Electro-ultrafiltration

Radovich, JM Behnam, B MuUon, C, Steady-State Modeling of Electro-Ultrafiltration at Constant Concentration, Separation Science and Teehnology 20, 315, 1985. 

Guizard C F. Legault, N. Idrissi, A. Larbot, L. Cot and G. Gavach. 1989. Electronically conductive mineral membranes designed for electro-ultrafiltration. J. Membrane Science 41 127-142. 

Cabral and coworkers [253] have investigated the batch mode synthesis of a dipeptide acetyl phenylalanine leucinamide (AcPhe-Leu-NH2) catalyzed by a-chymotrypsin in a ceramic ultrafiltration membrane reactor using a TTAB/oc-tanol/heptane reverse micellar system. Separation of the dipeptide was achieved by selective precipitation. Later on the same group successfully synthesized the same dipeptide in the same reactor system in a continuous mode [254] with high yields (70-80%) and recovery (75-90%). The volumetric production was as high as 4.3 mmol peptide/l/day with a purity of 92%. The reactor was operated for seven days continuously without any loss of enzyme activity. Hakoda et al. [255] proposed an electro-ultrafiltration bioreactor for separation of RMs containing enzyme from the product stream. A ceramic membrane module was used to separate AOT-RMs containing lipase from isooctane. Application of an electric field enhanced the ultrafiltration efficiency (flux) and it further improved when the anode and cathode were placed in the permeate and the reten-tate side respectively. 

The ultrafiltration of the microemulsion is a very useful operation for separating water and oil in these mixtures [117-120]. Because of the limited availability of solvent stable membranes, most of the work pubHshed so far was performed using ceramic membranes, which show a high adsorption of surfactant at the membrane surface and comparably low rejection rates of reverse micelles. Using electro ultrafiltration, where the concentration polarisation phenomenon of the reverse micelles (using the ionic surfactant AOT) at the membrane surface is depressed by asymmetric high voltage electrical fields, the rejection rates can be increased,but not to economical values [121,122]. 

Mesoporous dp = 2. .. 50 nm Carrier in liquid Affinity ligand in solid matrix anisotropic, isotropic track-etched immobilized in isotropic porous membrane isotropic, anisotropic Dialysis Carrier-mediated separation Ultrafiltration Electro- ultrafiltration... 

Ion-exchange membranes are currently used not only for more or less conventional separation processes like membrane electrolysis (mainly the chlor-alkali process), electrodialysis, dialysis or electro-ultrafiltration (cf. Table 2.1), but also in various... 

Karthik V, DasGupta S, and De S. Modeling and simulation of osmotic pressure controlled electro-ultrafiltration in a cross-flow system. J Membr Sci 2002 199 29 0. 

Since then, other colloidal oxide systems have been investigated in order to prepare ceramic mesoporous membranes designed for ultrafiltration. The preparation of an electronically conductive membrane from a Ru02 Ti02 mixed oxides sol and the application to an electro-ultrafiltration process [25,26], as well as the preparation of titania and zirconia ultrafiltration membranes [27], have been described following a colloidal process in which a partial destabilization of a metal oxide colloidal suspension is used to produce top layers with different pore size and pore volume in the mesoporous range. In agreement... 

Fig. 12.24. Schematic view of electro-ultrafiltration using conductive inorganic membranes.

Beechold, H., UltrafUtration and Electro-Ultrafiltration, Colloid Chemistry, Vol. 1, (J. Alexander, ed.). The Chemical Catalog Company (1926)... 

A three-cell apparatus (Vogel 724S) was used in electro-ultrafiltration [22]. The middle cell containing the material suspension had a stirrer and a water inflow. Each side of the middle cell was provided with a micropore filter attached to the platinum electrodes that separated the middle cell from the two outside chambers. These chambers had vacuum connections. Therefore, the ions accumulating at the respective electrodes were washed away by the continuous stream of the solution from the suspension in the middle cell to the eluate in the collecting tanks combined with the side chambers. A steady disequilibrium between the P on the materials and the respective soluble form in solution occurred and the materials were forced to replenish the P displaced away with the eluate. The concentration of P in the eluates was measured by UV-VIS spectrophotometry as phosphomolybdate [23]. 

Both quantitative and kinetics parameters of P release by electro-ultrafiltration EUF-P) were substantially affected by the presence of Al- or Fe- in the models, as well as by the various aggregation states of the investigated materials (Tables 4, 5 Figs. 1,2). 

Quantitative and kinetics parameters of P release isotherms by electro-ultrafiltration (EUF-P) ... 

Lee, H.-H., Weng, Y.-H. and Li, K.C. 2008b. Electro-ultrafiltration study on Aldrich humic substances with different molecular weights. Sep. Purif. Technol. 63 23-29. 

Enevoldsen AD, Hansen EB, Jonsson G (2007) Electro-ultrafiltration of industrial enzyme solutions. J Membr Sci 299(l-2) 28-37... 

Liithi and Luisi [44] have used a hoUow fiber membrane reactor for peptide synthesis catalyzed by a-chymotrypsin in microemulsion. Chang et al. [110] described the immobilization of lipase on liposomes, which, in turn, were solubilized in AOT/isooctane reversed micelles and used for the continuous glycerolysis of olive oil in an ultrafiltration cell. The half-Ufe of the Chromo. viscosum lipase was 7 weeks. The development of an ultrafiltration ceramic membrane bioreactor for the simultaneous lipolysis of olive oil and product separation in AOT/isooctane reversed micellar media has been also reported [106,107], Cutinase performance was also evaluated in a ceramic membrane reactor [9]. An attempt to minimize the surfactant contamination problem was based on the use of an electro-ultrafiltration method which can decrease the gel formation in the membrane surface, improving the filtration flux, achieving the separation of the AOT reverse micelles [187],... 

Figure 2.9. Schematic diagram of electro-ultrafiltration (adapted from Saxena et al., 2007).

Chaung-Hsieh, L.H., Weng, Y.H., Huang, C.P. Li, K.C. (2008) Removal of arsenic from groundwater by electro-ultrafiltration. Desalination, 234 (1-3), 402-408. 

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