Drying samples and storing hygroscopic materials under atmospheric or vacuum pressure are done in desiccators, which are airtight containers.
Dehydrators or dehumidifiers are other names for them.
Additionally, heated samples and items like crucibles are cooled using a desiccator. A drying agent is employed.
Because hygroscopic materials are known to collect moisture if left outside of the work atmosphere, desiccators are essential for cooling and storing them.
What is Desiccator
Desiccators are reusable containers with sealable lids that contain desiccants for preserving humidity materials like cobalt chloride paper.
Desiccators are frequently used to shield hygroscopic or water-reactive compounds from humidity.
Every time a desiccator is opened, the contents are exposed to ambient moisture.
The process of lowering the humidity also takes some time.
Desiccators contain a hygroscopic material called desiccant, responsible for absorbing water molecules from samples.
Water molecules are trapped within the desiccant’s structure, preventing them from escaping back into the surrounding air.
Typical desiccants include
Silicon jelly: Silica is a porous, non-flammable substance that is harmless, non-toxic, and can hold water molecules inside its structure.
It is the desiccant that is used most frequently. When heated to 85°C, it can be used again.
Molecular sieve: A artificial, uniformly sized, porous, crystalline aluminosilicate is known as a molecular sieve.
The best desiccant is capable of releasing water molecules that have become trapped inside a fully saturated silica gel.
Calcium sulfate: Calcium sulfate is a multipurpose desiccant designed for laboratory use.
It is non-corrosive, non-toxic, chemically stable, and harmless.
Additionally, it does not readily release the adsorbed water when exposed to room temperature.
Types of Desiccators
Desiccators come in four distinct varieties. That is:
1. Normal Desiccator
Desiccators of this kind require manual operation and supervision.
It is adaptable since any desiccant can be used, depending on cost and convenience.
To dry out the chamber, a desiccant is placed beneath or on any shelf.
The desiccant becomes saturated with water molecules due to continuous desiccation.
Desiccant that has reached saturation has to be replaced or heated-regenerated. It is affordable and easy to use.
2. Desiccator for Gas Purg
inert gas is provided in a slow, continuous flow to reduce humidity much more quickly than desiccants.
Gas purge desiccators function by eliminating moist air and replacing it with dry gas.
It is adaptable because it gives users the choice to shut off stopcocks and use conventional desiccants in place of inert gas.
The gas input and outlet on the gas purge desiccator’s wall allow for gas movement.
They can create a dust-free atmosphere and quickly reach the desired humidity level compared to regular and automated desiccators.
3. Automated Desiccator
Due to its capacity to regenerate the desiccants, this desiccator requires less manual maintenance than the norm.
Automated desiccators’ electric heaters and fans prevent saturation and always maintain a low relative humidity level, which allows the desiccant to be continuously renewed.
As a desiccant, it uses silica gel particles.
These desiccants can endure countless cycles of regeneration. It follows a predetermined cycle of desiccation and regeneration
4. Vacuum Desiccator
A vacuum pump is used in vacuum desiccators to remove air and moisture. Utilizing a vacuum pump lowers humidity, which facilitates air removal from the chamber and lowers oxygen levels.
Vacuum desiccators’ stopcocks aid in removing the liquid or gas from the inside.
Desiccants may also be used to power it.
For long-term storage of items that can be harmed by air, a vacuum desiccator is the best option.
Additionally, it can be applied to vacuum distillation procedures.
It is adaptable because the stopper can be taken out so the vacuum pump can be disconnected, and ordinary desiccants can be used inside.
Desiccator Parts
The desiccator is made up of a number of components, including
1. Desiccator Chamber
A desiccator chamber can be square or round.
Desiccators in the round shape often feature one shelf and a domed top to add more vertical space.
Cabinet-style desiccators provide for better stacking, more storage, and easier accessibility.
They frequently feature several shelves. Glass, polypropylene, polycarbonate, or acrylic cabinets can be used to make it.
It is made to provide a low-humidity environment that is useful for drying heated objects and preserving samples over a long period of time without suffering damage from chemical reactions brought on by moisture or fungus growth.
They can have varied configurations, varying height, and width possibilities, and they can be vacuum or non-vacuum cabinets.
2. Lid
The lid is made of the same material as the chamber.
It is positioned on the chamber’s roof.
The interface between the lid and chamber is greased with silicone to preserve the airtight seal.
3. Desiccator plate
The chamber is lined with a pair of mesh or sieves.
Cuvettes, Petri dishes, and other objects are kept in the top perforated plate along with the samples that will be dry or preserved. The desiccant is kept in place by a bottom plate.
The plates may be made of polypropylene or stainless steel.
4. Stopcock
This component is found in vacuum desiccators, which use them to purge the chamber of air and moisture
5. Vacuum pump
It speeds up the drying process by pumping air and moisture out of the chamber. It only exists in vacuum desiccators.
Uses of Desiccator
1. To dry out substances like Sodium, Potassium, and oxalic acid that are added to common solutions.
2. For the storage of substances like soil, dissolved solids, and other things that demand continuous weighing under dry circumstances.
3. For the cooling and long-term preservation of crystals of sodium hydroxide and other hygroscopic substances.
4. For the purpose of drying heat-sensitive materials like proteins and bacteria
Safety precautions while using a desiccator
1. Do not place hot items straight in the desiccator. The vacuum that results from the heated chemicals heating the air inside the chamber makes it challenging to open the lid.
2. It is advisable to cool an ignited crucible or similar extremely hot object before putting it in the desiccator.
3. A desiccator can be used to remove water from a sealed container that is not safe to open. Using the desiccator could leave the item in for a day or two in order to dry it out.
4. The desiccator also works well with items such as electronics, where small amounts of moisture are trapped in the components. To remove these trapped areas, put them inside the desiccator and wait until they are completely dried out before transferring them back into their original vessel
5. A wet crucible or other wet materials should not be put inside the desiccator because they could damage the desiccant. Avoid putting anything where it will quickly lose moisture and lose its effectiveness. , such as under the lid of a jar. How long can it last?
6. The performance and life span of a desiccant depend on what they are used for. They are most effective when used periodically to recharge them as needed, but maybe good for up to six months.
