Filtration membrane types

CNT membranes membrane membrane filtration membrane types... 

Certain parameters affect membrane fouling particle nature particle size and size distribution membrane type and structure surface interactions and the clogging mechanism. An important parameter is the method applied to the filtration technique, namely, crossflow or deadend filtration. The latter requires less pumping energy but tends to clog the membrane faster. 

Fig. 34.23. Principle of membrane-type filtration of olein and stearin. (From Tirtiaux, A., in World Conference Proceedings, Edible Fats and Oils Processing Basic Principles and Modern Practices, D. R. Erickson (Ed.), pp. 136-141, AOCS, Champaign, IL, 1990. With permission.)...

Pacifici and Viani, commenting on comparisons among results from different methods applied to protein binding, warn that methods for drug binding need to be standardized. Currently, results depend greatly on technique and interpretation of results thus, experimental details such as anticoagulant used, type of dialysis or filtration membrane, buffer characteristics, duration of experiment, and temperature should be taken into account. 

Pretreatment requirements. Pretreatment requirements include (a) contaminant concentration (b) ionic size of the contaminants (c) membrane type (d) presence of competing ions (e) suspended solid concentration and (f) water temperature. Pretreatment is commonly used to prevent fouling of the membrane. Typical pretreatment for NF and RO includes particle removal by filtration, sequestering hardness ions by precipitates, and pH control to prevent clogging. 

Al-akoum et al. experimentally and theoretically reported the flux enhancement in three particular systems shear-enhanced filtration with a vibrating membrane module, gas/liquid two-phase flows, and Dean vortices for yeast suspension system. They reported that the permeate flux was found to obey the empirical law J -- Twm (where Twm is the mean wall shear stress. Pa) with 0.43 < n < S7 and K depending on the membrane type and the yeast concentration for a particular system. 

There are three (3) types of pharmaceutical filtrations depth, cake, and membrane. Cake and depth are coarse filtrations, and membrane is a fine, final filtration. Membrane filtration and cross-flow filtration are discussed in Ch. 7. 

Ultrafiltration was used to determine the extent of europium binding to humic acid. While stirring, Eu(III) + Eu- 152 tracer was added to a 10 ml solution of humate at pH 4.2 (ace tate buffer) in an Amicon model 8050 ultrafiltration cell. After a 500 /xL aliquot was withdrawn for counting, the cell was immediately pressurized. An Amicon YM2 filtration membrane (1000 molecular weight cut-off) would retain the humic acid plus the bound europium while unbound Eu(III) would elute. One ml of filtrate was collected and tested for the presence of humate by measuring the visible spectrum of the solution with a Milton Roy Spectronic 1201. On cessation of filtration, 500 /xL aliquots were removed from the filtrate and the residual solution above the membrane. The samples were counted for the presence of Eu-152 in a well-type Nal(Tl) crystal connected to a single channel analyzer. 

Further distinction has to be made between conventional filtration of fine particle less than 10 pm in diameter, and microfiltration. It would be unusual for the filtration of such particles on a conventional fiher cloth to be described as ndcrofiltratian. Thus microfihration is constituted by the filtration of small particles and by the medimn which is used for the filtration. Conventional fihration is undertaken on filter cloths with a very open structure, see Chapter 4, whereas membrane fihration is usua% concerned with fihration enq>loying membrane media where the equivalent pore size is of the order of 10 pm, or less. These definitions are, however, becoming less distinct as it is now possible to obtain conventional fihration equ ment employing membrane-type fiher media, as discussed in Chapter 4, and crossflow microfilters enqploying conventional filter cloth. 

Membrane filtration Membrane separation processes use semipermeable membranes to separate impurities from water. The membranes are selectively permeable to water and certain solutes. A driving force is used to force the water to pass through the membrane, leaving the impurities behind as a concentrate. The amount and type of material removed depends upon the type... 

Application of LbL in different fields of nanotechnology has led to the use of various types of porous and rough surfaces for multilayer growth. One significant use has been foimd in the field of separation science, that is, development of filtration membranes by modifying the surface of the porous membrane support to improve separation performance and antifouling properties. Some examples of such porous membrane support materials are polyethersulfone (PES) ultrafiltration membranes, polyacrylonitrile (PAN) ultrafiltration membranes, membrane of PAN with acrylic acid s ments (poly(acrylonitrile-co-acrylic acdd), porous polyacrylonitrile/ polyethylene terephthalate (PAN/PET) substrates, cellulose acetate membranes, porous ceramic supports, and porous alumina supports. The multilayer materials used for such modifications are listed, but not limited to, common polyelearolytes used for LbL applications, such as PSS, PAH, PDADMAC, PAA, and poly(vinyl sulfate) (PVS) copolymers such as poly(4-styrenesulfonic acid-co-maleic acid) quaternary ammonium salts such as cetyl trimethyl ammonium chloride and tetramethyl ammonium chloride as cationic species or nanoparticles such as Ti02. 

A PVDF membrane filter has been shown to remove >10 particles of vims for vimses >50 nm independent of fluid type (8). Vimses smaller than 50 nm are not removed as efficientiy but are removed in a predictable manner which correlates to the vims particle size. The chemistry of the suspending fluid affects titer reduction for vimses <50 nm owing to other removal mechanisms, such as adsorption, coming into play. The effects of these other mechanisms can be minimized by using filtration conditions that minimize adsorption. 

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