Page 255 - Demo

“Your Safer Source for Science”
Chemical Disposal Procedures
253
FLINN METHOD
FLINN METHOD
#22b Peroxides, Organic
Organic peroxides are particularly dangerous materials that are highly flammable and explosive. Peroxides are sensitive to heat, shock, friction, or contact with combustible materials. These materials are classified by the EPA as characteristic (reactive) hazardous wastes. Leftover organic peroxides may be hydrolyzed as part of an experi- mental procedure.
Examples
Benzoyl peroxide and lauroyl peroxide
Materials Required
Sodium hydroxide solution, NaOH, 3 M—tenfold volume excess of the material to be destroyed, in a large glass beaker
Plastic spoon (optional)
Glass stirring rod
pH paper
Hydrochloric acid solution, HCl, 6 M
Overview
When reacted with base, benzoyl peroxide and lauroyl peroxide (the only substances we catalog for which this procedure is suggested) will cleave between the two joined oxygen atoms and form sodium benzo- ate or sodium laurate, which are soluble in water and innocuous. Use care not to go past the neutral point when adding acid to the aqueous solution. If the solution is acidic, some benzoic acid may precipitate out.
(C6H5CO2)2 + 2NaOH → 2C6H5CO2¯ Na+ + O2 Procedure
1
#23 Sulfides, Inorganic
Inorganic sulfides release highly toxic hydrogen sulfide gas on treatment with acid. These materials are classified by the EPA as char- acteristic (reactive) hazardous wastes and may not be disposed of in the trash or drain. Leftover soluble inorganic sulfides may be oxidized as part of an experimental procedure.
Examples
Sodium sulfide, ammonium sulfide
Materials Required
Large glass beaker
Glass stirring rod
Sodium hypochlorite solution, NaOCl Sodium hydroxide solution, NaOH, 0.5 M
Overview
Inorganic sulfides are easily oxidized to sulfate ions using sodium hypochlorite as an oxidizing agent.
Na2S + 4OCl¯ → Na2SO4 + 4Cl¯
A small amount of base is added to keep the solution basic. A basic solution is needed because inorganic sulfides react with acid to produce highly toxic hydrogen sulfide gas and the hypochlorite ion is more stable at a higher pH.
The products from the reaction are sulfate salts which are nonvola- tile, odorless and have low toxicity. These materials can be rinsed down the drain.
Procedure
1
Perform this procedure in a fume hood. Wear chemical splash goggles, chemical-resistant gloves and a lab coat or chemical-resistant apron.
Perform this procedure in a fume hood. Wear chemical splash goggles, chemical-resistant gloves and a lab coat or chemical-resistant apron. Exercise caution working with dry organic peroxides—they are fric- tion- and shock-sensitive.
2
Carefully add a small amount of water and break up any lumps in the organic peroxide with a plastic stirring rod. Do not grind the dry solid.
3
Water
Organic Peroxide
2
Dissolve the inor- ganic sulfide in 0.5 M NaOH solution. For ammonium sul- fide, use 100 mL of NaOH solution for every 10 mL of sul- fide solution.
3
Slowly add sodium hypochlorite solution (bleach) to the inor- ganic sulfide. Add 200 mL bleach for each 10 mL of ammonium sulfide or 5 g of sodium sulfide.
Pour the material into
3 M sodium hydrox-
ide solution. Allow to
stand at least 24 hours,
stirring frequently.
Benzoyl peroxide has
low water solubility,
so frequent agitation
is important to bring the decomposition reaction to completion.
NaOH
Inorganic Sulfide
Bleach
Organic Peroxide
3MNaOH
pH Paper
4
Using pH paper as a monitor, neutralize the solution with 6 M hydrochloric acid.
5
6M HCI
Flush the neutral solution down the drain with excess water.
FLINN METHOD #23 continued on next page.