1. DETERMINATION
OF
CARBON DIOXIDE
IN WATER
SAIMA ALEEM
M.PHIL
ENVIRONMENTAL CHEMISTRY

2. Introduction
Surface waters
 Surface waters normally contain less
than 10 ppm free carbon dioxide.
Ground water
Ground waters may easily exceed that
concentration.

3. Classical method
Buret titration method.
Improved evolution method.
Instrumental method
Coulometry method.

4. Fill the burette with standarized sodium
hydroxide.
Take a 100 ml of sample in a conical flask .
Add 10 drops of Phenolpthalein indicator.
CO2 + NaOH NaHCO3 + Na+ +
H2O

5. precaution
Sample must be fresh.
performed immediately after collection of
water sample.

6. REAGENTS
1.5 N sulfuric acid (for acidifying the
sample).
0.03N barium hydroxide (for absorbing
carbon dioxide).
Standard 0.04N hydrochloric acid( for
titrating the barium hydroxide).
Phenolphthalein indicator.

7. Blank determinations
 Transfer 200 ml boiled dislled
water in flask “A”.
 Introduce 40 ml. of barium
hydroxide solution into the
absorption tube, C.
 Add 0.2 ml. of phenolphthalein
indicator.
 Acidify the sample by the
addition of 25 ml. of 1.5 N
sulfuric acid from buret “I”.
 Apply heat to it by means of
the 300-watt hot plate.
 After 15 minute of recirculation
barium hydroxide is titrated
with standrized hydrochloric
acid.

8. Sample determination
 Transfer 200 ml water sample in a
flask “A”.
 Introduce 40 ml. of barium hydroxide
solution into the absorption tube, C.
 Add 0.2 ml. of phenolphthalein
indicator.
 Acidify the sample by the addition of
25 ml of 1.5 N sulfuric acid from
buret “I”.
 Apply heat to it by means of the 300-
watt hot plate.
 After 15 minute of recirculation
barium hydroxide is titrated with
standrized hydrochloric acid.

9. DETERMINATION OF CARBON DIOXIDE IN
WATER BY COULOMETRY
Collection of sample
 Sample are drawn into 12 individually borosilicate
glass bottles.

10. Procedure
 First the back ground level and calibration factor
have been determined.
 Dispense the sample (30 cm3) into the
stripping chamber.
 Acidify it with phosphoric acid (1.5 cm3).
 Record the final coulometer reading.
 when the coulometer titration rate returns to
the background level ,system is ready to
analyze next sample.

11. “ THANK YOU”