-HCl, feed velocity on the membrane surface, and pH. For the VMD unit, pressure difference and pH were replaced with feed temperature and vacuum pressure on the permeate side of membrane. Each process was carried out separately and the results were used to design a bench-scale process. In order to save time and money, the Taguchi method of experimental design was employed. The effects of feed concentration, pressure difference across the membrane, feed velocity on the membrane surface, and pH on the target variable, i.e., the membrane flux, in the UF process were 39.93, 38.65, 9.36, and 9.59,%, respectively. For the VMD process, these values were 64.79, 22.16, 6.21, and 2.14,% for feed temperature, feed concentration, vacuum pressure on the permeate side, and feed velocity on the membrane surface, respectively. [source] Test of flow field on the annular meridian plane in a tubular membrane separator with rotary tangential flowJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2004Cheng Duan Wang Abstract Enhancement of membrane microfiltration by rotary tangential flow is a new technique, which is based on the hydrocyclone mechanism. It improved the structure of the general membrane separator and the form of the liquid suspension flowing into the separator, so as to increase membrane fluxes and decrease membrane fouling. In our research, a tubular membrane separator with rotary tangential flow was designed for the first time. The flow field characteristics of polypropylene tubular membrane microfiltration in this tubular separator were studied systematically by means of the Particle Image Velocimetry (PIV) test. Streamlines and velocity distributions of the meridian plane of the separator under different operating parameters were obtained. The velocity distribution characteristics of rotary circular tangential flow were analyzed quantitatively with the following conclusions being obtained: (1)In the non-vortex area, no matter how the operating parameters (flux, entry pressure) change, the velocity near the rotary tangential flow entrance is higher than the velocity far from the entrance at the same radial coordinates. In the vortex area, generally the flow velocity of the inner vortex is lower than that of the outer vortex. At the vortex center, the velocity is the lowest, the radial velocity being generally equal to zero. In the vortex zone, the radial velocity is less than the axial velocity. (2)Under test conditions, the radial velocity and the axial velocity of the vortexes' borders are 1,2 times the average axial velocity in the annular gap of the membrane module. The maximum radial velocity and axial velocity of Taylor vortexes are 2,5 times the average axial velocity in the annular gap of the membrane module. (3)In the vortexes that formed on the meridian plane, it was found that mass transfer occurred between the inner and outer parts of the fluid. Much fluid moved from the outer vortexes into the inner ones, which was able to prevent particles blocking the membrane tube. Copyright © 2004 Society of Chemical Industry [source] | ||||||||||