Page 252 - Demo

Safety Reference Flinn Method #12b, continued
Procedure B: Nitrites
1b
Perform this reaction in a fume hood. Wear chemical splash goggles, chemical-resistant gloves, and a lab coat or chemical-resistant apron.
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FLINN METHOD
#13 Organic Sulfides, Mercaptans and Thioamides
Organic sulfides and mercaptans are toxic and should not be drain disposed. Because of their toxicity, they should only be disposed of by a licensed hazardous waste disposal company as described in Flinn Disposal Method #26c.
2b
Dissolve the inor- ganic nitrite salt in distilled water.
H2O
NH4OH
FLINN METHOD
3b
Add a 50% molar excess of ammonium hydroxide solution.
4b
Using pH paper to moni- tor the process, acidify the solution to pH 1 with 3 M hydrochloric acid. Stir for two hours.
5b
pH Paper
#14 Cyanides and Solid Metal Cyanide Complexes
All cyanides must be removed by licensed hazardous waste disposal. Cyanides are severe and rapid-acting poisons, being quickly absorbed into the body via the respiratory system, skin, eyes and mouth. Cyanides are identified as acutely hazardous, P-listed wastes by the EPA. They are also classified by the Resource Conservation and Recovery Act (RCRA) as characteristic hazardous wastes due to their reactivity with water to produce toxic hydrogen cyanide gas.
Compounds containing metal cyanide complex ions, such as potas- sium ferrocyanide or potassium ferricyanide, are generally considered non-toxic and are much less reactive than simple cyanide salts (see above). Complex iron cyanides may generate hydrogen cyanide in contact with concentrated hydrochloric acid or when heated. Nevertheless, both potassium ferrocyanide and potassium ferricyanide are classified as P-listed wastes.
The following detoxification procedure using bleach may only be applied to leftover solutions containing ferri- or ferrocyanide ions as part of an experimental procedure. The detoxification procedure may NOT be used to treat any cyanide-containing hazardous waste.
Examples
Potassium ferrocyanide, potassium ferricyanide
Materials Required
Large glass beaker
Glass stirring rod
Sodium hydroxide solution, NaOH, 3 M (twofold molar excess)
pH paper
Ice bath (optional)
Sodium hypochlorite solution (bleach)
Calcium hypochlorite solution, Ca(OCl)2, 30%
Overview
Ferro and ferricyanides are much less toxic than cyanide salts and are oxidized to cyanates by hypochlorite. A 50% molar excess of bleach is required to assure complete destruction.
CN¯ + OCl¯ → OCN¯ + Cl¯
Commercial bleach (5.25% sodium hypochlorite) or a 30% calcium
hypochlorite solution can be used for this procedure.
Procedure
1
Perform this procedure in a fume hood. Wear chemical splash goggles, chemical-resistant gloves, and a lab coat or chemical-resistant apron.
3M HCl
Check the pH of the solution and neutralize to pH 5–10. Rinse the solution down the drain with excess water.
FLINN METHOD #14 continued on next page.