Neutralizing Citranox for Waste Disposal

Q. We manufacture electronics and use Citranox to clean oil off of a variety of machined parts. However, our Municipal Water District does not allow the disposal of spent Citranox. Can you recommend a neutralizing procedure?

A.  Citranox® Liquid Acid Cleaner and Detergent is indeed a good choice and widely used across the electronics industry for its ability to remove both organic and inorganic residues (conductive salts, oxidation, etc.).

You will need 0.14 lbs, 0r 2 ¼ oz of baking soda (sodium bicarbonate) to neutralize a gallon of unused 1% Citranox solution to a pH near 7.    Note that some of the acidity in Citranox may be depleted by your cleaning process.  Consequently, this neutralization recipe results in a conservative recommendation that may use slightly more baking soda than might be needed.   You gain a higher confidence that you will in fact be above pH 6 as a result. A little overdosing of baking soda might cause the pH of the solution to rise as high as 8.5, but is not likely to rise much beyond that.  This is likely within the bounds of your local and municipal discharge criteria.

Add the baking soda by sprinkling it over the solution being neutralized so as to expose individual particles of baking soda rather than a big clump. Bubbling to release a small amount of carbon dioxide is normal. The amounts of carbon dioxide released are small and can be handled in a normal open, inside environment. When the bubbling has stopped, the pH is likely to be above pH 7.

Note that a 2% solution will need twice as much material for neutralization.  We recommend evaluating 1-2% solutions for cleaning of electronics parts and residues.  If a low-foaming detergent is required, Citrajet® Low-Foam Liquid Acid Cleaner/Rinse can be used and neutralized in the same manner.

If printed boards and other circuitry related components are in play, necessitating a completely ion-free cleaner, we recommend Detergent 8® Low-Foaming Ion-Free Detergent.

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