Desiccant

drying agentdesiccantsdryersdehydration agentdesiccatingdessicantdrierliquid desiccant
A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant.wikipedia
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Desiccation

desiccateddesiccatedesiccating
A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant.
A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.

Humectant

humectantsanti-caking agentholds moisture
A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant.
This is the opposite use of a hygroscopic material where it is used as a desiccant used to draw moisture away.

Calcium sulfate

calcium sulphateCaSO 4 Drierite
Other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves (typically, zeolites).
In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant.

Molecular sieve

molecular sievesmolecular sievingMol. Sieve
Other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves (typically, zeolites).
Other molecular sieves are used as desiccants (some examples include activated charcoal and silica gel).

Calcium chloride

CaCl 2 calciumanhydrous calcium chloride
Other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves (typically, zeolites).
Because the anhydrous salt is hygroscopic, it is used as a desiccant.

Cobalt(II) chloride

cobalt chlorideCoCl 2 cobalt chloride hexahydrate
One commonly used indicator is cobalt chloride (CoCl 2 ).
Because of the ease of the hydration/dehydration reaction, and the resulting color change, cobalt chloride is used as an indicator for water in desiccants.

Anhydrous

waterlessfree from the presence of water
Anhydrous cobalt chloride is blue.
Common desiccants include phosphorus pentoxide and silica gel.

Desiccator

Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items such as cobalt chloride paper for another use.

Insulated glazing

double glazingdouble glazeddouble-glazed
One example of desiccant usage is in the manufacture of insulated windows where zeolite spheroids fill a rectangular spacer tube at the perimeter of the panes of glass.

Moisture sorption isotherm

moisture sorption isothermswater vapor sorption isotherm
Desiccants may also be categorized by their type, either I,II,III,IV, or V. These types are a function of the shape of the desiccant's moisture sorption isotherm.

Sorbent

Sorbents
**Desiccants attract water, drying out (desiccating) the surrounding materials.

Solar air conditioning

solar coolingcoolingair conditioning
Air can be passed over common, solid desiccants (like silica gel or zeolite) or liquid desiccants (like lithium bromide/chloride) to draw moisture from the air to allow an efficient mechanical or evaporative cooling cycle.

Solvent

solventsorganic solventorganic solvents
Desiccants are also used to remove water from solvents, typically required by chemical reactions that do not tolerate water, e.g., the Grignard reaction.
Unless a desiccant is used which can destroy the peroxides, they will concentrate during distillation, due to their higher boiling point.

Humidity indicator

Sometimes a humidity indicator is included in the desiccant to show, by color changes, the degree of water-saturation of the desiccant.

Hygroscopy

hygroscopicdeliquescenthygroscopicity
A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant.
Owing to their very high affinity for water, these substances are often used as desiccants, also an application for concentrated sulfuric and phosphoric acids.

Absorption (chemistry)

absorptionabsorbentabsorbed
Commonly encountered pre-packaged desiccants are solids that absorb water.

Water

H 2 OHOliquid water
Commonly encountered pre-packaged desiccants are solids that absorb water.

Chemically inert

inertinertnesschemical inertness
Although some desiccants are chemically inert, others are extremely reactive and require specialized handling techniques.

Silicon dioxide

silicasiliceousSiO 2
The most common desiccant is silica, an otherwise inert, nontoxic, water-insoluble white solid.

Activated carbon

activated charcoalactive carbonactive charcoal
Other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves (typically, zeolites).

Zeolite

zeoliteszeoliticdachiardite
Other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves (typically, zeolites).

Percentage

percent%FG%
One measure of desiccant efficiency is the ratio (or percentage) of water storable in the desiccant relative to the mass of desiccant.