1. Water & it’s Industrial Applications Dr. Shuchita Agrawal BTIRT Sironja, Saga r 1

2. Content-  Introduction  Sources  Types  Impurities  Hardness  Types of Hardness  Degree of Hardness 2

3. Water Water is hydride of oxygen and can be represented by H2O. Without water no one can survive. It is the medium of all metabolic activities. Water is not only essential for the lives of Animals & Plants, but occupies a unique position in Industries. Mainly it is used to generate Steam. 3

4. 1.Surface water- rivers, lakes, reservoirs etc. 2.Underground water – wells and springs 3.Rain water 4. Sea water Sources of water 4

5. Surface water  River water – dissolved minerals Cl -, SO 4 2-, HCO 3 - of Cl -, SO 4 2-, HCO 3 - of Na+, Mg 2+, Ca 2+ and Fe 2+ Na+, Mg 2+, Ca 2+ and Fe 2+ suspended impurities- Organic matter, sand, rock suspended impurities- Organic matter, sand, rock composition is NOT constant – depends on the contact with soil. composition is NOT constant – depends on the contact with soil.  Lake water: High in organic and less in minerals. composition is constant. 5

6.  Rain water – pure form dissolved organic and inorganic particles and dissolved industrial gases CO 2, NO 2,SO 2 etc  Underground water- free from organic impurities due to filtering action of the soil  Sea water – very impure; too saline for industrial use except cooling 6

7. Impurities in water  Suspended impurities inorganic (clay, sand) organic (oil,plant, and animal matter)  Colloidal impurities- finely divided silica and clay  Dissolved impurities – salts and gases  Microorganisms – bacteria, fungi and algae 7

8. Hardness of water  Hardness prevents the lathering of soap. due to the presence of salts of Ca, Mg, Al, Fe and Mn dissolved in it. Soap – Na or K salts of long chain fatty acids C 17 H 35 COOH 2C 17 H 35 COONa + CaCl 2 → (C 17 H 35 COO) 2 Ca↓ + 2NaCl 2C 17 H 35 COONa + MgSO 4 → (C 17 H 35 COO) 2 Mg↓ + Na 2 SO 4 8

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10. DIFFERENCE  Hard Water Does not produce lather with soap Contains Ca and Mg salts Soap is wasted and cleaning quality is depressed Boiling point elevated, more time and fuel for cooking  Soft Water Produces lather easily with soap Does not contain dissolved Ca and Mg salts Cleaning quality of soap not depressed. Less fuel and time required for cooking 10

11. Types of Hardness  Temporary Hardness- caused by dissolved bicarbonates of Ca and Mg Also known as ‘alkaline or carbonate hardness’  Permanent Hardness – dissolved Cl- and SO 4 2- of Ca, Mg, Fe and Al etc 11

12. Temporary Hardness caused by dissolved bicarbonates of Ca and Mg Temporary hardness can be removed by boiling of water Ca(HCO 3 ) 2 → CaCO 3 ↓ + H 2 O + CO 2 ↑ Mg(HCO 3 ) 2 → Mg(OH) 2 ↓ + 2 CO 2 ↑ Also known as ‘alkaline or carbonate hardness’ Determined by titration with HCl using methyl orange as indicator 12

13. Permanent Hardness CaCl 2, MgCl 2, CaSO 4, MgSO 4, FeSO 4, Al 2 (SO 4 ) 3 Cannot be destroyed on boiling the water Also known as non-carbonate or non alkaline hardness non alkaline hardness = Total hardness – alkaline hardness 13

14. Hard Water  Advantages Tastes better Ca in water helps to produce strong teeth and bones Hard water coats lead pipes with layer of insoluble CaCO 3, preventing any poisonous lead dissolving in drinking water  Disadvantages no taste produces scum with soap produces scum with soap Boiler feed water should be free from hardness or even explosions can occur 14

15. Degree of Hardness  Hardness is expressed as equivalent amount (equivalents) of CaCO 3 Reason : Molar mass is exactly 100, and is the most insoluble salt that can be precipitated in water treatment. Equvalents of CaCO 3 = ( mass of hardness producing substance in mg/L) x100 / (eq.wt of substancex2) units – mg/L = ppm parts of CaCO3 equivalents in hardness in 10 6 parts of water parts of CaCO3 equivalents in hardness in 10 6 parts of water 15

16. CaCl 2 + 2C 17 H 35 COONa→(C 17 H 35 COO) 2 Ca 40+35.5×2 =111 40+35.5×2 =111 CaCO 3 + 2C 17 H 35 COONa→(C 17 H 35 COO) 2 Ca 40+12+16×3=100 40+12+16×3=100 1gm mole of CaCl 2 ≡ 1gm mole of CaCO 3 111 gm of CaCl 2 ≡ 100 gm of CaCO 3 1 gm of CaCl 2 ≡ 100/111 gm of CaCO 3 w gm of CaCl 2 ≡ w×100/111 gm of CaCO 3 16

17. Equivalent weight  Eq. wt = Molar mass/ no of charge on ion CaCO 3 MM/2 =100/2=50 NaClMM/1 =58.5/1=58.5 AlCl 3 MM/3 =133.3/3=44.43 Al 2 (SO 4 ) 3 MM/6 =342/6=57 17

18. Example 1:  A water sample contains 408 mg of CaSO 4 per liter. Calculate the hardness in terms of CaCO 3 equivalents.  Solution- Hardness = mg/L of CaSO 4 x 100/MM(CaSO 4 ) = 408 mg/L x 100/136 = 408 mg/L x 100/136 = 300 mg/L = 300 ppm = 300 mg/L = 300 ppm 18

19. Example 2  How many grams of MgCO 3 dissolved per liter gives 84 ppm of hardness?  Solution- Hardness = mg/L of MgCO 3 x 100/MM(MgCO 3 ) Hardness = mg/L of MgCO 3 x 100/MM(MgCO 3 ) 84 ppm = ppm of MgCO 3 x 100/84 84 ppm = ppm of MgCO 3 x 100/84 ppm of MgCO 3 = 84 ppm x (84/100) ppm of MgCO 3 = 84 ppm x (84/100) = 70.56 ppm = 70.56 ppm = 71 mg/L = 71 mg/L 19

20.  Calculation of hardness caused by each ion. Na+ - 20 mg/L Ca 2+ - 15 mg/L Na+ - 20 mg/L Ca 2+ - 15 mg/L Mg 2+ - 10 mg/L Sr 2+ - 2 mg/L Al 3+ - 0.3 mg/L Eq. of CaCO 3 = ( mass of hardness producing substance in mg/L) x100 (eq.wt of substance x 2) (eq.wt of substance x 2) CationEq.wtHardness Ca 2+ 40.0/237.5 Ca 2+ 40.0/237.5 Mg 2+ 24.4/241.0 Mg 2+ 24.4/241.0 Sr 2+ 87.6/2 2.3 Sr 2+ 87.6/2 2.3 Al 3+ 27.0/3 1.7 Al 3+ 27.0/3 1.7 Total hardness = 82.5 ppm 20

21. Potable Water (Drinking water) Characters  Colorless and odorless; good in taste  Turbidity should be less than 10 ppm  No objectionable dissolved gases like H 2 S or minerals such as Pb, As, Cr, Mn salts. or minerals such as Pb, As, Cr, Mn salts.  Alkalinity should not be high; pH 7.0 – 8.5  Total hardness less than 500 ppm  Free of harmful microorganisms.  Cl-, F-, and SO 4 2– less than 250, 15 and 250 ppm, respectively 250 ppm, respectively 21

22. Methods of disinfection of water 1. Bleaching powder (CaOCl 2 ) CaOCl 2 +H 2 O → Ca(OH) 2 + HCl + HOCl HOCl+ Germs → Germs killed HOCl+ Germs → Germs killed Enzymes of microorganism get deactivated by HOCl  Excess imparts bad taste and smell  Not stable during storage  Introduces Ca to water and thus increases hardness 22

23. 2. Chlorination  Commonly used disinfectant in water used directly as a gas or conc. solution. It produces HOCl, a powerful germicide. It produces HOCl, a powerful germicide. 0.3- 0.5 ppm chlorine is sufficient. 0.3- 0.5 ppm chlorine is sufficient. Cl 2 + H 2 O → HCl + HOCl Cl 2 + H 2 O → HCl + HOCl HOCl+ Germs → Germs killed HOCl+ Germs → Germs killed It was believed that the disinfecting action of chlorine is due to nascent oxygen. HOCl → HCl+[O] HOCl → HCl+[O] 23

24. But Gleen & Stumpf reported that the death Of micro-organism results from chemical reaction of HOCl with the enzymes of cell. Enzyme is essential for the metabolic process of micro-organism. So, death of micro- organism results due to inactivation of enzyme. HOCl →H + +OCl - HOCl →H + +OCl - OCl -, inactivate the enzyme. OCl -, inactivate the enzyme. 24

25. 3. Disinfection by ozone  O 3 → O 2 + O oxygen atom is a powerful oxidizing agent. 2 – 3 ppm is injected 10 – 15 min contact time Expensive method 25

26. Alkalinity  The capacity of water accept H+ is called alkalinity  The basic species responsible are 1.HCO 3 - + H + → H 2 O 2.CO 3 2- + H + → HCO 3 - 3.OH- + H+ → H 2 O Different from basicity; high pH Different from basicity; high pH pH is an intensity factor alkalinity is a capacity factor alkalinity is a capacity factor 1.00x10 -3 M NaOH - pH=11; neutralize 1.00x10 -3 mole acid 0.100 M NaHCO 3 - pH = 8.34, 0.100 mole acid 26

27.  Alkalinity of water is attributed to presence of i. caustic alkalinity (due to OH - and CO 3 2- ions) ii. Temporary hardness (due to HCO 3 - ions) i. [OH-] + [H+] → H 2 O -P -M ii. [CO 3 2- ] + [H+] → [HCO 3 - ] -P -M iii. [HCO 3 - ] + [H+] → H 2 O + CO 2 -M P = OH- + ½ CO 3 2- M = OH- + CO 3 2- + HCO 3 - 27

28. Biological oxygen demand (BOD)  BOD is the quantity of dissolved O 2 required by aerobic bacteria for oxidation of organic matter under aerobic conditions. source of effluent BOD(ppm) Domestic sewage 320 Cow shed sewage 3010 Paper mill 8190 BOD indicator of organic pollutants 28

29. Chemical oxygen demand (COD)  Defined as the oxygen consumed in the oxidation of organic and oxidizable inorganic matter. Use a strong oxidizing agent like K 2 Cr 2 O 7 COD > BOD ( O2 is a weak oxidizing agent) COD > BOD ( O2 is a weak oxidizing agent) COD test does not differentiate between bio-inert and bio degradable materials. 29

30. Thanks Contact- Contact- mrs.shuchitaagrawal@yahoo.com mrs.shuchitaagrawal@yahoo.commrs.shuchitaagrawal@yahoo.com 9977330500 9977330500 30