Elementary Neutralization

Elementary neutralization is an effective way to minimize or eliminate the production of corrosive chemical waste. The major concern about neutralization is the potential for the heat of reaction to get out of control. If it does, there can be a violent reaction or splashing of corrosive liquids. The procedure described here should help to control the heat.

Concentrated sodium hydroxide is good for neutralizing dilute acids. Many of the carbonate compounds work well also, but splattering can occur because of the production of relatively large amounts of carbon dioxide as a byproduct. Concentrated hydrochloric acid or sulfuric acid works well for neutralizing bases. Avoid a neutralizing agent that will result in a precipitate being formed.

Common mineral acids, hydroxides and acetic acid are the simplest corrosives to neutralize. Waste corrosive liquids suitable for neutralization should not contain other constituents, such as heavy metals, that would cause them to be regulated as hazardous wastes even after neutralization

If you have not done this before, keep the quantities small and work with familiar chemicals, then carefully scale up the treatment procedure to handle larger quantities.

Neutralization Procedure

1. Prepare plenty of neutralization agent. Be sure that you have enough spill control materials available in the event of a spill or splash.
   
2. Put on personal protective equipment, including gloves, safety goggles, face protection and an apron. When at all possible, work in a fume hood.
   
3. Dilute the corrosive material to a concentration of less than 5% by adding it to water, not the other way around. This will help control the heat of reaction.
   
4. Add the concentrated neutralization agent slowly and carefully until the pH is between 4 and 10. If heat is still a problem, add ice to the original solution.
   
5. As long as there is no precipitate, pour the solution down the drain.
   

For more information, contact James Boehlert at 258-7882.