StreifenInstitut

Removing of Spilled Chemicals

Here you will find hints how to remove chemicals which may cause a dangerous situation when they have been spilled. Please consider that this will not release you from your own liability to evaluate a concrete situation and to decide yourself what you should do best.

Generally there are the following methods:

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Volatile liquids dispose themselves.

If volatile liquids have been spilled in the lab just wait until they are evaporated. Leave the lab or close the fume hood respectively and come back if all is evaporated.

If bigger volumes of flammable liquids are spilled remove alle ignition sources (put out flames and switch off light and electrical equipment). Generally you cannot stand to breathe ignitable concentrations. In a typical lab with a volume of 220 m3 for example 10 l of diethyl ether have to be evaporated to deliver an ignitable atmosphere (equal distribution assumed). Already one-tenth of this concentration will cause dizziness. In reality the distibution of the concentration will be more complex because vapors of organic solvents are heavier than air and may indeed give ignitable concentrations close to the floor surface. On the other hand in the labs of the institute the air is (for that reason) also exhausted close to the floor. It is OK to switch of electrical equipment immediately after the liquid has been spilled, because the concentration in the air then is yet low.

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Use absorbents

In the literature you will find several absorbants to remove spilled liquids. Powders or granulated material designed for that purpose have the advantage to be chemically inert, so that no reaction will happen.

But how to remove powder or granulated material?

Generally you will need tools like a brush and a dustpan which will then be contaminated. A suitable alternative are cellulose sheets. Cellulose is a good absorbant and keeps its form when it is wet. So you can grab it with a pair of tweezers or crucible tongs an put it into a bin used for disposal. Just put one sheet onto the spilled liquid, wait until the sheet does not absorb any more liquid and then remove it and put the next sheet onto the liquit.

Consider that cellulose is not inert! In particular oxidizing agents like sulphuric acid, nitric acid or bromine never may be removed with cellulose!

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Sweeping of is often not the best way.

Quite often you will find the hint: "Sweep it up!" But what to do if the substance creates dust?

If the spilling of the compound has occured outside the fumehood the dust will go anywhere else - for example into your clothing!

It is not needed to dissolve the solid compound but if it is moistured with water it will not create dust any more.

If you pour or drop water onto the powder this will again create dust.
It is better to spray the water onto the powder.
Use a plant sprayer or an empty spray bottle of a household cleaner..

Do not treat compounds this way which may react with water - but maybe you can find other suitable solvents.

It is not necessary to use a dust-pan and a hand-brush to remove the wet powder. If you do not like to get more equipment contaminated just try to use cards - for example index cards to push the material together and even to remove it.

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Diluting is never wrong!

With sulphuric acid you may consider to look for an adsorbant, but with conc. hydrochloric acid or conc. nitric acid you should hurry up to stop the creation of the caustic vapors. Consider that conc. nitric acid is also a strong oxidysing agent and may ignite several materials.

All these acids can be deactivated by adding water. Since the spilled acids will be found as a thin film on a surface the heat developed by diluting the acids with water is perfectly transmitted. So do not fear spraying or boiling of the liquids when you dilute with water. Even chlorosulphonic acid will react moderately although in this case a lot of hydrogen chloride is developed which may enforce you to have a breathing protection if the mishap occurred outside of a fumehood.

The diluted acids may be neutralised with sodium hydrogencarbonate. Just spread the solid material onto the puddle until no more foaming is observed. Then you may remove the resulting salt solution with a cloth or wipe it into a floor drain. Consider that a lot of effort is needed to get the surface salt free again. You will have to wipe several times.

Minor volumes may directly flushed down the drain. Rinse with plenty of water.

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Keep cool!

A lot of people react hysterically if they hear "mercury".

Indeed it is labelled to be very toxic when it is inhaled, but it has a very low vapor pressure. This is the reason why all over the world only aproximately 10 people so far died because of a mercury intoxication.

Dangerous is a persistent intoxication over a long period of time. That is the reason why spilled mercury has to be removed thoroughly. You may do this courageously and without any breathing protection.

Spilled mercury can easily be brushed together - afterwards you will not detect any mercury at the brush. Further advice see regular disposal.

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