Contact person for the Institute of Physics: Anton Repko, room no. 191 in the main building (belonging to the Institute of Chemistry), tel. 02/59410 536.
- List and properties of chemicals employed at the Institute of Physics 2021 / version for printing, only the list
- Old system of warnings according to Council Directive 67/548/EEC and Commision Directive 2001/59/EC: R-phrases (nature of risks), S-phrases (preventive measures).
- New GHS nomenclature according to UN and Regulation (EC) No 1272/2008 of the European Parliament and of the Council: H statements (hazard notifications), P statements (precautionary instructions)
- Operating regulations for work with hazardous chemical agents (preliminary version in Slovak) / PDF
- Classification of dangerous properties according to EU + GHS symbols / PDF
- Chemical safety training / PDF
- Chemical resistance of gloves (latex, nitril, vinyl) / PDF
- Chemical resistance of plastics / PDF
supplements to the Operating regulations (in Slovak):
- Emergency plan for hazardous chemical agents / PDF
- List of hazadrous substances / PDF (extended list / PDF)
- Definition of corresponding H-statements and P-statements / PDF
Oxidizing substances (O)
- hydrogen peroxide, nitric acid, nitrates, potassium permanganate, perchloric acid
- they have to be stored separately from flammable substances; in the case of accident they tend to produce harmful smoke (in particular nitric acid), therefore I recommend to store them under fume hood (or inside it, it they are used frequently), or near the window
- waste with hydrogen peroxide can be decomposed by adding a small amount of potassium permanganate, but in case of acidic solution, it is necessary to neutralize it before, e.g., by sodium carbonate (otherwise the permanganate will dissolve and the reaction will cease); waste with halogens, chlorine water or hexavalent chromium can be reduced by ascorbic acid (vitamin C) or glucose; waste with nitrates and manganese componds are relativelly harmless
Very toxic substances (T+)
- have to be stored in a metal locker, separately from flammable stuff, and the corresponding responsible person has to have an inventory record (Book of toxic substances) for each substance, e.g., with a header: | record no. | date | accepted | issued | inventory amount | distributor | accepted by, signature | permit |. In the QUTE building, the person in charge (mainly for HF) is Peter Šiffalovič; in the main building (Institute of Chemistry) Ivan Sabo.
- in practice, we occasionaly use only hydrofluoric acid; I don’t assume any work with compounds of Cd, Hg, CrVI, Be, Ba, As, Se, Tl, U, CN‒, since we don’t have them anyway (in any case, below is given their neutralization to a less harmful form)
Neutralization and disposal of toxic substances
Hydrofluoric acid and soluble fluorides
It is a very dangerous chemical which, when spilled (even in dilute form), causes serious and irreversible skin corrosion, and possibly death, even without previous pain. The contaminated spot has to be rinsed immediately and thoroughly with water. Better still, immerse or wash the affected limb with a calcium salt solution (e.g. calcium acetate, lactate or gluconate; it should be available during any work with HF), even after washing with water. Other measures include application of calcium gluconate gel, drinking milk, or administration of calcium and magnesium tablets.
The fluoride ion precipitated by calcium into insoluble calcium fluoride (a harmless mineral fluorspar/fluorite, heat-resistant). If the precipitation is undesirable, a solution of sodium tetraborate (+ boric acid) can be used to neutralize the fluoride ion, but this reagent is less effective and slightly harmful to health, as are also the reaction products ‒ tetrafluoroborates ‒ which can then be disposed of after mixing with lime (then, insoluble fluoride and calcium borate are formed).
Mercury
In the case of breakage of a mercury-containing device, the spilled mercury should be collected in a closed container (it can then be handed over to company Safina free of charge). Contaminated surfaces should be sprinkled with powdered sulfur ‒ this produces mercury sulfide in the form of a black mass (red in its pure state). This is a stable mineral vermilion/cinnabarite that is only decomposed by aqua regia or incineration, so it must not be put in municipal waste. Iodine can also be used instead of sulfur (but the compound formed is more easily decomposed, and dissolves in KI solution).
Hexavalent chromium: chromates, dichromates, chromium(VI) trioxide
Solutions with hexavalent chromium should be acidified, e.g. with acetic, sulfuric or hydrochloric acid, and then alcohol (isopropanol, ethanol) or glucose should be added. Then wait until the orange-yellow colour disappears (the reaction may take several hours to complete). Solids are better disposed of by adding sulfur and melting (e.g. 6 g sulfur to 55 g K2Cr2O7) ‒ the product formed is harmless and can be disposed of in the bin; however, it should be checked beforehand to ensure that the yellow color is not leached out by water. Chromium(VI) trioxide can also be disposed of directly by careful thermal decomposition above 200°C in a larger glass container (in a fume hood!), in the absence of organic matter and other combustibles.
Soluble compounds of heavy metals: cadmium, mercury, lead, arsenic, thalium; partly affects also the less harmful metals (Mn, Co, Ni, Zn, Cu, Ag, Sb)
The addition of a soluble (ammonium, sodium) sulfide yields insoluble precipitates, but the initial sulfides are also toxic, and their excess dissolves As2S3, Sb2S3. As substitutes, EDTA, sodium thiosulfate or potassium rhodanide (thiocyanate; we don’t have it) can be used, producing soluble complexes with reduced toxicity. Compounds of cadmium, mercury and lead can also be neutralized to some extent by potassium iodide solution (in the case of mercury, lead and silver, a precipitate is formed, which (except for Ag) dissolves in excess KI). The preparation of soluble complexes can only be considered as a temporary measure (the solution cannot be poured off anyway). The combustion of sulfides releases the heavy metals back, so they have to be collected separately. Recycling of some metals is given below.
It may sometimes be advantageous to reduce the heavy metals from the original solution with zinc, thus reducing the volume of waste; however, this must not be used for arsenic, antimony and selenium, as toxic gaseous hydrides may form. Less harmful metals can also be precipitated with sodium hydroxide, and the precipitate is dried and then discarded or recycled.
Antidotes for the case of ingestion are EDTA, thiosulphate and activated charcoal.
Soluble anionic heavy metal compounds: vanadates, molybdenates, tungstates, arsenates, uranyl salts
The addition of quicklime or slaked lime (calcium oxide/hydroxide) precipitates insoluble calcium salts which can be discarded (except arsenic and uranium).
Other inorganic poisons
- Selenites can be reduced to elemental selenium (insoluble precipitate) using hydrochloric acid + potassium disulfite (do in a fume-hood!). Further, SeS2 can be precipitated with sodium sulfide in a slightly acidic environment (in a fume-hood!). Smaller amounts can be absorbed on iron hydroxide precipitate.
- Beryllium compounds ‒ there is usually a good demand for recycling; otherwise they need to be converted to oxide (e.g. using a slightly basic pH, or by annealing of the corresponding organic salt), which can be converted to insoluble form by high temperature (smelting with Al2O3+SiO2 leads to the mineral beryl). In the case of contamination of workplace by small amounts of beryllium dust, it is necessary to use vacuum cleaner with disposable filter and sack, and after vacuuming the workplace a small amount of cement or other siliceous powder is vacuumed as well. The filter and sack are then disposed with common waste.
- Soluble barium compounds ‒ the addition of a (sodium, potassium) sulfate solution precipitates insoluble harmless barium sulfate (baryte).
- Cyanides ‒ can be destroyed by the addition of hydrogen peroxide (to form cyanate, OCN‒) or sodium thiosulfate (to form thiocyanate, SCN‒). Less suitable is the addition of ferrous salt (a stable complex is formed); if trivalent iron (ferric salt) is also present, a blue precipitate is formed (can be used to indicate residual cyanide; but beware, thiocyanate forms a dark red color with trivalent iron).
Recycling of metals
Lead can be recycled by dissolution in nitric acid. Dissolution of lead iodide (needs at least 30% HNO3) produces also solid iodine. Insoluble lead sulfate can be converted to soluble state by first dissolving it in at least 10% NaOH solution, then the addition of NaHCO3 or NH4HCO3 will precipitate PbCO3, which is then flushed with water (liquid portions should be acidified with sulfuric acid to check for remaining PbSO4) and dissolved in nitric acid. The solutions in HNO3 are electrolyzed with platinum electrodes (at ca. 4 V), producing black lead oxide in a compact state at the anode (+), which is then collected. From the cathode (‒), fine lead twigs can be occasionally shaken off, which dissolve over time. The end of the electrolysis is indicated by absence of lead evolution at the cathode.
Silver can be dissolved in nitric acid and precipitated with (e.g. sodium) chloride. The precipitate of silver chloride is dissolved in ammonia (no other alkaline hydroxide must be added!) and reduced with zinc metal.
Gold (including precipitated nanoparticles) is first dissolved in aqua regia (a 3:1 mixture of hydrochloric + nitric acid), or by boiling in a solution of potassium permanganate in hydrochloric acid (do in a fume-hood!). The solution is filtered, a solution of Fe(II) sulfate or chloride is added, and then boiling produces a precipitate of pure gold.
Chlorinated organic solvents
These should be collected separately, especially if the chlorine is bound to the benzene ring. This also applies to non-chlorinated solvents in which there is a dissolved chlorinated organic impurity left from the reaction. The disposal company has to incinerate them in a special way so that dioxins are not produced. Small amounts can be destroyed by dissolving them in concentrated nitric acid, which is then diluted and electrolyzed with platinum electrodes until neutral reaction or ammonium smell (efficiency of the decomposition of organic compounds can be increased by the addition of silver). Chloroform can be left to evaporate.