Sublimation Apparatus Information
Sublimation apparatus are glass laboratory devices that facilitate the transformation of solids to gases or vice versa. The transition happens without an intermediate change of state to liquids. The primary objective of the instrument is purification of compounds.
When a solid is placed inside the device and heated under reduced pressure or in a vacuum, it vaporizes and condenses on a chilled surface known as a cold finger. The vapors leave impurities behind, making the collection of the pure compound possible.
The method is performed on solids with vapor pressures below their melting points. The process offers minimal exposure to harmful gases and allows operation at low temperatures.
Sublimation apparatus are available in complex configurations engaging a temperature gradient. This promotes the crystallization mechanism along the cold surface. The technique is suitable for refining or isolating more than two elements or impurities from a mixture and enables the separation of compounds with different sublimation points.
The simplest sublimation apparatus model comprises a segment for positioning the substance. A cooler section or the cold finger positioned above it allows the purified material to collect. The process occurs in conditions of decreased pressure. The following are a few types of apparatus:
- Microscale sublimer: The unit is appropriate for solids weighing about 0.5 grams. The space between the lower tip of the cold finger and the bottom of the flask holds about 3 milliliters.
- Sublimation adapter: The device consists of a condenser and an adapter. The former is placed in a vertical position within the adapter in flasks or tubes. A stopcock controls vacuum in the system.
- Non-vacuum sublimation apparatus: The top portion of this instrument contains a condenser that is cooled by water. The lower part features a flat-bottom flask. A grease-free ring joins the sections. The inverted condenser serves as a funnel, where the product is collected. The apparatus includes a stainless steel clamp.
- Cryogenic sublimation apparatus: The tool incorporates a flat base that enables gentle heating on a hot plate. The condenser comes with a wide opening, facilitating use with dry ice or liquid nitrogen. A ring helps join it with the flask. The construction includes a horseshoe clamp.
Sublimation is used in a number of unique applications, including:
- Frost-free freezers: These units operate with the help of a fan and air circulation. Sub-zero temperatures and circulating air accelerate the transformation. This allows the air to remain dry. The freezer's walls and shelves remain ice free, although ice cubes continue to form.
- Dye sublimation: This approach is ideal for pasting color on objects such as paper. A small heater vaporizes the solid dye, and the vapors, in turn, solidify on paper. The technique delivers a good quality final product. Printers using the method give satisfactory results at low resolutions. A typical black and white laser printer contains sublimation dyes. The colors are copied onto objects such as hats, mugs, and metals.
- Freeze-dried substances: The technology helps produce materials, including tea, soup, and medications. Such elements are obtained by means of lyophilization. First, a liquid is frozen, and then it is heated slowly at reduced pressure.
How Sublimation Apparatus Work
The following steps illustrate how sublimation works using a standard apparatus:
- Place a small amount of solid to undergo the change at the base of the sublimation implement. The substance is inserted in powdered form that aids in accelerating the process.
- The cold finger must be positioned at the bottom of the sublimator. The element's placement must ensure zero contact with the product. In an ideal setup, the cool surface hangs from the top without touching the walls of the instrument.
- Start cooling the system by attaching the hoses at the relevant ends of the equipment and allowing chilled water to flow into the center tube. The step will push the hot water out of the side tube and bring the temperature down.
- Slowly create a vacuum.
- Once the mechanism is stable, heat the bottom of the device. After some time elapses, the energy will give rise to purified crystals at the bottom of the cold finger. The crystals can then be removed to recover the final product. The cold finger must be extracted out of the system with care, so the product is not contaminated.
Selecting Sublimation Apparatus
Numerous product designs, including dedicated configurations, are available today. Check manufacturer's specifications to determine if the technical parameters of the particular equipment are aligned with the intended operation.