A Presentation onCRITICAL REVIEW

OF

“Indigo Dyeing of Polyamide Using Enzymes for Dye Reduction”Mojca Bozic and Vanja Kokol

Institute of Engineering Materials and Design, University of Maribor

Smetanova ulica 17, SI-2000 Maribor, Slovenia

Georg M. Guebitz

Institute of Environmental Biotechnology, Graz University of Technology Petersgasse 12, A-8010 Graz, Austria

Published in Textile Research Journal 2009

BY

Sareweshwra Nand Pandey

UNDER THE GUIDANCE OF

Prof. (Dr.) R. V. ADIVAREKAR

INTRODUCTIONThis presentation gives a summary of eco-friendly processes for the reduction of

vat dyes. Classical processes of indigo dyeing use sodium dithionite as reducing

agent, causing enormous environmental problems.

In this paper, a new process of indigo reduction using NADH- dependent

reductases from Bacillus subtilis in the presence of redox mediators is presented.

The efficiency of mediated enzymatic indigo reduction on the dyeing of

polyamides 6 and 6,6 was studied at 60°C, pH 7 and 11.

The authors have done an excellent work regarding environmental protection by

crude NADH-dependent reductases isolated from Bacillus subtilis for reduction of

indigo (C.I. Vat Blue 1) into its soluble form.

Successful reuse of the enzyme have confirmed by authors.

EXPERIMENTALChemicals

Materials

Redox Potential Determination

Dyeing

Determination of Colour and Colour

Fastness properties

ChemicalsThe authors have used following Chemicals in their study:-

Indigo (Fluka)

1,8-dihydroxy-9,10-anthraquinone (Aldrich)

NADH (β-nicotinamide adenine dinucleotide disodium salt) (Aldrich)

NaOH (Aldrich)

Na2S2O4 (Aldrich) as reducing agent

H2O2 (Aldrich) as the oxidizing agent

Crude enzymes (25–50 mg/ml of protein content as determined using the Lowry method) were isolated from B. subtilis

Nitrogen was employed for deaeration.

Materials The authors have used commercial polyamide 6,6 (95.6 g/m2,6.4 dtex) and

polyamide 6 (0.5 g/m2, 9.2 dtex) fabrics prepared for dyeing throughout the work.

Redox Potential Determination

Redox potentials of Na2S2O4 (5 g/l at pH 11) and indigo reductases from B.

subtilis without and with mediator (12.5 µM) in phosphate buffer solution (pH 4–

12) at different temperatures (25–65 °C) have monitored for 65 minutes by

authors.

The authors have used a pH meter (Mettler Toledo MA 235, pH/Ion Analyser)

for the measurements.

Dyeing

The authors have carried out dyeing of prewetted polyamide fabrics

with

enzyme and

conventional method

Dyeing with enzyme

Mediated enzymatic indigo dyeing and soaping processes.

Reuse of mediated enzymatic dyeing bath

The authors have carried out reusing of mediated enzymatic dyeing bath according to the

following procedure:

After polyamide material was enzymatically mediated dyed at selected pH and 60°C for 90

minutes, the polyamide was removed from the dye bath

The new polyamide sample was placed in the remained mediated enzymatic-bath with the

addition of starting indigo concentration and lost buffer.

After 90 minutes of the dyeing the procedure was repeated again with the new set of

polyamide sample.

conventional dyeing of polyamides

The authors have carried out conventional dyeing of polyamides using:-

1 gm Na2S2O4 as reducing agent per 1.5mg of indigo according to the standard dyeing

procedure, with 80:1 liquor ratio at both pH (Tris-HCl; pH 7 and Tris-NaOH; pH11).

Determination of Colour and Colour Fastness properties

The authors have determined the colour of the dyed fabrics from the reflectance

measurements using Spectraflash SF 600 PLUS spectrophotometer (Data colour) at

standard illuminant D65 using a 10° observer. The colour was evaluated by

CIELAB colour co-ordinates (L*, a*, b*, C* and h) and colour depth (K/S) was

calculated using the Kubelka-Munk equation: K/S = (1-R)2/2R

The authors have determined colour fastness to washing, light, alkaline and acid

perspiration using standards ISO 105-C04, ISO 150-B04, and ISO 105-E04,

respectively.

RESULTS AND DISCUSSION

Conditions for mediated enzymatic indigo reduction

The influence of mediator 1,8-dihydroxy-9,10-anthraquinone on the reduction potential of reductases

CIELAB colour values of differently indigo-dyed PA6 and PA6,6

Colour yield values of polyamide 6 and PA 6,6

The absorption properties of indigo in the case of mediated enzymatic dyeing

Effect of the dyeing time and pH medium on colour strength of enzymatically mediated indigo dyed polyamides

Effect of the indigo concentration and pH medium on colour strength

Effect of the mediated enzymatic reduction system reusing On colour strength

Wash, perspiration and light fastness properties of chemically and enzymatically mediated indigo-dyed PA6 and PA6,6

temperatures for mediated enzymatic indigo reduction

Indigo-reductases activity at pHs 7 and 11 versus different temperatures

The influence of mediator 1,8-dihydroxy-9,10-anthraquinone on the reduction potential of reductases

Influence of mediator on the reduction potential of reductases at different temperatures and pH 11 after

65 minutes.

Table 1 CIELAB color values of differently indigo-dyed PA6 and PA6,6 after 90 minutes of dyeing (0.16% owf) at 60 °C and pH

7

Table 2 CIELAB colour values of differently indigo-dyed PA6 and PA6,6 after 90 minutes of dyeing (0.16% owf) at 60 °C and pH 11.

Colour yield values of polyamide 6

Effect of the dyeing pH medium (pH 7 and 11) on colour depth of chemically and enzymatically (with and without mediator) dyed PA6 after 90 minutes.

Colour yield values of polyamide 6,6

Effect of the dyeing pH medium (pH 7 and 11) on color depth of chemically and enzymatically (with and without mediator) dyed PA6,6 after 90 minutes.

The absorption properties of indigo in the case of mediated enzymatic dyeing

Effect of the dyeing temperature and pH medium on color Strength of enzymatically Mediated indigo (0.16% owf) dyed polyamides after 90 minutes of dyeing at 600C

Effect of the dyeing time and pH medium on color strength of enzymatically mediated indigo dyed polyamides

Effect of the dyeing time and pH medium on color strength of enzymatically mediated indigo (0.16% owf) dyed polyamides after 90

minutes of dyeing at 60 °C.

Effect of the indigo concentration and pH medium on colour strength

Effect of the indigo concentration and pH medium on colour strength of polyamides dyed enzymatically mediated at 60 C for

90min.

Effect of the indigo concentration and pH medium on colour strength

Effect of the indigo concentration and pH medium on color Strength of polyamides dyed Chemically at 60 °C for 90 minutes

Effect of the mediated enzymatic reduction system reusingOn colour strength

Effect of the mediated enzymatic reduction system reusing On color strength of indigo (0.16%owf) dyed polyamides after 90

minutes of dyeing at pH 11.

Effect of the mediated enzymatic reduction system reusingOn colour strength

Effect of the mediated enzymatic reduction system reusing On color strength of indigo (0.16%owf) dyed polyamides after 90

minutes of dyeing at pH 7.

Wash, perspiration and light fastness properties of chemically and enzymatically mediated indigo-dyed PA6 and

PA6,6 Table show Wash, perspiration and light fastness properties of chemically and enzymatically mediated

indigo-dyed PA6 and PA6,6 after 90 minutes of dyeing (0.16 owf) at 60 °C and pH 7 after soaping.

Table show Wash, perspiration and light fastness properties of chemically and enzymatically mediated indigo-dyed PA6 and PA6,6 after 90 minutes of dyeing (0.16 owf) at 60 °C and pH 11 after soaping

CONCLUSIONS

Reductases from B. subtilis could substitute sodium dithionite in indigo dyeing

in the presence of mediator 1,8-dihydroxy-9,10-anthraquinone.

Dyeing experiments gave very good fastness properties for acid and alkali

perspiration, and satisfying results for wash and light fastness properties.

These results indicate that mediated enzymatic indigo reduction process could be

of significant interest in terms of economically and ecologically competitive

dyeing technology compared to actual chemical indigo reducing system.

In addition, with consideration of sensitiveness to the pH value, enzyme

mediated reduction system can be applied to recycle use at pH 11.

However, further work is required to establish the redox chemistry of the

enzyme mediated indigo reduction in order to optimize the process, as well as

trying to transfer it to other types of vat dyes requiring higher reduction potential.

CRITICAL REVIEW Title and Abstract

Introduction

Technical correctness

Clarity

Illustrations/Tables/Graphs

Bibliography

Title and Abstract

The authors have given sufficient data in abstract about their research work. They have

given a summary of eco-friendly processes for the reduction and oxidation of vat dyes

with a short and good content.

The title “Indigo Dyeing of Polyamide Using Enzymes for Dye Reduction” and abstract

gives brief idea about theme of paper.

Introduction

Authors have explained very clearly about introduction part. In the introduction part

authors has discussed about the importance of eco-friendly reducing agents in today’s

era because of the environmental problems caused by sulfur-based byproducts (i.e.

sulfites, sulfates, sulfur, etc.) formed in the decomposition of sodium dithionite and high

pH generated in a well manner.

As far as introduction is concerned authors has touched various aspects of the Indigo

Dyeing of Polyamide Using Enzymes for Dye Reduction topic.

Technical correctness

Authors have listed experimental chemicals in sufficient detail but Authors had

not given any reference for the selection of particular chemical concentration,

temperature and time in their paper. They should have mentioned the

characteristics and other standard parameters of the chemicals they have taken for

process.

The authors have not given enough information regarding the materials used. they

should have mentioned the quality of the fabric in detail like the construction

parameters epi, ppi. In substrate details regarding polyamide authors didn’t

mention the polyamide substrate specification in detail. The sample size selected is

not mentioned and it is very difficult to carry out further testing.

In their study authors have restricted himself to C.I. Vat blue 1 as far as the dye

ability part is concerned. On contrary they should have carried out the same

experiment for all other dyes also.

Technical correctness………

Authors should have included fastness tests like, multiple washing testing like

(EN ISO 6330:2002) and abrasion resistance (EN ISO 7854:2000) for assessing

true picture of fabric performance.

Commercial chemical used for performing the experiments were without further

purification. The result could have been obtained well if the authors followed the

process of purification.

The authors have shown redox reaction mechanism of indigo for better

understanding.

The authors have not subdivided results and discussions although authors have

discussed the results of these parameters neatly and clearly.

Authors have given test procedure which is understandable; but they have not

mention the test method procedure in detail.

ClarityIn this paper authors have explained the background of work first, in which they have discussed the importance of the work, its usage and some previous work on this subject. Introduction to the area of research and its significance are well discussed and gives a clear idea about the theme of the paper.

The paper is made with simple and easy language.The authors have organized the paper in a good step by step manner.Easily understandable terms. Introduction, Experimental, Results, Discussion & Conclusions are mentioned clearly.

Tables and graphs have been individually discussed clearly.

The paper sticks to the subject. Therefore paper is reasonably easy to follow and understand.

Authors have lacked clarity in writing the procedure for dyeing of polyamide with vat dyes in conventional method.

The some aspects like the vattsing procedure, sample size, chemical characteristics are missed out.

Illustrations/Tables/Graphs

The research work and experiments are summarized in tabulated and graphical manner by authors in which they have given direct relation between the parameter and testing results.

All graphs and table have explained clearly. Particularly all the parameters are explained.

There are 4 tables and 17 figures including graphs in complete paper. All of them are neat and without any mistakes.

All the information and details are distinguishly presented in the graph and table.

The graphs and tables illustrated in this manuscript are very well explained.The graphical and tabulate representation of all the data results obtained from

the experiments are very well interpreted and necessary for understanding.

BIBLIOGRAPHY

The authors have mentioned thirty seven main references. Almost all the

references have been cited in their work.

The Research paper references are quite a good in numbers.

All of the references reveals the required information about Indigo Dyeing of

Polyamide Using Enzymes for Dye Reduction.

All the references that have been cited are listed and vice versa. All the available

references are cross checked for the content and are found to be correct and in

agreement with what they have been cited for.

The authors have shown references in a well manner and the no. of references are

also good. Authors have mentioned references properly.

REFERENCES1. Vuorema, A.,John, P., Keskitalo, M., Kulandainathan, M. A., and Marken, F., Electrochemical and Sonoelectrochemical Monitoring of Indigo Reduction by Glucose, Dyes Pigm. 76,542–549 (2008).

2. The Journal of The Textile Institute Vol. 102, No. 1, January 2011, 87–92

3. Son, Y. A., Hong, J. P., and Kim, T. K., An Approach to the Dyeing of Polyester Fibre Using Indigo and Its Extended Wash Fastness Properties, Dyes Pigm. 61, 263–272 (2004)

4. Son, Y. A., Lim, H. T., Hong, J. P., and Kim, T. K., Indigo Adsorption to Polyester Fibres of Different Levels of Fineness, Dyes Pigm. 65, 137–143 (2005).

5. Burkinshaw, S. M., Chevli, S. N., and Marfell, D. J., The Dye- ing of Nylon 6,6 with Sulphur Dyes, Dyes Pigm. 45, 65–74 (2000).

6. Burkinshaw, S. M., Lagonika, K., and Marfell, D. J., Sulphur Dyes on Nylon 6,6 – Part2:the Effects of Reductant, Oxidant and Wash-off, Dyes Pigm.58, 157–170 (2003).

7. Burkinshaw, S. M., Lagonika, K.,and Marfell, D. J., Sulphur Dyes on Nylon 6,6 – Part 1: the Effect of Temperature and pH on Dyeing, Dyes Pigm. 56, 251–259 (2003).

8. Burkinshaw, S. M.,and Lagonika, K., Sulphur Dyes on Nylon6,6 – Part 3: Preliminary Studies of the Nature of Dye-fibre Interaction, Dyes Pigm. 69, 185–191 (2006).

REFERENCES………..

9. Baumgarte, U., Developments in Vat Dyes and Their Applica- tion 1974–1986, Rev. Prog. Colour. 17, 29–38 (1987).

10. Grull, D. R., Begli, A. H.,Kubadinow, N., Kunz, M., and Munir, M., Process for Reducing Sulphur and Vat Dyes, U.S. Patent 6,093,221 (1999).

11. Roessler, A.,and Crettenand, D., Direct Electrochemical Reduction of Vat Dyes in a Fixed Bed of Graphite Granules, Dyes Pigm. 63, 29–37 (2004).

12 .Roessler, A.,New Electrochemical Methods for the Reduction of Vat Dyes, Dissertation No. 15120, Swiss Federal Insti- tute of Technology, Zurich, Switzerland (2003).

13. Božic M.,and Kokol, V., Ecological Alternatives to the Reduction and Oxidation Processes in Dyeing with Vat and Sul- phur Dyes, Dyes Pigm. 76, 299–309 (2008).

14. Pricelius, S., Held, C., Sollner, S., Deller, S., Murkovic, M., Ullrich, R., Hofrichter, M., Cavaco-Paulo, A., Macheroux,P.,and Guebitz, G. M., Enzymatic Reduction and Oxidation of Fibre-bound Azo-dyes, Enzyme Microb. Technol. 40, 1732–1738 (2007).

15. Lowry O. H., Rosebrough, N. J., Farr, A. L., and Randall, R.J., Protein Measurement with the Folin Phenol Reagent, J. Biol. Chem. 193, 265–275 (1951).

16. Pricelius,S.,Held, C., Murkovic, M., Bozic, M., Kokol, V. Cavaco-Paulo, A., and Guebitz, G. M., Enzymatic Reduction of Azo and Indigoid Compounds, Appl. Microbiol. Biotechnol.77, 321–327 (2007).