Spills of Sodium Cyanide

Numerous accidental spills of sodium cyanide or potassium cyanide into rivers and streams have resulted in massive kills of fishes, amphibians, aquatic insects, and aquatic vegetation. Sources of poisonings were storage reservoirs of concentrated solutions, overturned rail tank cars, or discharge of substances generating free HCN in the water from hydrolysis or decomposition (Leduc... 

As in the case of most accidental spills, Eq. (39.6) would be the reaction since the water is generally not above 50°C. Thus, a spill of sodium cyanide in water would form hydrocyanic... 

The number of reported spills of sochum cyanide from 1974 to 1995 was extracted from the same NATES databank. It can be seen in Fig. 39.3 that no more than 2 spills of sodium... 

FIGURE 393 Number of sodium cyanide spills from 1974-1995. (Source Environment Canada, 2000.)... 

Bunding, drainage, spill recovery and spill neutralization. For example, floor and drain design must ensure no build-up of toxic or flammable vapours. Stores of sodium cyanide may require that ferrous sulphate is kept on hand for neutralization. 

Amounts allowed range from 5 ppm in cucumbers, lettuce, radishes, and tomatoes, to 250 ppm in spices. EPA also requires industries to report spills of 1 pound or more of potassium silver cyanide and 10 pounds or more of hydrogen cyanide, potassium cyanide, sodium cyanide, calcium cyanide, or copper cyanide. 

Potassium Cyanide Solutions. Wear breathing apparatus, eye protection, laboratory coat, and butyl rubber gloves. Instruct others to keep a safe distance. Cover the spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. Scoop the mixture into a container and transport to the fume hood. Slowly, and while stirring, add the slurry to a pail containing household bleach (about 70 mL/g of cyanide). Test the solution for the presence of cyanide using the Prussian blue test. To 1 mL of the solution, add 2 drops of a freshly prepared 5% aqueous ferrous sulfate solution. Boil the mixture for at least 60 seconds, cool to room temperature and add 2 drops of 1 % ferric chloride solution. Add 6 M hydrochloric acid (prepared by... 

Wear nitrile rubber gloves, laboratory coat, and eye protection. In the fume hood, add to a 1% solution of sodium hydroxide (about 50 mL/g of cyanide). While stirring, slowly add household bleach (about 70 mL/g of cyanide). Continue as for solution spills.4,6,7... 

Solid Sodium Cyanide. Sweep the sodium cyanide into a container and transport to the fume hood. Add to a solution of 1% sodium hydroxide (about 50 mL/g of cyanide). Slowly add the cyanide solution to household bleach as per waste disposal procedure. Wash spill site thoroughly with soap and water.4 6... 

In the event of a spill, remove all ignition sources, soak up the sodium cyanide or potassium cyanide with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area. 

Cyanide spills in general were tracked using data from National Analysis of Trends in Emergencies Systems (NATES) for 1974 to 1995 (Environment Canada, 2000). This is shown in Eig. 39.3 and includes spills of cyanide leachates, sodium cyanide, cyanide not otherwise specified (nos), and cyanide/copper tailings. As can be seen in Fig. 39.4, cyanide nos is the largest of the spills and may contain any cations with cyanide or the cyanide ion itself. 

Environment Canada. 1984. Sodium Cyanide, in Manual for Spills of Hazardous Materials, Environmental Protection Service, Environment Canada, Ottawa, ON. 

Have the materials on hand to absorb or neutralize erqrected spills, e.g. stores of ferrous sulphate in areas where sodium cyanide is transported, and ozone injectors on a stream where cyanide contamination from transport spills in a watershed coirld occirr. 

Other sources of hazard arise from the handling of such chemicals as concentrated acids, alkalis, metallic sodium and bromine, and in working with such extremely poisonous substances as sodium and potassium cyanides. The special precautions to be observed will be indicated, where necessary, in the experiments in which the substances are employed, and will also be supplied by the demonstrator. The exercise of obvious precautions and cautious handling will in most cases reduce the danger to almost negligible proportions. Thus, if concentrated sulphuric acid should be accidentally spilled, it should be immediately washed with a liberal quantity of water or of a solution of a mild alkali. 

Before the spill, the pH level of the river was probably less than 9. Most of the dissolved cyanide would therefore have formed hydrocyanic acid (HCN), a toxic gas that would have dissipated into the air. After a few hours, sodium hypochlorite was added, which would have resulted in the formation of cyanate and cyanogen chloride. Cyanogen chloride can cause throat and eye irritations and, being heavier than air, could have traveled significant distances from the spill (Moran, 1998). 

When 200 L of cyanide were spilled into the River Wey in Surrey, England in May 1999, peroxide was added to the river to save the fish. The peroxide breaks down into water and oxygen and raises the pH of the polluted water, causing the cyanide to break down more rapidly. The fish were saved by the additional oxygen added. The Environment Agency s Thames Region now includes peroxide crystals, or sodium carbonate peroxyhydrate, in their response kits for cyanide spills (OSHS, 1999). 

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