Safety Reference
Flinn Method #6, continued 5
Filter or decant off the supernatant liquid. Flush the liquid down the drain with excess water.
6
Allow the solid to dry, place it in a plastic container, and send it to a landfill.
#8 Azides and Azo- Compounds
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                   FLINN METHOD
#10 Bases, Strong and Weak, and Basic Anhydrides
                   FLINN METHOD
Elementary neutralization of corrosive acid and base solutions is a generally allowed disposal procedure. Two simple rules should be followed. First, the neutralization process should be mild. Any strong acids or bases should first be diluted to a concentration around 1 M or 10%. Second, the final product must be near neutral (pH 5–9) before discharge to the drain. In this procedure, bases are neutralized with dilute hydrochloric acid.
Examples
Ammonium hydroxide, sodium hydroxide
Materials Required
Large glass beaker
Glass stirring rod
Ice/water slush (optional) Hydrochloric acid, HCl, 3 M pH paper
Overview
Bases react with acids in aqueous solution to form a salt and water. NaOH + HCl → NaCl + H2O
The neutral soluble salts formed are generally innocuous, and can be rinsed down the drain with water.
Procedure
1
Wear chemical splash goggles, chemical-resistant gloves, and a lab coat or chemical-resistant apron. Use a fume hood if neutralizing ammonia solutions.
 Metal azides require licensed hazardous waste disposal as described in Flinn Disposal Method #26c. Azides should NOT be drain-disposed. They react with lead and copper in drain lines, solder joints and brass fittings to form unstable and explosive products. Drain systems have been destroyed by such explosions. In addition, azides are not biode- gradable and will kill the necessary bacteria present in the digestion system of wastewater treatment plants. Stocks of these materials should be kept low. Sodium azide is a P-Listed acutely hazardous waste.
2
Prepare a dilute solu- tion of (1 M or <10%) base by diluting a more concentrated solution or dissolving the solid into water. Considerable heat may be generated when dissolving a solid base. Use an ice/ water slush if needed to dissolve solid sodium or potassium hydroxide.
3
When solution is complete, slowly add 3 M hydrochlo- ric acid until the mixture is neutralized. Check with pH paper. More heat may be evolved in the neutraliza- tion process.
4
                                                                                       FLINN METHOD
                 #9 Carbon Disulfide
Ice/Water Slush
pH Paper
          Carbon disulfide is a P-Listed acutely toxic hazardous waste (P022). Any discarded commercial chemical product containing carbon disulfide as the sole active ingredient will require licensed hazardous waste disposal. Proper management of P-Listed wastes is extremely important because institutions that generate more than 1 kg per month (in any month) of acutely hazardous waste will be subject to the most stringent requirements for listing, storing and reporting all their hazardous waste.
        Please...Read the Narratives
Important narratives precede these specific chemical disposal methods! Please read each narrative carefully! Do not use these procedures if you are not comfortable with the chemistry. Do not use these procedures without first consulting with your local government regulatory officials. These procedures may not be used in some jurisdictions. All procedures involve some hazards and risks. Once again...read the narratives that precede these specific chemical disposal methods.
 3M HCl
 Rinse the neutral mixture down the drain with a 20-fold excess of water.