**5.2 Rossari's Bio- scouring enzyme – 'Scourenz ABE Liquid '**

From the above literature survey, it is very clear that the cotton can be bio- scoured using Pectinases enzyme. As we have seen there is a large pool of sources from which Pectinases enzyme can be obtained and also a huge number of combinations possible depending on the type of pectin degradation required. At Rossari Biotech Ltd, R & D department have developed a bio scouring enzyme named 'Scourenz ABE Liquid', that is successful in producing the desired scouring effects on cotton and its blends. It's a complex mixture of Protopectinases and Polygalacturonases that completes the bio scouring process in 30- 45mins and gives a fabric with absorbency within 4-5 seconds. Lower treatment temperature of 55- 60°C and milder acidic conditions with a pH requirement of 5- 5.5 are the advantages that have proven to be a boon to our customers that are currently using this enzymes.

The process route that has to be used for carrying out bio scouring operation is:

The actual bio-scouring process takes place at 550C. In this step the pectins are decomposed and emulsified. After bio-scouring, raising the temperature of the same bath to 900C helps in melting of waxes and oils. These released waxes are emulsified at high temperature and the bath is drained. This removes the entire impurities from the bath and the cotton substrate is ready for dyeing.

The enzymatic process of bio- scouring on bulk scale involves following stages:


Pre-treatment of Textiles Prior to Dyeing 231

 **Water Saving**: In bio- scouring process only one bath is used before the actual dyeing starts, whereas in conventional process a minimum of 5 baths are used. This leads to a total 4 bath saving. Considering an MLR of 1:7, the total amount of water that will be saved is about 28 litres for every Kg. processed. For a unit doing a 30 Mt. of bleaching every day, the amount of water that will be saved is 840,000 Litres per day. On annual

 **Temperature Saving**: The entire process takes place at a temperature of 550C as against 980C. The temperature difference is about 430C. The specific heat of water is 4.186 Joule/ gram K. It requires 4.186 joules of energy to heat 1 gm. of water by 1 Kelvin. Assuming an MLR of 1:7, for every Kg. of cotton, 7 litres of water is used during the bleaching process. In order to heat water from 55 degrees to 98 degrees the amount of

1260 KJ is the amount of energy that will be saved for every Kg. of material processed. If calculated the impact of same on yearly basis for a production plant doing a bleaching of 30

Thus on yearly basis a unit of daily production of 30 Mt. can save energy of the magnitude 1.38 x 107 MJ. If 1.38 x 108 MJ is extrapolated to various natural fuels available than we can

Coal (Anthracite) 27 510.63 Metric tonnes. 1400 kg Coal (Lignite) 15 919.55 Metric tonnes 2519.8 kg. Wood 15 919.55 Metric Tonnes 2519.8 kg. Diesel 44.80 307.45 Metric Tonnes 842 Kg. Kerosene 46.20 298.20 Metric Tonnes 817 Kg. All the above mentioned figures are taken considering 100% performance of the concerned parameters involved. If taken in to account boiler efficiency, Combustion efficiency, Heat

transfer losses, Steam Transportation losses than the figure will increase by 10 – 25%.

According to the United states Department of forestry, an average weight of a fully grown tree is about 680 Kg. Thus, by using Scourenz ABE Liquid, we would be indirectly contributing to plantation of 3.7 fully grown trees per day. Also, it will lead to reduction in contribution of global warming by any organization since we are inhibiting 1260 KJ of energy to enter in to our bio systems for every Kg. of cotton material bleached. Any organization will have its huge benefits in terms of carbon foot prints and help them to earn

 **Time Saving:** The process of conventional scouring takes place about 2hrs 50 min. for completion. Whereas the bio-scouring process will not take more than 50 min. for completion. Thus for every batch dyed we are saving 2hrs per batch. A conventional dyeing process takes place in about 7 hours. Whereas using bio- scouring the same

Fuel saved per year (6.41 x 106/ Calorific value)

Fuel saved per day

basis the amounts comes to be 306600,000 litres of water.

heat energy required will be:

save following quantity of fuel:

through carbon credits.

Amount of heat energy required per kg. of cotton = (98- 55) x 1000 x 4.186 x 7= 1259998 Joules = 1260 KJ

Mt. On daily basis, the amount comes out to be

Fuel Source Calorific Value

(MJ/Kg.)

Amount of heat liberated per year for 30 Mt./ Day Plant = 1260 x 30 x 1000 x 365 = 13797000000 KJ = 13797000 MJ

**Advantages:** 


Since at least two stages of the enzymatic reaction i.e. transport of enzyme molecules on the cotton substrate and transport of enzymatic reaction products from the cotton substrate in to the solution are controlled by diffusion, the overall rate of hydrolysis depends on the respective diffusion rates. This is the reason why, while carrying out bio- scouring high level of liquor exchange, agitation and turbulence is required. Mechanical agitation of the enzyme processing solution not only improves transport of bulky enzyme molecules toward the surface of the cellulose fabric and in to the interior of the cotton yarn but also helps in release of degraded pectin from the surface of the cotton in to the solution.

#### **5.3 Structure of the bio- scoured fibre against conventionally scoured fibre**

In conventional scouring the entire amount of pectin is removed from the cotton fibre. This pectin serves as a binding material for the cellulose fibrils. After its removal the coherence between the fibrils decreases due to which the strength of the structure goes down. Also it leads to harshness of yarn and increased hairiness on the surface.

While designing our bio- scouring enzyme we had the aim of removing the pectins to a level just enough that it facilitates the even absorbency of the yarn, but should not eliminate them completely from the surface. Presence of pectin leads to strength retention, lesser hairiness and smoother surface profile.

#### **Advantages:**

230 Textile Dyeing

 Transfer of hydrolytic reaction product to the aqueous phase. After breaking down and removing pectin, which binds, as a natural binder, non- cellulose substances within the fibre cellulose core, other non- cellulose substances can be removed from the cotton by

Since at least two stages of the enzymatic reaction i.e. transport of enzyme molecules on the cotton substrate and transport of enzymatic reaction products from the cotton substrate in to the solution are controlled by diffusion, the overall rate of hydrolysis depends on the respective diffusion rates. This is the reason why, while carrying out bio- scouring high level of liquor exchange, agitation and turbulence is required. Mechanical agitation of the enzyme processing solution not only improves transport of bulky enzyme molecules toward the surface of the cellulose fabric and in to the interior of the cotton yarn but also helps in

In conventional scouring the entire amount of pectin is removed from the cotton fibre. This pectin serves as a binding material for the cellulose fibrils. After its removal the coherence between the fibrils decreases due to which the strength of the structure goes down. Also it

While designing our bio- scouring enzyme we had the aim of removing the pectins to a level just enough that it facilitates the even absorbency of the yarn, but should not eliminate them completely from the surface. Presence of pectin leads to strength retention, lesser hairiness

release of degraded pectin from the surface of the cotton in to the solution.

leads to harshness of yarn and increased hairiness on the surface.

and smoother surface profile.

**5.3 Structure of the bio- scoured fibre against conventionally scoured fibre** 

Catalysis of surface hydrolytic reaction by the enzyme

using surfactants and by mechanical action.


Amount of heat energy required per kg. of cotton

= (98- 55) x 1000 x 4.186 x 7= 1259998 Joules = 1260 KJ

1260 KJ is the amount of energy that will be saved for every Kg. of material processed. If calculated the impact of same on yearly basis for a production plant doing a bleaching of 30 Mt. On daily basis, the amount comes out to be

Amount of heat liberated per year for 30 Mt./ Day Plant

= 1260 x 30 x 1000 x 365 = 13797000000 KJ = 13797000 MJ

Thus on yearly basis a unit of daily production of 30 Mt. can save energy of the magnitude 1.38 x 107 MJ. If 1.38 x 108 MJ is extrapolated to various natural fuels available than we can save following quantity of fuel:


All the above mentioned figures are taken considering 100% performance of the concerned parameters involved. If taken in to account boiler efficiency, Combustion efficiency, Heat transfer losses, Steam Transportation losses than the figure will increase by 10 – 25%.

According to the United states Department of forestry, an average weight of a fully grown tree is about 680 Kg. Thus, by using Scourenz ABE Liquid, we would be indirectly contributing to plantation of 3.7 fully grown trees per day. Also, it will lead to reduction in contribution of global warming by any organization since we are inhibiting 1260 KJ of energy to enter in to our bio systems for every Kg. of cotton material bleached. Any organization will have its huge benefits in terms of carbon foot prints and help them to earn through carbon credits.

 **Time Saving:** The process of conventional scouring takes place about 2hrs 50 min. for completion. Whereas the bio-scouring process will not take more than 50 min. for completion. Thus for every batch dyed we are saving 2hrs per batch. A conventional dyeing process takes place in about 7 hours. Whereas using bio- scouring the same

Pre-treatment of Textiles Prior to Dyeing 233

Bleaching using Sodium hypochlorite in batch method, the fabric is treated using 1-3 g/L available chlorine at alkaline pH of 11-11.5 at room temperature for nearly two hrs. Disadvantages of Hypochlorite bleaching are a) all protein impurities must be completely removed before bleaching otherwise the fabric may turns yellowish. b) Residual chlorine

As compared to other bleaching agents, bleaching the material with peroxide has following

Since hydrogen peroxide contains an atom of loosely combined oxygen, it has powerful oxidising properties. Due to this it has a bleaching action on textile substrate. In a neutral aqueous solution, hydrogen peroxide is ionised in to perhydroxyl and hydrogen ions.

H2O2 HOO- + H+ This perhydroxyl ion is supposed to be the active bleaching agent. But the bleaching effect is dependent greatly on the pH of the solution. In acidic or neutral pH, perhydroxyl and hydrogen ions are found in solution. These hydrogen ions have a tendering effect on cellulose due to its acidic nature. It is found that in acidic or neutral pH tendering effect of H+ ions is more than the bleaching effect of the HOO- ions. This tendering will in turn impart yellowness to the cotton substrate. So it is not recommended to carry out bleaching

H2O2 + OH- HOO- + H2O Here we can see that along with perhydroxyl ion and water molecules are in equilibrium. Due to this in alkaline pH we get more bleaching effect and less tendering of cotton. This is the reason why bleaching is carried out in alkaline pH. But it is observed that in alkaline medium although the damage to cotton fibre is less, the stability of peroxide itself is also very less. In absence of stabiliser, in alkaline medium at temperatures as high as 100- 1100C, the entire peroxide will get decomposed in less than 10 min. The presence of water hardness and the iron contamination in commercial processes further enhances the action of peroxide decomposition. If the bleaching is continued in such a way, that not only the bleaching efficiency will be hampered but also the uniformity of bleaching will not be good. Such material when taken for further dyeing will lead to problems like lesser depth, patchy dyeing etc. So it becomes mandatory to use a stabilising agent in bleaching baths to get good

Conventionally Sodium Silicate was used as a stabiliser for peroxide bleaching. It stabilizes the peroxide solutions considerably even at pH of 10. It takes about 54min. for peroxide to decompose to extent of 50% in presence of silicate. The stabilising affect can be explained as

1. It is a universal bleaching agent and can be used for bleaching cotton, wool, silk, jute.

must be removed otherwise fabric may be damaged.

3. Superior fastness can be achieved

5. Lesser chemical degradation of cotton 6. Lesser tendency of after yellowing

2. Weight loss is less as compared to hypochlorite bleaching

On the other hand, in alkaline condition following equilibrium exists:

advantages:

4. Better absorbency

**6.1 Bleaching chemistry** 

in acidic conditions.

bleaching performance.

follows:

dyeing can be completed in 5 hours. In terms of percentage the time saving will be 29%. Thus any process house can raise its production by 29% approximately by using the bio-scouring process.


**Gain Type Saving Parameter Amount**  Tangible and direct measurable gain Energy Cost 1.51 Rs./ kg. Weight Loss Less by 2.5% (4.0 Rs./Kg.) Softener cost -15% (20 paise/ Kg.) Chemical Cost 75 paise/ Kg. Water saving 28 litres/ Kg. Intangible gain leading to benefits Loom performance Improved by 4% (Direct increase in profit by 3%) Time saving 2 hours. (If utilised will give 29% higher profits)

**Summary of benefits:** 

#### **6. Bleaching6**

Traditional bleaches for cleaning clothes are hypochlorite and persalts. The proportions used differ widely, depending on the local environmental legislations. Over the last few years major changes have occurred in the bleach compounds used in the detergent formulations all over the world, as the chlorine – containing bleach compounds, which were popular for their low temperature application have been withdrawn for the market and their usage has become limited. This is due to the formation of highly toxic chlorinated organic by products (AOX) during the bleaching process as well as effluents discharged there from. Moreover, the legal regulations have stipulated very low limiting values for AOX in the textile effluent. Nowadays textile industries are obliged to bleach without using chlorine-containing compounds.


Bleaching using Sodium hypochlorite in batch method, the fabric is treated using 1-3 g/L available chlorine at alkaline pH of 11-11.5 at room temperature for nearly two hrs. Disadvantages of Hypochlorite bleaching are a) all protein impurities must be completely removed before bleaching otherwise the fabric may turns yellowish. b) Residual chlorine must be removed otherwise fabric may be damaged.

As compared to other bleaching agents, bleaching the material with peroxide has following advantages:


232 Textile Dyeing

 **Smoother surface profile:** Presence of pectin in yarn helps to give a smoother profile. This binding agent prevents the hairiness of the cotton that gets generated due to abrasion with processing equipment's. Also pectin itself acts as a softener for the cotton. So the application of final softener can be reduced from 25- 40%. Smoother profile will

 **Lesser Weight loss:** Weight loss in bio- scouring process is not more than 1.5%. In conventional process the weight loss is close to 4%. The total saving in the weight loss can be close to 2.5%.In this era, where the cotton prices have shown a steady inflation,

 **Environmental benefits:** Reduced effluent treatment cost, as avoiding caustic soda, which in turn reduces TDS. During conventional scouring if we consider TDS to be

**Lesser cost of Auxiliaries:** In a conventional scouring recipe the chemicals used and

**Gain Type Saving Parameter Amount** 

Traditional bleaches for cleaning clothes are hypochlorite and persalts. The proportions used differ widely, depending on the local environmental legislations. Over the last few years major changes have occurred in the bleach compounds used in the detergent formulations all over the world, as the chlorine – containing bleach compounds, which were popular for their low temperature application have been withdrawn for the market and their usage has become limited. This is due to the formation of highly toxic chlorinated organic by products (AOX) during the bleaching process as well as effluents discharged there from. Moreover, the legal regulations have stipulated very low limiting values for AOX in the textile effluent. Nowadays

Maximum Levels for the indirect discharge of effluent

Pollutant Limits

AOX 0.5 ppm

textile industries are obliged to bleach without using chlorine-containing compounds.

Energy Cost 1.51 Rs./ kg. Weight Loss Less by 2.5% (4.0 Rs./Kg.) Softener cost -15% (20 paise/ Kg.) Chemical Cost 75 paise/ Kg. Water saving 28 litres/ Kg.

Loom performance Improved by 4% (Direct

Time saving 2 hours. (If utilised will

increase in profit by 3%)

give 29% higher profits)

also help in improving the loom running efficiency by 4% at least.

this will be a considerable advantage to the process owner.

100% the Scourenz ABE Liquid process has only 20-40% TDS.

bio-scouring process.

their respective cost are:

Tangible and direct measurable gain

Intangible gain leading to benefits

**6. Bleaching6**

**Summary of benefits:** 

dyeing can be completed in 5 hours. In terms of percentage the time saving will be 29%. Thus any process house can raise its production by 29% approximately by using the


#### **6.1 Bleaching chemistry**

Since hydrogen peroxide contains an atom of loosely combined oxygen, it has powerful oxidising properties. Due to this it has a bleaching action on textile substrate. In a neutral aqueous solution, hydrogen peroxide is ionised in to perhydroxyl and hydrogen ions.

#### H2O2 HOO- + H+

This perhydroxyl ion is supposed to be the active bleaching agent. But the bleaching effect is dependent greatly on the pH of the solution. In acidic or neutral pH, perhydroxyl and hydrogen ions are found in solution. These hydrogen ions have a tendering effect on cellulose due to its acidic nature. It is found that in acidic or neutral pH tendering effect of H+ ions is more than the bleaching effect of the HOO- ions. This tendering will in turn impart yellowness to the cotton substrate. So it is not recommended to carry out bleaching in acidic conditions.

On the other hand, in alkaline condition following equilibrium exists:

#### H2O2 + OH- HOO- + H2O

Here we can see that along with perhydroxyl ion and water molecules are in equilibrium. Due to this in alkaline pH we get more bleaching effect and less tendering of cotton. This is the reason why bleaching is carried out in alkaline pH. But it is observed that in alkaline medium although the damage to cotton fibre is less, the stability of peroxide itself is also very less. In absence of stabiliser, in alkaline medium at temperatures as high as 100- 1100C, the entire peroxide will get decomposed in less than 10 min. The presence of water hardness and the iron contamination in commercial processes further enhances the action of peroxide decomposition. If the bleaching is continued in such a way, that not only the bleaching efficiency will be hampered but also the uniformity of bleaching will not be good. Such material when taken for further dyeing will lead to problems like lesser depth, patchy dyeing etc. So it becomes mandatory to use a stabilising agent in bleaching baths to get good bleaching performance.

Conventionally Sodium Silicate was used as a stabiliser for peroxide bleaching. It stabilizes the peroxide solutions considerably even at pH of 10. It takes about 54min. for peroxide to decompose to extent of 50% in presence of silicate. The stabilising affect can be explained as follows:

Pre-treatment of Textiles Prior to Dyeing 235

**6.4 KOOLWHITE 2020 Liquid - Instant whiteness guaranteed at low temperature**  In the coming times chemical processes in everyday's life has to be environmentally safe, cost effective and sparing energy. While designing this molecule we had the target of lowering the bleaching temperature without reducing the bleaching performance. As the bleaching temperature decreases, the activity of traditional bleaching agent like hydrogen peroxide is reduced. To maintain the bleaching efficiency, effective catalysts are required. Several transition metal complexes with different ligands are reported to be promising low temperature peroxide bleach catalysts. In an intensive research carried out at our R&D centre, it has been found that transition metal derived complexes and related ligand systems are effective

catalyst for oxidation of colouring matter by hydrogen peroxide at lower temperatures.

and thus produces a bleaching effect. This can be pictorially represented as follows:

M M

M

M

this catalyst the bleaching can be carried out at temperatures as low as 800C.

Similar kind of complexes in combination with peroxide have been reported to exhibit remarkable catalytic activity, in presence of suitable buffers, for stereo- selective epoxidation of olefins, oxidation of alkanes and alcohols at ambient temperature. For the first time these have been deployed commercially on a bulk scale in textile as a bleaching catalyst. Using

At this low temperature, in alkaline medium the release of perhydroxyl ions is slower as compared to 1000C. The metal- ligand system complexes these released perhydroxyl ions and prevent its decomposition in to water and oxygen. This further increases the stability of the perhydroxyl ions in the alkaline solution. When this 'Metal- Ligand- Perhydroxyl ion' complex comes in contact with an oxidizable colouring matter impurity on the textile substrate, the perhydroxyl ion is released. This released ion oxidizes the colouring matter

The major advantage of the molecule is that due to its stable intermediate structure it is

For carrying out bleaching on various cotton substrates a typical bleaching recipe using

**Chemicals RFD Full white**  Kleenox Knitz Liquid 1.5 g/L 1.5 g/L Koolcat Liquid 0.1 % 0.1% Koolwhite 2020 liquid 0.8% 1%

Caustic 1.2 g/L 2 g/L Peroxide 2.5 g/L 7 g/L

relatively inert to cotton material and leads to lesser oxy-cellulose formation.

Koolwhite 2020 liquid can be stated as follows:

**100% Cotton Woven:** 

Na2SiO3 + Ca+2 Ca (Sio3)2 + Na+

Na2SiO3 + Mg+2 Mg (Sio3)2 + Na+

This way the water hardness is removed from the solution. But this advantage is accompanied by a disadvantage that the calcium and magnesium silicate formed are sparingly soluble in water and get deposited on the surface of bleaching equipment leading to abrasion of fabrics, difficulty in washing off. Due to this silicates have been replaced by new generation stabilizing agent. One of these category includes magnesium based compounds like magnesium hydroxide, Magnesium – EDTA (Ethylene Diamine tetra acetic acid), copolymer of styrol- maleic acid with magnesium haloids, magnesium silicates etc. Other group of stabilising agents include polyorganosiloxanes such as poly-methyl and poly-ethyl siloxanes which along with stabilising effect have an added benefit of reducing the abrasion resistance when used for bleaching of yarn or sewing threads.

The world is facing a crisis of energy consumption, and the situation is worsening day by day. Correct practices for energy, consumption has become essential in everywhere of life, from industrial as consumer practices. The textile industry as a whole has taken some measures in this direction by combination of several step processes into one step process, the less use of water in processing to reduce the expense of energy in drying and chemical processing at lower temperatures.

The entire bleaching process takes place near about 3 hours for a full white process and about 2 hours for a RFD process.

#### **6.2 Drawback of the conventional bleaching process**

A very interesting phenomenon comes in to picture when we analyse the conventional bleaching process. Till now, it is very clearly understood that with increase in temperature the stability of peroxide decreases rapidly in alkaline medium. The bleaching temperature that is used conventionally is around 1000C. At this temperature the peroxide is highly unstable. So in order to stabilise the peroxide we are adding an external stabiliser. These two facts are contradictory to each other:


#### **6.3 Need for research**

Bleaching at low temperatures (ambient temperature to 30°C to 80°C) Catalytic bleaching

	- lower the bleaching temperature (65- 80 °C; no steamer)
	- shorten the bleaching time (5-10 min)
	- decrease the damage of the fabric (DP value > 2000)
	- reduce the chemical consumption with lower pH range (3 g H2O2/l, pH 10)

Na2SiO3 + Ca+2 Ca (Sio3)2 + Na+

Na2SiO3 + Mg+2 Mg (Sio3)2 + Na+ This way the water hardness is removed from the solution. But this advantage is accompanied by a disadvantage that the calcium and magnesium silicate formed are sparingly soluble in water and get deposited on the surface of bleaching equipment leading to abrasion of fabrics, difficulty in washing off. Due to this silicates have been replaced by new generation stabilizing agent. One of these category includes magnesium based compounds like magnesium hydroxide, Magnesium – EDTA (Ethylene Diamine tetra acetic acid), copolymer of styrol- maleic acid with magnesium haloids, magnesium silicates etc. Other group of stabilising agents include polyorganosiloxanes such as poly-methyl and poly-ethyl siloxanes which along with stabilising effect have an added benefit of reducing

The world is facing a crisis of energy consumption, and the situation is worsening day by day. Correct practices for energy, consumption has become essential in everywhere of life, from industrial as consumer practices. The textile industry as a whole has taken some measures in this direction by combination of several step processes into one step process, the less use of water in processing to reduce the expense of energy in drying and chemical

The entire bleaching process takes place near about 3 hours for a full white process and

A very interesting phenomenon comes in to picture when we analyse the conventional bleaching process. Till now, it is very clearly understood that with increase in temperature the stability of peroxide decreases rapidly in alkaline medium. The bleaching temperature that is used conventionally is around 1000C. At this temperature the peroxide is highly unstable. So in order to stabilise the peroxide we are adding an external stabiliser. These two

3. This makes us think as to why not lower the temperature of bleaching to a level that without decreasing the scouring efficiency we can achieve same bleaching efficiency at

4. On this idea, Rossari, which has always believed in innovating ways to make the process more eco- friendly and cost effective, has brought a new molecule to revolutionize the bleaching process used in textile industry. We are launching this

reduce the chemical consumption with lower pH range (3 g H2O2/l, pH 10)

1. Destabilization of peroxide by selection of a higher bleaching temperature

molecule in the name of 'Koolwhite 2020' in the commercial market.

Bleaching at low temperatures (ambient temperature to 30°C to 80°C)

lower the bleaching temperature (65- 80 °C; no steamer)

decrease the damage of the fabric (DP value > 2000)

shorten the bleaching time (5-10 min)

2. Addition of external stabiliser in order to stabilise the peroxide.

that obtained in conventional high temperature process.

the abrasion resistance when used for bleaching of yarn or sewing threads.

processing at lower temperatures.

about 2 hours for a RFD process.

facts are contradictory to each other:

**6.3 Need for research** 

Use of catalysts in order to

Catalytic bleaching

**6.2 Drawback of the conventional bleaching process** 

#### **6.4 KOOLWHITE 2020 Liquid - Instant whiteness guaranteed at low temperature**

In the coming times chemical processes in everyday's life has to be environmentally safe, cost effective and sparing energy. While designing this molecule we had the target of lowering the bleaching temperature without reducing the bleaching performance. As the bleaching temperature decreases, the activity of traditional bleaching agent like hydrogen peroxide is reduced. To maintain the bleaching efficiency, effective catalysts are required.

Several transition metal complexes with different ligands are reported to be promising low temperature peroxide bleach catalysts. In an intensive research carried out at our R&D centre, it has been found that transition metal derived complexes and related ligand systems are effective catalyst for oxidation of colouring matter by hydrogen peroxide at lower temperatures.

Similar kind of complexes in combination with peroxide have been reported to exhibit remarkable catalytic activity, in presence of suitable buffers, for stereo- selective epoxidation of olefins, oxidation of alkanes and alcohols at ambient temperature. For the first time these have been deployed commercially on a bulk scale in textile as a bleaching catalyst. Using this catalyst the bleaching can be carried out at temperatures as low as 800C.

At this low temperature, in alkaline medium the release of perhydroxyl ions is slower as compared to 1000C. The metal- ligand system complexes these released perhydroxyl ions and prevent its decomposition in to water and oxygen. This further increases the stability of the perhydroxyl ions in the alkaline solution. When this 'Metal- Ligand- Perhydroxyl ion' complex comes in contact with an oxidizable colouring matter impurity on the textile substrate, the perhydroxyl ion is released. This released ion oxidizes the colouring matter and thus produces a bleaching effect. This can be pictorially represented as follows:

The major advantage of the molecule is that due to its stable intermediate structure it is relatively inert to cotton material and leads to lesser oxy-cellulose formation.

For carrying out bleaching on various cotton substrates a typical bleaching recipe using Koolwhite 2020 liquid can be stated as follows: **100% Cotton Woven:** 


Pre-treatment of Textiles Prior to Dyeing 237

The specific heat of water is 4.186 Joule/ gram K. It requires 4.186 joules of energy to heat 1 gm. of water by 1 Kelvin. Assuming an MLR of 1:7, for every Kg. of cotton, 7 litres of water is used during the bleaching process. In order to heat water from 80 degrees to 100 degrees

586 KJ is the amount of energy that will be saved for every Kg. of material processed. If calculated the impact of same on yearly basis for a production plant doing a bleaching of 30

Thus on yearly basis a unit of daily production of 30 Mt. can save energy of the magnitude 6.41 x 106 MJ. If 6.41 x 106 MJ is extrapolated to various natural fuels available than we can

Coal (Anthracite) 27 237.5 Metric tonnes. 651 kg Coal (Lignite) 15 427.7 Metric tonnes 1172 kg. Wood 15 427.7 Metric Tonnes 1172 kg. Diesel 44.80 143 Metric Tonnes 392Kg. Kerosene 46.20 138.7 Metric Tonnes 380 Kg.

All the above mentioned figures are taken considering 100% performance of the concerned parameters involved. If taken in to account boiler efficiency, Combustion efficiency, Heat

According to the United states Department of forestry, an average weight of a fully grown tree is about 680 Kg. Thus, by using Koolwhite 2020 Liquid as the bleaching catalyst we would be indirectly contributing to plantation of 1.5 trees per day. Also, it will lead to reduction in contribution of global warming by any organization since we are inhibiting 586 KJ of energy to enter in to our bio systems for every Kg. of cotton material bleached. Any organization will have its huge benefits in terms of carbon foot prints and help them to earn through carbon credits.

The intermediate manganese- perhydroxyl ion complex formed is a more stable complex as compared to perhydroxyl ions itself. Due to this the oxidation reaction becomes more site specific and there is a higher degree of decolourization and lesser degree of fibre damage. Fabric or yarn bleached using Koolwhite 2020 shows a lesser oxy-cellulose formations

Current Std. 2466 2453 2374 22.4 22.2 21.3 Koolwhite 2020 2466 2621 2412 22.4 22.6 22.1

CSP readings RKM readings **Grieg RFD Full white Grieg RFD Full white** 

transfer losses, Steam Transportation losses than the figure will increase by 10 – 25%.

Fuel saved per year (6.41 x

106/ Calorific value) Fuel saved per day

**Advantages of the process**  *Environmentally friendly* 

save following quantity of fuel:

*Strength retention* 

Bleaching Process

the amount of heat energy required will be: Amount of heat energy required per kg. of cotton = (100- 80) x 1000 x 4.186 x 7= 586040 Joules = 586 KJ

Mt. On daily basis, the amount comes out to be

Fuel Source Calorific Value

compared to conventional bleaching process.

Amount of heat liberated per year for 30 Mt./ Day Plant = 586 x 30 x 1000 x 365= 6416700000 KJ = 6416700 MJ

(MJ/Kg.)


#### **6.5 Bulk trial results**

Today Kool'white 2020 is not merely a concept or a theoretical hypothesis but a wellestablished commercial bleaching catalyst that is giving benefits to our customer in terms of cost, time, and money saving and helping them to evolve as a green technologies user in international market. It has increased their market credibility and buyers prefer ability considering the fact that the ultimate consumer has become more conscious about the type of product it's using and its consecutive environmental impact.

#### **Advantages of the process**
