Cleaning Up Spills of Mineral Acids and Bases

This method was developed by Margaret-Ann Armour, Assistant Chair of the Chemistry Department at the University of Alberta.

By following the procedures outlined below, the aqueous solution is neutralized and the acids and bases are converted to their salts according to reactions 1 and 2

HX + NaOH ==> NaX + H2O (1)
MOH + HCl ==> to MCl + H2O (2)

Materials Needed

See Table 1 for approximate quantities.

• Spill mix may be prepared by mixing equal volumes of sodium carbonate, bentonite (clay cat litter) and dry sand. The sodium carbonate helps to neutralize the spill, the bentonite absorbs the liquid and eliminates fumes, and the sand moderates and smothers any reaction that might occur.
• Cold water
• 5% aqueous sodium hydroxide or 5% aqueous hydrochloric acid

Procedures

1. Cover the spilled material with enough spill mix to absorb all of the liquid.
   
2. Fill a plastic pail ¾ full with cold water. Add the spill mixture. Place in fume hood.
   
3. Test the pH of the solution. If the pH is less than 5, add solid sodium carbonate or 5% aqueous sodium hydroxide to neutralize it. If the pH is more than 9, add 5% aqueous hydrochloric acid to neutralize it. Stir the mixture thoroughly.
   
4. After the solids have settled, decant the neutral aqueous liquid to the drain.
   
5. Discard the solid residue in the regular laboratory trash or dry it and reuse it in a spill mix.

Table 1. Quantities of spill mix required to absorb 100 mL of some mineral acids and bases, and volumes of acid or base required to neutralize the resulting aqueous solution.

For more information, contact Robin Izzo or Steve Elwood at 258-5294.