Permeation, centrifugal filtration

Pharmaceutical Removal of suspended matter is a frequent application for MF. Processes may be either clarification, in which the main product is a clarified liquid, or solids recovery. Separating cells or their fragments from broth is the most common application. Clarification of the broth in preparation for product recovery is the usual objective, but the primary goal may be recovery of cells. Cross-flow microfiltration competes w l with centrifugation, conventional filtration by rotary vacuum filter or filter press and decantation. MF delivers a cleaner permeate, an uncontaminated, concentrated cell product... 

The amount of polymer adsorbed on each sample was measured by pressure filtration through a 0.1 m filter, followed by analysis of the filtrate for residual polymer by gel permeation chromatography with refractive index determination. Particle zeta potentials were measured by taking a small sample of the solids from the centrifuge and re-suspending them in the supernatant prior to analysis in a Malvern Instruments Zetasizer . The concentration of all other types of ions in the supernatant was analysed by ICP atomic emission spectroscopy. 

Even though the interest in microwave-assisted extraction (MAE) has increased during the last 10 years, this technique has not been utilized much in food and feed applications. Only a few papers can be found with the combination of POPs and food/feed samples. This may be because MAE applications frequently require laborious and tedious clean-up of the extracts before final analysis. In some cases, only a simple filtration or centrifugation may be sufficient to separate the solid matrix from the extract but since MAE most often is more exhaustive than selective, extensive clean-up procedures based on for example solid-phase extraction is commonly needed for removal of interfering compounds (73-75). Other techniques that have been used for clean-up of MAE extracts are gel permeation chromatography (75), solid-phase micro extraction (77, 78), and liquid-liquid extraction (79). 

Screening Equipment Filtration Cake Filters Centrifugal Filters Principles of Cake Filtration Clarifying Filters Liquid Clarification Gas Cleaning Principles of Clarification Crossflow Filtration Types of Membranes Permeate Flux for Ultrafiltration Concentration Polarization Partial Rejection of Solutes Microfiltration... 

We measured permeation of anionic and cationic electrolyte ions through poly(L-lysine-fl/r-terephthalic acid) microcapsule membranes as a function of pH of the medium at different ionic strengths. The solutes used were 5-sulfosalicylic acid as an anion and phenyltrimethylammonium chloride as a cation. We suspended water-loaded poly(L-lysine-a/r-terephthalic acid) microcapsules in a buffer solution and mixed this with a 5-sulfosalicylic acid solution or phenyltrimethylammonium chloride solution. The final concentration of the microcapsules is 20 % (v/v). We determined the solute concentration in the suspension medium spectrophotometrically at suitable time intervals after separating microcapsules by centrifugation and filtration through a Millipore filter. 

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