Page 259 - Demo

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Chemical Disposal Procedures
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FLINN METHOD
FLINN METHOD
#26c 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 for more information on choosing an acceptable disposal firm. Remember that the school has cradle-to-grave respon- sibility 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 hazard- ous 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.
#27f Heavy Metals and Their Salts and Compounds
Heavy metals require licensed hazardous waste disposal. The heavy metals listed below are classified by the EPA as toxicity charac- teristic 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 regula- tory 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 list below. 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.
FLINN METHOD
TCLP regulatory level
100 mg/L 1 mg/L
5 mg/L
5 mg/L 0.2 mg/L 5 mg/L
#27a ScrapMetals
FLINN METHOD
Metal
Barium (Flinn Method #27h) Cadmium
Chromium
Lead
Mercury (Flinn Method #27b) Silver (Flinn Method #11)
#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
Large beaker
Glass stirring rod
Sulfuric acid, H2SO4, 3 M
Filtration apparatus (optional)
Wide-mouth plastic container with screw top pH paper
Sodium carbonate, Na2CO3
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 neutral- izes 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.
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.
#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.
#27c Phosphorus,RedandWhite(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 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.
#27d Antimony,Vanadium,andTheirCompounds
FLINN METHOD
FLINN METHOD
FLINN METHOD
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 require- ments for all their hazardous wastes. They should be disposed of properly by a licensed hazardous waste disposal company according to Flinn Disposal Method #26c.
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.