Determination of Iodine Value of Activated Carbon


Volumetric flask,

conical flask,




filter paper


* 0.1N Iodine solution ( 40 gm KI in 1 Ltr of Distilled water ).

* 0.05N Sodium Thiosulphate solution (12.5 gm Na2S2O3.5H2O in 1 Ltr Distilled water)

* 1% Starch solution

* Activated carbon


I Standardisation of Iodine solution

* Take 10c.c of 0.1N Iodine solution in conical flask.

* Add 2 drops of Starch solution.

* The pale yellow colour of Iodine Soln turns Blue.

* Titrate with 0.05 N Sodium Thiosulphate till it becomes Colourless.

* Burette reading corresponds to blank reading.(B)


* Weigh very accurately 0.2 gm of Activated carbon

* Introduce it into the Iodine flask which should be completely dry

* Add 40cc of 0.1N Iodine solution

* Shake the flask for 4 minutes and filter it

* Collect the filterate in a dry flask and Titrate 10cc of the filtrate against

Standard Sodium thiosulphate solution using starch as indicator

* Burette reading corresponds to (A)


Iodine value: C x Conversion factor; mg/gm

Factor:Mol wt. of iodine (127) x normality of iodine x 40 / Wt. of carbon x Blank reading


Note: Iodine test should be performed on dry basis

Carbon should be dried in oven at 110oC for three hours before weighing

Iodine value is expressed in mg/gm of carbon

5 throughts on "Determination of Iodine Value of Activated Carbon"

  1. Gud day.I saw another formula about the iodine value of activated carbon,that they are using a conversion factor in the computation of iodine.The conversion factor depends on the normality of the filtrate?Is it the same with your formula?thanks

  2. I’ve 2 questions for you regarding the determination of the value of iodine in powdered activated carbon:
    1-(Collect the filterate in a dry flask and Titrate 10cc of the filtrate against
    Standard Sodium thiosulphate solution using starch as indicator)
    This sentence, I do not understand please can you tell me more clearly?
    2-How to prepare 1% Starch solution in the form of liquid because of the starch in the form of a solid?

  3. Just one question, where does the 40 come from in the conversion factor and does it have units?

  4. I tried same but I didn’t get Perl yellow colour of potassium iodine solution and not even blue color after add 2 drops of 1%starch solution.
    I can’t understand what mistakes I had done . Please reply with exactly how to make potassium iodine solution with point need to care about like sunlight and storage.

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