Centre de traitement chimique C.T.C. Inc.
1225-Z, rue J.A. Bombardier
Saint-Nicolas (Québec) G7A 2P4
Téléphone/Phone : (418) 831-1135
Télécopieur/Fax : (418) 831-1137
NEUTRALIZATION OF ACIDS
Neutral B (fresh and spent)
FRESH ACID
For appreciable quantities of acid, neutralization with an alkaline material is required before disposal.
Proper clothing and equipment should be available for use. Rubber gloves, rubber aprons, and safety
goggles are a must for personnel safety. A supply of the proper range of pH paper or an electronic
portable pH meter is recommended for monitoring the progress of the neutralization. After the
neutralization is complete, the pH should be 7.0 7.5. Because the neutralization usually involves an
exothermic reaction (heat is given off), and a release of carbon dioxide gas in the form of
effervescence, care must be exercised to prevent spillage or skin contact.
Since certain agencies of municipal, provincial and federal governments have been established to
protect the waters of the country from pollution, all rules and regulations applying to a given location
should be ascertained and observed.
Table 1 shows the amount of various alkalis required to neutralize one (1) gallon or 4.54 litres of
different fresh acids.
SPENT ACID
When waste acid is discharged into a city system, neutralization with controlled quantities of alkali
such as soda ash, bicarb or caustic soda should be employed to prevent corrosion and pollution of the
city water system. As with fresh acids, proper clothing and equipment should be provided for
personnel to dispose of spent acids. Approximately ½ of the required amount of alkali as described in
Table 1 should be used with the neutralization of the spent acid.
It should be noted that we are only dealing with the neutralization of the acid in question and not the
contaminants contained in it as a result of a cleaning procedure or a metal treatment. Waste disposal
of unwanted chemicals may require deactivation or modification of the material by chemical means
and should be handled by qualified personnel using approved procedures.
After the neutralization, a pH meter of the proper range of pH paper should be used to determine the
pH of the resulting solution. If the pH is still below 7.0 then more alkaline material should be added
until the pH is in the 7.0 7.5 range. Then, if all other contaminants have been treated, the resulting
solution can be released into the water system.
SMALL VOLUME NEUTRALIZATION
For very small quantities of acid (less than 4.5 litres, 1 gal.) a sump may be provided with an acid
proof grating at the sewer opening. With the sump packed with limestone, small fresh acid and
spent acid discharges are readily neutralized.
TABLE 1
FRESH ACIDS
AND THEIR ALKALI NEUTRALIZATION EQUIVALENTS
(Imperial Measures in Italics)
ACID
To neutralize 4.54 L
(1 gal.)
Of acid requires
ACETIC ACID
8 Be 56%
4.54 litres / 4.8 kg
1 gal. / 10.6 lbs
PHOSPHORIC ACID
53 Be 75%
4.54 litres / 7.1 kg
1 gal. / 15.7 lbs
MURIATIC ACID
20 Be 32%
4.54 litres / 5.3 kg
1 gal. / 11.6 lbs
NITRIC ACID
42 Be 67%
4.54 litres / 6.3 kg
1 gal. / 14 lbs
SULPHURIC ACID
66 Be 93%
4.54 litres / 8.3 kg
1 gal. / 18.4 lbs
ALKALI
SODA ASH
(Na2CO3)
Sodium Carbonate
BICARB
(NahCO3)
Sodium Bicarbonate
NEUTRAL B
Sodium Hydroxide
2.5 kg
5.25 lbs
5.0 kg
11 lbs
2.5 kg
5.25 lbs
3.0 kg
6.5 lbs
4.5 kg
10 lbs
2.0 kg
4.5 lbs
2.25 kg
3.75 lbs
3.75 kg
8.5 lbs
1.75 kg
4.0 lbs
3.5 kg
8 lbs
5.75 kg
12.5 lbs
2.75 kg
6 lbs
8 kg
17.5 lbs
13.5 kg
29.5 lbs
6.3 kg
14 lbs