Filter aid

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Filter aids are chemically inert substances that physically and mechanically support filtration . They should not be confused or equated with flocculants .

A basic distinction is made between the following types of filter aids:

  • Substances that promote the formation of a filter cake in suspensions with few solids.
  • Substances that by their mass themselves form a fine-pored filter .
  • Substances that loosen a thick or too firm filter cake.

Filter aids are used to make it easier to clean the actual filter or filter insert or to prevent solids from the suspension from clogging the filter or getting into the filtrate. Examples of frequently used filter aids are cellulose , silica gel , kieselguhr or perlite . Asbestos is no longer used due to its harmfulness . The aids are generally used in water treatment , beverage filtration and, more specifically, in the chemical industry .

literature

  • Hermann Römpp: Römpp Chemie Lexikon . 9th edition. Thieme Georg Verlag, 1995, ISBN 3-13-102759-2 . (P. 1357 f.)

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