determination of chlor

1. Determination of Active Chlor
Air and water Analysis

2. Chlor Compounds in Water
Chloride ion (Cl-)
Chlorine gas (Cl2)
Sodium hypo chloride (NaOCl)
Ca(OCl)2
Hypo chloride acid (HOCl)
Active chlor
Inactive chlor

3. Disinfectant
 Active chlor
 Ultra violet light
 Heating
 Ozone
 Advantages of chlor:
Cheap
Kerja disinfektan : cukup lama (beberapa jam setelah
penaburan)

4. The use of disinfectan
Active chlor :
Drinking water instalations
Swimming pools
Heating :
Well : for drinking water
Ozone :
Packing mineral water
Ultraviolet light :
Refill drinking water

5. Active chlor
Functions :
Disinfectant
Oxidizing agent
Organic compound destructor

6. The types of active chlor
Cl2 :
In water  proceed of hidrolysis :
Cl2 + H2O H+ + Cl- + HOCl
HOCl OCl- + H+
Equilibrium of Cl2 , HOCl, and OCl-
The fraction of them depends on solution pH
The highest activity as disinfectant : HOCl

7. The dependency of the fraction on pH
pH = 1-3 : Cl2 and HOCl
pH = 3-6 : HOCl
pH = 6-9 : HOCl and OCl-
pH > 9 : OCl-
pH
Fraction (%)
1 3 6 9

8. Ca(OCl)2
In water :
Ca(OCl)2 + 2H2O 2 HOCl + Ca(OH)2
HOCl OCl- + H+

9.  Free chlor available :
[Cl2] + [HOCl] + [OCl-]
 Attached chlor available : when NH3 present
HOCl + HN3 NH2Cl + H2O pH≥ 7
NH2Cl + HOCl NHCl2 + H2O 4< pH < 6
NHCl2 + HOCl NCl3 + H2O pH < 3
NH3 adequate  NH2Cl is stable
The chlor is in excess  NH2Cl is broken down into N2
and HCl
Low disinfection power

10.  Total chlor available = Free chlor + Attached chlor

11. Determination of active chlor
concentration
Iodo-iodimetry:
Addition of I2 (pH <8) or KI (pH < 3-4)
Indicator starch/amylum
Standard solution Na2S2O3
Decreasing pH : dengan asam setat
Execution after less than 2 h of sampling
Water sample should be kept on dark bottle

12. Reaction :
OCl- + 2KI + 2 CH3COOH  I2 + 2CH3COOK + 2H2O
NH2Cl + 2KI + 2 CH3COOH  I2 + CH3COOK + KCl +
CH3COONH4
I2 + amylum  I2-amilum blue solution
I2 + 2 Na2S2O3  Na2S4O6 + 2NaI

13. Interferences :
Oxidizable metal ions : Fe(II) dan Mn(II)
Reducing agents : S=, NO2
-
Sun light and lamp light

14. Calculation :
Active chlor as sebagai Cl2 (mg/L) =
(B-A). M/2 . 71 . 1000
-------------------------------
V sample (ml)
A : vol. of Na2S2O3 for blank
B : vol. of Na2S2O3 for sample

15. Kadar klor yang dibubuhkan pada PAM di USA
Rata-
rata
Maksimum Minimum
Kebutuhan klor (mg Cl2/L)
Residu klor aktif (mg Cl2/L)*
Waktu kontak (menit) **
•*: sebelum distribusi
•** : termasuk deteksi dalam
sumur jernih
3
1,2
45
65
7
720
0
0-0,04
0

16. The affects of residual active chlor (as
HOCl)
Irritant for eyes (even can cause blind)
and skin (feel as burned)
When it is swollen  the bottom
respiratory track felt as burned