3. The course comprised –
1. Applied chemistry: Water & water treatment,
surfactants
2. Dyeing: Dyeing theory & mechanism,
Mordant dyes, Pigments, Mineral colors
3. Printing: Special types of thickener, Screen
printing technology
4. Finishing: Softener, Special types of finishing
4. Don’t be a serious student
Be a smart & innovative student
5. Water and
Water Treatment
Water can be classified as -
1. Rain water.
2. Surface water stock in ocean, rivers or
lakes.
3. Subsoil water, which has percolated a small
distance into the ground.
4. Deep well waters which have usually
percolated through several layer.
6. General characteristics of water
Water shows maximum density at 4ºC,
1 gm/cc. its specific gravity is also 1.
Freezing temperature 0ºC and boiling
temperature is 100ºC.
7. Properties of textile supply
water
Minimum Standard Acceptable limits
Color Colorless
Smell Odorless
pH value Neutral (pH 7- 8)
Water hardness < 25 ppm of Ca CO3
Acidity/Alkalinity < 100 mg/l as Ca CO3
Dissolved solids < 150 mg/l
Filterable solids < 50 mg/l
Suspended solids < 1 mg/l
Turbidity < 5 mg/l
Dissolved oxygen Not permit
Carbon dioxide < 50 mg/l
Iron (Fe) < 0.1 mg/l
Copper (Cu) <0.005 mg/l
Manganese (Mn) < 0.02 mg/l
9. Water Hardness
Generally soaps create foam in water,
but in present of some materials the
foam creation is reduced and need more
soap for producing foam, and this
condition of water is called water
hardness.
10. Reasons of water hardness
1. Temporary hardness:
Ca(HCO3)2, Mg(HCO3)2, Fe(HCO3)2
2. Permanent hardness:
CaCl2, CaSO4, Ca(NO3)2, MgCl2,
MgSO4, Mg(NO3)2
13. Definition of Different Hardness
1. 1º H (German) Hardness: 10 mg CaO in
1 litre of water
2. 1º H (French) Hardness: 10 mg CaCO3
in 1 litre of water
3. 1º H (English) Hardness: 10 mg CaCO3
in 0.7 litre of water
4. 1º H (American) Hardness: 1 mg CaCO3
in 1 litre of water
14. Other scales for expressing
water hardness -
Parts per million (ppm): The number of parts of
substances per million parts of water is known ppm. It
is also called American hardness. It can be expressed
by another way like mg/l or gm/m3.
Grains per U.S. gallon (gpg): The number of grains of
substances per 1 U.S. gallon of water (1 U.S. gallon of
water weighs 8.33 pound) is known gpg.
Parts per hundred thousand (pp/100,000): The number
of parts of substances per 100,000 parts of water is
known pp/100,000.
Grains per imperial gallon (gpg imp): The number of
grains of substances per 1 British imperial gallon of
water (1 imperial gallon of water weighs 10.0 pound) is
known gpg imp.
16. Conversion factor of different
water hardness scale
Scale Hardness
USA D GB F
1º USA 1.0 0.056 0.07 0.1
1º D 17.9 1.0 1.25 1.79
1º GB 14.3 0.8 1.0 1.43
1º F 10.0 0.56 0.7 1.0
17. Classification of water
according to hardness
Hardness
rating
ppm of
CaCO3
(grains/US
gallon) of CaCO3
Soft 0 to <75 0 to <5.2
Medium 75 to < 150 5.2 to <10.5
Hard 150 to < 300 10.5 to <21
Very hard 300 and above 21 and greater
18. Problems causes by hard
water in wet processing and
their correction
Consequences of using hard water –
Precipitation of soaps;
Redeposition of dirt and insoluble soaps on the fabric
being washed – this can cause yellowing and lead to
unlevel dyeing and poor handle;
Precipitation of some dyes as calcium or magnesium
salts;
Scale formation on equipments and in boilers and
pipelines;
Reduction of the activity of the enzymes used in
desizing;
Decrease solubility of sizing agents;
Coagulation of some types of print pastes;
Incompatibility with chemicals in finishing recipes
19. (A) Problems in boiler
Ca(HCO3)2 → CaCO3 + CO2 + H2O
Mg(HCO3)2 → MgCO3 + CO2 + H2O
MgCO3 + H2O → Mg(OH)2 +CO2
20. Heat loss for pipe scaling
Scale thickness (mm) % heat loss (approx.)
1.00 10
3 17
5 22
10 30
20 43
21. Boiler feed water quality:
Parameter Acceptable limit
Appearance Clear, without residue
Residual hardness <5 ppm
Oxygen <0.02 mg/l
Temporary CO2 0 mg/l
Permanent CO2 <25 mg/l
Iron <0.05 mg/l
Copper <0.01 mg/l
pH (at 25º C) 8.0 - 9.0
Boiler feed water temp. >90º C
22. B) Problems in processing
Wastage of soap (reaction with soap)
2 C17H35COONa + CaSO4 → (C17H35COO)2Ca +↓
Na2SO4
Reaction with dyestuffs
- reaction with dyes and lead dye wastage
- sometimes it produces a duller shade
23. How does the water hardness
affect the textile processing?
Desizing Deactivate enzymes and makes it
insolubilize some size materials like
starch and PVA
Scouring Combine with soap, precipitate metal-
organic acids. Produce yellowing of off-
white shades, reduce cleaning efficiency,
and water absorption
Bleaching Decompose bleach baths
Mercerizing Form insoluble metal oxides, reduce
absorbency and luster
24. Dyeing Combine with dyes changing their
shades, insoubilize dyes, cause tippy
dyeing, reduce dye diffusion and hence
results in poor washing and rubbing
fastness.
Printing Break emulsions, change thickener
efficiency and viscosity, and those
problems indicated for dyeing
Finishing Interfere with catalysts, cause resins
and other additives to become
nonreactive, break emulsions and
deactivate soaps
25. Estimation of
water hardness
Using direct reading digital meter or
strip
In laboratory it is usually determined
by titration with a standardized
solution (e.g. Na-EDTA) – for mechanism see my
book
26. Estimation of total (permanent
& temporary) hardness of
supply water (by di-sodium salt of EDTA)
Basic principle:
- Titration of sample water against standards (0.01M)
EDTA solution
Preparation of 0.01M or 0.02N EDTA
solution:
Molecular weight of disodium salt of EDTA
(CH2COOH)2 N2(CH2)2(CH2COONa)2.2H2O
= (12+1*2+12+16*2+1)×2 + 14*2+(12+2)*2+
(12+1*2+12+16*2+23)×2 + 2*18
= 118+ 28+28+162+36
= 372
27. Therefore,
In 1M solution of 1000ml contain 372 gm Na2-EDTA
In 0.01M solution of 1000ml contain 3.72 gm Na2-EDTA
In 0.01M solution of 100ml contain 0.372 gm Na2-EDTA
Preparation of ammonia buffer
solution:
- 145ml of liquor ammonia (NH4OH) of specific
gravity 0.88+15gm NH4Cl + distilled water to
make 250ml solution to give a pH of 10.
28. Procedure:
- Add 1ml of buffer solution (NH4OH+NH4Cl) to
100ml of the original water sample. Add 3-4
drops of Eriochrome Black T indicator (0.2g dye
in 15ml of triethanol amine + 5ml of ethanol)/
1tablet (making powder) total hardness
indicator.
- Titrate against 0.01M prepared EDTA solutions in
burette until the color charges from wine red
(or violet) to pure blue (or turquoise) with no
reddish tone; then calculate the total hardness
in terms of ppm of CaCO3.
30. Calculation:
Total hardness =
Volume of 0.01M EDTA solution in ml
--------------------------------------× 1000 ppm of CaCO3.
Volume of sample water in ml
31. Determination of temporary
hardness of supply water
Basic principle:
- This can be estimated by titration of
sample water against standard
solution of hydrochloric acid ( 0.05N
HCl).
32. Preparation of 0.05N HCl:
Molecular weight of HCL = 1 + 35.5 = 36.5
& Equivalent weight of HCl = 36.5
Therefore,
1000 ml of 1N HCl contain 36.5 gm HCl
1000 ml of 0.05N HCL contain (36.5 x 0.05) or 1.825
gm HCl
So, 100 ml of 0.05N HCl contain 0.1825 gm HCl
Let, the concentration of diluted HCl is 35%, then
35 gm HCl present in 100 ml of diluted HCl
& 0.1825 gm HCl present in {(100 x 0.1825)/35} or
0.528 ml diluted HCl
33. Procedure:
- Add 1cc or 2 – 3 drop [from the solution of (0.1
gm solid methyl orange + 100cc distilled
water)] methyl orange indicator to 100ml of
fresh distilled water & titrate against 0.05N
HCl. Let the titration reading be ‘a’ ml.
- Now titrate 100 ml of the sample water against
0.05N HCl using the same indicator (methyl-
orange). Let the titration reading ‘b’ ml.
34. Observation:
- Reading should be taken when the
color of indicator change orange to
red.
Table I: Experimental data for
reading ‘a’
Table II: Experimental data for
reading ‘b’
36. Determination of permanent
hardness of supply water (by di-
sodium salt of EDTA)
Preparation of 0.01M or 0.02N EDTA solution:
Molecular weight of disodium salt of EDTA
(CH2COOH)2 (N2CH2)2(CH2COONa)2.2H2O
= (12+1*2+12+16*2+1)×2 + 14*2+(12+2)*2+
(12+1*2+12+16*2+23)×2 + 2*18
= 118+ 28+28+162+36
= 372
Therefore,
In 1M solution of 1000ml contain 372 gm Na2-EDTA
In 0.01M solution of 1000ml contain 3.72 gm Na2-EDTA
In 0.01M solution of 100ml contain 0.372 gm Na2-EDTA
37. Preparation of ammonia buffer
solution:
- 145ml of liquor ammonia (NH4OH) of specific
gravity 0.88+15gm NH4Cl + distilled water to
make 250ml solution to give a pH of 10.
38. Procedure:
- Take 100ml of sample water in a conical flask;
boil it (around 30 minutes) to about 50 ml;
cool and filter to remove bicarbonate residual
(temporary hardness) and to expel carbon
dioxide. Dilute it to by distilled water to make
100 ml. Add 2ml of ammonia buffer solution
followed by one tablet of hardness indicator.
- Titrate against 0.01M prepared EDTA solutions
from burette until the color charges from wine
red (or violet) to pure blue (or turquoise) with
no reddish tone; then calculate the hardness in
terms of ppm of CaCO3.
39. Table: Experimental data
Calculation:
Total hardness =
Volume of 0.01M EDTA solution in ml
---------------------- × 1000 ppm of CaCO3.
Volume of sample water in ml
40. Methods for water softening
Lime-soda process
Base exchange process
Demineralisation process
Sequestering agent
41. 1. Lime-Soda process
In this process hydrated lime and sodium
carbonate is used to remove the hardness.
- For temporary hardness –
Ca(HCO3)2 + Ca(OH)2 → 2 CaCO3 + 2 H2O
Mg(HCO3)2 + Ca(OH)2 → MgCO3 + CaCO3 + 2 H2O
MgCO3 + Ca(OH)2 → Mg(OH)2 + CaCO3
- For permanent hardness –
CaSO4 + Na2CO3 → CaCO3 + Na2SO4
MgCl2 + Ca(OH)2 → CaCl2 + Mg(OH)2
CaCl2 form is removed by –
CaCl2 + Na2CO3 → 2 NaCl + CaCO3
42. Permutit process (Base/ Ion
exchange method)
Permutit’ means exchange; in this
process, hard water is treated with base
exchange complex or Zeolites to remove
the hardness of water. Zeolites are naturally
occurring insoluble mineral of the sodium
aluminosilicate type complex (e.g. NaAlSiO4.
3H2O ≈ Na-Permutit). This type of ion
exchanger may produce artificially.
44. Regeneration of Zeolites
For regeneration of sodium salt of the zeolite
involves passing a concentrated solution
(generally 10%) of NaCl through the
exhausted zeolites.
Ca-Permutit + 2NaCl → 2Na-Permutit + CaCl2
45. Demineralization method
The newer synthetic polymer ion exchangers
are much more versatile than the zeolites and
are widely used for water softening and
demineralization. They are often called ion
exchange resins. This reagent can remove all
mineral salts to complete demineralisation of
hard water. It has two types of ion exchanger
– Cation exchanger and Anion exchanger.
46. A) Cation exchange:
Cation exchanger has replaceable H+ or Na+ ion. Cation exchange
resins are organic in nature (made up by polymerization of
polyhydric phenols with formaldehyde. It is also manufactured by
sulphonation of coal). These reagents replace the ions of hard
water by hydrogen, leaving the water an equivalent amount of
acids.
For temporary hardness –
H2R + Ca(HCO3)2 → CaR + 2H2CO3
H2CO3 → CO2 + H2O
For temporary hardness –
H2R + CaCl2 → CaR + 2HCl
H2R + CaSO4 → CaR + H2SO4
General reaction –
2(Polymer – SO3¯H+) (s) + Ca²+ (aq) (Polymer –↔
SO3¯)2Ca²+ (s) + 2H+ (aq)
47. B) Anion exchange:
Anion exchanger has replaceable OH¯ ion. In this unit acid is
absorbed
by the anionic exchanger which displaces the anionic groups like Cl¯,
SO4¯ ¯, from acids.
General reaction –
2(Polymer – NR3+OH¯) (s) + 2Cl¯ (aq) 2(Polymer – NR3+Cl¯)↔
(s) + 2HO¯ (aq)
Water can be totally demineralised by firstly exchanging all
cations using s strongly acid form of a cation exchanger. Thus a
solution of salts M+X¯ becomes a solution of acid H+X¯, the M+
ions being retained by the resin. Subsequently a strongly basic
form of an anion exchanger absorbs the X¯ ions and liberates
OH¯ ions into water. These then neutralize the H+ ions from the
first step. The reslt is retention of all anions and cations and the
neutralization of H+ and OH¯ to form pure demineralization
water.
2H+ (aq) + 2OH¯ (aq) 2H2O↔
48. Regeneration of reagents:
1. Cation exchanger –
(Polymer – SO3¯)2Ca²+ (s) + 2HCl ↔
2(Polymer – SO3¯H+) (s) + Ca2Cl
2. Anionic exchanger –
2(Polymer – NR3+Cl¯) (s) + 2NaOH ↔
2(Polymer – NR3+OH¯) (s) + 2NaCl
49. Sequestering agents
Addition of a sequestering agent to the water
avoids many problems from relatively low
concentrations of undesirable metal ions.
Example –
EDTA (ethylenediamine tetra-acitic acid), related
aminocarboxylic acids, polyphosphates such as
sodium tetrametaphosphate Na4P4O12, Calgon -
Sodium hexametaphosphate Na6P6O18.
50. Surface Active Agents
The term surfactant is a blend of surface
active agent. Surfactants are usually
organic compounds that are amphiphilic,
meaning they contain both hydrophobic
groups (their "tails") and hydrophilic groups
(their "heads").
when added to a liquid, reduces its surface
tension, thereby increasing its spreading
and wetting properties.
In the dyeing of textiles, surface-active
agents help the dye penetrate the fabric
evenly.
52. Detergent
A detergent (as a noun; "detersive" means
"cleaning" or "having cleaning properties";
adjective "detergency" indicates presence or degree
of cleaning property) is a material intended to
assist cleaning.
Today, detergent surfactants are made from a
variety of petrochemicals (derived from petroleum)
and/or oleochemicals (derived from fats and oils).
Although the cleansing action of soaps and
detergents is similar, the detergents do not react as
readily with hard water ions of calcium and
magnesium. Detergent molecular structures consist
of a long hydrocarbon chain and a water soluble
ionic group.
54. Anionic detergents:
The detergents which
consist negative ionic
group are called anionic
detergents. The majority
are alky sulfates and
others are generally
known as alkyl benzene
sulfonates.
55. Cationic detergents
The cationic classes of
detergents have a
positive ionic charge and
are called "cationic"
detergents. In addition
to being good cleansing
agents, they also
possess germicidal
properties which makes
them useful in hospitals.
Most of these detergents
are derivatives of
ammonia. A cationic
detergent is most likely
to be found in a
shampoo or clothes
"rinse".
56. Nonionic detergents
Nonionic surfactant
molecules are
produced by first
converting the
hydrocarbon to an
alcohol and then
reacting the fatty
alcohol with ethylene
oxide. They are not
ionize in water. They
are very popular in
textile uses.
57. Advantages and disadvantages
of synthetic detergents
Effective cleaning in hard water
They are not precipitate as insoluble
Ca/Mg salts (gummy substance) on
material
They are not very good detergent as
soap
Incompatibility, in case of opposite
ionic nature
Environmental hazard
