Membrane-based filtration

Likewise, to the inevitable phenomena of membrane fouling, all membrane based filtration processes require periodic cleaning. Without a safe practical, reproducible, cost effective and efficient cleaning procedure, the viability of cross-flow filtration may be highly questionable. Membrane cleaning process must be capable of removing both external and internal... 

Membrane fouling A phenomenon characteristic of all membrane-based filtration processes in which the membrane adsorbs or interacts with feed components. Membrane fouling causes a flux decrease and may also increase the retention of certain components in the feed. Membrane fouling is typically a time-dependent phenomenon and often independent of concentration. In some situations a partial dependence on concentration may be observed. 

G.B. Sigal, D.G. Hafeman, J.W. Parce and H.M. Mcconnell, Electrical-properties of phospholipid-bilayer membranes measured with a light addressable potentiometric sensor, ACS Symp. Ser., 403 (1989) 46-64. J.D. Olson, P.R. Panfili, R. Armenta, M.B. Femmel, H. Merrick, J. Gumperz, M. Goltz and R.F. Zuk, A silicon sensor-based filtration immunoassay using biotin-mediated capture, J. Immunol. Methods, 134(1) (1990) 71-79. 

Nano filtration According to the International Union of Pure and Applied Chemistry (lUPAC) recommendations [16] nanofiltration is a pressure-driven membrane-based separation process in which particles and dissolved molecules smaller than about 2 nm are retained. ... 

Dai X-P, Luo RG, Sirkar KK. A membrane-based integrated bioseparation process. Adv Filtration Sep Technol A 1999 13 545-549. 

Membrane-based separation processes are recognized as environmentally friendly alternatives to conventional separation techniques such as distillation or extraction. The field of large-scale applications covers the range of drinking water processing, potable water production, waste-water treatment, application in the food and pharmaceutical industries, recovery of aroma and active substances as well as sterile filtration of pharmaceuticals and clarification of beverages. 

Suitable nanofiltration membranes based on the spiral-wound module technique are available from various suppliers they usually consist of a carrier film, a spacer, and the filtration membrane. After separation, the lower phase is heated preferably to ca. 25 C, adjusted to a predetermined pH by addition of acid, and pumped at ca. 30 bar through a battery of pressure tubes suitably arranged in parallel and fitted with spiral-wound modules. 

MIP membranes based on the photo-reactive copolymer PAN-co-DTCS and finally imprinted by photo-grafting, had also the typical asymmetric, not yet optimized pore structure, so that only very low permeabilities could be used. Due to the low flux and the long filtration time, the binding capacities were quite high [32]. 

Nanofiltration membranes based on poly(ether ether ketone) modified with a mixture of ammonia with Ar or hydrogen show much better dye filtration parameters than the unmodified or commercial membranes (Buonomenna et al. 2009). 

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