Titration of Alkaline Etching Solutions for Activity

A test kit is available for this titration procedure (see below) or supplies can be ordered individually

Complete Test Kit Part Number: OKT9601-79 (or 45218519)

Solution-Item	Item	Amount	Part Number	BASF Number
Gardotest Indicator 2	Phenolphthalein	30 mL	OKT-2246-G	50560520
Gardotest Indicator 98	Eriochrome Black T / Sodium Chloride	30 g	OKT-9257-G	50560640
Gardotest Indicator 193	Methyl Red Indicator	60 mL	OKT-2292-H	50560527
Gardotest Solution 90	0.10 M Versene (Disodium EDTA)	250 mL	OKT-9656-K	50560654
Gardotest Solution 91	0.10 M Zinc Sulfate	250 mL	OKT-9657-K	50560656
Gardotest Solution 90	0.10 M Disodium EDTA	250 mL	OKT-9656-K	50560654
Gardotest Solution 99	Buffer (Ammonium Chloride/Ammonium Hydroxide)	100 mL	OKT-4255-J	50560562
Gardotest Solution 116	10% Sulfuric Acid	250 mL	OKT-6542-K	50560625
Gardotest Solution 202	0.50 N Sulfuric Acid	250 mL	OKT-6090-K	50560582
Gardotest Solution 215	20% Barium Chloride	250 mL	OKT-9655-K	50560653
Glass Bottle	120 mL	2	OKT-9688	45218454
Direct Reading Pipette, Glass	0.0 to 5.0 mL	7	OKT-9685	45218454

Refer to the product specific technical information sheet for the appropriate sample size and multiplying factor F or ask your technical sales representative if not listed here.

Procedure

Part I: Total Titration (Active Etchant plus Sodium Aluminate Contamination):

1.    Fill the 120 mL sample bottle about half full with tap water. Next, add 5-6 drops of Gardotest Indicator 2. 2.     Measure precisely 5 mL sample using one of the droppers and add it to the mixture prepared in step 1. The color will be red. 3.    Fill another 5 mL dropper precisely to the zero mark with Gardotest Solution 215 and add it to the mixture prepared in step 2. Swirl to mix. Allow to stand at least 5 minutes

4.   Fill the 5 mL glass direct reading pipette precisely to the zero mark with Gardotest Solution 202. Add this to the mixture in the sample bottle a few drops at a time, swirling between additions, until the color changes from red to white and holds for at least 2 minutes. Record the number of mL used. Call this Titration T. CALCULATION  T x F  =  vol % (g/L or oz/gal) active etchant plus sodium aluminate contamination = A

Part II: Aluminum Contamination up to 27 g/L (3.6 oz/gal):

1. Fill the 120 mL sample bottle about half full with tap water. Using the 1 mL dropper measure out precisely 1.0 mL of the etchant solution to be tested. 2. Add this to the water in the sample bottle. Swirl to mix. 3. Add 2 drops of Gardotest Indicator 193 and swirl to mix. Next, add Gardotest Solution 116, a few drops at a time with swirling between additions, until the yellow color changes to a clear, light red. 4. A cloudy precipitate usually forms when the solution first starts to change color from yellow to red. Continue adding Gardotest Solution 116 until the cloudiness has all disappeared and a clear light red color remains.

5. Using the 5 mL dropper, add precisely 10.0 mL of Gardotest Solution 90 to the mixture in the bottle. Swirl to mix. Next, add 3.0 mL of Gardotest Solution 99 and swirl to mix. The color should be a clear, very light yellow. Finally, add 1 mini-spoonful of Gardotest Indicator 98 to the contents of the bottle and mix well. The color should change to a distinct blue. 6. Fill the 5 mL calibrated pipette precisely to the zero mark with Gardotest Solution 91 and add this, a few drops at a time with swirling between additions, until the color changes from blue to wine red. Record the number of mL used. Call this Titration T. This completes the analysis.

CALCULATION

(10 – T) x 4.0 = aluminum contamination (g/L NaOH bound as sodium aluminate) = B
(10 – T) x 0.53 = aluminum contamination (oz/gal NaOH bound as sodium aluminate) = B

FINAL CALCULATION

A – B = g/L or oz/gal active etchant in solution. (NaOH)

Note: Part II may be calculated to give aluminum expressed in other ways:
(10 – T) x 2.7 = g/L of aluminum
(10 – T) x 0.36 = oz/gal of aluminum
(10 – T) x 0.82 = %NaAlO2
(10 – T) x 0.40 = %NaOH

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NOTE:

1. Using the procedure as outlined in part II above, aluminum content of solutions up to 27.0 g/L or 3.6 oz/gal can be measured.

2. If the solution contains more than 27.0 g/L or 3.6 oz/gal of aluminum, the color of the solution will turn red instead of blue after adding Gardotest Indicator 98 in step 3. If this happens, empty the sample bottle, rinse thoroughly with tap water and start again. Proceed to step 3 and then, using the 5 mL dropper four times, add precisely 20 mL of Gardotest Solution 90. Complete the titration as directed.

(20 – T) x 2.7 = g/l of aluminum
(20 – T) x 0.36 = oz/gal of aluminum
(20 – T) x 2700 = parts per million (ppm) aluminum

3. Depending on the amount of aluminum in solution it may be necessary to add 30 ml or even 40 mL of Gardotest Solution 90. Adjust the calculation accordingly:
(30 – T) x 2.7 = g/L of aluminum
(30 – T) x 0.36 = oz/gal of aluminum

or

(40 – T) x 2.7 = g/L of aluminum

4. (40 – T) x 0.36 = oz/gal of aluminum

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SUGGESTION OF OTHER PRODUCTS YOUR COMPANY MAY USE

• CLEANERS
• ETCHANTS
• DEOXIDIZERS
• RUST PREVENTIVES
• METALWORKING FLUIDS (coolants and lubricants)
• WASTE WATER TREATMENT CHEMICALS
• FLOOR CLEANERS AND MAINTENANCE PRODUCTS
• PROCESS EQUIPMENT/CONTROL SYSTEMS

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