Title: Fuller's Earth
Additional Names: Floridin
Literature References: A nonplastic variety of kaolin containing an aluminum magnesium silicate. The name is derived from an ancient process of cleaning or fulling wool, to remove the oil and dirt particles, with a water slurry of earth or clay. At the present time, the term fuller's earth is applied to any clay that has adequate decolorizing and purifying capacity to be used commercially in oil refining without chemical treatment. It is sometimes considered to be synonymous with montmorillonite, q.v., kaolinite (Al2O3.2SiO2.2H2O) and Halloysite (Al2O3.2SiO2.4H2O). A long list of minerals likely to be found in fuller's earth is given by Porter, U.S. Geol. Surv. Bull. 315, 268 (1907), C.A. 1, 1684 (1907), and the opinion is expressed that fuller's earth results from the decompn of hornblendes and augites rather than from feldspars. Fuller's earth has for its base a series of amorphous, hydrous aluminum silicates that have a rather persistent colloidal (used in its widest sense) structure. It is to this colloidal structure, which is not lost at 130° and possibly higher, that the bleaching power is due. The bleaching efficiency of fuller's earth is usually increased by treatment with dilute acids.
Use: Decolorizer for oils and other liquids; filtering medium; filler for rubber; in agricultural formulations; also instead of absorbent charcoal. |