Acetone leaves a residue

subjects

Handling acetone

Acetone is highly flammable! Therefore, when working, it must always be ensured that there are no potential sources of ignition (electrical sparks!) If acetone vapors develop. The vapors can lead to drowsiness and fatigue if you are not in use for a long time. Due to its fat dissolving effect, acetone can make the skin rough and cracked. Therefore, skin protection should be ensured when working with acetone. Next Gloves If there is frequent contact, skin care with suitable care products also plays an important role.

Rooms in which Acteon is used must be good ventilated be.

application

Acetone is characterized by its solubility in fat and its low boiling point. The main application for acetone at the institute is the cleaning or degreasing of work equipment. But be careful, acetone dissolves Machine oil rather bad, on the other hand it is good e.g. Fingerprints and other grease loosened. It is therefore not suitable to clean workpieces that have come into contact with oil. In this case, acetone could even be counterproductive, as the adhesive forces can cause dirt particles to adhere permanently to the surface (source: Karl Brunn and Rolf Jensen Metal cleaning and degreasing).

If larger amounts of acetone are used up at work, it is a good idea to collect this extra. Acetone can easily be purified by distillation and reused as a solvent. For this purpose, I offer collection containers in the laboratory.

Substitutes

A disadvantage of all solvents is theirs relative low purity of the quality commonly used, e.g. compared to deionized water. Acetone is usually offered at 99.5%. If water does not destroy the items to be cleaned, it is a good, harmless substitute as a cleaning agent; if a surfactant is added to it in the first step, it dissolves oil and fat very well and can then easily be diluted with distilled water Remove water. It has the advantage over organic solvents that it dissolves inorganic salts more easily.

The residues frequently observed with acetone are against it no Pollution. This is usually water that has condensed due to the evaporating acetone and, during the condensation, leaves the dust in the air as an impurity on the surface.

For clarification, a table that compares the purity of acetone and water.

Distillation processTrace element content in µg / ml
 CuPb
normal least.0,20,055
once in Jenaer Glasapp least.0,00010,003
Ion exchanger0,00350,0015
Acetone p.A.27,8138,9

Even if the information on the p.A. Delivery maximum values ​​are so clearly recognizable that acetone never has the purity of distilled water. Water can reach. Also much more expensive purities e.g. for spectroscopy or for gas chromatography show higher levels of contamination.
In the chemistry laboratory there are both simply dist. Water from a Jena glass apparatus and deionized water are available.

Cleaning of metals

If water is to be avoided or the surface has to be extremely grease-free, there are various methods that are either better or more environmentally friendly than acetone.

A new method of cleaning metal surfaces is laser technology, with which the grease or other impurities such as e.g. Paint can be removed without leaving any residue. Whether this process is practicable for cleaning the desired metal parts depends on their surface and is e.g. not applicable to pipes.

But there are also solvents that are similar or better degreasing and more environmentally friendly, e.g. Orange oil.

Cleaning of glass

A common procedure in the chemistry laboratory to make glass parts free of grease is treatment with a concentrated lye (3M). In this way the surface of measuring devices (burettes or pipettes) can be made free of grease. The removed liquids then flow off without residue and the measuring accuracy is guaranteed.

A similar cleaning effect can be achieved with concentrated sulfuric acid. In addition to fat, almost all other organic contaminants - such as Dust - dissolved and removed. In doing so, the acid must be made hot (usually around 120 ° C). This can produce very toxic gases. Therefore, this type of cleaning should only be carried out with great care (gloves & protective goggles) and always under the hood.

(p) 2004 J. Strübig start