Lab Test Book CHT

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Our department for applied technique is always at y our service for further information and advice.

Our technical advice and recommendations given verbally, in writing or by trials are believed to be correct. They are neither binding

with regard to possible rights of third parties nor do they exempt you from your task of examining the suitability of our products for the

intended use. We cannot accept any responsibility for application and processing methods which are beyond our control.

If producers or sources of different chemicals are mentioned for evidence reaction tests, it is done without evaluation. It is impossible

to take into account all chemical producers in such an infomation brochure.

Methods of evidence ........................................................................1

Chemical damaging of cellulosic fibres................................................... 1 Qualitative evidence for iron.................................................................... 2 Qualitative evidence for hydro- or oxycellulose....................................... 2 Qualitative evidence of hydrocellulose with silver nitrate ........................ 2 Qualitative evidence of oxycellulose with methylene blue....................... 3 Qualitative evidence of damaged cotton by swelling test (immaturity control by swelling test)........................................................................... 3 Evidence of fats and oils on the fabric .................................................... 4 Red-green test ........................................................................................ 5 Determination of absorbency .................................................................. 6 The degree of desize – the TEGEWA-violet scale.................................. 8 pH- value on the fabric ............................................................................ 9 Conductivity test...................................................................................... 9 Evidence of non ionic residual surfactants............................................ 10

Identification of fibre materials .....................................................12

Hydrogen peroxide ........................................................................16

Properties of commercially available H2O2-solutions ............................ 16 Storage and storage life of hydrogen peroxide ..................................... 16 Stoichiometrical calculation of the active content in H2O2-solutions ..... 17 Analysis of H2O2-content in bleaching baths......................................... 17 Analysis of H2O2-content on fabric ........................................................ 20 Semi-quantitative analysis of hydrogen peroxide content with titanyl chloride.................................................................................................. 22 Semi-quantitative analysis of hydrogen peroxide content with Merck-test rods ..................................................................................... 24

Alkali ................................................................................................25

Analysis of alkali-content in liquors ..................................................... 25

Sodium hypochlorite (chlorine bleach lye) .......... .......................27

Properties of commercially available chlorine bleach lye ....................................27 Reactions of sodium hypochlorite .......................................................................27 Active chlorine ....................................................................................................28 Analysis of active chlorine content in sodium hypochlorite bleaching liquors ......28 Dechlorination.....................................................................................................30

Sodium chlorite ..............................................................................32

Properties of commercially available sodium chlorite..........................................32 Reactions of sodium chlorite...............................................................................32 Analysis of sodium chlorite content in bleaching baths .......................................33 Destruction of residual chlorite............................................................................36

Persulphates .................................................................................. 37

Properties of persulphates ................................................................................. 37 Analysis of persulphate content in addition to hydrogen peroxide in bleaching baths.................................................................................................................. 37

Silicates .......................................................................................... 41

Properties of commercially available silicates of sodium.................................... 41 Properties of commercially available metasilicates ............................................ 41 Other properties of silicate of soda..................................................................... 41

Water hardness .............................................................................. 44

Analysis of water hardness (total hardness)....................................................... 46 Conversion factors in common units for water hardness .................................... 47

Average polymerisation degree (DP-value) ................................ 47

Fluidity F ......................................................................................... 49

Annex .............................................................................................. 50

Density and concentration of sulphuric acid, hydrochloric acid, nitric acid, caustic soda and caustic potash solution ....................................................................... 50 Brief instruction - titration of hydrogen peroxide ................................................. 56 Brief instruction - titration of caustic lye.............................................................. 57

Methods of evidence

1

Methods of evidence Pretreatment exerts a strong influence on all following processes, like dyeing, printing etc. Mistakes made in pretreatment can hardly be corrected or even not at all in later processes. The following simple test methods help to determine mistakes prior to processing or to obtain the chemical evidence for them so that damaging effects can be avoided.

Chemical damage of cellulosic fibres Cellulosic fibres can be chemically damaged by different influences, such as • catalytic damage during hydrogen peroxide bleach caused

by heavy metal contamination. • damage by contamination of fabric with concentrated

acids, mostly mineral acids like hydrochloric or sulphuric acid.

• damage by insufficiently stabilized hydrogen peroxide bleach.

Such damages become visible by holes or by a general reduction of tear strength or the DP value (average polymerisation degree). The so-called catalytic damage is a problem of pretreatment which quite often occurs. It is caused by the presence of heavy metals, which have a catalyzing effect in peroxide bleach and promote a spontaneous peroxide decomposition and finally fibre damage. In addition to copper and manganese, there is mostly iron or rust in pretreatment coming from the greige goods itself or introduced onto the fabric e.g. by the following reasons • Metal abrasion during storage or transport of fabric. • Rusty pipelines or machines parts in the pretreatment

plant. • Contamination of the industrial water with heavy metals. The presence of iron on fabric or in industrial waters can be proven rather easily.

Holes caused by catalytic damaging

èq=oK=_bfqifè=dj_e=

Methods of evidence

2

Qualitative proof of iron Ammonium thiocyanate (NH4SCN) forms a very red complex with iron. This proof can be obtained directly on the fabric or as well as in aqueous solutions. Procedure The fabric sample is treated with a solution of 1-2 spatula tops of ammonium thiocyanate (NH4SCN) in approx. 10-15 ml hydrochloric acid of 10%. A very red iron thiocyanate complex is formed if there is iron.

Qualitative proof of hydro- or oxycellulose Damaged cellulose forms hydro-and oxycellulose at the damaged parts and this can be proven by simple means. Independently from the reason for the damaging, that means by acid or oxidation agents, a mixture of hydro- and oxycellulose is formed. By means of the following reactions of evidence it is indeterminate whether the damaging was caused by oxidation agents or acids.

Qualitative proof of hydrocellulose with silver nitrate The hydrocellulose with the reducing effect separates elementary silver from a silver nitrate solution, and this becomes visible at the damaged parts by a yellow brown to black dyeing. Procedure The degreased sample free of size and finish is treated for some minutes at 80°C in an ammoniacal silver nitrat e solution.

OO

O

OH

OHO

OH

OH

CH2OH

CH2OH

O

OH

OH

CH2OH

OO

OH

OH

CH2OH

OH

OH

OH

CH2OH

O

CH

OH

OH

OH

CH2OH

OC

H

OO

OH

OH

CH2OH

CH2OH

OH

OH

CHOH

COOH

CH

O

HC

O CH2OH

CHOH

COOH

Undamaged cellulose Cellulose

Hydrocellulose

Oxycellulose


Methods of evidence

3

Then it is rinsed with distilled water and with diluted ammonia solution. Production of the ammoniacal silver nitrate solutio n A solution of 10 g silvernitrate in 100 ml water is mixed carefully with a ammonia solution of 10 % until the white sediment which had been formed is dissolved again.

Qualitative evidence of oxycellulose with methylene blue The basic dye methylene blue strongly dyes oxycellulose very much because of the carboxylic groups and the depth of the dyeing corresponds to the degree of the damage. Procedure The degreased sample which is free of size or finishing is dyed in a hot and aqueous methylene blue solution of 0.1% at 60 °C for 5 min. Then it is washed with boiling distilled water until there is no dye left.

Qualitative evidence of damaged CO by swelling test (immaturity control by swelling test) Undamaged CO fibre pieces treated with caustic soda show a phenomena which looks like mushrooms at the fibre ends under the microscope. However considerably chemically damaged CO fibre do not show such characteristic phenomena. Because of this it is possible to distinguish chemically damaged fibres from mechanically damaged ones.

To note: Merzerised CO reacts like damaged CO. Caution is advised.

To note: The swelling reaction can be done successfully only on CO fibres. Mercerised CO reacts in the same way as damaged CO. Caution is advised.


Methods of evidence

4

Procedure Fibres are taken from damaged and undamaged parts of a sample. Th cotton fibres are cut vertically to the fibre direction in pieces of 2 to 3 mm with some sharp-edged scissors or a razorblade. They are put on an object holder, covered with a cover glass, and caustic soda of 10 to 15% is added from the side by means of glass capillary. The fibres are compared under the microscope by transmitted light and magnified as large as possible. At the undamaged CO there are phenomena looking like mushrooms at the fibre ends. Chemically damaged CO does not show such "mushroom" phenomena, or only to a small degree.

Evidence of fats and oils on the fabric Residual oils and fats on the fabric often coming from preperations can have disturbing effects during dyeing e.g. resist effects. The evidence of fats or oils can be provided by a fat dye Ceres red 7B. Procedure The Ceres red stock solution is diluted with water at a ratio of 1:9 just before the application. This dilution is the utility solution. The fabric which is to be analyzed is treated with the utility solution at 60 °C at a liquor ratio of 1:60 for 5 - 10 minutes. Then wash off cold for approx. 1 min, dry and fix the dye at 150 °C for 3 min. The fats which are on the fabric are dyed in an intense red shade.

Undamaged CO

Damaged CO

Ceres red 7B corresponds to Color Index Number C.I. 26050.

Fabric free of oil or fat

Fabric with oil stripes


Methods of evidence

5

Production of Ceres red stock solution

Ceres red 7B 0.4 g/l CHT-DISPERGATOR SMS 1.0 g/l

The dye and the dispersant are ground in a plate and pasted with cold soft water. The solution is filled up with soft water at 1 l. With time, the Ceres red dye precipitates to the bottom of the container. Therefore the solution has to be shaken or stirred before it is applied.

Red-green test Analysis of effects of caustification and mercerisation of CO and CV and of ripe and unripe CO Variations in the degree of caustification and mercerisation lead to differences of dyeability and colour depth. The following test helps to recognize such differences. If a fibre sample is treated in a solution with both direct dyes of Tubantin red 8BL conc. and Tubantin green BL highly concentrated (BEZEMA AG), mercerised materials are dyed from grey to green. This is because of the affinity differences of dyes, depending on the degree of caustification and mercerisation, and the materials which have not been treated with lye become red. The red-green-test can be applied to differentiate between ripe and unripe CO. The ripe fibres are dyed red in the test and the unripe green. Dead CO fibres are dyed much less or not at all. They can be recognized as well by their neppy agglomerations in the fibre texture.

not caustified

100 g/l NaOH 100 %

150 g/l NaOH 100 %

200 g/l NaOH 100 %

Differences of degree of caustification and mercerisation

Dead CO

Sodium chlorite 30 vol.% solution

Short name N 30

[g/kg] approx. 245 (= 24.5 %)

[g/l] 300

Aspect slightly greenish-yellow clear liquid

Density (20)[g/cm3] 1 22

Solubility in water at 20 °C

unlimited

Start of crystallisation [°C] approx. -15

Reaction alkaline (pH-value approx.13)

NaClO2 - concentrations


Methods of evidence

6

Procedure The CO sample is wet-out well with boiling distilled water and then treated with the following dyeing recipe: After dyeing rinsing is carried out as follows (liquor ratio 1:40): - 2 times rinse cold - 1 time rinse for 30 s with boiling water - 2 times rinse cold Then dewater the sample and air dry it.

Analysis of absorbency The textile absorption or hydrophilic effect is mostly analyzed by the following two methods:

• TEGEWA-drop test • Capillary rise method

The TEGEWA-drop test is usually applied for the rapid determination of the absorbency. In case of small differences of absorbency and if the best possible absorbency is necessary for the further transformation of the textile, the more complicated capillary rise method is advantageous.

0

10

20

30

40

50

60

70

80

90

100

110

120

0 10 20 30 40 50 60

Time [min]

Tem

pera

ture

[°C

]

TUBANTIN red 8BL conz. C.I. Direct red 81 TUBANTIN green BL highly conc. C.I. Direct green 26

For more details see TEGEWA-drop test: „TEGEWA-drop test – a method for a rapid determination of textile absorption“ „Melliand Textilberichte 68 (1987), 581-583

0.8 % TUBANTIN red 8BL conc. 3.2 % TUBANTIN greenBL hightly conc.

take out after 15 and 30 min and add 2.5 % NaCl (normal

salt

Liquor ratio 1:40

45 min at 98 °C

add fabric at boiling temp.


Methods of evidence

7

TEGEWA-drop test – brief description The test material is put into the tension device and a drop of aqueous patent blue of 0.2 % is applied. As soon as the drop touches the test material, time is measured. As soon as the shiny surface of the drop is no longer visible, time measuring is stopped. Evaluation criteria are the following: • sinking time of the drop • spread diameter of drop. • picture of flowing. Jagged borders of the drop can indicate

woven fabric e.g. on irregularly distributed residual deposits of size, warp waxes etc.

Capillary rise procedure – brief description There are different variations of the capillary rise procedure, and the two most important are mentioned in the following. Strips of approx. 3 x 25 cm in warp and weft direction (or in longitudinal or transversal direction) are taken out and hung in water colorated with dye (e.g. solution V of patent blue 0.2 %). Variation 1 (DIN 53924) As soon as the sample is immersed in the liquid, the capillary rise is taken in mm after 10, 30 and 60 s from mark A at the liquor surface. Variation 2 Wait until the liquid level is at a height of 10 mm (mark B) and take time until mark C at 20 mm is obtained.

10 mm

20 mm

30 mm

40 mm

A

B

C

Bad pretreatment

Good pretreatment


Alternative for Patentblau V

ERKA Typ S 4030 Ringe Kuhlmann GmbH & Co KG Hamburg, Germany

Methods of evidence

8

The degree of desize – the TEGEWA-violet-blue scale Because there is a relation between the colour intensity of the iodine starch complex and the residual starch content on the fabric, the colour reaction of starch and free iodine is applied to judge in a semi-quantitative way the residual size content or better the residual content of starch after the pretreatment. Procedure A fabric sample of approx. 4 x 4 cm is laid for one minute into a iodine solution at a concentration c = 0.005 mol/l, rinsed with cold water for a short time and then dapped off with a starch free filter paper and compared immediately with the TEGEWA-violet scale. Evaluation goo

The mark 9 on the scale indicates a complete starch elimination, and mark 1 an insufficient one. Fabrication of the iodine solution To produce the 0.005 mol/l iodine solution preferably ready-made solutions (e. g. Fixanal or Titrisol) are applied at a concentration of c(I2) = 0.05 mol/l (= 0.1 N). Of this solution 50 ml are taken and filled up to a litre with distilled water. The solution itself can be made as follows: 10 g potassium iodide are dissolved in 100 ml of water, 0.65 g of iodide are added and agitated until complete dissolution. Then filling up with distilled water up to 1 l.

9 = completely desized

See further details to TEGEWA-violet scale: „The Violet Scale, a criterion for assessing the desizing degree of starch-sized fabrics“ Textil praxis international 12 (1981), 1331-1332, 1349-1350

good

bad

good

average

Remark Because of the volatility of the iodine, iodine solutions should always be kept in a brown flask closed with a ground-in stopper.

Remark A complete description of the evidence of sizes is at disposal in a separate CHT brochure


Methods of evidence

9

pH value on the fabric The pH value on the fabric is determined by the following method: • According to DIN EN 1413. The sample is extraced in cold

distilled water for 2 h at a liquor ratio of 1:50 and then the pH is measured in the extract.

• With Morapex extraction. The sample is extracted with hot distilled water at the Morapex and then the pH measured as well in the extract.

• Dropping of a pH-indicator directly on the sample. pH-value determination with pH-indicator – brief description The easiest method is the pH-determination by dropping a pH-indicator (e.g. of Merck) directly on the sample. This procedure does not give absolutely reliable results, but at least a rough estimation about the pH on the fabric. The sample is moistened with distilled water, and then the pH-indicator is dropped on. Then it is compared with the colour scale.

Determination of the conductivity The electrolyte content (residual alkali, neutralisation salts and others) of a pretreated material has an important influence on the print result of a pigment printing. A high electrolyte concentration leads, for example, to a decrease of the printing paste viscosity, and therefore to an increasing and thus unwanted penetration of the print. A measure for the electrolyte content of a fabric is the electrical conductivity which can easily be determined. Procedure 4.00 – 10.00 g of the test fabric are weighted in a round-bottom flask of 250 ml, distilled water is added at a liquor ratio of 1:20, and the solution is boiled for 1 h by reflux. After cooling and filtering, measurement of the conductivity of the extract by means of a conducting meter. The measuring value is given in µS/cm or mS/cm.

pH-Indicator (Merck)

pH 3.5

pH 6.5

pH 8

Conducting meter

high conductivity (180 µS/cm)

Print side

Back side

low conductivity (20 µS/cm)

Print side

Back side

Morapex A (Habotex)


Methods of evidence

10

Evidence of non ionic residual surfactants Some reactive dyes (mostly turquoise types) react sensitively in the presence of non ionic surfactants which had been unsufficiently eliminated from pretreatment. If non ionic residual surfactants are suspected to be the reason for a problem, their presence can be proven in the extract after extraction of the fabric in cold water according to the so-called Draggendorff-reaction. Procedure The material to test is extracted at a liquor ratio of 1:20 with cold distilled water at 5°C for 5 minutes (e.g. in beaker). It is important that the temperature of the water is approx. 5 °C; because it guarantees that the non ionic surfactants are removed from the fabric to the water phase extract quantitatively. 10 ml of the extract are prepared in a test tube. Then 2 ml of Draggendorff-reagent are given to the extract, and the test tube is agitated. The orange deposit is absorbed through stainless steel filter, and the filter paper is dried. Judgement The intensity of the desposit is a measure for the concentration of the present non ionic surfactant. Depending on the chemical base of a surfactant precipitations of different intensity can result, and therefore a series of concentrations of the applied surfactants should be produced for comparative purposes and to allow a semi-quantitative result by this. 10 ml of every different surfactant solution is mixed with the reagent and filtered. Fabrication of the Draggendorff-reagent The ready-made Draggendorff reagent can be applied only for a limited time, and therefore it is best to produce two different stock solutions (A and B), which are mixed just before their application.

Precipitations of a reactive dye with a non ionic surfact

Example series of concentrations of a

non ionic surfactant

Concentration in g/l

0.0

0.02

0.05

0.10

0.15

Concentration in % on weight of

fabric (LR 1:20)

0.0

0.04

0.10

0.20

0.30


Methods of evidence

11

Solution A: 1.7 g of bismuth nitrate are dissolved in 20 ml of pure acetic acid. After addition of 80 ml of water, a solution of 40 g of potassium iodide, 100 ml of distilled water and 200 ml pure acetic acid are filled up to 1000 ml in a graduated flask. Solution B: A barium chloride solution of 20 % in distilled water Ready-made reagent: Mix 2 volume parts of solution A with 1 volume part of solution B. èq=oK=_bfqifè=dj_e=èq=oK=_bfqifè=dj_e=

Identiification of fibre materials

12

Identification of fibre materials For a quantitative analysis of the fibre materials on natural or synthetic basis and their mixtures there are instructions of analysis at disposal in the technical literature. To identify the individual fibres there are different qualitative rapid methods like burning test, dry distillation, dyeing reaction, microscopical analysis or dissolution in acids, alkali, organic solvents. Burning test and dry distillation For the burning test the fibre which is to be analyzed is held into the flame, and the criteria of burning, fume, odour and residue are judged. In the dry distillation the fibres are heated in a dry test tube, and the vapours are tested on their pH value by means of a moistened pH paper.

Fibre Burning test Dry distillation

Odour Burning, residue pH-value Vegetable fibres like cotton, linen, hemp, viscose

of burnt paper

burns down fast, white grey ashes pH 5-6

Animal fibres, like wool, silk

of burnt hair burns slowly, white grey ashes

pH 9-10

Acetate fibres sour, like acid

burns fast, burnt-out particles with

subsequent white grey ashes

pH 2-3

Polyester fibres sweetish and stinging

melts and burns, sooting only in flame,

glassy, ropy melt, black enamel pearl

pH 3-4

Polyamide fibres slightly of burnt hair

goes on melting and burning without sooting, glassy yellow to brown,

ropy melt

pH 10-11

Burning test Dry distillation

Natural and man-made fibres


Remark In case of fibre mixtures caution is advised. Mixed pH values might turn up and the identification becomes difficult. Preliminary tests should be burning test and dry distillation.

Identification of fibre materials

13

Fibre Burning test Dry distillation

Odour Burning, residue

pH-value

Polyacrylonitrile-fibres sweetish

melts and burns, then soots, black and

brittle melting residue pH 10-11

Polyurethanes malodorous

melts and goes on burning, without

sooting, black, hard and brown metling

residue

pH 10-11

Polyethylene fibres

like burning candle

melts and goes on burning without

sooting, light brown and brittle melting

residue

pH 5-6

Polypropylene-fibres

like burning candle

melts but does not burn, white smoke,

yellowish melt pH 6-7

Dyeing method The dyeing method with special dye reagents can be applied without any problems, and allows a good to rough evaluation depending on the material which is to be analyzed e.g. fabric out of one fibre kind, mixed articles of singular or uniform fibres. This does not work on dyed material, and therefore coloured fabric has to be stripped before testing. The dyeing method serves only as a preliminary test because it can be applied only under certain conditions on stripped or pretreated fabric. Special fibre material reagents for the analysis of fibre materials are offered under the name of „Neocarmin“ by the company FESAGO Chemische Fabrik Dr. Gossler, 69207 Sandhausen. The producer supplies colour scales for identification together with the reagents. Analysis of man-made fibres For a uniform fibre mixture, dyeing reactions or burning tests are not sufficient to identify singular components. A classification is possible only by a process of separation with different dissolving tests with organic or inorganic chemicals.

Man-made fibres


Identiification of fibre materials

14

The following dissolving behaviour in different solvents describes only the qualitative analysis. There are further methods in technical literature for the quantitative determination.

Ace

tate

Tria

ceta

te

Pol

yam

ide

6.6

Pol

yam

ide

6

Pol

yest

er

Pol

yacr

ylon

itrile

Pol

yure

than

e

Pol

ypro

pyle

ne

Pol

yeth

ylen

e

Acetone ❑ ■ ■ ■ ■ ■ ■ ■ Dimethylformamide ❑ ❍ ■ ❍ ❍ ❍ ❍ ● ● Dioxane ❑ ❑ ■ ■ ■ ■ ■ ■ ● o-Dichlorobenzene ● ■ ■ ■ ❍ ■ ❍ ❍ ❍ Phenol 40% ❑ ❑ ❑ ❑ ❍ ● ❍ ● ● Xylol ■ ■ ■ ■ ■ ■ ■ ❍ ❍ Formic acid (98%) ❑ ❑ ❑ ❑ ■ ■ ❍ ■ ● Pure acetic acid ❑ ❑ ❍ ❍ ■ ■ ● ■ ● Hydochloric acid conc. ❑ ❑ ❑ ❑ ■ ■ ▲ ■ ● Sulphuric acid conc. ❑ ❑ ❑ ❑ ❑ ❑ ❑ ● ● KOH 40% ■ ■ ■ ■ ▲ ■ ▲ ● ● ❑ cold soluble ❍ soluble at boiling temperature ■ insoluble ● insoluble, but changes during boiling ▲ swells and decomposes during boiling

partly soluble during boiling Analysis of natural fibres A rapid analysis of singular cellulose fibres e.g. cotton, viscose or protein fibres like wool and silk cannot be taken for granted, especially not if it is a uniform fibre mixture. Dyeing reactions and a microscopical analysis mostly can give an indication, but for singular determinations sometimes complicated wet chemical analyses have to be carried out (see technical literature).

Natural fibres

Dissolving behaviour


Identification of fibre materials

15

As simple examples can be mentioned

Vegetable fibres Animal fibres

Burning test Dyeing test

Vegetable fibre: odour of burnt paper Animal fibre: Odour of burnt hair

Mercerised not mercerised cotton

Microscopical analysis

Red-/green test

Not mercerised: typical cork-screw like twists of the fibre; kidney shaped cross-section Mercerised: smooth fibre, round cross-section

Ripe and unripe cotton Red-/green test Ripe cotton fibre: red dyeing Unripe cotton fibre green dyeing

Cotton regenerated cellulosic fibres


Dyeing method

Cotton: typical cork-screw like twists of the fibre Regenerated cellulosic fibre: smooth fibre

Cotton Bast fibre


Different longitudinal section pictures of the fibres

Wool Silk

Dissolving tests microscopical

analysis dyeing method

Wool: dissolves during boiling in NaOH of 5%, typical scales layer Wild silk: dissolves only partly even if boilt for a longer time

Pure silk (bombyxs mori) and wild (e.g. Tussahsilk) silk

Dissolving tests

Pure silk: dissolves during boiling in HCl conc. (after approx. 60 sec.) Wild silk: dissolves only after boiling for a longer time

Different procedures of analysis


Hydrogen peroxide

16

Hydrogen peroxide Chemical formula: H2O2 Molar mass: 34.02 g/mol

Properties of commercially available H 2O2-solutions

Storage life and storing of hydrogen peroxide In presence of catalytic substances hydrogen peroxide easily decomposes in an exothermal reaction to water and oxygen. Stability of hydrogen peroxide is influenced by: • Heavy metals

(Iron, copper and manganese even in smallest concentrations reduce very much the hydrogen peroxide stability).

• pH-value (The best pH value is between 3.5 and 4.5)

• The concentration of hydrogen peroxide (The higher the H2O2-concentration is, the more decomposition tends to diminish).

• Temperature (At a higher temperature of about 10 °C, the reacti on speed

• increases at a factor of 2.2). • Influence of light

(Hydrogen peroxide should be stored in containers which are impervious to light).

• Other soilings (Soiling of any kind reduces substantially the stability of hydrogen peroxide).

Aktive oxygen Peroxides have -O-O- groups, of which an oxygen atom can easily be separated as „active oxygen“ . (For calulation see below)

Decomposition of H 2O2

H2O2 (liq.) → H2O (liq) + ½ O2 (g.)

∆H = -98.31 kJ/mol

Short name W 30 W 35 W 50 W 60

[% by weight] 30 35 50 60

[Vol.-%] 111 132 199 249

[g H 2 O 2 /kg] 300 350 500 600

[g H 2 O 2 /l] 334 396 598 745

Active oxygen content [% by weight] 14. Jan 16. Mai 23. Mai 28. Feb

Density ( ρρρρ20) [g/cm 3 ] 1.114 1.132 1.195 1.241

Acid content 0.5 - 5 mmol H+/l

H2O2 -concentrations


Hydrogen peroxide

17

For the above mentioned reasons hydrogen peroxide should be protected from light and stored in its original containers or special tanks. Stoichiometric calculation of active oxygen content in H 2O2-solutions For the determination of the active oxygen content the bimolecular decomposition reaction of hydrogen peroxide is taken as basis:

H2O2 →→→→ H2O + ½ O2

34.0146 g/mol → 18.0152 g/mol + ½ · 31.9988 g/mol

Out of 34.0146g H2O2 100 % result from ½ · 31.9988g = 15.9994g of so-called active oxygen. The conversion factor of % by weight of H2O2-solution in active oxygen is the following:

4,704solutionOHby weight %

34.01461015.9994sol.OH by weight %

sol.][g/kgoxygen Active

22

22

⋅−=

⋅⋅−=

In bleaching baths normally the total content of hydrogen peroxide is determined and not the active oxygen content.

Determination of H 2O2-content in bleaching baths The hydrogen peroxide content can be determined by titration with potassium permanganate (permanganometrically) or with iodine (iodometrically). Titration with potassium permanganate certainly is the most often used method, and therefore it is the only procedure which is mentioned here.

Example 1

How much active oxygen in g/kg does a H2O2-solution of 50% contain ? Active oxygen = 50 · 4.704 = 235g/kg = 23.5%

Example 2

How much active oxygen does a bleaching bath with 10ml/l H2O2 50% (density ρ20 = 1,132 g/cm3) contain? 10 ml H2O2 50% contain 10 ⋅ 1.132 = 11.32 g H2O2 50% or 11.32g H2O2 50% /1000ml

g/l2.71000

11,32504.704x =

⋅⋅=

Aktive oxygen content = 2.7 g/l


Hydrogen peroxide

18

Permanganometric determination of H 2O2 Titration with potassium manganate in sulphuric acid solution is often running from colourless to slightly pink. The equivalent mass ratios result from the reaction equation or equivalent numbers of potassium permanganate and hydrogen peroxide.

Equivalent number z

Molar mass

Hydrogen peroxide 2 34.0146 g/mol

Potassium permanganate

5 158.034 g/mol

The equivalent ratios result from:

n(eq) (KMnO4) = n(eq) (H2O2)

)(KMnOz)O(HM)O(Hz)O(Hm

)(KMnOn

)O(HM)O(Hz)O(Hm

)Oz(H)O(Hn)(KMnOz)(KMnOn

422

22224

22

2222222244

⋅⋅

=

⋅=⋅=⋅

Normally a solution of 0.02 mol/l (= 0.1 N) KMnO4 is applied. Then the following equation is valid:

g1.7007)O(Hm2

5g/mol34.0146KMnOmol0.02)O(Hm

5g/mol34.01462)O(Hm

KMnOmol0.02

22

422

224

=

⋅⋅=

⋅⋅=

According to this 1 ml of a solution of 0.02 mol/l (= 0.1 N) KMnO4-exactly corresponds to 0.0017 g H2O2 100 %. Normally a solution of 0.1 N (= 0,02 mol/l) potassium permanganate is applied for titration. However special solutions can be applied as well, e.g. for the AATCC test 102 a solution of 0.588 N or for Europe a solution of 0.23 N. The main reason for these special solutions is a direct relation between consumption of potassium permanganate and the hydrogen peroxide concentration. The consumption of a 0.23 N potassium permanganate solution in case of a sample of 10 ml just gives the content of ml/l H2O2 35%.

Reaction of H 2O2 with KMnO 4 5 H2O2 + 2 MnO4

- + 6 H+ → 2 Mn2+ + 5 O2 ↑ + 8 H2O


Hydrogen peroxide

19

Procedure of titration An aliquot part is taken, normally 1 to 10 ml of the bleaching bath and given into an Erlenmeyer flask containing approx. 10 ml of a sulphuric acid (20%). The titration is carried out immediately with the potassium permanganate solution to a faint pink colour. Calculation The variables applied for calculation are the following ones:

V Consumption in ml of a KMnO4 solution at a concentration of x mol/l.

x mol/l KMnO4

Concentration of the applied potassium permanganate solution, normally 0.02 mol/l = 0.1 N

F ml of taken quantity of bleaching liquor

ρ ρ ρ ρ Density of hydrogen peroxide solutions (H2O2 35%ig = 1.132; H2O2 50% = 1.195)

W % by weight of hydrogen peroxide solution

The following calculation formula are such that calculation can be done with every concentration of potassium permanganate solution and every concentration of hydrogen peroxide. Normally a 0.02 mol/l = 0.1 N of potassium permanganate solution is applied. Calculation of H 2O2-concentration in g/l:

WF2100V34.01465KMnOmol/lx

%xOHg/l 422 ⋅⋅

⋅⋅⋅⋅=−

WFV65.8503KMnOmol/lx 4

⋅⋅⋅

=

Example For titration of F = 10ml bleaching liquor with 0.02mol/l KMnO4-solution (= 0.1 N) are used V = 8.5ml KMnO4-solution. How much of H2O2 50% (W=50) in g/l does the bleaching liquor contain ?

0510

8,565.850302.0%502O2Hg/l

⋅

⋅⋅=

g/l H 2O2 50% = 2,89g/l

1 ml 0.02 mol/l KMnO 4 =

0.0017g H2O2 100%


Remark: In the annex, there is a very much simplified variation of the titration instruction.

Hydrogen peroxide

20

Calculation of H 2O2-concentration in ml/l:

ρ⋅⋅⋅⋅⋅⋅⋅=−

WF2100V34,01465KMnOmol/lx

%xOHml/l 422

ρ⋅⋅⋅⋅=

WFV65,8503KMnOmol/lx 4

Determination of H 2O2-content on the fabric To verify the application of chemicals during impregnation processes the hydrogen peroxide content can be determined directly on the fabric in a quantitative way. Procedure A piece of approx. 2-3 g is cut out of the fabric after impregnation and given immediately into an Erlenmeyer flask containing approx. 100 ml of an sulphuric acid of 20%. With the potassium permanganate solution titration is done up to first persisting violet dyeing. Then the sample is taken out of the flask, rinsed briefly with water, dried and weighted. Calculation The parameters of calculation are the following:

V Consumption in ml of KMnO4-solution with a concentration of x mol/l.

x mol/l KMnO4

Concentration of the applied potassium permanganate solution, normally 0.02 mol/l = 0.1 N

M Mass of taken sample in grammes

ρρρρ Density of hydrogen peroxide solution (H2O2 35% = 1.132; H2O2 50% = 1.195)

W % by weight of hydrogen peroxide solution

Example For titration of F = 10ml of bleaching liquor with 0.02 mol/l KMnO4-solution (= 0.1 N) V = 8.5 ml KMnO4-solution are consumed. How much H2O2

50% in ml/l (W=50, ρ=1.195) does the bleaching liquor contain?

195.10510

8,565.850302.0%502O2Hml/l

⋅⋅

⋅⋅=

ml/l H 2O2 50% = 2,42 ml/l


Hydrogen peroxide

21

The following calculation formula are such that calculation can be done at every concentration of potassium permanganate solution and every concentration of hydrogen peroxide. Normally a 0.02 mol/l = 0.1 N potassium permanganate solution is applied. Calculation of the H 2O2-concentration in g/kg:

WM2100V34.01465KMnOmol/lx

%xOHg/kg 422 ⋅⋅

⋅⋅⋅⋅=−

WMV65.8503KMnOmol/lx 4

⋅⋅⋅=

Calculation of H 2O2-concentration in ml/kg:

ρWM2100V34.01465KMnOmol/lx

%xOHml/lkg 422 ⋅⋅⋅

⋅⋅⋅⋅=−

ρWMV8503.65KMnOmol/lx 4

⋅⋅⋅⋅=

Reagents Potassium permanganate solution To produce the potassium permanganate solution preferably ready-made solutions are applied. If the solution is produced, it is done as follows: For a 0.02 mol/l KMnO4-solution 3.1607 g of solid potassium permanganate are weighted and dissolved in distilled water. After complete dissolution of the potassium permanganate, filling up with distilled water up to the marking in a 1 l graduated flask.

Example After impregnation a samplehaving a mass of 2.8 g is taken. For titration with 0.02mol/l KMnO4-solution (= 0,1 N) V = 8,5ml KMnO4-solution is consumed. How much H2O2 50%(W=50) ml/kg are on the fabric ?

195.1058.2

8.565.850302.0%ig502O2Hml/kg

⋅⋅

⋅⋅=

ml/kg H 2O2 50% = 8.6 ml/kg

Example After impregnation a sample having a mass of 2.8 g is taken. For titration with 0.02mol/l KMnO4-solution (= 0,1 N) V = 8.5ml KMnO4-solution are consumed. How much H2O2 50% (W=50) in g/kg are on the fabric ?

058.2

8.565.850302.0%ig502O2Hg/kg

⋅⋅⋅

=

g/kg H 2O2 50% = 10.3 g/kg


Hydrogen peroxide

22

Semi-quantitative determination of the hydrogen peroxide content with titanylchloride For hydrogen peroxide a semi quantitative determination can be done in a bath sample or directly on the fabric with titanylchloride. Particularly in case of cold dwelling procedures or steaming processes (before the washing off) the fabric can be determined very rapidly on its residual peroxide content and the recipe can be modified accordingly in case of need. The determination method is based on a colour change during the reaction of hydrogen peroxide with titanylchloride (TiOCl2). Depending on the concentration of hydrogen peroxide there is a yellow to a deeply orange red dyeing. Depending on the determination of the hydrogen peroxide content on the fabric or in a solution, there are two colour scales at disposal. Determination in aqueous solutions – colour scale L

0.5 ml of the test solution are mixed on a white droplet plate with 1 drop of titanylchloride solution. After approx. 1 min the colour shade is compared with the colour scale. The content of hydrogen peroxide is given in ml/l. Determination directly on the fabric – colour scale T 2 – 3 drops of titanylchloride solution are spotted onto the textile and the reagent is left to act for 20 – 30 s. The colour shade is compared with the colour scale. The content of hydrogen peroxide is given in ml/kg. If there is not any yellow colouration, there is hardly any hydrogen peroxide. Fabrication of the titanylchloride solution 10 ml of titan(IV)chloride is slowly dropped in 20 ml hydrochloric acid conc. and stirred. The reaction should be done under an extractor hood because of the very strong exothermic reaction and the development of hydrogen chloride (fumes). After having produced the mix, the solution is heated up to boiling and after 1 min 800 ml of diluted hydrochloric acid (1 part of conc. hydrochloric acid and two parts of water). After cooling off, the solution is ready for use.

Reaction of H 2O2 with titanylchloride [Ti ⋅ aq]2+ + H2O2 → [Ti(O2) ⋅ aq]2+ + H2O yellow to orange

Colour scale L Determination of hydrogen peroxide in aqueous solutions.

Colour scale T Determination of hydrogen peroxide directly on the fabric


Hydrogen peroxide

23


Hydrogen peroxide

24

Semi-quantitative determination of the hydrogen peroxide content with Merck-test sticks

Application for aqueous solutions

1. Take test sticks and close the tube again. 2. Dip test stick for 1 sec into the test solution so that the

reactive zone is completely wet. 3. Take out test stick and shake off excess liquid and

compare the reactive zone after 15 sec with the colour scale.

Depending on the blue dyeing of the stick, a value of 0 – 25 mg/l hydrogen peroxide is read off from the Merck-test stick container scale.


Alkali

25

Alkali In pretreatment the following alkali are used:

• Caustic soda (NaOH), solid or in solution • Soda (sodium carbonate, Na2CO3) • Ammonia solution • Silicates or silicate of soda

Determination of alkali content in liquors The quantitative determination of the three alkalis in the bath are carried out by acidimetrical titration with salt or sulphuric acid (mostly 0.1 N). The end point of the titration is indicated by a suitable acid-base indicator like e.g. phenol phthalein, methylorange or by a colour change. Titration An aliquot part, usually 1 to 10 ml, of the liquor is given into an Erlenmeyer flask containing some distilled water. It is titrated with the acid solution up to the colour change of the indicator. Calculation The parameter of calculation are the following:

V Consumption in ml of acid-solution. Normally 0.1 mol/l (= 0.1 N) hydrochloric acid or 0.05 mol/l (= 0.1 N) sulphuric acid

F ml of taken liquor quantity.

f

Factor for the conversion on caustic soda, soda or ammonia 1 ml = 4.0 mg caustic soda (NaOH) 1 ml = 5.3 mg soda (Na 2CO3) 1 ml = 1.7 mg ammoniac (NH 3) Valid for hydrochloric acid of 0.1 mol/l (= 0,1 N) or sulphuric acid of 0.05 mol/l (= 0,1 N)e.

Common indicators

Indicator Colour change

of →→→→ to

Phenol phthalein

red → colourless

Methyl orange orange → ret

Methyl red yellow → ret

Remark: In the annex there is a very much simplified version of the tiitration instruction.


Alkali

26

For a 0.1 mol/l (= 0,1 N) hydrochloric acid or 0.05 mol/l (= 0,1 N) sulphuric acid, the concentrations of different alkalis are found as follows. Alkali in g/l:

Ff V

Alkalig/l⋅=

Particularly in continuous processes caustic lye is applied instead of solid caustic soda. In such cases it is useful to get the caustic lye content in g/l or ml/l. It is necessary to take account of the density and the concentration of the applied caustic lye for the calculation. The parameters of calculation are the following:

V Consumption in ml of acid solution. Usually hydrochloric acid of 0.1 mol/l (= 0,1 N) or sulphuric acid of 0.05 mol/l (= 0.1 N)

F taken quantity of liquor in ml .

ρ ρ ρ ρ Density of caustic lye (NaOH 50%ig = 1.53)

W % by weight of caustic lye

Caustic lye in g/l:

WF1004

%x NaOHg/l⋅⋅⋅=− V

Caustic lye in ml/l:

ρ⋅⋅⋅⋅=−

WF1004

%x NaOHml/lV

Example F = 10 ml are taken of a bleaching liquor and titrated with hydrochloric acid of 0.1 mol/l with phenol phthalein as indicator. The consumption of the acid is: 11.2 ml. Which content of caustic soda (f = 4) in the liquor ?

10

11,2 4100%NaOHg/l

⋅=

g/l NaOH 100% = 4.5 g/l

Example

For titration of F = 10ml of bleaching liquor of 0.1 mol/l of hydrochloric acid (= 0.1 N) V = 11.2 ml hydrochloric acid solution is used. How much caustic lye of 50% in g/l (W=50) does the bleaching liquor contain ?

5001

1002.114%50 NaOHg/l

⋅⋅⋅= g/l

NaOH 50% = 9 g/l

Example

For titration of F = 10ml bleaching liquor 0.1 mol/l hydrochloric acid (= 0.1 N) V = 11.2 ml hydrochloric acid solution is used. How much caustic of 50% lye in g/l (W=50, ρ=1.53) does the bleaching liquor contain ?

1.5350011002.114

%50 NaOHml/l⋅⋅⋅⋅=

ml/l NaOH 50%ig = 5,9 ml/l


Sodium hypochlorite (chlorine bleaching lye)

27

Sodium hypochlorite (Chlorine bleaching lye) Chemical formula: NaOCl Molar mass: 74.5 g/mol

Properties of common chlorine bleaching lye

% by weight 12.5 Content of active chlorine of

commercially available chlorine bleach g/l

approx. 150

Reactions of sodium hypochlorite The most important reactions for bleaching with sodium hypochlorite are the following:

Hydrolysis NaOCl + H2O → NaOH + HOCl

Release of bleaching agent HOCl → HCl + [O]

Maximal HOCl-development NaOCl + HCl → NaCl + HOCl

Formation of free chlorine „Active chlorine“ HOCl + HCl → H2O + Cl2

Summarized in a diagram the pH-dependance of the composition of sodium hypochlorite bleaching liquors is as follows: The best pH range for bleaching is between 9 and 12.

„Active chlorine“ is the quantity of chlorine which is released during acidification of sodium hypochlorite with hydrochloric acid (see below)


0

20

40

60

80

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14pH-value

Con

cent

ratio

n [%

]

Cl2 HOClOCl -

b est r ang e f o r b leaching p r o cess


28

Active chlorine Although chlorine does not have any bleaching effect, active chlorine is defined as the quantity of chlorine which is released during acidification of sodium hypochlorite with hydrochloric acid.

Determination of active chlorine content in sodium hypochlorite bleaching baths The quantitative determination of the content of active chlorine is done by a iodometric titration. Out of an acid potassium iodide solution (KI) sodium hypochlorite separates an equivalent quantity of iodine (I) to the quantity of chlorine (Cl2), and it can be titrated with sodium thiosulphate solution (Na2S2O3). The equivalence mass ratios result of the reaction equation or the equivalence numbers of sodium thiosulphate and of chlorine (Cl2).

Equivalence

number z Molar mass

Chlorine 2 70.906 g/mol

Sodium thiosulphate 1 158.10 g/mol

The equivalence ratios are the following:

n(eq) (Na2S2O3) = n(eq) (Cl2)

)OS(Naz)(ClM)(Clz)(Clm

)OS(Nan

)(ClM)(Clz)(Clm

)z(Cl)(Cln)OS(Naz)OS(Nan

3222

22322

2

2222322322

⋅⋅=

⋅=⋅=⋅

Normally a 0.1 mol/l (= 0.1 N) Na2S2O3-solution is applied. The calculation ist:

g3.545)(Clm2

1g/mol70.906OSNamol0.1)(Clm

1g/mol70.9062)(Clm

OSNamol0.1

2

3222

2322

=

⋅⋅=

⋅⋅=

That means that 1 ml of a 0.1 mol/l (= 0,1 N) Na2S2O3-solution corresponds to exactly 3.545 mg Cl2 or active chlorine.

Transformation of sodium hypochlorit e with iodide 2 HOCl + 4 I- + 2 H+ → 2 I2 + 2 Cl- + 2 H2O Back titration of iodine with sodium thiosulphate

2 S2O3

2- + I2 → 2 I- + S4O62-

Active chlorine HOCl + HCl → H2O + Cl2



29

Procedure of Titration An aliquot part, usually 1 to 10ml, is taken from the bleaching liquor and given into an Erlenmeyer flask containing some distilled water and approx. 10ml potassium iodide solution (approx. of 10%). Then approx. 20ml of a sulphuric acid solution of 20% are added. The transformation which takes place of sodium hypochlorite with potassium iodide to iodine is recognisable by a stronger brown colouration of the solution. With a sodium thiosulphate solution of 0.1 ml/l (= 0.1 N) titration is done until a weak brown colouration is obtained. After addition of 5 ml of a starch solution (approx a solution of 1 % of some soluble starch) the titration solution gets a strong blue dyeing. Titration is continued with sodium thiosulphate solution until the titration solution becomes colourless. Calculation The parameter of calculation are the following:

V Consumption in ml of a Na2S2O3-solution with a concentration of 0.1 mol/l (= 0.1 N).

F ml of taken quantity of bleaching liquor

1ml of 0.1mol/l Na 2S2O3 = 0.00355g active chlorine Calculation of active chlorine content in g/l:

F1000V00355.0

chlorine Activeg/l⋅⋅=

Example For titration of F = 10ml bleaching liquor with 0.1 mol/l (= 0.1 N) sodium thiosulphate solution are consumed V = 6,8 ml Na2S2O3 solution. How much active chlorine in g/l does the bleaching bath contain ?

01

10008.600355.0chlorine Activeg/l

⋅⋅=

g/l Aktive chlorine = 2.41 g/l

1ml 0.1mol/l Na 2S2O3 =

0.00355g active chlorine



30

Dechlorination Dechlorination has two purposes: 1. Elimination of the active chlorine from the fabric, because it

would damage the fibres during drying and storing. 2. Separation of chloramines (chlorine protein compounds). Vegetable fibres are composed of protein compounds of the protoplasma and form so-called chloramines in contact with chlorine bleach lye. Chloramines tend to form hypochlorite in an humid atmosphere, and this has a fibre damaging effect during storing. In addition to that chloramines separate hydrochloric acid during the drying process and this might cause fibre damage as well. Dechlorination agent Dechlorination can be done with reducing agents or with hydrogen peroxide:

Dechlorination agent

Theoretically necessary quantity for the destruction of 1g/l of active

chlorine

Sodium thiosulphate (Antichlorine)

4 x HOCl = 2 x 35.5g active chlorine = 158.1g sodium thiosulphate

1g/l active chlorine = 0.55g/l sodium thiosulphate

Sodium hydrogen sulphite

(Bisulphite)

1 x HOCl = ½ 35.5g active chlorine = 104.06g sodium hydrogen sulphite

1g/l active chlorine = 2.9g/l sodium hydrogene sulphite

Sodium dithionite (Hydrosulphite)

3 x HOCl = 1.5 x 35.5g active chlorine = 158.1g sodium hydrogen sulphite

1g/l active chlorine = 1.5g/l sodium hydrogen sulphite

Hydrogen peroxide

1 x HOCl = ½ 35.5g active chlorine = 34.02g hydrogen peroxide

1g/l active chlorine = 0.48g/lH2O2 100% = 1.21ml/l H2O2 35% = 0.8ml/l H2O2 50%

Sodium thiosulphate 4 HOCl + S2O3

2- + H2O → 2 SO4

2- + 6 H+ + 4 Cl-

Sodium hydrogen sulphite HOCl + HSO3

- → HSO4

- + H+ + Cl-

Sodium dithionite 3 HOCl + S2O4

2- + H2O → 2 SO4

2- + 5 H+ + 3 Cl-

Hydrogen peroxide HOCl + H2O2 →

Cl- + H2O + H+ + O2

Formation of chloramines Protein compound R-NH2 + NaOCl → R-NHCl + NaOH Chloramine

Decomposition of chloramines in a humid atmosphere R-NHCl + H2O



31

Determination of active chlorine content in commercially available chlorine bleach lyes In commercially available chlorine bleaching lyes the active chlorine content usually is at 140 – 160 g/l. To test the content of active chlorine, the concentrated chlorine bleaching lye is diluted before the titration. Titration is done with the same method as for the d iluted bleaching bath. A dilution of 20 – 50 ml concentrated chlorine bleach lye per liter with distilled water is advised. Calculation The parameters of calculation are the following:

KV Dilution of KV ml concentrated chlorine bleach lye per liter. Usually 20 – 50 ml/l.

V Consumption in ml of Na2S2O3- solution with a concentration of 0.1 mol/l (= 0.1 N).

F ml of taken quantity of diluted chlorine bleach lye for titration.

Calculation of active chlorine content in g/l:

VKF00011000V00355.0

chlorine Activeg/l⋅

⋅⋅⋅=

Example KV = 20 ml commercially available chlorine bleach lye was diluted on a liter. Of this diluted solution F = 10 ml were taken out and titrated with 0.1 mol/l (= 0.1 N) Na2S2O3 solution. A consumption of V = 8.5 ml Na2S2O3 solution was found. How much active chlorine in g/l does the concentrated bleaching lye contain.

2001

100010005.800355.0chlorine Activeg/l

⋅⋅⋅⋅

=

g/l Active chlorine = 150 g/l


Sodium chlorite

32

Sodium chlorite Chemical formula: NaClO2 Molar mass: 90.5 g/mol

Properties of commercially available sodium chlorite

Reactions of sodium chlorite The most important reactions for bleaching with sodium chlorite are the following. Alkaline sodium chlorite solutions are very stable at room temperature. In an acid medium, however, sodium chlorite solutions are rapidly decomposed.

Hydrolysis NaClO2 + H2O → NaOH + HClO2

Release of bleaching agent HClO2 → HCl + 2 [O]

Decomposition of bleaching agent in an acid solution Formation of chlorine dioxide

5 HClO2 → 4 ClO2 + HCl + 2 H2O

3 HClO2 → 2 HClO3 + HCl

Sodium chlorite 30 vol.% solution

Short name N 30

[g/kg] approx. 245 (= 24.5 %)

[g/l] 300

Aspectslightly greenish-yellow clear

liquid

Density ( 20) [g/cm 3 ] 1 22

Solubility in water at 20 °C

unlimited

Start of crystallisation [°C] approx. -15

Reaction alkaline (pH-value approx.13)

NaClO2 - concentrations


Sodium chlorite

33

Summarized in a diagram the pH dependance of the composition of sodium chlorite bleach liquors is as follows: Determination of sodium chlorite content in bleach liquors The quantitative determination of the content of sodium chlorite content is obtained by iodometric titration. Sodium chlorite separates from an acid potassium iodide solution (KI) a quantity of iodine (I) equivalent to the sodium chlorite (NaClO2), which can be titrated with sodium thiosulphate solution (Na2S2O3). The equivalence mass relations result from the reaction equation or equivalence numbers of sodium thiosulphate and sodium chlorite.

Equivalence

number Molar mass

Sodium chlorite 4 90.5 g/mol

Sodium thiosulphate 1 158.10 g/mol

Transformation of sodium chlorite with iodide ClO2

- + 4 I- + 4 H+ → 2 I2 + Cl- + 2 H2O Back titration of iodine with sodium thiosulphate

2 S2O3

2- + I2 → 2 I- + S4O62-


0

20

40

60

80

100

0 1 2 3 4 5 6 7 8 9 10 11 12

pH-value

Con

cent

ratio

n [%

]

ClO2

HClO2 ClO2-

b est rang e f o r

b leaching p rocess

Sodium chlorite

34

The equivalence ratios result from:

n(eq) (Na2S2O3) = n(eq) (NaClO2)

)OS(Naz)(NaClOM

)(NaClOz)(NaClOm)OS(Nan

)(NaClOM)(NaClOz)(NaClOm

)z(NaClO)(NaClOn)OS(Naz)OS(Nan

3222

22322

2

2222322322

⋅⋅

=

⋅=⋅=⋅

Usually a solution of 0.1 mol/l (= 0.1 N) Na2S2O3 is applied. The following equation is valid:

g2,2625)(NaClOm4

1g/mol90,5OSNamol0,1)(NaClOm

1g/mol90,54)(NaClOm

OSNamol0,1

2

3222

2322

=

⋅⋅=

⋅⋅=

That means that 1 ml of a solution of 0.1 mol/l (= 0.1 N) Na2S2O3-solution exactly corresponds to 0.00226g NaClO2 100%. Procedure of titration An aliquot part is taken, normally 1 to 10ml of the bleaching liquor and given into an Erlenmeyer flask containing some distilled water and approx. 10ml of potassium iodide solution (approx. 10%). Then approx. 20ml of a sulphuric acid solution of 20% are added. The transformation of sodium hypochlorite with potassium iodide to iodine becomes visible by a strong brown colouration of the solution. With a sodium thiosulphate solution of 0.1 ml/l (= 0.1 N) a titration is done until a slightly brown titration is obtained. After addition of 5 ml of a starch solution (approx. solution of 1 % of a soluble starch) the titration solution gets a strong blue colouration. Titration with a sodium thiosulphate solution is continued until the titration solution becomes colourless. èq=oK=_bfqifè=dj_e=

Sodium chlorite

35

Calculation The calculation parameters are the following:

V Consumption in a Na2S2O3- solution with a concentration of 0.1 mol/l (= 0.1 N).

F Taken quantity of bleach liquor in ml

ρ ρ ρ ρ Density of sodium chlorite solution NaClO2 24.5% (30 Vol.%, N 30) = 1.22

W % by weight of sodium chlorite solution

1ml of a 0.1mol/l Na 2S2O3 = 0.00226g NaClO2 100 % Calculation of sodium chlorite content in g/l:

WF1001000V00226.0

%100NaClOg/l 2 ⋅⋅⋅⋅=

Usually sodium chlorite solutions are applied (mostly 24.5 %, 30 Vol.%, N 30). Calculation of sodium chlorite content in ml/l:

ρ⋅⋅⋅⋅⋅=

WF1001000V00226,0

%100NaClOml/l 2

Example For titration of F = 10ml of bleach liquor with 0.1 mol/l (= 0.1N) sodium thiosulphate solution V = 4.2ml Na2S2O3 solution is consumed. How much sodium chlorite 100% in g/l does the bleach liquor contain ?

10010

10010004.20.00226100%

2NaClOg/l

⋅

⋅⋅⋅=

g/l NaClO 2 100% = 0.95g/l

1ml 0.1mol/l Na 2S2O3 =

0.00226g NaClO2 100 %

Example For titration of F = 10ml of bleach liquor with 0.1 mol/l (= 0.1N) sodium hiosulphate solution V = 5.0ml Na2S2O3 solution is consumed. How much sodium chlorite 24.5% ml/l (W=24.5, ρ=1.22) does the bleach liquor contain ?

22.15.2410

10010005.00.00226%5,24

2NaClOml/l

⋅⋅

⋅⋅⋅=

ml/l NaClO 2 24.5% = 3.78ml/l


Sodium chlorite

36

Destruction of residual chlorite The destruction of residual chlorite is obtained in particular with the reducing agents sodium hydrogen sulphite (bisulphite) and sodiumsulphite. In contrast to the situation in sodium hypochlorite bleach, hydrogen peroxide and sodium thiosulphate are less suitable for this purpose. Before the reducing agents are added, the bleach liquor should be neutralized to avoid smell because of the formation of sulphure dioxide (SO2) from the reducing agent.

Reducing agent Theoretically necessary quantity to

destruct 1g/l sodium chlorite 100%


(Bisulphite)

1 x 90.5g NaClO2 = 2 x 104.06g NaHSO3

1g/l NaClO2 100% = 2.3g/l sodium hydrogen sulphite

Sodium sulphite

1 x 90.5g NaClO2 = 2 x 126.04g Na2SO3 = 2 x 252.14g Na2SO3 7 H2O

1g/l NaClO2 100% = 2.8g/l sodium sulphite = 5.6 g/l sodiumsulphite heptahydrate


ClO2- + 2 HSO3

- → 2 SO4

- + 2 H+ + Cl-

Sodium sulphite ClO2

- + 2 SO32- →

2 SO4- + Cl--


Persulphates

37

Persulphates

Properties of persulphates

Persulphates slowly decompose in aqueous solution, particularly at higher temperatures. For this reason solutions of persulphates are stable only to a limited degree. A higher bath temperature than 40 °C should be absolutely avoided.

Evidence of persulphate content in addition to hydrogen peroxide content in bleaching liquors In cold bleaches, persulphate is added in additon to hydrogen peroxide. On the contrary to hydrogen peroxide a direct titration of persulphate with potassium permanganate is not possible, because persulphates do practically not react with permanganate because of their rather high oxidation potential at room temperature. However the determination of the persulphate content is possible by an indirect titration. In the following the determination of hydrogen peroxide and persulphate in bleaching liquors will be described.

NameAmmonium persulphate

Potassium persulphate

Sodium persulphate

Chemical formula (NH4)2S2O8 K2S2O8 Na2S2O8

Molar mass [g/mol] 228,2 270,3 238,2

Active oxygen content (minimum)

[%] 6,9 5,8 6,5

10 °C [g/100g] 49 3,0 46

20 °C [g/100g] 54 5,5 54

30 °C [g/100g] 59 8,8 58

Solubility, g/100 g aqueous solution at

Decomposition of persulphate

S2O82- + H2O

→ 2 SO42- + 2 H+ + ½ O2


Persulphates

38

Principle of titration Titration of hydrogen peroxide and persulpate is done in the same bath sample as follows: 1. A liquor sample is taken and first the content of hydrogen

peroxide is titrated as usually with potassium permanganate. Because persulphate does not react with permanganate under these conditons, in this completely titrated sample there is only pure persulphate. Complete titration is absolutely necessary to destroy the hydrogen peroxide.

2. A defined iron (II) salt solution is added to the completely

titrated sample. A part of the iron (II) is oxidated by persulphate to iron(III). The iron(II) which was not oxidated is back titrated with potassium permanganate, and the content of persulphate is calculated.

Procedure 1. Fabrication of iron (II) (II) salt solution A suitable iron (II) salt for the titration of persulphates is the ammonium iron (II) sulphate, which is known under the name of Mohr’s salt. Approx. 40 g of ammonium iron (II) sulphate are dissolved by vigourously shaking and with addition 100 ml of sulphuric acid of 10 % to one litre. The solution contains approx. 5.7 g/l Fe2+. 2. Determination of the content of iron (II) in the blank sample The iron (II) of the fabricated ammonium iron (II) sulphate solution is slowly oxidated to iron (III) by oxygen from the air. For this reason the actual content of iron (II) has to be determined before the titration is done. 20 ml of the ammonium iron (II) sulphate solution are mixed with approx. 20 ml of sulphuric acid of 10 % and with a potassium permanganate solution (normally 0.02 mol/l = 0.1 N), which is applied for all further titrations, and tritrated until the colour shade change to light pink is obtained.

The content of iron (II) in the ammonium iron (II) sulphate solution (= blank sample) should be determined again before every titration.

Ammonium iron(II)sulphate =

Mohr’s salt

(NH4)2Fe(SO4)2 ⋅ 6 H2O


Persulphates

39

The consumption of potassium permanganate solution is recorded (VB). It serves for the calculation of the persulphate content. 3. Determination of the content of hydrogen peroxid e in the bleaching bath A liquor sample is taken, usually 5 – 10 ml with approx. 20 ml of sulphuric acid of 10 % and the content of hydrogen peroxide is determined with potassium permanganate (see also chapter HYDROGEN PEROXIDE). In cold bleaching liquors the content of hydrogen peroxide is normally rather high. For this reason it is advised to apply a KMnO4 solution of 0.2 mol/l (= 1 N) instead of the usual 0.02 ml/l (= 0.1 N), so that the consumption is not too high. For the titration of persulpate a solution of KMnO4 of 0.02 mol/l (= 0.1 N) should be applied. The completely titrated sample is applied for furth er titration. 4. Determination of the content of persulphate 20 ml of the ammonium iron (II) sulphate solution are added to the completely titrated sample. At any rate the same quantity of ammonium iron (II) sulphate solution has to be added as for the blank value determination. Then titration is done with the potassium permanganate solution which served for the determination of the content of iron (II) in the ammonium iron (II) sulphate solution (= blank sample), until the colour shade change to ligh pink is obtained (VP).

VB = consumption of potassium permanganate solution in case of a titration of 20 ml ammonium iron II sulphate solution (= blank sample).

VP = Consumption of potassium permanganate solution out of the titration of the before completely titrated liquor sample.

Titration of hydrogen peroxide with a solution of 0.2 mol/l (= 0.1 N) KMnO4.


Persulphates

40

Calculation The parameters for the calculation are the following:

F ml taken quantity of bleaching liquor.

VB

Consumption of potassium permanganate solution with a concentration of x mol/l (usually 0.02 mol/l = 0.1 N) in titration of the ammonium iron (II) sulphate solution in the blank sample.

VP

Consumption of potassium permanganate solution with a concentration of x mol/l (usually 0.02mol/l = 0,1 N) in titration of completely titrated bath samples.

x mol/l KMnO4

Concentration of the applied potassium permanganate solution. Normally 0.02 mol/l = 0.1 N

f

Conversion factor for sodium-, potassium or ammonium persulphate. 1 ml = 11.910 mg sodium persulphate 1 ml = 13.515 mg potassium persulphate 1 ml = 13.515 mg ammonium persulphate for a solution of 0.02 mol/l of KMnO4

Calculation of the H 2O2-concentration: The determination and calculation of the hydrogen peroxide concentration is done as described in the chapter about HYDROGEN PEROXIDE. Calculation of the persulphate concentration: The following calculation formula is such that it can be calculated with every concentration of potassium permanganate solution. Only the concentration in mol/l should be known. Independently from the applied potassium permanganate solution for the conversion on sodium-, potasium or ammonium persulphate the factors f have to be taken out of the above given table.

F0.02

KMnOmol/l x)V-(Vg/l 4PB

⋅⋅⋅

=f

ePersulphat

Example In a cold bleach bath the content of sodium persulphate is to be determined. Titration of 20 ml ammonium iron (II) sulphate solution (= blank vat) gave a consumption of 0.02 mol/l KMnO4- solution (= 0.1 N) of VB = 20.4 ml. F = 10 ml of the cold bleach bath was taken and first the content of hydrogen peroxide was determined with a solution of 0.2 mol/l (= 1 N) KMnO4 . The liquor sample which had been completely tritrated in this way was then mixed with 20 ml ammonium iron (II) sulphate solution and titrated with 0.02 mol/l KMnO4-solution (= 0.1 N) up to the colour shade change to light pink. A consumption of KMnO4 of VP = 13.7 ml was recorded. The content of sodium persulphate is calculated as follows:

100.02

910.110.02 13.7)-(20.4epersulphat-Nag/l

⋅⋅⋅

=

g/l Na-persulphate = 8 g/l


Silicates

41

Silicates

Properties of commercially available sodium silicates

Properties of commercially available metasilicates

Other properties of silicate of soda • In combination with magnesium compounds (e.g. Epsom

salt) there is a good stabilizing effect in the hydrogen peroxide bleach.

• Silicates increase the soil suspending property of washing baths.

NameNa-

metasilicate anhydrous

Na-metasilicate 5-hydrate

Na-metasilicate 9-hydrate

Chemical formula Na2SiO3 Na2SiO3⋅5 H2O Na2SiO3⋅9 H2O

Molar mass [g/mol] 140 230 302

Silicium oxide SiO 2 [%] 46.2 - 47.6 28.0 - 29.4 21.8 - 23.8

Sodium oxide Na 2O [%] 50.4 - 51.8 28.1 - 29.5 21.7 - 23.7

Dry substance [%] 96.5 - 99.5 56.5 - 58.5 44 - 47

Name Sodium silicate Sodium silicate

37/40 40/42

Density ( ρρρρ20) [g/cm 3 ] 1,34 - 1,38 1,38 - 1,40

Density in °Be [°Be] 37 - 40 40 - 42

Silicium oxide SiO 2 [%] 26,5 - 28,5 28 - 30

Sodium oxide Na 2O [%] 8 - 9 8,5 - 9,3

Mole ratio (SiO2 : Na2O) 3,3 - 3,5 3,2 - 3,4

Weight ratio (SiO 2 : Na2O)

3,2 - 3,4 3,1 - 3,3

Viscosity at 20°C [mPa ⋅ s] 50 - 150 100 - 240


Hardness of water

42

• Silicates have a very high sequestering power on heavy metals and thus have an anticatalytic effect

• Silicates hydrolyze at high temperatures and can form insoluble silicic acid.

• Silicates form insoluble compounds with alkaline earths and can cause sediments on fibres and machine parts.

• Silicates have a high buffering power.

Alkali content of silicates For the calculation of the alkali content (caustic lye) of silicates the following decomposition reaction is taken as a basis:

Na2O + H2O →→→→ 2 NaOH

61.979 g/mol + 18.0152 g/mol → 2 ⋅ 39.99 g/mol

2 ⋅ 39.99 g = 79.98 g of sodium hydroxide (NaOH) are formed of 61.979g Na2O. The parameter of calculation are the following:

W Content of sodium oxide (Na2O) (37/40 = 8.5%; 40/42 = 8.9%)

ρ ρ ρ ρ Density of sodium silicate (37/40 = 1.36; 40/42 = 1.39)

V Applied quantity of silicate of soda in ml/l (in case of metasilicates in g/l)

Calculation of NaOH-concentration in g/kg: Corresponding to the sodium oxide indications (Na2O) of above given table the sodium hydroxide content of the silicates can be calculated as follows.

W904.12

W61.979

1079,98][g/kg100%NaOH

⋅=

⋅⋅=

Example

How much NaOH g.kg does sodium silicate 37/40 contain? The Na2O-content of this silicate of soda is indicated with 8-9 % in the table (medium value 8.5 %). NaOH 100% = 12.904 · 8.5 = 110g/kg = 11 %

Remark The data of density and content of sodium oxide are the average values of above given tables. It is possible that the values differ from the applied sodium silicate. Therefore the data should better be taken from the specifications.

Silicate precipitations with hardening substances

(schematically)

Si Si Si Si Si Si Si SiO O O O O O O O O

O OH

OH

OH

ONa ONa ONaO O O O

Ca

Ca

O O ONa ONaO

Mg

Ca

O

SiSi Si Si Si Si Si SiO O O O O O O O O

OH

ONa

O O

OH ONa

ONa

ONa ONa

O O O O

OOH

Mg

MgCaMg

Ca-silicate deposits on cotton fibres


Silicates

43

Calculation of NaOH-concentration in g/l: In bleach liquors sodium silicate is normally applied in ml/l. The sodium hydroxide content (NaOH) out of sodium of silicate in such a bleaching bath is calculated as follows:

1000ρVW904.21

100061.979ρVW79.98

][g/l100%NaOH

⋅⋅⋅=

⋅⋅⋅⋅=

For metasilicates it is not possible to indicate density because it is a solid substance. Therefore the calculation formula for metasilicates is the follwing:

1000VW904.21

100061.979VW79.98

][g/l100%NaOH

⋅⋅=

⋅⋅⋅=

Example In a bleach liquor V=10ml sodium silicate 37/40 (ρ=1.36, W=8.5) is applied. How much NaOH 100 % in g/l does the bath contain ?

100036,1015,8904,21

][g/l100%NaOH⋅⋅⋅=

NaOH 100% = 1.49 g/l


Hardness of water

44

Hardness of water Hardness of industrial waters can have a considerable influence on pretreatment and dyeing results. High hardness for example can cause: • Deposits of hardening substances on machines or textiles. • Precipitations of dyes which are sensitive to hardness in

the dyeing liquor. For this reason a regular control of the hardness of the industrial water can be very helpful so that possible reasons for defects can be recognized early and eliminated. On thebasis of the total hardness of water it is differentiated between carbonate hardness (former temporary hardness) and permanent hardness. The carbonate hardness forms insoluble Ca- or Mg-carbonates during boiling and therefore causes deposits whereas the permanent hardness remains in solution even at a higher temperature.

Determination of water hardness (total hardness) Ca- and Mg-ions can be determined in ammoniacal solution complexometrically with EDTA (ethylene diamine tetraacetate) and with Eriochrom black T (or indicator buffer tablet) as indicator. Procedure of titration 100 ml are taken of the water sample and an indicator-buffer tablet is dissolved in it. 2 ml ammonia 25 % are added and heated up at 40 °C. The solution becomes more or le ss red depending on the water hardness. Then titration is carried out immediately with 0.1 mol/l EDTA-solution from red to green. Calculation The parameters of calculation are the following:

V Consumption in ml of EDTA-solution at a concentration of x mol/l.

F Taken quantity of water sample in ml

x mol/l EDTA

Concentration of applied EDTA-solution, usually 0.01 mol/l.

Total hardness (GH) Total concentration of all dissolved calcium- and magnesium ions. Carbonate hardness (KH) = Ca- nd Mg-hydrogen carbonates. During boiling insoluble Ca- or Mg-carbonate is formed: Ca(HCO3)2 → CaCO3 + H2O + CO2

Permanent hardness = Ca- and Mg-chlorides, sulphates, nitrate and others

Hardness classification

Total hardness ° dH

Description

0-7 7-14 14-21 > 21

soft

medium hard

very hard


Hardness of water

45

EDTA always forms with metal ions a 1:1 complex. 1 mol EDTA binds 1 mol of a metal ion, e.g. calcium. Table:

= 0.4008 mg Ca = 0.5608 mg CaO = 1.00 mg CaCO3 = 0.24305 mg Mg = 0.4030 mg MgO

1 ml of 0.01 mol/l EDTA-solution

corresponds to

0.01 mmol metal = 0.8431 mg MgCO3

Calculation of content of hardening substances in mmol/l:

F1000VEDTAmol/lx

mmol/l⋅⋅=

With this formula the content of CaCO3 can be exactly calculated in mg/l. Calculation of content of hardening substances in °dH: According to definition: 1 °dH = 10 mg/l CaO = 7.19 mg/l MgO

F10005.608VEDTAmol/lx

dH⋅⋅⋅=°

Example For the titration of F = 100ml of a water sample with 0.01 mol/l EDTA-solution V = 13ml EDTA-solution is consumed. How much mmol/l of hardness does water contain ?

100100013EDTAmol/l0.01

mmol/l⋅⋅=

mmol/l hardness = 1.3 mmol/l

Example For the titration of F = 100ml of a water sample 0.01 mol/l EDTA-solution V = 13ml EDTA-solution is consumed. How much °dH has the water ?

10010005.60813EDTAmol/l0,01

dH⋅⋅⋅=°

°dH = 7.3 °dH

N

N

CH2

CH2

O

O

CH2C

O

CH2C

O

Ca2+

CH2

CO

O

CH2

CO

O

EDTA-complex


Hardness of water

46

Conversion factors for common units of water hardness

Definition of different hardness data

mmol/l Alkaline earth ions

English hardness

French hardness

German hardness

Russian hardness

ppm as CaCO3

1mmol/l alkaline earth ions

1 7,02 10 5,6 40 100

1 °English hardness 0,14 1 1,429 0,7999 5,714 14,29

1 ° French hardness 0,1 0,7 1 0,5599 4 10

1 °German hardness 0,18 1,25 1,786 1 7,144 17,85

1 °Russian hardness 0,025 0,175 0,25 0,14 1 2,5

1ppm as CaCO3 0,01 0,07 0,1 0,06 0,4 1

1 °German hardness

10 mg/l CaO

1 °French hardness

10 mg/l CaCO3

10 mg/0,7 l CaCO3

14.29 mg/l CaCO4

1American hardness (USA)

1 mg/l CaCO3

1 °English hardness


Average polymerisation degree and fluidity

47

Average degree of polymerisation (DP-value) The cellulose molecule is a polysaccharide composed of β-1.4 linked glucose units. The so-called polymerisation degree gives evidence of the number of chain elements (glucose units). E.g. if there is chemical damage in bleaching, the long chain molecule is separated into smaller fragments. The polymerisation degree decreases. If the cellulose is completely dissolved in a solvent, the viscosity of the solution is higher at a higher polymerisation degree, because there are more of the bigger molecules and vice versa. Due to this the polymerisation degree of a cellulose fibre can be determined by a viscosity measurement. The average polymerisation degree only reflects the extent of a chemical damage, and can be used to distinguish between chemical and mechanic damage. This is different from the determination of the tear strength e.g. , the average polymerisation degree is completely independent from the structure of the fabric and thus much more specific. Measuring method There are four procedures for the viscosimetric determination of the polymerisation degree of cellulose fibres and cellulose material with the difference in solvents.

• Cuoxam procedure • The cupriethylene diamine procedure • EWNN - procedure • Nitrate procedure

The fibre material is dissolved in a solvent according to all procedures (in case of the nitrate procedure after a preceding nitration) and the running time of the solution is measured by means of a capillary as well as the running time of the pure solvent as reference. The fibre material applied for the DP value determination should be free of sizes, finishs etc. The methods for the determination of the average polymerisation degree are all very difficult, and a lot of experience and accuracy is needed, so that the measurements should be carried out only in well equipped laboratories.

n = degree of polymerisation

n/3

OO

O

OH

OHO

OH

OH

CH2OH

CH2OH

O

OH

OH

CH2OH

Remark Difficulties can be caused by resin finished, reactive dyed or mercerized fabrics depending on the procedure because sometimes the fibre material is not completely dissoved in the solvent and measuring becomes impossible.



48

Calculations According to Staudinger the following formula is valid for the DP-value:

km1

C1

η

ηηDP

0 ⋅⋅−=

η: Runnning time of solution in sec. η0: Running time of solvent in sec c: Cellulose concentration in g/l Km: Constant of solvent There is a decrease of the polymerisation degree in case of every damage, and its amount on the other hand gives conclusion on degree of the damage. According to O. Eisenhut the functioning of polymerisation degree - decrease = fibre damage is defined as damage factor by the following formula:

2log

120002000

log ��

� +−= PtPtx

s

Pt: DP – value of cellulose before the chemical treatment Ptx: DP – value of cellulose after the chemical treatment 2000: DP – value of CO as point of reference The relation of the DP value before and after the damaging and the damaging factor is shown in the following graph.

DP-values of different fibres

Substrate DP - value Natural fibres: Cotton, flax, Ramie Regenerated cellulose: Copper procedure Viscose procedure Acetate procedure

2000 – 3000

400 – 500 250 – 400 200 – 300

Judgment of damaging degree s-factor judgment 0.01–0.20 0.21–0.30 0.31–0.50 0.51–0.75 > 0.75

very good – undamaged good, very gentle bleaching sufficient slightly damaged very much damaged


damaging factor

1600

2000

2400

2800

3200

3600

800 1200 1600 2000 2400 2800 3200 3600

DP-value after damaging

DP

-val

ue b

efor

e da

mag

ing

1,0 0,8 0,4 0,2 0,00,61,2


49

Fluidity F In different countries not the DP-value but the fluidity number is given. The basis of the measuring procedure to determine the fluidity number is like the principle of the DP-determination, that means the determination of viscosities. Strictly speaking the fluidity is the reciprocal value of the dynamic viscosity. Calculations The fluidity formula is:

tk

t

CF

'

−=

C: Constant of viscosimeter k: Factor of correction t: Run-out time of solvent ρ: Density of solvent There is the following relation between DP-value and fluidity:

573F

F74,35log2032DP −��

�� +⋅=

Illustrated in a diagram:

ρ

CC ' =

Judgement of fluidity

Fluidity Judgement ≤ 2 2.1-3.5 3.6-5.0 5.1-8.0 > 8.0

undamaged good, very gentle bleach sufficient slightly damaged very damaged

Relation between DP value and fluidity

600

1000

1400

1800

2200

2600

3000

3400

0 2 4 6 8 10 12 14 16 18 20

Fluidity

DP

-val

ue


Annex – Density and concentration of sulphuric acid, hydrochloric acid, nitric acid, caustic lye and caustic potash

50

Annex Density and concentration of sulphuric acid, hydrochloric acid, nitric acid, caustic lye and caustic potash solution

Density °Be

ρ20 % w/w g/l % w/w g/l % w/w g/l % w/w g/l % w/w g/l

1,000 0,0 0,261 2,609 0,360 3,600 0,333 3,330 0,159 1,590 0,197 1,970

1,005 0,7 0,985 9,904 1,360 13,670 1,255 12,610 0,602 6,050 0,743 7,470

1,010 1,4 1,731 17,483 2,360 23,840 2,164 21,860 1,045 10,550 1,295 13,080

1,015 2,1 2,485 25,223 3,370 34,210 3,073 31,190 1,490 15,120 1,839 18,670

1,020 2,7 3,242 33,068 4,390 44,780 3,982 40,620 1,937 19,760 2,380 24,280

1,025 3,4 4,000 41,000 5,410 55,450 4,883 50,050 2,384 24,440 2,931 30,040

1,030 4,1 4,746 48,884 6,430 66,230 5,783 59,570 2,839 29,240 3,480 35,840

1,035 4,7 5,493 56,852 7,460 77,210 6,661 68,940 3,289 34,040 4,030 41,710

1,040 5,4 6,237 64,865 8,490 88,300 7,530 78,310 3,735 38,840 4,580 47,630

1,045 6,0 6,956 72,690 9,510 99,380 8,398 87,760 4,199 43,880 5,121 53,510

1,050 6,7 7,704 80,892 10,520 110,460 9,259 97,220 4,655 48,880 5,660 59,430

1,055 7,4 8,415 88,778 11,520 121,540 10,120 106,770 5,107 53,880 6,200 65,410

1,060 8,0 9,129 96,767 12,510 132,610 10,970 116,280 5,562 58,960 6,740 71,440

1,065 8,7 9,843 104,828 13,500 143,780 11,810 125,780 6,017 64,080 7,280 77,530

1,070 9,4 10,510 112,460 14,490 155,040 12,650 135,360 6,471 69,240 7,820 83,670

1,075 10,0 11,260 121,040 15,480 166,410 13,480 144,910 6,928 74,480 8,360 89,870

1,080 10,6 11,960 129,170 16,470 177,880 14,310 154,550 7,378 79,680 8,890 96,010

1,085 11,2 12,660 137,360 17,450 189,330 15,130 164,160 7,827 84,920 9,429 102,310

1,090 11,9 13,360 145,620 18,430 200,890 15,950 173,860 8,283 90,280 9,960 108,560

1,095 12,4 14,040 153,740 19,410 212,540 16,760 183,520 8,734 95,640 10,489 114,860

1,100 13,0 14,730 162,030 20,390 224,290 17,580 193,380 9,189 101,080 11,030 121,330

1,105 13,6 15,410 170,280 21,360 236,030 18,390 203,210 9,643 106,560 11,560 127,740

1,110 14,2 16,080 178,490 22,330 247,860 19,190 213,010 10,097 112,080 12,080 134,090

1,115 19,3 16,760 186,870 23,290 259,680 20,000 223,000 10,554 117,680 12,610 140,600

1,120 15,4 17,430 195,220 24,250 271,600 20,790 232,850 11,007 123,280 13,140 147,170

1,125 16,0 18,090 203,510 25,220 283,720 21,590 242,890 11,463 128,960 13,660 153,670

1,130 16,5 18,760 211,990 26,200 296,060 22,380 252,890 11,919 134,680 14,190 160,350

1,135 17,1 19,420 220,420 27,180 308,490 23,160 262,870 12,344 140,100 14,706 166,910

1,140 17,7 20,080 228,910 28,180 321,250 23,940 272,920 12,825 146,200 15,220 173,510

1,145 18,3 20,730 237,360 29,170 334,000 24,710 282,930 13,279 152,040 15,741 180,230

1,150 18,8 21,380 245,870 30,140 346,610 25,480 293,020 13,729 157,880 16,260 186,990

Caustic potashSulphuric acid Hydochloric acid Nitric acid Caustic ly e


Annex – Density and concentration of sulphuric acid, hydrochloric acid, nitric acid, caustic lye and caustic potas

51

Density °Be


1,155 19,3 22,030 254,450 31,140 359,670 26,240 303,070 14,182 163,800 16,780 193,810

1,160 19,8 22,670 262,970 32,140 372,820 27,000 313,200 14,634 169,760 17,290 200,560

1,165 20,3 23,309 271,550 33,161 386,320 27,761 323,410 15,090 175,800 17,810 207,490

1,170 20,9 23,950 280,210 34,180 399,910 28,510 333,570 15,538 181,800 18,320 214,340

1,175 21,4 24,580 288,810 35,200 413,600 29,250 343,690 15,990 187,880 18,840 221,370

1,180 22,0 25,210 297,480 36,230 427,510 30,000 354,000 16,441 194,000 19,350 228,330

1,185 22,5 25,840 306,200 37,270 441,650 30,740 364,270 16,891 200,160 19,860 235,340

1,190 23,1 26,470 314,990 38,320 456,010 31,470 374,490 17,345 206,400 20,370 242,400

1,195 23,5 27,100 323,850 39,370 470,470 32,210 384,910 17,797 212,680 20,879 249,510

1,200 24,0 27,720 332,640 - 32,948 395,380 18,253 219,040 21,380 256,560

1,205 24,5 28,330 341,380 - 33,680 405,840 18,709 225,440 21,880 263,650

1,210 25,0 28,950 350,290 - 34,410 416,360 19,160 231,840 22,380 270,800

1,215 25,5 29,570 359,280 - 35,160 427,200 19,615 238,320 22,880 277,990

1,220 26,0 30,180 368,200 - 35,930 438,350 20,072 244,880 23,380 285,240

1,225 26,4 30,790 377,180 - 36,700 449,580 20,526 251,440 23,869 292,400

1,230 26,9 31,400 386,220 - 37,480 461,000 20,979 258,040 24,370 299,750

1,235 27,4 32,010 395,320 - 38,250 472,390 21,438 264,760 24,860 307,020

1,240 27,9 32,610 404,360 - 39,020 483,850 21,897 271,520 25,360 314,460

1,245 28,4 33,220 413,590 - 39,800 495,510 22,355 278,320 25,850 321,830

1,250 28,8 33,820 422,750 - 40,580 507,250 22,813 285,160 26,340 329,250

1,255 29,3 34,420 431,970 - 41,360 519,070 23,273 292,080 26,830 336,720

1,260 29,7 35,010 441,130 - 42,140 530,960 23,730 299,000 27,320 344,230

1,265 30,2 35,600 450,340 - 42,920 542,940 24,190 306,000 27,800 351,670

1,270 3,6 36,190 459,610 - 43,700 554,990 24,643 312,960 28,290 359,280

1,275 31,1 36,780 468,940 - 44,480 567,120 25,098 320,000 28,770 366,820

1,280 31,5 37,360 478,210 - 45,270 579,460 25,556 327,120 29,250 374,400

1,285 32,0 37,950 487,660 - 46,060 591,870 26,014 334,280 29,731 382,040

1,290 32,4 38,530 497,040 - 46,850 604,370 26,478 341,560 30,210 389,710

1,295 32,8 39,100 506,340 - 47,630 616,810 26,941 348,880 30,680 397,300

1,300 33,3 39,680 515,840 - 48,420 629,460 27,403 356,240 31,150 404,950

Caustic potashSulphuric acid Hydrochloric aicid Nitric acid Caustic lye



52

Density °Be


1,305 33,7 40,250 525,260 - 49,210 642,190 27,868 363,680 31,620 412,640

1,310 34,2 40,820 534,740 - 50,000 655,000 28,330 371,120 32,090 420,380

1,315 34,6 41,390 544,280 - 50,850 668,680 28,794 378,640 32,560 428,170

1,320 35,0 41,950 553,740 - 51,710 682,570 29,261 386,240 33,030 436,000

1,325 35,4 42,510 563,260 - 52,560 696,420 29,727 393,880 33,500 443,880

1,330 35,8 43,070 572,830 - 53,410 710,350 30,195 401,600 33,970 451,800

1,335 36,2 43,620 582,330 - 54,270 724,500 30,652 409,200 34,430 459,640

1,340 36,6 44,170 591,880 - 55,130 738,740 31,134 417,200 34,900 467,660

1,345 37,0 44,720 601,480 - 56,040 753,740 31,613 425,200 35,360 475,590

1,350 37,4 45,260 611,010 - 56,950 768,830 32,089 433,200 35,820 483,570

1,355 37,8 45,800 620,590 - 57,870 784,140 32,561 441,200 36,280 491,590

1,360 38,2 46,330 630,090 - 58,780 799,410 33,059 449,600 36,735 499,600

1,365 38,6 46,860 639,640 - 59,689 814,760 33,553 458,000 37,190 507,640

1,370 39,0 47,390 649,240 - 60,670 831,180 34,015 466,000 37,650 515,810

1,375 39,4 47,920 658,900 - 61,689 848,230 34,502 474,400 38,105 523,950

1,380 39,8 48,450 668,610 - 62,700 865,260 35,014 483,200 38,560 532,130

1,385 40,1 48,970 678,230 - 63,721 882,530 35,495 491,600 39,010 540,290

1,390 40,5 49,480 687,770 - 64,740 899,890 36,000 500,400 39,460 548,490

1,395 40,8 49,990 697,360 - 65,840 918,470 36,502 509,200 39,920 556,890

1,400 41,2 50,500 707,000 - 66,970 937,580 37,000 518,000 40,370 565,180

1,405 41,6 50,967 716,090 - 68,100 956,810 37,495 526,800 40,820 573,520

1,410 42,0 51,520 726,430 - 69,230 976,140 37,986 535,600 41,260 581,770

1,415 42,3 51,984 735,580 - 70,390 996,020 38,473 544,400 41,710 590,200

1,420 42,7 52,510 745,640 - 71,630 1017,150 38,986 553,600 42,155 598,600

1,425 43,1 53,010 755,390 - 72,860 1038,250 39,495 562,800 42,600 607,050

1,430 43,4 53,500 765,050 - 74,090 1059,490 40,000 572,000 43,040 615,470

1,435 43,8 54,000 774,900 - 75,351 1081,280 40,502 581,200 43,479 623,930

1,440 44,1 54,490 784,660 - 76,710 1104,620 41,028 590,800 43,920 632,450

1,445 44,4 54,970 794,320 - 78,070 1128,110 41,550 600,400 44,360 641,000

1,450 44,8 55,450 804,030 - 79,430 1151,740 42,069 610,000 44,790 649,460

Sulphuric acid Hydrochloric acid Nitric acid Caustic lye Caustic potash



53

Density °Be


1,455 45,1 55,930 813,780 - 80,880 1176,800 42,584 619,600 45,230 658,100

1,460 45,4 56,410 823,590 - 82,390 1202,890 43,123 629,600 45,660 666,640

1,465 45,8 56,890 833,440 - 83,911 1229,290 43,631 639,200 46,094 675,280

1,470 46,1 57,377 843,440 - 85,500 1256,850 44,163 649,200 43,469 638,990

1,475 46,4 57,840 853,140 - 87,289 1287,520 44,692 659,200 46,960 692,660

1,480 46,8 58,310 862,990 - 89,070 1318,240 45,216 669,200 47,390 701,370

1,485 47,1 58,780 872,880 - 91,130 1353,280 45,737 679,200 47,820 710,130

1,490 47,4 59,240 882,680 - 93,490 1393,000 46,255 689,200 48,250 718,930

1,495 47,8 59,700 892,520 - 95,460 1427,120 46,796 699,600 48,674 727,680

1,500 48,1 60,170 902,550 - 96,730 1450,950 47,333 710,000 49,100 736,500

1,505 48,4 60,620 912,330 - 97,990 1474,750 47,841 720,000 49,530 745,430

1,510 48,7 61,080 922,310 - 99,260 1498,830 48,371 730,400 49,950 754,250

1,515 49,0 61,540 932,330 - - 48,898 740,800 50,380 763,260

1,520 49,4 62,000 942,400 - - 49,421 751,200 50,800 772,160

1,525 49,7 62,450 952,360 - - 49,967 762,000 51,220 781,100

1,530 50,0 62,910 962,520 - - 50,484 772,400 51,640 790,090

1,535 50,3 63,360 972,580 - - - -

1,540 50,6 63,810 982,670 - - - -

1,545 50,9 64,260 992,810 - - - -

1,550 51,2 64,710 1003,010 - - - -

1,555 51,5 65,150 1013,090 - - - -

1,560 51,8 65,590 1023,200 - - - -

1,565 52,1 66,030 1033,370 - - - -

1,570 52,4 66,470 1043,580 - - - -

1,575 52,7 66,910 1053,840 - - - -

1,580 53,0 67,350 1064,130 - - - -

1,585 53,3 67,790 1074,470 - - - -

1,590 53,6 68,230 1084,860 - - - -

1,595 53,9 68,660 1095,120 - - - -

1,600 54,1 69,090 1105,440 - - - -

Caustic potashSulphuric acid Hydrochloric acid Nitric acid Caustic lye



54

Density °Be


1,605 54,4 69,530 1115,960 - - - -

1,610 54,7 69,960 1126,360 - - - -

1,615 55,0 70,390 1136,800 - - - -

1,620 55,2 70,820 1147,280 - - - -

1,625 55,5 71,250 1157,810 - - - -

1,630 55,8 71,670 1168,220 - - - -

1,635 56,0 72,090 1178,670 - - - -

1,640 56,3 72,520 1189,330 - - - -

1,645 56,6 72,950 1200,030 - - - -

1,650 56,9 73,370 1210,610 - - - -

1,655 57,9 73,800 1221,390 - - - -

1,660 57,1 74,220 1232,050 - - - -

1,665 57,4 74,640 1242,750 - - - -

1,670 57,7 75,070 1253,670 - - - -

1,675 58,2 75,490 1264,450 - - - -

1,680 58,4 75,920 1275,460 - - - -

1,685 58,7 76,340 1286,330 - - - -

1,690 58,9 76,770 1297,410 - - - -

1,695 59,2 77,200 1308,540 - - - -

1,700 59,5 77,630 1319,710 - - - -

1,705 59,7 78,060 1330,920 - - - -

1,710 60,0 78,490 1342,180 - - - -

1,715 60,2 78,930 1353,650 - - - -

1,720 60,4 79,370 1365,160 - - - -

1,725 60,6 79,810 1376,720 - - - -

1,730 60,9 80,250 1388,330 - - - -

1,735 61,1 80,700 1400,150 - - - -

1,740 61,4 81,160 1412,180 - - - -

1,745 61,6 81,620 1424,270 - - - -

1,750 61,8 82,090 1436,580 - - - -

Sulphuric acid Hydrochloric acid Nitric acid Caustic lye Caustic potash



55

Density °Be


1,755 62,1 82,570 1449,110 - - - -

1,760 62,3 83,060 1461,860 - - - -

1,765 62,5 83,576 1475,110 - - - -

1,770 62,8 84,080 1488,220 - - - -

1,775 63,0 84,610 1501,830 - - - -

1,780 63,2 85,160 1515,850 - - - -

1,785 63,5 85,740 1530,460 - - - -

1,790 63,7 86,350 1545,670 - - - -

1,795 64,0 86,990 1561,470 - - - -

1,800 64,2 87,690 1578,420 - - - -

1,805 64,4 88,430 1596,160 - - - -

1,810 64,6 89,230 1615,060 - - - -

1,815 64,8 90,120 1635,680 - - - -

1,820 65,0 91,110 1658,200 - - - -

1,821 65,0 91,334 1663,190 - - - -

1,822 65,1 91,560 1668,220 - - - -

1,823 65,1 91,780 1673,150 - - - -

1,824 65,2 92,000 1678,080 - - - -

1,825 65,2 92,250 1683,560 - - - -

1,826 65,3 92,510 1689,230 - - - -

1,827 65,3 92,825 1695,910 - - - -

1,828 65,4 93,030 1700,590 - - - -

1,829 65,4 93,361 1707,570 - - - -

1,830 65,4 93,640 1713,610 - - - -

1,840 65,9 95,598 1759,000 - - - -

Caustic potashSulphuric acid Hydrochloric acid Nitric acid Caustic lye


Annex – Brief instruction Titration of hydrogen peroxide

56

Brief instruction - Titration of hydrogen peroxide Procedure of titration An aliquot part is taken out, usually 1 to 10 ml, of the bleaching bath and given into an Erlenmeyer flask containing approx. 10 ml of a sulphuric acid of 20%. Titration is done immediately with a potassium permanganate solution of 0.02 mol/l (= 0./1 N) on a first persisting pink-violet colouration. Calculation

ml/l H 2O2 x-% = consumption of KMnO 4-solution ·factor

Example For titration of 2 ml bleach liquor with solution of 0.02mol/l KMnO4 (= 0.1 N) 8.7ml of KMnO4-solution are consumed. How much H2O2 of 50% in ml/l does the bleaching liquor contain ? The factor for 2 ml of bleaching liquor and of H2O2 50% is 1.423 (see table). ml/l H 2O2 50% = 8.7 · 1.423 = 12.4 ml/l

Valid for a potassium permanganate solution of 0.02 mol/l (= 0.1 N)

Factor for

H2O2 100%

in g/l in g/l in ml/l in g/l in ml/l

1 ml 1,701 3,401 2,846 4,859 4,293

2 ml 0,850 1,701 1,423 2,430 2,146

5 ml 0,340 0,680 0,569 0,972 0,859

10 ml 0,170 0,340 0,285 0,486 0,429

H2O2 35%

Factor for

Sample of bleach liquor

H2O2 50%

Factor for

Remark Calculation is only valid for a 0.02 mol/l (= 0.1N) potassium permanganate solution.


Annex – Brief instruction Titration of caustic lye

57

Brief instruction - Titration of caustic soda Procedure of titration An aliquot part, usually 1 to 10 ml of the bath are taken and given into an Erlenmeyer flask containing some distilled water. Titration is done with 0.1 mol/l hydrochloric acid or 0.05 mol/l sulphuric acid (both of 0.1 N) up to the colour shade change of the indicator phenol phthaleine of red to colourless. Calculation ml/l or g/l of NaOH x-% = consumption acid solution · factor

Example 1 For titration of 2ml of bleach liquor with 0.1mol/l HCl-solution Lösung (= 0.1 N) 9.3ml of HCl-solution are consumed. How much NaOH 100% in g/l does the bleach liquor contain ? The factor for a sample of 2 ml bleach liquor and NaOH 100% is 2 (see table). g/l NaOH 100% = 9:3 · 2 = 18.6 g/l

Example 2 For titration of 2ml bleach liquor with HCl solution of 0.1mol/l HCl (= 0,1 N) 9.3 ml HCl-solution are consumed. How much NaOH 50% in ml/l does the bleach liquor contain ? The factor for a sample of 2 ml of bleaching liquor and NaOH of 50% is 2.615 (see table). ml/l NaOH 50% = 9.3 · 2.614 = 24.3 ml/l

Valid for a hydrochloric acid of 0.1 mol/l or sulphuric acid of 0.05 mol/l (both 0.1 N)

Factor for

NaOH 100 %

in g/l in g/l in ml/l in g/l in ml/l

1 ml 4,000 8,000 5,229 12,099 8,896

2 ml 2,000 4,000 2,614 6,050 4,448

5 ml 0,800 1,600 1,046 2,420 1,779

10 ml 0,400 0,800 0,523 1,210 0,890

Sample of bath

Faktor for

NaOH 50 %

Factor for

NaOH 38 °Be

Remark The calculation is only valid for a hydrochloric acid of 0:1 mol/l (= 0.1N) – or a sulphuric acid solution of 0.05 mol/l (= 0.1 N)


Annex – Brief instruction Titration of hydrogen peroxide

58

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Documents

Lab Test Book CHT