Glovebox

A glovebox is a sealable plastic or glass box that can be isolated from atmospheric conditions. It has openings to which special gloves are fastened, through which a chemist can manipulate glassware and apparatuses inside the box.

Design

Gloveboxes tend to have a simple construction. Most have a prism or rectangular like shape. The walls are made of either plastic (polyacrylate) or glass. For economic and ergonomic reasons, many glovebox types only have one transparent wall, the other walls being made of either metal, such as stainless steel or another impermeable and chemically resistant material. The front window has two openings where special gloves made of butyl rubber or neoprene are fastened, through which the operator can manipulate the objects and reagents inside the glovebox chamber. The gas in a glovebox is pumped through a series of scrubbers to remove any contaminants. If nitrogen is required for the inert atmosphere, air is pumped through a series of molecular sieves to remove moisture and other gasses. The oxygen is removed by passing the air through a column containing hot copper metal which oxidizes. Other metals can also be used, though copper is cheaper and is easier to regenerate. If other inert gasses, such as argon are used, no special scrubbing is required, as it comes straight from the tank. Additionally, molecular sieves and oxygen scrubbing materials can also be added inside the glovebox if there's reasons to suspect the glovebox isn't airtight sealed.

On one side of the glovebox, an antechamber with two pressure doors is used to introduce/remove materials in and outside the glovebox. After introducing the material inside the antechamber, the outside door is closed. The air inside is flushed out with a pump and inert gas is introduced. This procedure is repeated 3-4 times. After the last insertion of inert gas, the inside door is open and the material is either taken inside with the help of the closest glove or some other mechanism, assuming the antechamber has one.

There are two main types of gloveboxes:

• Inert atmosphere gloveboxes, used for air sensitive chemicals such as organometallic compounds and alkali metals, that must be contained within a very high purity inert atmosphere.
• Hazardous substances gloveboxes, used for dangerous materials such as radioactive materials and biological cultures (infectious disease agents e.g.). Extremely toxic compounds, such as organophosphate compounds or certain poisons are also included in this category.

Inert atmosphere gloveboxes are typically kept at a higher pressure than the outside air, so that any microscopic leaks are mostly leaking inert gas out of the box instead of letting air in. On the other hand, hazardous substances gloveboxes are always kept at a lower pressure than the outside air, to prevent the leaking of any hazardous materials.

If the walls are thick enough and the gloves are well fastened, it is possible to create vacuum in the glovebox and perform various vacuum experiments. However, as explained by Adam Savage, it is extremely difficult to move your hand while wearing a glove pressurized at sea level inside a vacuum chamber.

DIY glovebox

You can make a simple glovebox out of air-tight plastic boxes, which can be found in many hardware stores. All you need to do it cut two holes for the large gloves and attach a gas inlet for inert gas, as well as an outlet to release the pressure.

For a more sturdier model, you can make one from various fluid impermeable materials, such as plastic, cement, glass, metal. For sealing the joints, use an adhesive which is water and solvent resistant and most important is not porous when hardened (does not increase in volume as it cures). Avoid using wood, unglazed ceramic, as these allow air to enter. If you're adding a door to the glovebox window, make sure you use clamps to hold it to minimize air diffusion.

While sandblasting booths are very similar in design to gloveboxes, you will need to redo the sealing in order to function as a proper glovebox, which is a lot harder than it seems.

Uses

Gloveboxes are very useful for an amateur chemist. First, they provide a compact, autonomous alternative to fume hoods when experimenting with toxic volatile compounds, such as hydrofluoric acid. A glovebox does not require bulky ventilation and electricity, it is easily mobile, one can perform the experiments, then carry the glovebox outside and open it there, exposing it to the wind and decontaminating it safely.

Second, a glovebox allows experimenting with substances hypergolic with air in an inert atmosphere. It can be filled with nitrogen or argon.

Third, a glovebox allows experimenting with certain radioactives, including most alpha-active isotopes, because both the box itself and the gloves provide adequate shielding from alpha radiation. Some gloveboxes are specially made for experimenting with radioactive materials and offer extra radiation shielding; such gloveboxes can be used to experiment with nearly any radioactives.

Gloveboxes are ideal for cultivating organisms, such as bacterial cultures and fungi, as it is easy to limit contamination. This is useful for biochemical research projects.

Safety

However, there is a hazard gloveboxes pose which fume hoods do not. Buildup of explosive gas mixtures, such as hydrogen and oxygen, or hydrogen and chlorine, is dangerously easy in a glovebox if you don't know what you are doing. In this case, a glovebox may explode.

A mad scientist with good enough technical skills can modify a glovebox, adding a simple system of forced ventilation to it, connected with the outdoors through rubber or silicon tubing, to which one can attach the box or detach and re-seal it. Such a device will remove this disadvantage of the glovebox and provide it with all advantages of a fume hood. However most gloveboxes have an overpressure release system so adding ventilation can be recommended.

Acrylic gloveboxes have the disadvantage of being susceptible to certain solvents, such as halogenated solvents and ethers. A glass panel may be glued inside the glovebox over the acrylic one, though this increases the cost and the complexity of the device. Likewise, fluorine and hydrofluoric acid vapors will also corrode the glass.

Relevant Sciencemadness threads

• Glove box oxygen and moisture removal
• Removal of Oxygen & Carbon Dioxide from Air (Glovebox Design)