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Testing Soda Ash & Hydrogen Peroxide

In Textile Processing the following materials are considered to be basic chemicals or bulk chemicals used in processing. The quality of each product whether basic  or auxiliary chemical would certainly affect the final quality of textile processing. So a good dye-house should have a continuous quality monitoring procedure like one shown below.  As and when a new product or chemical enters your dye-house, its quality should be compared with the previous supply without fail.

Soda Ash:

Weigh accurately 1 gram of Soda ash and dissolve in 50ml of distilled water. Titrate this slowly with 1.0N HCl, using methyl orange as indicator.

Total alkalinity as Na2CO3.% by weight = 5.3 x V x 1 / Wt where 'V' is the volume of HCl consumed and 'wt' is the exact weight of soda ash taken for titration.

Repeat the above titration for 3 times, tabulate and take the average reading as the % concentration of Soda ash as Sodium carbonate.

Hydrogen Peroxide:

Take 10ml of Hydrogen Peroxide solution and dilute it to 500ml using distilled water. From this diluted solution of Hydrogen peroxide take 10ml and add 20ml of 1.0N H2SO4.. Titrate against 0.1N KMNO4 (potassium permanganate). The end point is the appearance of light pink color. Repeat this titration 3 times and tabulate the readings. Find out the average titration value (V).

Strength of Hydrogen Peroxide = V x 0.1 x 50 x 17/ 10 x 3.03 [volumes].

Commercially Hydrogen Peroxide is available in two concentration - viz., 35% and 50%.

In the above calculation please note that 1 ml of 0.1N KMNO4 is equal to 0.0017g 100% H2O2.

Determination of Hydrogen Peroxide content in bleach bath:

Hydrogen Peroxide content can be determined by titration against standard potassium permanganate solution.

Procedure:

To carry out the titration, measure 100ml dilute (10%) Sulphuric acid solution into a 250ml conical flask.

Titrate with KMNO4 (0.1N) to a faint pink color.

Pipette say 10 ml of bleach bath solution (V) in to the beaker containing the dilute acid and titrate immediately with potassium permanganate to the same light pink color. Let the titer value be A ml of 0.1N KMNO4.

Calculation:

Since 1 ml of KMNO4 (0.1N) is equivalent to 0.0017g H2O2 100%, then V ml bleach bath solution will contain     0.0017 x A gram of H2O2 100%.

The strength of the bleach bath is therefore = 0.0017 x A x 1000 / V g/l H2O2 100%.

Example: Titration of 10 ml of bleach liquor sample required 8.5 ml of 0.1N KMNO4. What is the H2O2 content of the bath in grams/liter?

Calculation: H2O2 content = 0.0017 x 8.5 x 1000/ 10 = 1.445 g/l H2O2 100%