Amorphous diatomite

MicrocrystaUine Silicas. Various microcrystalline (cryptocrystalline) materials such as flint, chert, and diatomaceous earth are found ia nature (see Diatomite). These may arise from amorphous silica, often of biogenic origin, which undergoes compaction and microcrysta11i2ation over geologic time. 

Approximately 40% of synthetic amorphous siUca production is in Europe, followed by North America at 30%, and Japan at 12%. Although deposits of naturally occurring amorphous siUcas are found in all areas of the world, the most significant commercial exploitation is of diatomaceous earth in industrialized countries (see Diatomite). This is because of the high cost of transportation relative to the cost of the material. Worldwide manufacturers of amorphous siUca products are Hsted in Table 2. 

Packed columns contain an inert and stable porous support on which the stationary phase can be impregnated or bound (varying between 3 to 25%). The solid support is made of spheres of approximately 0.2 mm in diameter, obtained from diatomites, silicate fossils (such as kieselguhr, tripoli) whose skeleton is chemically comparable to amorphous silica. These materials, which have a specific surface area ranging from 2 to 8 m2/g, have been commercialised by several companies such as Johns Manville, under the name of Chromosorb , and are used universally. Other synthetic materials have been developed such as Spherosil , made of small silica beads. All of these supports have a chemical reactivity comparable to silica gel because of the presence of silanol groups. 

Diatomite. also known as diatomaceous earth, or kieselgubr, consists mainly of accumulated shells or frustules of intricately structured amorphous hydrous silica secreted by diatoms, which are microscopic, onc-celled golden brown algae of the class Bacillariophyceae. Diatoms exist in many different environments and arc abundant in regions of oceanic upwelling. 

Diatomite A sedimentary rock formed by the burial and diagenesis of sediments consisting of abundant microscopic and amorphous silica shells from marine microorganisms. 

SYNS AMORPHOUS silica CELITE D.E. DIATOMACEOUS EARTH, NATURAL DIATOMACEOUS SILICA DIATOMITE ... 

The yield of salt on the base of diatomite was 32% that is 2.4 times lower than the yield of salt on the basis of silica sol. This fact is explained by the quantity of the amorphous part in biogenic silica. Such a yield of the ammonium salt of the tricatechol ether of monosilicic acid on the basis of diatomite is in accordance with yield of liquid glass (40%) leached from native diatomite. 

Most packed column supports are prepared from diatomaceous earth, which is composed of skeletons of diatoms. The diatomite is basically an amorphous... 

For amorphous materials, sludges or other poor filtering products, improved filtration characteristics and/or filtrate clarity are enhanced with the use of filter aids. Slurry additives such as diatomaceous silica or perlite (pulverized rock), are employed to aid filtration. Diatomite is a sedimentary rock containing skeletons of unicellular plant organisms (diatoms). These... 

SYNONYMS amorphous silica, diatomaceous earth, diatomaceous silica, diatomite, infusorial earth. 

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