Can I throw away hydrochloric acid?

Emergency disposal of chemicals

Waste is never composed in an exactly reproducible way. Your chemical waste originated in your area of ​​activity, which is why you should be best able to know and assess its composition. The information given here has been compiled to the best of your knowledge and belief, but it is your responsibility to assess whether this information is sensible and safe to use in your specific case. Existing disposal regulations that you have made with disposal companies or your school administration take precedence over the information given here in the event of a conflict! Notes, feedback and questions are welcome.

We are introducing some types of waste to you here by way of example and want to use them to record ways in which waste can be disposed of correctly. You must decide for yourself whether it makes sense to manage the type of waste described below at your facility based on the amount of waste you generate.

Please note the list of chemicals that may not (no longer) be used at the school!

Even if chemicals are spilled, they must be cleaned up. The problem: It is now only a matter of secondary importance to dispose of the chemicals correctly and in an environmentally friendly manner; the primary objective is to avoid health hazards that arise from exposure of the people involved.

After such an incident, you may have to act very quickly and not make any mistakes! Problematize the problem among your colleagues and determine measures and write them down (operating instructions!). With the help of these operating instructions, you not only refresh your knowledge of the necessary measures yourself, but also instruct the future trainee teachers on the basis of these instructions!

Absorbent materials

You can pick up spilled liquids in one of the following ways:

  • Rag
    Suitable for water-soluble substances, the quantities found can be thrown into the sink with a clear conscience by wringing out your rag and rinsing with fresh water.

  • cellulose
    Suitable for organic liquids. If the liquid is not volatile, the wetted cellulose is placed in a disused wide-necked jar (preferably made of plastic) and sealed. If the liquid evaporates, it is best to let it flash off in the fume cupboard. Used pulp is disposed of as operating waste. You should always have plenty of pulp in stock for emergencies. A 5 kg package with 60 x 40 cm cellulose sheets is not too much and it is also not expensive! Cellulose is not suitable for absorbing strong oxidizing agents! With highly concentrated nitric acid there is a risk of ignition!

  • Vermiculite
    Vermiculite is a very inert, absorbent mineral, which is therefore used for the safe packaging of hazardous substances for transport. Whenever you receive an ordered liquid chemical in a tin can, after which you have to laboriously peel the bottle out of strange brown crumbs, you are dealing with vermiculite, which would have absorbed the contents of the bottle if it had broken. Do not throw these crumbs away, but collect them in a large container! If something is spilled, the vermiculite gives you another alternative to absorb a spilled liquid without having to worry about the liquid reacting with the vermiculite.

When picking up spilled hazardous substances, do not touch rags or cellulose with your bare hands! You even need a very robust skin protection when picking up hazardous substances, because you have to handle the mud with your hands. You can achieve a very good protective effect if you put on household gloves over disposable gloves, i.e. each hand with you two Protect gloves. There is absolutely no harm in keeping a pair of particularly chemical-resistant protective gloves on hand for such cases. A suitable material is, for example, "Viton". However, such a pair of gloves costs at least € 40.

Even when wearing gloves, avoid direct contact as much as possible! Pulp or rags can also be pushed back and forth with crucible tongs. On the floor, a scrubber helps to push the edging materials around. Be careful not to step on any areas of the floor that are still contaminated! Otherwise you will spread the problem over a wide area! Also, make sure that when you stoop or bend over work surfaces, no parts of your clothing come into contact with contaminated areas!

Low-boiling organic solvents, e.g. diethyl ether

Low-boiling solvents dispose of themselves faster than you can handle, but they pose a risk of explosion. If you leak a bottle of diethyl ether, there is no such thing right away a risk of explosion, because the ether has to evaporate first. So you can and should (!) - however instantly - remove all sources of ignition. It depends on the amount spilled in which area you have to remove the sources of ignition. Don't just think of Bunsen burners, but also electrical devices, e.g. magnetic stirrers, and in the worst case, the refrigerator. Just pull the plug if that goes faster! It's good if you have an emergency power switch: press it boldly!

Diethyl ether has a lower explosion limit of 50 g per cubic meter of air. Let's assume your chemistry room is 7 m wide, 15 m long and 3 m high: That would result in a volume of 315 m3. If, in the event of an accident, you were to evenly mix the ether vapor developed with the room air with a large propeller, you would have to spill a total of 15.75 kg or 22 l. That sounds reassuring at first. Unfortunately, ether vapor behaves quite differently: It is heavier than air and therefore preferably sinks to the ground and spreads there. The air can therefore easily become explosive near the ground, even in distant places! Is the door to your preparation room open at the moment? It can be good or bad if the ether vapor spreads there too. It is good if the problem is diluted and more diverse ventilation options are available. Bad if there are other ignition sources in the adjoining room, all of which have to be switched off first.

The first systemic effects (dizziness) set in at a breathing air concentration of 2000 ppm. With even distribution by means of a propeller, this concentration would be reached with the evaporation of 1.9 kg or 2.7 l. You can already smell the ethereal smell when only 1/100 of this amount is evaporated. It follows:

  • If you smell the smell of ether, you don't necessarily fall right away passed out!
  • Before the ether / air mixture explodes, you will be passed out for a long time!

So the health-threatening problem is urgent. The measures are: all-students-out-immediately-in-between-the ignition sources-off, -all-windows-open, -then-after-the-students-and-close-the-door-behind-them-and-that -all-swiftly !!

Practice this with your students as part of the safety briefing!

Of course, there are also less dramatic cases: If you spill 100 ml of diethyl ether in the fume cupboard, simply close the sash, pull out all the plugs of the electrical devices operated there and wait, bored, until the ether has evaporated by itself.

Higher-boiling organic solvents, e.g. toluene

The same applies as for low-boiling solvents: They can ignite and they are harmful to health. It all only takes a little longer because they don't develop solvent vapor as quickly as low boilers. Determine whether the spilled solvent with the H-phrases H224: liquid and vapor extremely flammable; H225: Highly flammable liquid and vapor. - or whether it is only with the H-phrase H226: Flammable liquid and vapor. is classified. In the latter case, the flash point is above room temperature and the substance cannot generate any ignitable vapor / air mixtures at room temperature.

You will find the slower steam development good for now. But once you have cleared the room, this becomes a problem because it takes a correspondingly long time for the solvent to evaporate voluntarily. If someone is to go in and clean up the spilled liquid, that person will need respiratory protection. Without training and a medical proficiency test, however, you are not allowed to work while wearing respiratory protection. So you would have to inform the fire brigade.

High-boiling solvents, e.g. ethylene glycol

As a rule, there are no longer any risk of inflammation. The health hazard from inhalation also takes a back seat. What should be considered now is a possible health hazard from skin contact, because the oily stuff does not evaporate by itself - you have to absorb it yourself. How you need to protect yourself depends on the individual case. Please note the above information. Basically, cellulose is well suited for absorption. High-boiling water-soluble liquids that are not hazardous substances (e.g. glycerine) are of course best picked up with a cloth.

Acids

  • The motto: "Never put the water on the acid, otherwise the monster will happen" loses its validity when sulfuric acid (... and all other acids) is spilled, because the acid pool experiences excellent cooling through the underground and will not splash, if you dilute with water!

So diluting spilled concentrated acids with water is never a bad thing. Smoking hydrochloric acid then no longer smokes and concentrated sulfuric acid loses its oxidation potential. If you want to neutralize a spilled acid after diluting it, never use caustic soda! You can never distribute the lye evenly over the puddle in such a way that the acid is "titrated" everywhere up to the equivalence point. Use sodium bicarbonate! Where the puddle is still acidic, the hydrogen carbonate foams when it is added. If it is no longer acidic, the hydrogen carbonate will no longer do anything. Be prepared for the fact that e.g. 1/2 l of spilled sulfuric acid will produce an enormous amount of salt. Even after careful wiping, you will notice that salt crusts remain when the surface is dried. So you will wipe again - and you will still find salt residue as you dry it. You will have to wipe quite often!

If you brush away a splash of sulfuric acid with pulp, it doesn't matter if the pulp turns black and decomposes. However, cellulose is not suitable for absorbing large amounts of sulfuric acid! Better dilute and take a rag! For personal protective equipment, please note the instructions above!

If you have spilled so highly concentrated nitric acid that brown nitrous gases rise, you have as long as you can hold your breath for all of your measures, because the nitrous gases are extremely damaging to the lungs! Nevertheless, immediate dilution with water is very important. The dilution not only stops the formation of nitrous gases, but also the very strong oxidation effect in high concentrations! If highly concentrated nitric acid is spilled, there is an acute risk of fire, e.g. with dirt lying on the floor (under the furniture!). So: first right away dilute with water! After that, feel free to take a while to discuss how the puddle should now be removed.

Alkalis

The same applies analogously as with acids: Highly concentrated products are first diluted and then absorbed. Caustic solutions have the disadvantage of producing a soapy, greasy film on surfaces. So contaminated floors are slippery. According to the RiSU (III-2.6.1) you can sprinkle sodium hydrogen sulfate on the spilled liquid for neutralization. In contrast to the neutralization of spilled acids with sodium hydrogen carbonate described above, there is no end point control here and you can also poorly mix the puddle. The likely result will be that the spilled liquid is already acidic in some places and still basic in other places. According to RiSU, you can also use sodium hydrogen carbonate as an alternative. This will dull strongly basic solutions, but will not be able to completely neutralize them. Careful hand protection when absorbing the liquid is therefore particularly important here.

bromine

According to DGUV information 213-098 (list of substances for the RiSU), schoolchildren are not allowed to have anything to do with pure bromine. Solutions of the elementary bromine in hexane or in water ("bromine water") are more safe to handle. You only have to deal with the pure bromine when you take the storage bottle out of the poison cabinet and put it in the fume cupboard to prepare new solutions. Nevertheless, accidents involving bromine always happen in schools!

We describe the handling of bromine, including the emergency measures, on a separate page.

Spilled solids

You will be able to sweep up a lot of solids. If you are dealing with spilled hazardous substances that you do not want to have leftovers on the hand brush, you can, for example, wipe up with index cards and record them. You should have a few index cards (well suited: DIN a5) on hand for this purpose. Dusty hazardous substances are easier to handle when they are moistened - even those that do not dissolve in water. It is important not to moisten with a hard jet of water (squirt bottle!), But with gently sprayed water (e.g. flower sprayer or empty household cleaner bottle). Substances that react strongly with water (e.g. lithium aluminum hydride) may only come into contact with water after most of it has already been recorded dry, e.g. with index cards or if the surface is only lightly "powdered".

mercury

Do not be fooled by the H-phrase "H330: Danger to life if inhaled." intimidate. Mercury has such a weak vapor pressure at room temperature that you are not in acute danger if you bend over a puddle of mercury. Still, mercury is very dangerous. Namely, it accumulates in the body. So if you inhale the mercury for days, weeks and months, you will suffer an excruciating death! Spilled mercury must therefore be completely removed!

Droplets of mercury that have fallen on the floor burst into countless small droplets on impact, which can be spread over a wide area due to the kinetic energy. However, mercury is easy to sweep up. So sweep up a large area with a hand broom (mercury usually does not adhere to the broom bristles). As a rule, you can then sweep the mercury onto a dustpan and then dispose of it. Even if no mercury residues can be seen afterwards on the hand broom and garbage dump, they should be kept in a well-ventilated place.

Even if mercury cannot be pipetted, small droplets can still be sucked up with a pipette (plastic disposable pipette). So this is another way of picking up spilled mercury, but it is tedious because you have to pick each droplet of mercury one by one.

  • Mercury must always be disposed of separately from all other types of waste! Even if your waste mixture contains quite a bit of other and very little mercury, e.g. quite a lot of ground waste with very little mercury, it remains a mercury waste! Label the collection container in a comprehensible way (e.g. "ground waste containing mercury")

  • Never think of throwing sulfur, zinc powder or iodine carbon on any spilled mercury !! You do not achieve anything - at least nothing positive! Everything poured on top does nothing to the mercury but only increases the amount of waste and thus the disposal costs and the effort to get the surface clean again! Defend yourself energetically against so-called "old hands" who now want to stand by your side with various powders from your chemical collection !!

It is true that zinc, for example, amalgamates with mercury, but it must have a shiny metallic surface for this. In the air, however, zinc is coated with a passivating oxide layer.

You can see the ineffectiveness of sulfur in a video. (Unfortunately, experiments are carried out very carelessly, namely on a desk without a safety tub.)

Iodine carbon can, in fact, be mercuryfumes adsorb. However, it is ineffective against liquid mercury.

A working absorbent to pour on is "Mercurisorb". However, it is quite expensive and the mercury can be easily removed without this aid.

If the mercury is spilled on the work surface, you can sweep it up with a flat bristle brush (as used in art class). Tools with small mercury droplets can also be cleaned in this way. Anyone who handles mercury should have a bristle brush as an emergency aid in advance! If there are nooks and crannies in a contaminated device, you can put it in a large bowl and wash the small droplets out of the squirt bottle with a little ethanol. The solvent is then decanted and the collected mercury can then be disposed of.