By: Edward Menezes


Why bio-auxiliaries are needed?


Modern society expects bio-auxiliary to be the answer for many worldwide problems like depletion of energy sources, incurable illnesses and pollution, among other problems. Industrial use of biotechnology, known as white biotechnology, is bringing about new products and processes aimed at the use of renewable resources, as well as the application of green technologies with low energy consumption and environmentally healthy practices.


Textile processing is a growing industry that traditionally has used a lot of water, energy and harsh chemicals-starting from pesticides for cotton-growing to high amounts of wash waters that result in waste streams causing high environmental burdens.


As textile fibers are polymers, the majority being of natural origin, it is reasonable to expect there would be a lot of opportunities for the application of bio-auxiliary to textile processing.


Enzymes - nature's catalysts and bio-auxiliaries - are the logical tools for development of new biotechnology-based solutions for textile wet processing.


What Indian dyestuff and Textile auxiliary manufacturer need to do?


  • To develop environmentally safe product to replace the restricted product
  • Develop innovative synthesis route to eliminate unintentional impurities.
  • Bring more awareness among textile producers for overall Eco-Toxicological requirements.
  • Need to develop in-house capability for the evaluation of restricted Ecological & Toxicological parameters.


Eco-friendliness and eco-regulations


Normally bio-auxiliaries are biodegradable, thereby no chances of increase the pollution load, more user friendly from human body contact, medical and hygienic point of view, reduce effluent generation so effluent treatment cost becomes lesser keeping pollution free discharge to environment.


Use of Sugar polymers:


Problems with inorganic content


Phosphates


  • Eutrophicating
  • Non dissolvable metal sedimentation
  • Poor Stability


EDTA, NTA


  • Poor biodegradability
  • Remobilising of heavy metals Polyacrylates
  • Can only be eliminated
  • Non toxic


Silicates


  • Silicate incrustation
  • Soft handle degrading


The present invention relates to water-soluble, acid-groups-containing graft copolymers which are at least partially biodegradable and are based on sugars and monoethylenically unsaturated carboxylic and sulfonic acids as well as optional further monomers.

 

This inhibits the negative effects of the water hardness and high fe3+-dispersing capacity, the dispersive action on pigments, the use in washing liquors and dye baths, as well as the use as auxiliary agents in the manufacture of paper and leather.


In these applications of the water-soluble polymers it is important that multivalent metal ions are complexed, hardness elements of the-water are prevented from precipitating or that pigments are dispersed in a high concentration at a low viscosity.


Pretreatment of cotton with a multifunctional sugar-co-polymer and a special wetting/washing agent in acid medium.


Degradability of sugar co-polymer


Saccharose = intended breaking point

Bacteria attack

High biological degradation


Washing of dyed material using sugar co-polymers


The use of the polymers according to the present invention is described with reference to a discontinuous washing of a cotton fabric which had been subjected to reactive dyeing.


At first, the dyeing liquor is drained off followed by:






 

Comparison

 

 

 

Conventional
Processes

Disadvantages

Bio-remedies

Advantages

Acid desizing

  • Hydo-cellulose formation takes place.
  • Tremendous loss in strength

Alpha amylase

  • Only hydrolyse starch.
  • High desizing efficiency
  • No strength loss

Fading -using
Pumice stone

  • Loss of strength of the fabric
  • Yarn structure in fabric detoriates
  • Accumulation of large amounts of sludge together with fibre residues and indigo pigments which had to be disposed.
  • Unloading the machine after stone treatment is very difficult because stones and their split off remainders were all over and had to be removed from the trousers.
  • Pumice stones are a natural raw material and their occurrence is limited.
  • Fading efficiency absolutely dependent on hardness and size of the stone.

Cellulase Enzymes

  • Specific in action
  • No chances of damaging Yarn structure in fabric.
  • No high abrasion strength loss
  • Saves water
  • Saves time
  • Process flexibility
  • No damage to fabric

Bleaching
(Oxidative and
reductive)

  • AOX Problem
  • Yellowing
  • Strength Loss

Lacasse/
Peroxidases

  • Less strength loss compared to peroxide treatment.
  • No residual peroxide.
  • No use of stabilizer.

Scouring

  • Hazardous as high BOD,
  • COD, TDS levels
  • Rinsing Cost (Labour/ water/corrosion)
  • High effluent treatment
  • Alters morphology of cotton fibre.
  • Strong neutralization required.
  • Higher weight loss

Bio Scouring
Concept

  • Milder Process
  • Less Environmental
  • Impact in terms of TDS, BOD & COD
  • Saves Energy, water
  • Eliminates core alkali  neutralisation
  • Improved whiteness & absorbency with reduced strength and weight loss

 

Soaping

  • Non biodegradable
  • May increase the alkalinity on the fabric.

Enzymatic washing off for Reactive, Vat and indigo dyes. Enzymes like Laccases, Lignin peroxidases and Manganese peroxidases destroy many colour producing compounds along with special effect on fabric.

  • Excellent Specificity
  • Works only on reactive dye hydrolysate
  • Eco-friendly
  • Biodegradable
  • Leaves rinse bath clear
  • Saves water and Energy
  • Cost effective
  • Excellent Quality Standards
  • Improves fastness properties

1)    Rinsing with overflow at 60 C for 10 min.

2)    Rinsing in fresh bath at 90 C for 10 min.

3)    Allowing to stand with 1 g/I polymer ace. to Example 9 at 90-95 C for 10 min. rinsing at 45 C for 15 min.


The cotton fabric has an intensive color, shows no bleeding and exhibits good wash fastness.


The above-mentioned periods of time, temperatures and sequences are intended to be illustrative. The polymers according to the present invention can also be used under other washing conditions.


German ban-


The findings of the various Research Institutes of Europe who were engaged in the field of Textile research, that some of these dyes are potentially carcinogenic.

Arylamines encompassed by European laws banning azo dyes are tabulated in the adjoining Table.


Fibre manufacturing

Novel fibre-forming biopolymers are now being manufactured using large-scale fermentation equipment. For example, the bacterial storage compound polyhydroxybutyrate (PHB) has been developed by Zeneca Bioproducts (formerly ICI Agricultural Division) and is produced under the trade name 'Biopol'.

This high molecular weight linear polyester has good thermoplastic properties (melting point 180C) and can be melt spun into fibres. Biocompatibility and biodegradability makes PHB fibres ideally suited for surgical use; sutures made from PHB are slowly degraded by the body's enzymes. Zeneca is currently using Biopol in conventional plastics applications such as shampoo bottles.



 

Arylamines Encompassed by European Laws Banning Azo Dyes

No.

Name

CASno.1

1

4-aminobiphenyl

92-6

2

Benzidine (4,4'-diaminobiphenyl)

92-87-5

3

4-chloro-o-toluidine

95-69-2

4

2-naphthylamine

91-59-8

5

4-0-tolylazo-o-toluidine, (4-amino-2,3- dimethylazobenzene, o-aminoazotoluene)

97-56-3

6

2-amino-4-nitrotoluene

99-55-8

7

4-chlorobenzenamine

106-47-8

8

2,4-diaminoanisole_
(4-methoxy-m-phenylenediamine)

615-05-4

9

4,4'-diaminodiphenylmethane_
(4,4'-methylenedianiline)

101-77-9

10

3,3'-dichlorobenzidine

91-94-1

11

3,3'-dimethoxybenzidine (o-dianisidine)

119-90-4

12

3,3'-dimethylbenzidine (4,4'-bi-o-toluidine)

119-93-7

13

4,4'-methylenedi-o-toluidine, _
(4,4'-methylenebis-2-methylaniline)

838-88-0

14

p-cresidine (6-methoxymethylaniline)

120-71-8

15

2,2'-dichloro-4,4'-methylene-dianiline_
(4,4'-methylene-bis-(2-chloro-aniline) )

101-14-4

16

4,4'-oxydianiline (4,4-diaminodiphenylether)

101-80-4

17

4,4'-thiodianiline

139-65-1

18

o-toluidine (2-aminotoluene)

95-53-

19

4-methyl-m-phenylenediamine _
(2,4-diaminotoluene)

95-80-7

20

2,4,5- trimethylani line

137-17-7



The price of the polymer is still considered too high for many fibre applications and ultimately Biopol might be produced by plants. Zeneca seeds are experimenting with a genetically engineered variety of grape which can synthesise Biopol.

Other biopolymers currently of particular interest in wound-healing applications include the polysaccharides chitin, alginate, dextran and hyaluronic acid. Chitin and its derivative chitosan are important components of fungal cell walls although these polymers are, at present manufactured from sea food (shellfish) wastes. Patents taken out by the Japanese company Unitika cite the use of fibres made out of chitin in wound dressings.


At BTTG, research has been directed towards the use of intact fungal filaments as a direct source of chitin or chitosan fibre to produce inexpensive wound dressings and other novel materials.

Wound dressings based on calcium alginate fibres have already been developed by Courtaulds and are marketed under the trade name 'Sorbsan'. Present supplies of this polysaccharide rely on its extraction from brown seaweed's. However, a polymer of similar structure can also be produced by fermentation from certain species of bacteria.

 

Dextran, which is manufactured by the fermentation of sucrose by Leuconostoc mesenteroides or related species of bacteria, is also being developed as a fibrous non-woven for speciality end-uses such as wound dressings.

Bio-auxiliary in dyes and pigments


Manufacturing of natural dyes from different wood berk, leaves, fruits, tea extraction becomes a novel approach towards the use of biomaterial in dyeing. Textile auxiliaries such as dyes could be produced by fermentation or from plants in the future (note: before the invention of synthetic dyes in the nineteenth century many of the colours used to dye textiles came from plants. e.g. woad, indigo and madder).

Many micro-organisms produce pigments during their growth which are substantive as indicated by the permanent staining that is often associated with mildew growth on textiles and plastics. It is not unusual for some species to produce up to 30% of their dry weight as pigment.

Several of these microbial pigments have been shown to be benzoquinone, naphthoquinone, anthraquinone, perinaphthenone and benzofluoranthenequinone derivatives, resembling in some instances the important group of vat dyes.

Micro-organisms would therefore seem to offer great potential for the direct production of novel textile dyes or dye intermediates by controlled fermentation techniques replacing chemical synthesis which has inherent waste disposal problems (e.g. toxic heavy metal compounds).

The production and evaluation of microbial pigments as textile colorants is currently being investigated at BTTG.


Waste Management


Biotechnology can be used in new production processes that are themselves less polluting than the traditional processes and microbes or their enzymes are already being used to degrade toxic wastes. Waste treatment is probably the biggest industrial application of biotechnology. Specific problems pertaining to the textile industry include colour removal from dyehouse effluent, toxic heavy metal compounds and pentachlorophenol used overseas as a rot-proofing treatment of cotton fabrics but washed out during subsequent processing.


Currently much research is being carried out to resolve these problems and biotechnology would appear to offer the most effective solutions. Biological treatment of effluent is termed as secondary treatment. The objective of treatment is to achieve bio-flocculation.


The micro-organisms convert the colloidal and dissolved carbonaceous matter into various gases and cell tissues. The cell tissues have a specific gravity slightly higher than that of water and hence can be removed by gravity settling. Bacterium 'shewanella sp' can couple growth to the biodegradation of reactive azo dyes.


It is thought that colour removal process involves transfer of electrons from the cell to the dye molecule, via a dye reductase, this results in reduction of the chromophore i.e., the azo bonds, to produce a significantly less coloured solution that contains amines.


Lignin peroxidase, manganese peroxidase and Laccase are produced by white rot fungi and are believed to involve in degradation of lignin and wide variety of recalcitrant xenobiotic compounds. Many rot fungi including pycnoporuscinnacarit, pleurotusostreatus, etc. have been found to be efficient in degrading dyes.


White rot fungi may oxidatively degrade dyes by means similar to lignin degradation typically associated with enzymes.


End use of bio-auxiliaries in textiles


Textile processing with bio-auxiliaries aims to provide the textile technologist with an understanding of enzymes and their use with textile materials and in process engineering. It covers all the relevant aspects of textile processing with bio-auxiliaries, from the chemical constitution and properties of textile materials as potential substrates for bio-auxiliaries, to the processing of these materials; from basic biochemistry and enzymology to the industrial application of bio-auxiliaries.

 

 



Major applications of bio-auxiliary in the textile industry:


  • Improvement of plant varieties used in the production of textile fibres and in fibre properties.
  • Improvement of fibres derived from animals and health care of the animals.
  • Novel fibres from biopolymers and genetically modified micro-organisms
  • Replacement of harsh and energy demanding chemical treatments by enzymes in textile processing
  • Environmentally friendly routes to textile auxiliaries such as dyestuffs
  • Novel uses for enzymes in textile finishing
  • Development of low energy enzyme based detergents
  • New diagnostic tools for detection of adulteration and Quality Control of textiles
  • Waste management


Biodegradable surfactant


Surfactants (surface active agents) are major components of cleaning products. Surfactants are classified according to their electrical charge: anionic (negative charge), nonionic (no charge), cationic (positive charge) and amphoteric (either positive or negative charge).

Anionic surfactants are effective in removing particulates (dirt, dust) and oily solids. Soap is an anionic surfactant.


Nonionic surfactants are less seriously affected by water hardness and are especially useful in products designed to require little rinsing.

However, neither is environmentally preferable.


Conslusion:

  • Need to increase the eco awareness
  • Need to adapt Eco friendly manufacturing and processing processes
  • Need for more competent testing laboratories.


About the Author:


Mr. Edward Menezes is the Director of Rossari Biotech, Mumbai.

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