Electrically aided filters

A dielectrofilter [Lin and Benguigui, Sep. Purif. Methods, 10(1), 53 (1981) Sisson et al., Sep. Sei. Teennol., 30(7-9), 1421 (1995)] is a device which uses the action of an electric field to aid the filtration and removal of particulates from fluid media. A dielectrofilter can have a very obvious advantage over a mechanical filter in that it can remove particles which are much smaller than the flow channels in the filter. In contrast, the ideal mechanical filter must have all its passages smaller than the particles to be removed. The resultant flow resistance can be use-restrictive and energy-consuming unless a phenomenon such as dielectrofiltration is used. 

The factor C and the exponent y must be determined by experiments with pilot settlers. These terms combine all the unknown parameters. The cross-sectional area, S, of the settler should be chosen in such a way that the superficial velocity, of the dispersed phase does not exceed 5-9mms . Often aids for coalescing (e.g., packages of inclined plates or filter cartridges made of metal or plastic) (Fig. 9.23) are used. There are several ways of predetermining coalescence [31-33]. Furthermore, in special cases electrical fields and centrifuges are used to support coalescence [34]. 

Preparation of dry sample. Transfer two 35g portions of the sample to two 2j4 inch glass funnels, each funnel having a filter paper folded and inserted in it. With the aid of suction, wash the Hg fulminate with enough 95% ethyl alcohol to remove most of the water. Place the filter paper holding the Hg fulminate in a small evaporating dish and dry in a sealed unit electric oven or a steam oven at 40°C—50°C to constant weight... 

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