Pressure filtration method

Three different types of material were used to study the pressure-filtration method. Those were 1) Kentucky 9/14 coal, 2) slurries from low-temperature reactions (low conversion to soluble products, high solids content), and 3) slurries from high-temperature reactions (high conversion to soluble products, low solids content). These particular types were chosen because the first represents a material that is difficult to extract the second, a material that was difficult to extract with some solvents and more easily extracted with others and the third, a material that can be extracted with most solvents. 

The THF solubility values (Table III, SCT 65 69) demonstrate that the extractions using the pressure-filtration method are thorough, and the solubility values are comparable to the continuous Soxhlet-extraction method When the same procedure was performed using cyclohexane, a large difference was seen between low-temperature Soxhlet-extraction values and the pressure-filtration values ... 

Slip casting is a low-pressure filtration method where capillary suction provides the driving force (of the order of 0.1-0.2 MPa) for liquid removal and formation of a cast layer at the mould surface. The casting rate is controlled by the resistance to flow by the cast layer and the mould. Usually, the mould resistance is negligible and the increase in the cast layer thickness, Z, with time, t, can be written as follows ... 

This cycle of vaporisation of the solvent, condensation, extraction, and vacuum-filtration may be repeated any number of times in a solid-fluid serial extractor. The occurrence of an extractive material fluid bed as a result of the flow of boiling hot vapour provides for effective extraction, while pressure filtration provides for short cycle times. This functional principle makes it possible to achieve filtration pressures which are 50-100 times more effective than when using the Soxhlet method, where only the low hydrostatic pressure of the extractive fluid operates. Solid-fluid-vortex extraction according to the proprietary FEXTRA (Feststoff Extraktion) principle is low cost. 

Vacuum filtration involves carrying out filtration under reduced pressure and provides a faster method of separating a precipitate from a filtrate than traditional gravity filtration methods. A Buchner, Hirsch or sintered glass funnel can be used during vacuum filtration. 

Biological fouling was monitored using the customary indicators of RO performance, including flux (productivity), salt passage, and bundle pressure drops (AP). In addition, the total bacteria count (TBC) of the RO feed water and the reject brine stream were also obtained using the membrane filtration method (Ref. 6). The increase in TBC between the feed and reject portions of the system had been found in the preliminary stages of... 

Absolute Viscosimetric Method for the Determination of Endocellulase Activities. Experimental Setup of the Viscosimetric Measurements. The substrate, buffer, and enzyme solutions are prepared in the same manner as described in the section on light scattering. However, no clarification of the substrate solution by pressure filtration is needed. 

The precipitates commonly encountered in the analytical laboratory are practically insoluble and can be washed with unlimited quantities of liquid. Organic products, on the other hand, are usually more or less easily soluble in the solvent employed, and hence it is always necessary to use the smallest possible amount of wash liquid which will completely remove the adhering mother liquor. For this reason, gravity filtration is of litde value. Instead, filtration methods must be used which provide an appreciable pressure difference above and below the filter. This pressure difference is obtained by applying pressure above the filter, or suction below it. 

Pressure filtration—A method of filtration in which the pressure differential used to drive the filtration is induced by impressing a high pressure on the inlet side of the filter medium. 

A more conunon alternative are filtration methods generally relying on the time it takes for a given volume of eeU suspension to pass through micropore membranes at constant pressure (Sato et al., 1977). Although this method only gives average information on the... 

In addition to the dip-coating method, ceramic layers on a porous substrate can also be formed by filtration of a sol or by filtration of a suspension using the substrate as a filter and applying an external pressure. These methods are not discussed in this chapter. The reader is referred to Ref. [1] for more information. 

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