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FLINN METHOD
#27c Licensed Hazardous Waste Disposal
Many hazardous laboratory wastes require licensed hazardous waste disposal. It is
important to choose a licensed and reputable firm. Please read the introduction on
page 735 for more information on choosing an acceptable disposal firm. Remember
that the school has cradle-to-grave responsibility for its chemicals—documented
proof that the chemicals have been properly disposed is required.
Ask for and check references to make sure the firm is reputable and reliable.
Do not automatically choose the low bid!
Request a certificate of disposal for the chemicals.
Prior to licensed disposal, segregate and store hazardous waste in chemically
resistant containers that are free of leaks or residues. Keep containers tightly
closed at all times except when adding or removing waste. Label each container
“Hazardous Waste” and add the name (identity) and amounts of all chemicals added
to the container, along with the accumulation start date (the date you begin collecting
waste in the container). Do not mix different types of characteristic hazardous
wastes as unpredictable reactions may occur, generating heat and pressure inside
the container. Check the chemical computability of all chemicals added to a waste
container.
FLINN METHOD
#27a Scrap Metals
Some metals may have commercial value as scrap. If you do not wish to retain
them, try to sell them. Otherwise dispose of them according to Flinn Disposal
Method #26a.
FLINN METHOD
#27b Mercury Metal
Procedure
Mercury metal must not be disposed of by any means except to return it to a
supplier for recycling. Mercury Waste Solutions, Inc. (1-800-741-3343) is a major
mercury recycler and may be a disposal option. Under no circumstances should any
other method of disposal be attempted. Metallic mercury is never buried, burned,
placed down a drain or otherwise put into the environment. Mercury compounds
also require licensed hazardous waste disposal according to Flinn Disposal Method
#27f.
FLINN METHOD
#27c Phosphorus, Red and White (Yellow)
Phosphorus is a highly reactive and very flammable material. White phosphorus
is pyrophoric, a poison and ignites spontaneously in air. Red phosphorus is not
pyrophoric, but it is very flammable and can react explosively with strong oxidizing
agents. Both chemicals must be handled with extreme caution and disposed of by
a licensed hazardous waste disposal company.
FLINN METHOD
#27d Antimony, Vanadium and Their Compounds
Antimony and its compounds are toxic and may be harmful to the environment.
The vanadium compounds vanadium pentoxide and ammonium meta-vanadate
are classified as P-Listed acutely hazardous toxic wastes and require licensed
hazardous waste disposal. Proper management of P-Listed wastes is extremely
important. Institutions that generate more than 1 kg per month (in any month)
of acutely hazardous waste will be subject to the most stringent generator
requirements for all their hazardous wastes. They should be disposed of properly
by a licensed hazardous waste disposal company according to Flinn Disposal
Method #26c.
FLINN METHOD
#27f Heavy Metals and Their Salts and Compounds
Heavy metals require licensed hazardous waste disposal. The heavy metals listed
here are classified by the EPA as toxicity characteristic hazardous wastes based
on the Resource Conservation and Recovery Act (RCRA). Landfill disposal of heavy
metals and all of their compounds is generally prohibited and subject to strict
regulatory limits for the amount or concentration of the metal or metal ion that
may be disposed. The regulatory limits are defined based on a test (laboratory
procedure) called the Toxicity Characteristic Leaching Procedure (TCLP). TCLP
limits for the various heavy metals in this category are included in the following
list. Aqueous solutions of heavy metal ions are also restricted from sewer (drain)
disposal by most publicly owned treatment works (POTW). Check with your local
POTW for sewer discharge limits that apply in your area. General guidelines for
hazardous waste disposal are described in Flinn Disposal Method #26c.
Metal TCLP regulatory level
Barium (Flinn Method #27h) 100 mg/L
Cadmium 1 mg/L
Chromium 5 mg/L
Lead 5 mg/L
Mercury (Flinn Method #27b) 0.2 mg/L
Silver (Flinn Method #11) 5 mg/L
FLINN METHOD
#27h Barium Compounds
Soluble barium salts are extremely toxic and are classified by the EPA as
characteristic (toxic) hazardous wastes. Aqueous solutions of barium salts may be
precipitated in the form of barium sulfate to reduce the volume of hazardous waste
requiring disposal.
Examples
All barium salts (i.e., barium nitrate, barium hydroxide, barium chloride)
Materials Required
Sodium carbonate, Na2CO3
Sulfuric acid, H2SO4, 3 M
Filtration apparatus (optional)
Glass stirring rod
Large beaker
pH paper
Wide-mouth plastic container with screw top
Overview
Barium sulfate is highly insoluble. This procedure produces barium sulfate in an
acidic solution. Note that the only acid that will work in this procedure is sulfuric
acid. The acid serves a double purpose in the case of barium hydroxide and barium
peroxide in that it neutralizes the hydroxide ion in addition to its primary purpose of
furnishing sulfate ion to react with the barium ion. Once the precipitation reaction
is complete, the solid is separated from the supernatant liquid and any excess
acid is neutralized with sodium carbonate. Solid barium sulfate requires licensed
hazardous waste disposal. See the general guideline in Flinn Disposal Method #26c.
The neutralized supernatant should be tested for residual barium and may be rinsed
down the drain with excess water.
Ba+2 + SO4–2 → BaSO4 (solid)
2H+ + CO3–2 → CO2 (gas) + H2O
Procedure
1
Wear chemical splash goggles, chemical-resistant gloves and a lab coat or
chemical-resistant apron.
FLINN METHOD #27h continued on next page.