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Layer Resistance (layer + resistance)
Selected AbstractsThe Zwitterion Effect in Ionic Liquids: Towards Practical Rechargeable Lithium-Metal Batteries,ADVANCED MATERIALS, Issue 20 2005N. Byrne Practical lithium-metal batteries are the ultimate goal of battery researchers. The addition of a zwitterionic compound (see Figure) to an ionic liquid electrolyte doped with a lithium salt results in a 100% enhancement of the current densities achieved in the cycling of a lithium-metal cell. This phenomenon arises due to increased lithium-ion mobility or a reduced solid electrolyte interphase layer resistance. [source] CLARIFICATION OF WATERMELON (CITRULLUS LANATUS) JUICE BY MICROFILTRATIONJOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2008Ch. CHHAYA ABSTRACT Microfiltration of watermelon juice was conducted using stirred membrane cell in continuous mode. The experiments were conducted at operating pressures of 136.5, 204.7 and 276 kPa, and stirring speeds 1,200 rpm (Re = 1.40 × 105), 1,400 rpm (Re = 1.63 × 105) and 1,600 rpm (Re = 1.87 × 105). Permeate flux decline was analyzed using a first-order kinetic model, and correlations were developed for the steady-state polarized layer resistance with the operating conditions, e.g., transmembrane pressure difference, Reynolds number and membrane resistance. The permeate flux was calculated based on the developed correlation, and found to be in good agreement with the actual experimental flux. The change in quality parameters of clarified juice was marginal compared to that of original juice. PRACTICAL APPLICATIONS The application of membrane technology is one of the emerging areas in food industry. The major application includes fruit juice clarification and concentration. Because of the nonthermal nature of membrane separation, the juice can be clarified at room temperature and packed aseptically for a longer shelf life without the loss of its initial quality parameters. The major problem during clarification is decline in permeate flux of fruit juice with time. Identification of causes for flux decline is essential for designing of membrane modules to make the clarification process commercially viable. The quality of juice during storage is vital, and therefore, determination of variation of its physicochemical properties during storage is also important. [source] QUANTIFICATION OF FLUX DECLINE OF DEPECTINIZED MOSAMBI (CITRUS SINENSIS[L.] OSBECK) JUICE USING UNSTIRRED BATCH ULTRAFILTRATIONJOURNAL OF FOOD PROCESS ENGINEERING, Issue 4 2005P. RAI ABSTRACT Ultrafiltration of enzymatically treated mosambi (Citrus sinensis [L.] Osbeck) juice was performed in a batch, unstirred membrane cell. Thin film composite polyamide membrane of molecular weight cut-off 50,000 was used. The flux-decline mechanism was identified by the growth of a gel-type layer over the membrane surface. The flux decline, the gel resistance, the gel-layer thickness and various domains of resistances were calculated at a constant pressure difference in the range of 276,552 kPa. The conventional gel-filtration theory was employed to analyze the flux-decline behavior. The calculated permeate flux and gel-layer resistances were consistent with the experimental results. The calculated gel-layer thickness varied from 4.12 to 74.1 µm for different operating condition (pressure) and time. The time at which the gel resistance becomes equal to the membrane-hydraulic resistance ranged from 13 to 31 s for the pressure range studied herein. Thus, the deposited layer resistance to permeate flow was substantial, throughout the whole operation, except in the first few seconds. [source] Effects of Ionic Environments on Bovine Serum Albumin Fouling in a Cross-Flow Ultrafiltration SystemCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2007S. Salg Abstract The influence of electrostatic interactions on membrane fouling during the separation of bovine serum albumin (BSA) from solution was studied in a cross-flow ultrafiltration system. Experiments were carried out at different pH values between 3.78 and 7.46; and for different ionic strengths between 0.001,M and 0.1,M. The changes in permeate flux, cake layer resistance, zeta potentials of BSA and polyether sulfone (PES) membranes, and electrostatic interaction energies, were evaluated. At all of the ionic conditions studied, PES membranes are negatively charged. However, BSA molecules are either negatively or positively charged depending on the ionic environment. Whereas the cake layer resistance decreased with increasing pH and ionic strength, the permeate fluxes increased. The calculated electrostatic energy was a minimum at the isoelectric point (IEP) of BSA. However, at this point, the cake resistances corresponding to fouling at each ionic strength, were not minimized. Below the IEP of BSA, the electrostatic forces were attractive, while above the IEP, repulsive electrostatic forces were dominant. [source] Resistance to CO2 diffusion in cuticular membranes of amphibious plants and the implication for CO2 acquisitionPLANT CELL & ENVIRONMENT, Issue 1 2007HENNING FROST-CHRISTENSEN ABSTRACT Cuticular membranes (CMs) were isolated from leaves of amphibious and submerged plants and their CO2 resistances were determined as a contribution to establish quantitatively the series of resistances met by CO2 diffusing from bulk water to the chloroplasts of submerged leaves. The isolation was performed enzymatically; permeabilities were determined and converted to resistances. The range of permeance values was 3 to 43 × 10,6 m s,1 corresponding to resistance values of 23 to 295 × 103 s m,1, i.e. of the same order of magnitude as boundary layer resistances. The sum of boundary layer, CM, leaf cell and carboxylation resistances could be contained within the total diffusion resistance as determined from the photosynthetic CO2 affinity of the leaf. From the same species, the aerial leaf CM resistance was always higher than the aquatic leaf CM resistance. In a terrestrial plant, the CM resistance to CO2 diffusion was found lower in leaves developed submerged. [source] | ||||||||||