Diatomaceous earth

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Raw piece of diatomite.

Diatomaceous earth (D.E.) more commonly known as diatomite, kieselgur/kieselguhr or celite, is a naturally occurring, soft and frangible siliceous sedimentary rock. Diatomaceous earth mainly consists of fossilized remains of diatoms, a type of hard-shelled algae, with other impurities such as metals (usually iron and calcium) and minute traces of organic matter.

Properties

Chemical

Diatomaceous earth consists mostly of silicon dioxide and resists corrosion by acids.

Heating diatomite between 800-1000 °C in a kiln will cause it to turn orange-red.

Physical

Diatomite is a white-ish light solid, with an abrasive feel, and highly porous. It also displays cleavage. Kieselgur is very light, with a density of 2.3 g/cm3 (bulk) and 0.256 g/cm3 (powder).

Availability

Diatomaceous earth is available in many garden shops as insect killer. It can also be purchased online.

Projects

  • Water filtration
  • Adsorbing agent
  • Thermal insulator
  • Make dynamite
  • Catalyst support

Handling

Safety

Powdered diatomaceous earth is irritant to lungs and long-term exposure may cause silicosis.

Storage

Diatomite should be stored in closed bottles.

Disposal

No special disposal is required, though it's best to avoid scattering it in air.

References

Relevant Sciencemadness threads