Indian Journal of Fibre & Textile Research Vol. 33, March 2008, pp. 52-57
Ecofriendly discharge printing on cotton fabrics using laccase enzyme I Abd El-Thalouth, F Kantouch, S H Nassar & H M El-Hennawia Textile Research Division, National Research Center, Cairo, Egypt and
M Adel Youssef Chemistry Department, Faculty of Science, Helwan University, Helwan, Egypt Received 13 April 2007; revised received and accepted 10 September 2007 Laccase enzyme formulation has been used in discharge printing of cotton fabrics dyed with different reactive dyes and the effect of enzyme conc., pH of the printing paste, treatment time and temperature of enzymatic treatment as well as the viscosity of the printing paste on colour discharge studied. The optimum conditions for discharge printing are found to be 4.5 pH, 60°C temperature, 1 h time of treatment, and the 90.4 poise viscosity at a shear rate of 31.61s−1. The concentration of enzyme depends on the nature of dye used. Keywords: Cotton fibre, Discharge printing, Laccase enzyme, Reactive dye IPC Code: Intl.Cl.8 D06P
1 Introduction The theory of discharge printing involves the degradation by chemical reagents of the chromophore system of the dyestuffs applied to the textile materials.1 There are mainly two types of discharging agents, namely oxidizing agents, and reducing agents.2 The most important discharging agents in textile printing today are reducing agents. The latter comprise sulphoxylic acid derivatives and tin salts, in particular stannous chloride. The reaction takes place during the steaming fixation step and the quality of the product depends, to great extent, on the temperature and moisture content of the fixation room; any error will cause destruction of the cellulose material. Recently, the environmental and industrial safety conditions increased the potential for use of enzymes in textile processing to ensure ecofriendly production. The use of enzymes in textile processing is wellknown and for some technologies is well established, e.g. in denim bleaching.3 Laccase is the newest enzyme class to be introduced into the denim finishing area. The first commercial product was introduced in 1996 (refs 4, 5). This product exhibited ___________ a To whom all the correspondence should be addressed. E-mail:
[email protected]
good performance, but handling characteristics were not ideal. A fully-formulated solid laccase has been commercially available for the denim market since 1999 (ref. 6). The commercial laccase formula contains laccase, an enzyme mediator, buffer and a non-ionic surfactant.7 Pure laccase was obtained from this formulation and its activity was determined.8 The first laccase studied was originated from Rhus vernicifera tree and many other laccases are being discovered and studied from various plant and microbial sources.9-11 The ability of laccase to catalyse the oxidation of phenolic and non-phenolic compounds has gained much attention over the years in many industrial and environmental fields; particular commercial interest is the potential use of these enzymes to decolorize a wide range of synthetics dyes.12 The range of dyes, which can be decolorized by using laccase, may be expanded by additionally applying defined mediators. Mediators are low molecular weight compounds that are easily oxidised by laccases producing very reactive radicals which attack more complex substrates before return to its original state.13-15 The present work was, therefore, aimed at using an ecofriendly laccase enzyme instead of the harmful reducing agents to obtain discharge printing on cotton fabrics coloured with different reactive dyes.
EL-THALOUTH et al.: ECOFRIENDLY DISCHARGE PRINTING ON COTTON FABRICS
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aforementioned three reactive dyes, using the recipe as given below:
2 Materials and Methods 2.1 Materials
Mill desized, bleached and mercerized cotton fabrics (130 g/m2), produced by Misr/ Helwan for Spinning and Weaving Company, was used. Three different reactive dyes (supplied from ICI, Egypt), namely Sunzol Brilliant Violet 5R (C.I. Reactive Violet 5) which is monoazo metal complex and its reactive center is vinylsulphone (Scheme 1); Sunzol Brilliant Blue BB (C.I. Reactive Blue 220) whose reactive center is vinylsulphone and chemical structure is based on formazan; and Sunzol Red BB (C.I. Reactive Red 21) which is a monoazo reactive dye and its reactive center is vinylsulphone also, were used. High viscosity sodium alginate from brown algae, manufactured by Fluka Chemical Company, was used as a thickening agent. Denilite IIS (a commercial product based on laccase enzyme), supplied by NovoNordisk Company, Denmark, was used.
Reactive dye Urea Sodium alginate Sodium carbonate Water ______ Total
: 30 g : 100 g : 30 g : 30 g :Yg _______ 1000 g
After printing, the samples were left in an oven for different intervals of time and at different temperatures. Finally, the printed fabrics were steamed at 101˚C for 5 min followed by washing. 2.2.3 Washing
The printed fabrics were washed with running water followed by hot water. After the washing, the fabrics were again washed with soap (2g/L non-ionic detergent, namely Aspkon 1030) at 90-95˚C for 5 min, rinsed with hot water followed by cold water and finally air dried.
2.2 Methods 2.2.4 Test Methods
2.2.1 Bioprinting of Cotton Fabric
The cotton samples were first printed with a printing paste containing the thickening agent and the enzyme only (white paste), using the recipe as shown below: Enzyme
: 50,100,120,140,160,180, 200, 220 or 240 g/kg Sodium alginate : 30 g Water :Yg _______ ______ Total 1000 g The printed cotton fabrics were allowed to dry at ambient conditions. 2.2.2 Over Printing of Cotton Samples
The bioprinted cotton samples were then over printed with printing pastes containing one of the Cu MeO HO3SOCH2CH2O2S
OH N
NHCOCH3
N
HO3S
Scheme 1 — Chemical structure of C.I. Reactive Violet 5
SO3H
The colour strength (K/S) of the printed samples was evaluated by light reflectance technique.16 The tensile strength test was carried out according to the ASTM standard test method D-1682-1924 on a tensile strength apparatus FMCW 500 (Veb Thuringer Industries Work Rauenstein 11/2612 German) at 25±2ºC and 60±2% relative humidity.17 The rheological properties of the printing pastes were measured using rotary viscometer (Rheomat-15, Zürich, Switzerland). The apparent viscosity (η) was calculated from the shearing stress (τ) in dynes/cm2 and rate of shear (D) in s−1 according to the following equation: η(poise) = τ /D 3 Results and Discussion The laccase enzyme has been used instead of conventional reducing agents, viz. rongalite, which is harmful to the environments under a variety of conditions. The effect of enzyme concentration, pH, treatment time and treatment temperature as well as the viscosity of the printing pastes and their rheological properties on colour discharge performance has been studied.
INDIAN J. FIBRE TEXT. RES., MARCH 2008
54 3.1 Effect of Enzyme Concentration
To study the effect of commercial laccase formula concentrate, a series of white printing pastes containing only the thickening agent and different enzyme concentrations (50, 100, 120, 140, 160, 180, 200, 220 or 240 g/kg) was prepared as per the recipe mentioned in section 2.2.1, maintaining the pH at 4.5. The cotton fabrics were then printed with these pastes using screen printing technique. Another sample was printed in the absence of enzyme for comparison. After air drying, the printed fabrics were over printed with coloured printing pastes. The latter was prepared according to the recipe mentioned section 2.2.3 for different reactive dyes, namely Sunzol Brilliant Violet 5R, Sunzol Brilliant Blue BB or Sunzol Red BB. After over printing, the samples were kept in a laboratory oven at 60ºC for 1 h followed by fixation via steaming at 101˚C for 5 min. Finally, the samples were washed according to the procedure mentioned earlier followed by drying at ambient conditions and assessed for K/S values (Table 1). It is clear from Table 1 that regardless of the nature of the reactive dyes used the K/S decreases as the concentration of enzyme in the white paste increases. However, the decrease in K/S by increasing the concentration of the enzyme is irregular. The optimum condition for colour discharge, i.e. the lowest K/S, was found to be dependent on the nature of the reactive dye used. The lowest K/S values are observed at the enzyme concentrations of 220g, 200g and 180 g/kg for Sunzol Red BB, Sunzol Brilliant Blue BB and Sunzol Brilliant Violet 5R respectively. The maximum per cent decrease in the colour strength of the three aforementioned printing pastes is 98.9%, 99 % and 96.8 % respectively. The printed samples show clear net prints.
The variation in amount of enzyme to obtain the lowest K/S on using the reactive dyes may be due to the difference in the chemical structure, reactivity, structural configuration, hydrogen bonding and substituent of the three reactive dyes. 3.2 Effect of pH
It has been reported that most enzymatic activities are extremely sensitive to the pH.18 Therefore, the effect of pH on the activity of laccase enzyme in discharge of the colour has been studied. Different printing pastes containing the reactive dyes as well as laccase enzyme with optimum concentration which gives the lowest K/S, as mentioned in section 3.1, were prepared. The pH values of the pastes were adjusted at 3.5, 4.5, 5.5, 6.5 and 7.5 and the prepared pastes were applied to cotton fabrics. Table 2 shows the maximum decrease in colour strength at pH 4.5, regardless of the nature of the dyestuff used and the highest activity of laccase enzyme. The current data reveals that the laccase enzyme has its optimum activity at pH 4.5. Enzymes, being proteins, exhibit zwitter ion properties. The proton donating or proton accepting groups in enzyme catalytic sites are at their required state of ionization at a selected pH, showing the enzyme its optimal activity. Any increase or decrease in pH results in lowered reaction rates. A variation of pH during the course of reaction may bring about an alteration of the protein structure with a denaturing effect on the enzyme or the ionisation of the active site.18 3.3 Effect of Temperature
It has been reported that the enzymes exhibit maximum activity at a specific range of temperature.18
Table 1 — Effect of enzyme concentration on the colour discharging of the printed cotton fabrics Concentration of enzyme g/kg 0(untreated fabric) 50 100 120 140 160 180 200 220 240
Sunzol Red BB K/S % decrease in K/S 6.84 1.00 0.36 0.44 0.31 0.28 0.198 0.93 0.07 0.19
85.3 94.7 93.5 95.5 95.9 97.1 86.4 98.9 97.2
Sunzol Brilliant Blue BB K/S % decrease in K/S 6.39 0.49 1.25 1.08 0.25 0.22 0.15 0.06 0.17 0.20
92.3 80.4 83 96 96.6 97.7 99 97.3 96.9
Sunzol Brilliant Violet 5R K/S % decrease in K/S 3.77 0.39 0.27 0.21 0.22 0.22 0.12 0.22 0.25 0.144
89.6 92.8 94.19 94.2 94.2 96.8 94.2 93.4 96.3
EL-THALOUTH et al.: ECOFRIENDLY DISCHARGE PRINTING ON COTTON FABRICS
Hence, it is of great interest to investigate the effect of drying temperature on the reactive dye colour discharge by laccase enzyme. To achieve this goal, cotton fabric samples were printed with white pastes containing the aforementioned enzyme followed by over printing with the reactive dye printing pastes. After printing, the samples were subjected to drying at different temperatures, such as 30, 40, 50, 60 or 70˚C. Finally, the goods were washed according to the procedure mentioned earlier. It is observed from Table 3 that as the drying temperature increases from 30°C to 60˚C the K/S value decreases from 0.31 to 0.07, from 0.25 to 0.06, and from 0.24 to 0.12 for Sunzol Red BB, Sunzol Brilliant Blue BB and Sunzol Brilliant Violet 5R respectively. Further increase in the drying temperature shows an increase in K/S value. The decrease in K/S by increasing the drying temperature from 30°C to 60°C may be due to the increase in activity of enzyme because of the increased possibilities of its molecule coming closer to the substrate molecule. Increasing the temperature beyond 60°C may affect reversibly the activity of the enzyme. 3.4 Effect of Enzymatic Treatment Time
It has been reported19 that in the initial period of time the amount of substrate which has been transformed is directly proportional to the length of treatment time. After this initial period, the rate of reaction starts decreasing and the amount of reaction is no longer directly proportional to the treatment
time. Provided the substrate is present in excess, the explanation of this phenomenon is the progressive loss of enzyme activity after a period of time. This may be due to the effect of heat on the tertiary structure of the enzyme or due to the formation of some product or side product of the reaction which inhibits the enzyme. Therefore, the printed cotton samples were subjected to a drying process for various intervals of time in order to determine the optimum time available for attaining maximum colour removal. The treatment was carried out at 60ºC for 20, 40, 60, 80,100,120,140 and 160 min, followed by steaming at 101ºC for 5 min, washing and drying. Finally, the printed samples were assessed for K/S. Table 4 shows that the colour removal increases regularly by increasing the treatment time until it reaches its maximum at 60 min. Increasing the drying time beyond 60 min causes a slight increase in the K/S which remains almost constant on further increase in treatment time. This may be due to the progressive loss of enzyme activity as previously mentioned.19 3.5 Influence of Viscosity and Rheological Properties
The rheological properties of the printing pastes and their viscosity control dye penetration, depth of the shade, sharpness of the print and levelness. It is, therefore, of interest to investigate the effect of the rheological properties of the white pastes which contains the enzyme at a concentration of 200g/kg printing paste. Hence, different printing pastes containing different concentrations of sodium
Table 2 — Effect of pH on K/S of printed fabrics pH of printing paste
3.5 4.5 5.5 6.5 7.5
Sunzol Red BB K/S % decrease in K/S 0.5 92.69 0.07 98.99 0.243 96.4 0.9 86.8 1.7 75
Sunzol Brilliant Blue BB K/S % decrease in K/S 0.238 96.28 0.06 99 0.197 96.92 1.08 83.1 3.56 44.3
Sunzol Brilliant Violet 5R K/S % decrease in K/S 0.37 90.19 0.12 96.8 0.488 87.1 0.7 81.4 2.56 34.5
Table 3 — Effect of drying temperature on K/S of the printed samples Temperature °C 30 40 50 60 70
Sunzol Red BB K/S % decrease in K/S 0.31 0.27 0.3 0.07 1.2
95.5 96 95.6 98.99 82.4
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Sunzol Brilliant Blue BB K/S % decrease in K/S 0.25 0.21 0.3 0.06 0.3
96.1 96.7 90 99 95.3
Sunzol Brilliant Violet 5R K/S % decrease in K/S 0.244 0.2 0.23 0.12 0.26
93.5 94.7 92.8 96.8 93.1
INDIAN J. FIBRE TEXT. RES., MARCH 2008
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Table 4 — Effect of drying time on K/S of the printed samples Time of treatment min 20 40 60 80 100 120 140 160
Sunzol Red BB K/S % decrease in K/S 0.57 0.169 0.07 0.14 0.15 0.176 0.126 0.19
Sunzol Brilliant Blue BB K/S % decrease in K/S
91.7 97.5 98.99 98 97.8 97.4 98.2 97.2
0.22 0.17 0.06 0.16 0.2 0.22 0.22 0.19
96.6 97.3 99 97.5 96.9 96.6 96.6 97
Sunzol Brilliant Violet 5R K/S % decrease in K/S 0.24 0.22 0.12 0.22 0.23 0.24 0.25 0.26
93.6 94.2 96.8 94.2 93.9 93.7 93.4 93.1
Table 5 — Effect of apparent viscosity on % decrease in K/S Alginate in printing paste %
Apparent viscosity at a shear rate of 30.38-31.61 s−1 poise
2 2.5 3 3.5 4 4.5
40.43 61.105 90.4 109.77 122.68 490.71
Sunzol Red BB K/S % decrease in K/S 0.566 0.32 0.07 0.14 0.33 0.486
94.6 95.3 98.99 97.9 97.2 96.8
Sunzol Brilliant Blue BB K/S % decrease in K/S 0.275 0.207 0.06 0.16 0.17 0.193
95.6 96.7 99 97.5 97.3 96.9
Sunzol Brilliant Violet 5R K/S % decrease in K/S 0.24 0.21 0.12 0.18 0.19 0.2
93.6 94.5 96.8 95.2 95 94.6
nature of the dyestuff used. Further increase in the apparent viscosity shows a reduction in the % decrease in the K/S. It can be concluded that the maximum discharging action could be obtained on using 3% sodium alginate which gives an apparent viscosity of 90.4 poise at a shear rate of 31.61 s−1.
Fig. 1 — Rheograms of different concentrations of soduim alginate
alginate, viz. 2, 2.5, 3, 3.5, 4, 4.5% have been prepared, and their rheological properties and apparent viscosity measured on Rheomat-15. The results reveal that all the pastes are characterized by non-Newtonian pseudoplastic behaviour, and their apparent viscosity increases by increasing the concentration of sodium alginate in the paste as it is clear from Fig. 1 and Table 5. It is clear from the data that as the apparent viscosity increases from 40.43 poise to 90.4 poise, the % decrease in the K/S increases, regardless of the
4 Conclusions Innovative technology of using laccase formulation has been used successfully in discharge printing of cotton fabrics dyed with different colours of reactive dyes . The optimum conditions for using laccase formulation are found to be 4.5 pH, 60°C temperature and 1h treatment time. The optimum viscosity of the printing paste is found to be 90.4 poise at a shear of 31.61s−1 while the concentration of enzyme depends on the nature of the dye used. References 1 Hardalov I, Colourage Annual, (1992) 61. 2 Gulrajani M L, Colourage, XL (9) (1993) 15. 3 Heine E & Hoecker H, in Smart Fibres, Fabrics and Clothing, edited by T Xiaoming (CRC Pr LIc Boca Raton) 2001, 254. 4 Kierulff J V, Text Horizons, October/ November (1997). 5 Vollmond T, BioTimes, 8 (1997) 4.
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14 Zille A, Ramalho P, Tzanov T, Millward R, Aires V, Cardoso M T, Ramalho M H, Guebitz G & Cavaco-Paulo A, Biotechnol Prog , 20 (5) (2004) 1588. 15 Almansa E, Kandelbauer A, Pereira L, Cavaco-Paulo A & Guebitz G, Biocatal Biotransform, 22 (5/6) (2004) 315. 16 Judd D B & Wyszecki G, Colour in Business,Science and Industry, 3rd edn (John Wiley and Sons , Cleveland, USA), 1975. 17 Statement Test Method, 1682 (American Society of Testing of Materials), 1994. 18 Shukla S R, Umesh Sharma & Kulkarni K S, Colourage, XLVII (2) (2000) 19. 19 Colin Wynn H, The Structure and Function of Enzymes (Edward Arnold, London), 1974.