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Bioscouring of jute fabric by cellulase-free alkalo-thermostable xylanase from Bacillus pumilus ASH
Journal of Molecular Catalysis B: Enzymatic 85–86 (2013) 43–48
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Bioscouring of jute fabric by cellulase-free alkalo-thermostable xylanase from Bacillus pumilus ASH Gaurav Garg a , Saurabh Sudha Dhiman b , Richa Gautam a , Ritu Mahajan a , Arun Kumar Patra c , Jitender Sharma a,∗ a
Department of Biotechnology, Kurukshetra University, Kurukshetra-136 119, India Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul 143-701, South Korea c Department of Textile Chemistry, The Technological Institute of Textile and Sciences (TIT&S), Bhiwani-127 021, India b
a r t i c l e
i n f o
Article history: Received 10 May 2012 Received in revised form 2 August 2012 Accepted 2 August 2012 Available online 10 August 2012 Keywords: Xylanase Bioscouring Bleaching Brightness Yellowness
a b s t r a c t Alkalo-thermostable xylanase from Bacillus pumilus ASH has been evaluated for bioscouring of jute fabric. An enzyme dose of 5 IU/g of oven dried jute fabric resulted in release of more reducing sugar and weight loss as compared to control when incubated at 55 ◦ C. An incubation time of 120 min was sufficient to increase the whiteness and brightness of fabric up to 3.93 and 10.19% respectively and also decreased the yellowness by 5.57%. Addition of chelating and wetting agent greatly enhanced the fabric properties. Bioscouring of jute fabric with xylanase enzyme along with EDTA and Tween-20 resulted in an increase of 9.63, 4.28 and 10.71% of reducing sugars, whiteness and brightness respectively as compared to conventional process. Bleaching of bioscoured jute fabric, further improved the various properties like tenacity, brightness, yellowness and whiteness. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Jute is amongst the oldest lignocellulosic bast fibrous crops in the world. Jute is natural biodegradable, long fiber and typically golden in color that has many advantages like high tensile strength, good thermal conductivity etc. [1,2]. It constitutes second most common cellulosic fiber in the world after cotton. Jute fiber is composed mainly of cellulose (58–63%), hemicelluloses (20–24%), lignin (12–14%), waxes (0.4–0.8%), pectin (0.2–0.5%), protein (0.8–1.5%), mineral matter (0.6–1.2%) and traces of tannin and coloring matters [3,4]. The xylan portion of the jute can be removed by the use of xylanase enzyme which makes the jute softer and improves its various properties. Natural fibers like ramie, flax, hemp, cotton etc. are being used in textiles, but due to the coarse nature of jute fiber, it is used chiefly for packing material i.e. to make cloth for wrapping bales of raw cotton, and to make sacks and coarse cloth. So taking into account the shortage and cost of other natural fibers, an attempt has been made to decrease the coarseness and to improve various properties of the jute through scouring process. Scouring removes the non-cellulosic material from the fabric to make it softer and finer but some
∗ Corresponding author. Tel.: +91 1744 239239; fax: +91 1744 238277. E-mail address: [email protected] (J. Sharma). 1381-1177/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.molcatb.2012.08.002
amount of non cellulosic material must be retained so that the fiber must have enough tenacity and length [5–7]. The existing chemical scouring process makes the fabric finer and softer but reduces its various properties like tenacity, brightness and whiteness. In addition to this, use of chemicals also causes the environmental pollution. Concentrated alkaline solutions of scouring process not only cause threat to the environment but also attack non-specifically on cellulosic portion of the fiber leading to weight and strength loss. In comparison to chemical process, bioscouring is an alternative and more environmental friendly process in removing the noncellulosic impurities from the raw jute to make the surface softer [8]. Different combinations of commercially produced enzymes like pectinase, xylanase and laccases have been used to evaluate their effect on jute fabric [9–11]. But the reports on the use of crude enzymes isolated from microbial sources for the treatment of jute fabric are very few [12,13]. Also, in contrast to drastic alkaline conditions conventionally used treatment with xylan degrading enzymes would not affect the cellulose backbone and thus avoid fiber damage [14]. In this study, an attempt has been made to evaluate the effect of cellulase-free alkalo-thermostable xylanase from Bacillus pumilus ASH by optimizing different independent variables, on various jute properties through bioscouring process. Bioscouring has been compared with chemical scouring in order to check the effectiveness of bioscouring process. Further the bleach boosting effect of xylanase
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has been assessed in terms of improvement in various jute properties. 2. Materials and methods 2.1. Microorganism The bacterial strain used in the present investigation was isolated from sanitary landfill and identified as B. pumilus ASH by the Institute of Microbial Technology (IMTECH), Chandigarh, India on the basis of its morphological, physiological and biochemical characterization. It has been given MTCC Accession No.7411. The culture was maintained and stored at 4 ◦ C on nutrient agar medium. 2.2. Enzyme production The enzyme production was studied in Erlenmeyer flask (250 mL) containing 50 mL of basal medium having (g/L): yeast extract, 5.0; MgSO4 ·7H2 O, 0.2; KH2 PO4 , 1.0 supplemented with wheat bran, 5.0 and peptone, 5.0; pH 8.0. The flasks were inoculated with 2% (O.D. ∼ 0.5) of the overnight grown inoculum and incubated at 37 ◦ C under shaking conditions (200 rpm). The enzyme was harvested by centrifuging at 10,000 × g for 15 min [15]. 2.3. Xylanase assay Xylanase activity was assayed according to the method of Bailey et al. [16] by using 1% birchwood xylan (Sigma–Aldrich, USA) dissolved in 0.1 M sodium phosphate buffer (pH 7.0). The enzymatic reaction was carried out at 60 ◦ C for 10 min. The enzyme activity was determined by estimating the amount of reducing sugars released during the enzyme substrate reaction using Miller’s method [17]. One unit (IU) of xylanase activity is defined as the amount of enzyme that catalyzes the release of 1 mol of reducing sugar equivalent to xylose per min under the specified assay conditions. Similarly assay for cellulase was carried out using CM – cellulose and cellulose as substrate. 2.4. Pretreatment of raw jute Greige jute – plain weave, epi (ends per inch) × ppi (picks per inch) – 16 × 16, GSM (g/m2 ) – 250 was used in the investigation. Fabric was washed with distilled water for 30 min (at ambient temperature) in order to extract water soluble constituents followed by drying in oven at 50 ◦ C till constant weight was obtained. This oven dried fabric was used for further studies. All the experiments were performed in triplicate and the standard deviation was calculated on the mean value. 2.5. Bioscouring of jute fabric 2.5.1. Optimization of different variables Optimization of different independent variables for treatment of jute fabric was carried out at moisture ratio of 1:30. For the optimization of different reaction parameters such as pH, buffer molarity, enzyme dose, temperature, retention time and rpm, 2 g of washed oven dried jute fabric was taken in dry flask. Experiments were conducted over a broad range of buffers pH 6.5–9.0 and different buffer molarity from 10 to 100 mM of optimized pH. Enzyme dose was varied ranging from 1 to 12.5 IU/g oven dried fabric. Optimization of retention time and temperature was carried out by treating the moistened jute fabric at different retention time ranging from 20 to 160 min at temperatures varying from 40 to 65 ◦ C. The jute fabric was treated at static as well as under shaking conditions (50–80 rpm). To determine the effectiveness of different treatment processes, the supernatant obtained after treatment was
used for the determination of reducing sugars and the jute fabric was washed in tap water, rinsed with distilled water and dried in an oven at 50 ◦ C for 24 h for determination of its different properties viz. brightness, whiteness, yellowness, and weight loss.
2.5.2. Optimization of chelating agent Ethylene diamine tetra acetate (EDTA) was used as chelating agent. The concentration of chelating agents was varied between 0.5 and 25 mM in combination with enzyme. To determine the effect of different concentrations of EDTA, the effluent after the treatment was used for the determination of reducing sugars and the jute fabric was washed in tap water, rinsed with distilled water and dried in an oven at 50 ◦ C for 24 h for determination of its different properties viz. brightness, whiteness, yellowness, and weight loss.
2.5.3. Optimization of wetting agent Different wetting agents like lissapol D, triton X-100 and Tween-20 were used to evaluate their effect on jute properties in combination with enzyme. The optimization of wetting agent concentration was performed at the conditions optimized for the enzyme treatment. For the optimization, the concentration of different wetting agents was varied between 0.1 and 2.0% (v/v). The effect of different wetting agents and their concentrations was determined in the same way as mentioned above for chelating agent in addition to wettability drop test.
2.6. Scouring of jute fabric Chemical treatment of fabric was carried out by method of Sharma [18] and Chattopadhyay et al. [19] with some modifications. For chemical treatment, jute sample 2 g was dipped in 0.6% (w/v) NaOH at 1:30 fabric to liquor ratio with 0.1% (v/v) wetting agent i.e. Tween 20. The scouring was done at 95 ◦ C for 60 min. After the treatment, the effluent was used for the determination of reducing sugars and the jute fabric was washed in tap water, followed by rinsing in distilled water and then subjected to oven drying at 50 ◦ C for 24 h. The dried fabric was further analyzed for its different properties. At the optimized conditions of bioscouring, different sets of experiments were performed to evaluate the effect of each component individually as well as in combination on removing non-cellulosic impurities and water absorbency property of the fabric. Ten sets of treatment were applied on the fabric: (a) buffer only, (b) buffer and enzyme, (c) buffer and chelating agent, (d) buffer, chelating agent and enzyme, (e) buffer and wetting agent, (f) buffer, wetting agent and enzyme, (g) buffer, wetting agent and chelating agent, (h) buffer, wetting agent, chelating agent and enzyme, (i) chemical control and (j) chemical treatment.
2.7. Bleaching The enzyme control, xylanase treated, chemical control and chemically treated jute fabric were subjected to bleaching chemicals such as hydrogen peroxide (H2 O2 ) 5 g/L, sodium silicate 2.5 g/L, EDTA 1 mM, soda ash (Na2 CO3 ) 1 g/L. The fabric to liquor ratio for effective bleaching process was 1:100 at pH 10.5 [20]. The jute fabric for bleaching was incubated in water bath at 85 ◦ C for 90 min. After bleaching, the fabric was thoroughly washed in tap water, followed by rinsing in distilled water and dried in an oven at 50 ◦ C for 24 h. The dried fabric was further used for the determination of various fabric properties like brightness, whiteness, yellowness and tenacity.
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2.8. Evaluation of fabric properties 2.8.1. Reducing sugars Reducing sugars was measured by a Dinitro salicylic acid reagent [17] after each treatment. The supernatant obtained after the treatment was used for the determination of reducing sugar. The reducing sugars were measured in mg/g. 2.8.2. Wettability drop test Wettability of the fabric was measured by means of the drop test before and after the scouring process to check the bioscouring efficiency for subsequent finishing treatments. Water absorbency was evaluated according to an AATCC (American Association of Textile Chemists and Colourists) Test method 39-1980 evaluation of wettability [21] at room temperature. The time between the contact of water drop with the fabric and the disappearance of the water drop into the fabric was counted as the wetting time. Average values of three determinations were taken. Wetting time of less than 1 s is considered as an indicator of adequate water absorption efficiency of the fabric [8,22]. 2.8.3. Weight loss (%) The weight loss of jute fabric after treatment was assessed by using gravimetric approach. The oven dried fabric sample was weighed before and after the treatment and the weight loss was calculated according to the following relationship: weight loss (%) =
W1 − W2 × 100 W1
where, W1 and W2 are the weights of oven dried fabric before and after the treatment respectively [10]. 2.8.4. Whiteness index, yellowness index and brightness index The whiteness index [23], yellowness index [24] and brightness [25] of the samples were measured after treatment using a Macbeth Color-Eye® spectrophotometer. 2.8.5. Tenacity The tenacity of the samples was measured after bleaching using the Goodbrand tensile strength tester in lbs (pounds). 3. Results and discussion In order to explore the potential of cellulase-free xylanase produced by B. pumilus ASH in textile industry, various factors like buffer pH, molarity of buffer, enzyme dose, temperature, time period, rpm, chelating and wetting agent dose, etc. were tested in order to choose the best condition for the effective bioscouring of jute fabric. The detailed properties of the jute were studied to determine the effect of xylanase treatment. Different ranges of buffer pH and molarity were tested to find the best condition at which enzyme shows the maximum activity. Phosphate buffer of pH 7.5 and molarity 75 mM was found to be the optimum for the treatment of jute fabric with xylanase (Tables 1 and 2). The molarity of buffer has strong effect on enzyme activity as ionic strength of buffer system differs considerably at any one molarity and pH. Increase in xylanase activity with increase in molarity with maximum activity at 100 mM sodium phosphate buffer (pH 7.0) has been reported by Sharma et al. [26]. Maximum bioscouring efficiency was observed at an enzyme dose of 5 IU/g of oven dried fabric (Table 3) whereas enzyme dose of 4% was reported by Vigneswaran and Jayapriya [11]. Further increase in enzyme dose has no significant effect on bioscouring efficiency. Xylanase enzyme showed the best result when the jute fabric was incubated at 55 ◦ C for 120 min as shown in Tables 4 and 5. Samanta et al. reported that brighter jute fiber was obtained at 4% of mixed enzyme when incubated at 55 ◦ C
45
for 120 min at pH 4.8 [27]. Agitation at slow speed of 60 rpm was found to be the best in comparison with static condition (Table 6). Reducing sugars of 2.09 mg/g of dry jute fabric were obtained after optimized condition where as 0.55 mg/mL of reducing sugars were reported when combination of xylanase, cellulase and pectinase was used in case of jute/cotton blended fabric [28]. Any variation in the optimized condition resulted in deterioration in fabric properties. For the optimization of chelating agent and wetting agent, the fabric was treated with their different concentrations in the presence of enzyme at the conditions optimized for enzyme treatment. A concentration of 1.0 mM of EDTA gave the best results when applied in combination with enzyme as shown in Table 7. Among the various wetting agents, Tween-20 at the concentration of 0.5% (v/v) was found to be the best for the effective bioscouring (Table 8). Jute fabric was subjected to ten different treatments conditions as shown in Table 9. Addition of enzyme to buffer resulted in an increase of 3.93 and 10.19% in whiteness and brightness respectively and a decrease of 5.57% in yellowness in comparison to buffer only (Table 9). Improvement in whiteness is mainly due to the delignification of the jute fabric which results in the uniform surface of the fabric because of enzymatic hydrolysis (Vigneswaran and Jayapriya [11]). As reported by Vigneswaran and Jayapriya, the brightness of mixed enzyme treated (xylanase, cellulase and pectinase) jute fabric was more in comparison to the raw jute [11]. Addition of EDTA further to buffer and enzyme solution resulted in an increase in brightness and whiteness. Addition of EDTA facilitates the removal of water extractable impurities and calcium ions from the region that connect the macromolecule in pectin to one another or pectin to other polysaccharides [29]. Similarly, Csiszar et al. reported that EDTA markedly enhanced the apparent activity of commercial xylanases and pectinases in cotton bioscouring, accelerating the degradation and removal of impurities [30]. The result is in contradiction to the results of Losonczi et al. who demonstrated that application of EDTA in different concentration neither inhibited nor increased the activities of xylanase in pure xylanase preparation [31]. Wetting agent in combination with enzyme resulted in an increase of 5 and 13.61% in whiteness and brightness respectively (Table 9). Wetting agent reduces the surface tension of water thereby enabling in the better penetration of enzyme to the jute fabrics. Maximum bioscouring was obtained when buffer in combination with enzyme, wetting agent and chelating agent was used. It resulted in 4.19 and 12.52% increase in whiteness and brightness compared to buffer in combination of wetting agent and chelating agent respectively. Chemical treatment of jute fabric resulted in 9.96 and 30.97% decrease in whiteness and brightness respectively as compared to control. Whereas for bioscouring the decrease was 15.56 and 42.12% for whiteness and brightness respectively compared to chemical scouring. Similarly a decrease in whiteness and brightness of chemically scoured jute had been reported earlier [19,27]. The wetting time of the bioscoured fabric was lower to that of chemically scoured fabric which indicates the suitability of enzyme in the scouring process. The maximum reducing sugars released were 2.39 mg/g of oven dried jute when treated with enzyme, wetting agent and chelating agent whereas chemical treatment resulted in release of 2.18 mg/g of reducing sugars as shown in Fig. 1. Maximum weight loss was observed in chemical treatment process in comparison to all other treatment processes (Fig. 2). 3.1. Bleaching of jute fabric After treatment, controls, enzyme treated and chemical treated jute fabric were subsequently bleached. Bioscouring of jute fabric resulted in an improvement of various physical properties of jute fabric after bleaching. Whiteness and brightness of enzyme treated bleached fabric increased 10.96 and 15.64% respectively compared
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Table 1 Effect of different buffer pH on fabric properties. pH
Buffer
Reducing sugar (mg/g)
DW 6.5 7.0 7.5 8.0 8.5 8.5 9.0
– Phosphate Phosphate Phosphate Phosphate Phosphate Glycine NaOH Glycine NaOH
1.59 1.66 1.77 1.97 1.80 1.70 1.77 1.68
± ± ± ± ± ± ± ±
Weight loss (%)
0.06 0.07 0.06 0.10 0.09 0.05 0.04 0.16
0.78 0.79 0.85 0.92 0.89 0.86 0.84 0.82
± ± ± ± ± ± ± ±
0.02 0.04 0.03 0.02 0.03 0.01 0.02 0.01
Whiteness (hunter) 44.07 44.51 44.77 45.09 44.71 44.56 44.36 44.29
± ± ± ± ± ± ± ±
0.15 0.20 0.10 0.06 0.05 0.12 0.10 0.09
Yellowness (ASTM-E-313) ± ± ± ± ± ± ± ±
40.53 40.39 39.61 38.83 38.96 39.13 39.67 40.26
0.13 0.12 0.11 0.11 0.10 0.13 0.15 0.22
Brightness (ISO 2470) 15.09 15.49 15.70 15.97 15.68 15.61 15.39 15.28
± ± ± ± ± ± ± ±
0.15 0.16 0.13 0.14 0.07 0.05 0.11 0.10
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at retention time of 120 min, at 55 ◦ C at 100 mM buffer molarity. Table 2 Effect of different buffer molarity on fabric properties. Buffer (mM)
Reducing sugar (mg/g)
10 25 50 75 100
1.76 1.81 1.91 1.99 1.91
± ± ± ± ±
0.04 0.02 0.06 0.05 0.05
Weight loss (%) 0.80 0.86 0.90 0.98 0.91
± ± ± ± ±
Whiteness (hunter)
0.02 0.04 0.03 0.04 0.02
44.63 45.16 44.88 45.25 45.05
± ± ± ± ±
0.23 0.15 0.21 0.14 0.15
Yellowness (ASTM-E-313) 40.00 39.66 39.31 38.64 38.97
± ± ± ± ±
0.21 0.15 0.19 0.09 0.14
Brightness (ISO2470) 15.49 15.91 15.75 16.06 15.79
± ± ± ± ±
0.12 0.09 0.15 0.18 0.11
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at retention time of 120 min, at 55 ◦ C at buffer of pH 7.5. Table 3 Effect of different enzyme dose on fabric properties. Enzyme dose (IU/g)
Reducing sugar (mg/g)
0 1 2.5 5.0 7.5 10.0 12.5
1.05 1.56 1.84 1.99 1.98 1.96 1.96
± ± ± ± ± ± ±
Weight loss (%)
0.06 0.08 0.10 0.05 0.05 0.03 0.01
0.60 0.79 0.87 0.99 0.95 0.91 0.85
± ± ± ± ± ± ±
0.03 0.06 0.04 0.03 0.03 0.02 0.03
Whiteness (hunter) 43.70 44.08 44.79 45.17 45.09 45.08 44.92
± ± ± ± ± ± ±
0.16 0.14 0.17 0.11 0.09 0.03 0.12
Yellowness (ASTM-E-313) 40.91 39.94 39.74 38.86 38.92 38.53 39.19
± ± ± ± ± ± ±
0.15 0.13 0.10 0.16 0.19 0.11 0.14
Brightness (ISO2470) 14.78 15.15 15.52 15.98 15.20 16.25 15.06
± ± ± ± ± ± ±
0.12 0.13 0.08 0.15 0.20 0.16 0.13
All the experiments were performed at retention time of 120 min, at 55 ◦ C at buffer pH 7.5 of molarity 75 mM. Table 4 Effect of different incubation temperature on fabric properties. Incubation temperature (◦ C)
Reducing sugar (mg/g)
40 45 50 55 60 65
1.62 1.78 1.96 2.01 1.77 1.65
± ± ± ± ± ±
Weight loss (%)
0.02 0.09 0.10 0.05 0.09 0.07
0.87 0.89 0.96 1.06 0.95 0.89
± ± ± ± ± ±
0.02 0.06 0.04 0.07 0.04 0.08
Whiteness (hunter) 44.15 44.24 44.90 45.22 44.99 44.26
± ± ± ± ± ±
0.09 0.11 0.16 0.15 0.13 0.14
Yellowness (ASTM-E-313) 40.15 40.05 39.69 38.80 38.92 39.24
± ± ± ± ± ±
0.08 0.11 0.16 0.09 0.11 0.19
Brightness (ISO2470) 14.89 15.20 15.72 16.10 15.95 15.40
± ± ± ± ± ±
0.23 0.15 0.11 0.12 0.16 0.13
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at retention time of 120 min, at buffer pH 7.5 of molarity 75 mM. Table 5 Effect of different incubation time on fabric properties. Incubation time (min)
Reducing sugar (mg/g)
20 40 60 80 100 120 140 160
1.51 1.78 1.94 1.96 2.00 2.01 1.97 1.90
± ± ± ± ± ± ± ±
0.09 0.09 0.03 0.06 0.05 0.03 0.04 0.03
Weight loss (%) 0.87 0.95 1.01 1.03 1.04 1.06 0.97 0.92
± ± ± ± ± ± ± ±
0.10 0.06 0.05 0.04 0.02 0.03 0.04 0.02
Whiteness (hunter) 43.70 43.75 44.25 45.05 45.17 45.22 45.05 44.81
± ± ± ± ± ± ± ±
0.05 0.04 0.16 0.12 0.05 0.04 0.11 0.13
Yellowness (ASTM-E-313) 40.37 40.52 39.73 39.42 38.94 38.80 39.04 39.45
± ± ± ± ± ± ± ±
0.23 0.15 0.19 0.11 0.13 0.09 0.16 0.13
Brightness (ISO2470) 14.58 14.79 14.83 15.27 15.87 16.10 15.97 15.89
± ± ± ± ± ± ± ±
0.15 0.19 0.11 0.21 0.23 0.09 0.13 0.11
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM. Table 6 Effect of agitation on fabric properties. Agitation (rpm)
Reducing sugar (mg/g)
0 50 60 70 80
1.68 1.97 2.09 1.98 1.92
± ± ± ± ±
0.06 0.11 009 0.12 0.06
Weight loss (%) 0.89 1.08 1.20 1.04 0.95
± ± ± ± ±
0.09 0.05 0.03 0.08 0.06
Whiteness (hunter) 43.07 43.92 45.23 45.20 45.14
± ± ± ± ±
0.18 0.21 0.17 0.11 0.16
Yellowness (ASTM-E-313) 40.44 40.27 38.65 39.00 39.53
± ± ± ± ±
0.14 0.15 0.16 0.17 0.11
Brightness (ISO 2470) 14.34 14.94 16.21 15.99 15.88
± ± ± ± ±
0.15 0.13 0.14 0.11 0.09
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min.
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Table 7 Effect of different concentration of chelating agent (EDTA) on fabric properties. EDTA (mM)
Reducing sugar (mg/g)
0 0.5 1.0 2.5 5.0 10.0 15.0 20.0 25.0
2.09 2.21 2.24 2.22 2.19 2.15 2.15 2.13 2.11
± ± ± ± ± ± ± ± ±
Weight loss (%)
0.06 0.11 0.05 0.06 0.04 0.05 0.08 0.03 0.03
1.22 1.48 1.54 1.50 1.49 1.45 1.37 1.34 1.25
± ± ± ± ± ± ± ± ±
0.10 0.05 0.04 0.03 0.02 0.04 0.03 0.02 0.08
Whiteness (hunter) 45.19 46.20 46.27 46.25 46.19 46.15 46.13 46.18 46.17
± ± ± ± ± ± ± ± ±
Yellowness (ASTM-E-313)
0.12 0.15 0.05 0.04 0.05 0.02 0.02 0.12 0.15
38.79 38.15 38.07 38.20 38.37 38.42 38.61 38.67 38.71
± ± ± ± ± ± ± ± ±
0.09 0.15 0.11 0.14 0.13 0.08 0.11 0.12 0.15
Brightness (ISO2470) 16.13 17.36 17.56 17.39 16.83 16.54 16.41 16.32 16.19
± ± ± ± ± ± ± ± ±
0.11 0.09 0.15 0.16 0.15 0.14 0.18 0.09 0.11
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min.
Table 8 Effect of different wetting agents on fabric properties. Wetting agent
Concentration (%, v/v)
Reducing sugar (mg/g)
Control Lissapol D Lissapol D Lissapol D Lissapol D Lissapol D Lissapol D Triton X-100 Triton X-100 Triton X-100 Triton X-100 Triton X-100 Triton X-100 Tween-20 Tween-20 Tween-20 Tween-20 Tween-20 Tween-20
– 0.1 0.25 0.5 1.0 1.5 2.0 0.1 0.25 0.5 1.0 1.5 2.0 0.1 0.25 0.5 1.0 1.5 2.0
2.09 2.11 2.12 2.14 2.16 2.19 2.17 2.12 2.16 2.18 2.16 2.16 2.15 2.15 2.20 2.22 2.20 2.17 2.15
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.02 0.03 0.02 0.03 0.01 0.05 0.03 0.06 0.04 0.01 0.03 0.02 0.03 0.01 0.04 0.03 0.02 0.04 0.02
Weight loss (%) 1.23 1.27 1.29 1.34 1.38 1.41 1.39 1.22 1.31 1.37 1.35 1.34 1.34 1.28 1.37 1.49 1.41 1.38 1.35
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.02 0.01 0.03 0.04 0.02 0.01 0.03 0.04 0.02 0.03 0.01 0.02 0.03 0.05 0.01 0.03 0.01 0.02 0.05
Water drop
Whiteness (hunter)
23 ± 1 5 ± 0.57 4±1 4 ± 0.57 3 ± 0.57 2±1 2 ± 0.57 2 ± 0.57 2±1 1 ± 0.57 <1 <1 <1 1 ± 0.57 1 ± 0.57 <1 <1 <1 <1
45.12 45.22 45.31 45.52 45.79 46.11 45.72 45.40 45.79 45.94 45.68 45.31 45.28 45.52 45.97 46.24 45.68 45.33 45.30
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
Yellowness (ASTM-E-313)
0.10 0.06 0.08 0.13 0.16 0.21 0.19 0.16 0.11 0.13 0.22 0.06 0.05 0.09 0.16 0.14 0.09 0.11 0.15
38.88 38.50 38.46 38.34 38.24 37.98 38.10 38.73 38.38 38.11 38.16 38.36 38.38 38.60 38.14 37.97 38.27 38.37 38.40
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.11 0.03 0.05 0.18 0.17 0.14 0.09 0.23 0.26 0.04 0.05 0.09 0.15 0.10 0.08 0.16 0.14 0.05 0.04
Brightness (ISO 2470) 15.97 16.00 16.22 16.24 16.63 16.78 16.73 16.04 16.27 16.52 16.45 16.28 16.26 16.27 16.57 17.27 16.80 16.61 16.57
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.05 0.07 0.15 0.03 0.13 0.04 0.05 0.17 0.19 0.05 0.07 0.03 0.02 0.16 0.14 0.15 0.21 0.18 0.16
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min.
Table 9 Effect of different treatment mode on fabric properties. S no.
Treatment mode
Water drop (s)
Whiteness (hunter)
A B C D E F G H I J
Buffer Buffer + enzyme Buffer + EDTA Buffer + enzyme + EDTA Buffer + Tween-20 Buffer + enzyme + Tween-20 Buffer + Tween-20 + EDTA Buffer + enzyme + EDTA + Tween-20 Control (chemical treatment) Chemical treatment
30 ± 2 26 ± 2 27 ± 3 24 ± 1 1 ± 0.57 <1 1 ± 0.57 <1 28 ± 1 2 ± 0.57
43.52 45.23 44.42 46.15 43.97 46.17 45.08 46.97 44.05 39.66
± ± ± ± ± ± ± ± ± ±
0.21 0.12 0.09 0.11 0.12 0.15 0.11 0.13 0.15 0.09
Yellowness (ASTM-E-313) 40.93 38.65 40.18 38.17 40.20 37.85 39.23 37.11 40.26 43.25
± ± ± ± ± ± ± ± ± ±
0.09 0.16 0.15 0.23 0.03 0.11 0.18 0.17 05 0.12
Brightness (ISO2470) 14.71 16.21 15.32 17.61 15.28 17.36 15.97 17.97 15.01 10.36
± ± ± ± ± ± ± ± ± ±
0.15 0.12 0.11 0.15 0.19 0.21 0.14 0.16 0.14 0.19
Enzymatic treatment was performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min. Tween-20 (0.5%, v/v), EDTA (1.0 mM).
with chemically treated bleached jute (Table 10). Enzyme treatment resulted in decrease in tenacity of the fabric as compared to control which is mainly due to the partial surface hydrolysis of fibers due to enzyme as reported by Vigneswaran and Jayapriya [11]. The decrease in tenacity is more in case of chemically treated fabric (7.5%) than enzyme treated fabric (2.7%) which may be due to
release or dissolution of different extent of hemicelluloses, waxes, fats and other impurities which give strength to the fabric [10]. Alkali pretreatment is mainly responsible for reduction in whiteness index after bleaching [32]. The enzyme treatment can be conducted before or after the bleaching process [33]. It has been reported that if enzyme treatment was given before bleaching, it
Table 10 Effect of different treatment on fabric properties after bleaching. Jute fabric sample
Whiteness (hunter)
Control Bioscoured (enzyme treated) Chemical control Scoured (chemical treated)
76.64 78.46 77.12 70.71
± ± ± ±
0.26 1.03 0.24 0.51
Yellowness (ASTM-E-313) 18.12 16.41 17.85 22.42
± ± ± ±
1.15 0.95 0.15 0.26
Brightness (ISO2470) 55.63 57.22 56.05 49.48
± ± ± ±
0.34 0.35 0.13 0.24
Tenacity (lbs) 73 71 72.5 67
± ± ± ±
1.5 0.57 0.21 0.51
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G. Garg et al. / Journal of Molecular Catalysis B: Enzymatic 85–86 (2013) 43–48
1.0 mM of EDTA as chelating and 0.5% Tween-20 as wetting agent imparts optimal improvement to the jute properties like whiteness, brightness and yellowness thereby making it finer, softer, cleaner and brighter than the chemical process. The approach described in the present work seems to be convincingly reproducible and environment friendly which can be easily adopted by the textile industry. Acknowledgement The authors gratefully acknowledge Kurukshetra University, Kurukshetra, India for providing laboratory facilities during the course of investigation.
Fig. 1. Effect of different pretreatment mode on reducing sugars (mg/g) in jute fabric.
Fig. 2. Effect of different pretreatment mode on weight loss (%) in jute fabric.
resulted in increase of whiteness index, whereas whiteness index decreased if enzyme treatment was done after bleaching of fabric which may be due to the back staining of the fabric [33]. Enzyme treatment before bleaching resulted in an increase in pore volume and increase in the amount of exposed lignin to the bleaching chemicals which might be responsible for enhancement of bleaching process [29]. As compared to chemical treatment, enzymatic treatment consumes less energy and gives cleaner technology with better fabric quality [34]. 4. Conclusions An attempt has been made to replace the harsh chemicals used during scouring of jute with xylanase enzyme produced from B. pumilus ASH which can specifically target the non-cellulosic impurities. Bioscouring is a cost effective and environment friendly process. It has been observed that the xylanase in combination with chelating and wetting agent is more effective for bioscouring process to remove hemicelluloses to make the fabric softer. Application of 5 IU/g enzyme dose at 55 ◦ C for 120 min at buffer pH of 7.5 with
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Journal of Molecular Catalysis B: Enzymatic journal homepage: www.elsevier.com/locate/molcatb
Bioscouring of jute fabric by cellulase-free alkalo-thermostable xylanase from Bacillus pumilus ASH Gaurav Garg a , Saurabh Sudha Dhiman b , Richa Gautam a , Ritu Mahajan a , Arun Kumar Patra c , Jitender Sharma a,∗ a
Department of Biotechnology, Kurukshetra University, Kurukshetra-136 119, India Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul 143-701, South Korea c Department of Textile Chemistry, The Technological Institute of Textile and Sciences (TIT&S), Bhiwani-127 021, India b
a r t i c l e
i n f o
Article history: Received 10 May 2012 Received in revised form 2 August 2012 Accepted 2 August 2012 Available online 10 August 2012 Keywords: Xylanase Bioscouring Bleaching Brightness Yellowness
a b s t r a c t Alkalo-thermostable xylanase from Bacillus pumilus ASH has been evaluated for bioscouring of jute fabric. An enzyme dose of 5 IU/g of oven dried jute fabric resulted in release of more reducing sugar and weight loss as compared to control when incubated at 55 ◦ C. An incubation time of 120 min was sufficient to increase the whiteness and brightness of fabric up to 3.93 and 10.19% respectively and also decreased the yellowness by 5.57%. Addition of chelating and wetting agent greatly enhanced the fabric properties. Bioscouring of jute fabric with xylanase enzyme along with EDTA and Tween-20 resulted in an increase of 9.63, 4.28 and 10.71% of reducing sugars, whiteness and brightness respectively as compared to conventional process. Bleaching of bioscoured jute fabric, further improved the various properties like tenacity, brightness, yellowness and whiteness. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Jute is amongst the oldest lignocellulosic bast fibrous crops in the world. Jute is natural biodegradable, long fiber and typically golden in color that has many advantages like high tensile strength, good thermal conductivity etc. [1,2]. It constitutes second most common cellulosic fiber in the world after cotton. Jute fiber is composed mainly of cellulose (58–63%), hemicelluloses (20–24%), lignin (12–14%), waxes (0.4–0.8%), pectin (0.2–0.5%), protein (0.8–1.5%), mineral matter (0.6–1.2%) and traces of tannin and coloring matters [3,4]. The xylan portion of the jute can be removed by the use of xylanase enzyme which makes the jute softer and improves its various properties. Natural fibers like ramie, flax, hemp, cotton etc. are being used in textiles, but due to the coarse nature of jute fiber, it is used chiefly for packing material i.e. to make cloth for wrapping bales of raw cotton, and to make sacks and coarse cloth. So taking into account the shortage and cost of other natural fibers, an attempt has been made to decrease the coarseness and to improve various properties of the jute through scouring process. Scouring removes the non-cellulosic material from the fabric to make it softer and finer but some
∗ Corresponding author. Tel.: +91 1744 239239; fax: +91 1744 238277. E-mail address: [email protected] (J. Sharma). 1381-1177/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.molcatb.2012.08.002
amount of non cellulosic material must be retained so that the fiber must have enough tenacity and length [5–7]. The existing chemical scouring process makes the fabric finer and softer but reduces its various properties like tenacity, brightness and whiteness. In addition to this, use of chemicals also causes the environmental pollution. Concentrated alkaline solutions of scouring process not only cause threat to the environment but also attack non-specifically on cellulosic portion of the fiber leading to weight and strength loss. In comparison to chemical process, bioscouring is an alternative and more environmental friendly process in removing the noncellulosic impurities from the raw jute to make the surface softer [8]. Different combinations of commercially produced enzymes like pectinase, xylanase and laccases have been used to evaluate their effect on jute fabric [9–11]. But the reports on the use of crude enzymes isolated from microbial sources for the treatment of jute fabric are very few [12,13]. Also, in contrast to drastic alkaline conditions conventionally used treatment with xylan degrading enzymes would not affect the cellulose backbone and thus avoid fiber damage [14]. In this study, an attempt has been made to evaluate the effect of cellulase-free alkalo-thermostable xylanase from Bacillus pumilus ASH by optimizing different independent variables, on various jute properties through bioscouring process. Bioscouring has been compared with chemical scouring in order to check the effectiveness of bioscouring process. Further the bleach boosting effect of xylanase
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has been assessed in terms of improvement in various jute properties. 2. Materials and methods 2.1. Microorganism The bacterial strain used in the present investigation was isolated from sanitary landfill and identified as B. pumilus ASH by the Institute of Microbial Technology (IMTECH), Chandigarh, India on the basis of its morphological, physiological and biochemical characterization. It has been given MTCC Accession No.7411. The culture was maintained and stored at 4 ◦ C on nutrient agar medium. 2.2. Enzyme production The enzyme production was studied in Erlenmeyer flask (250 mL) containing 50 mL of basal medium having (g/L): yeast extract, 5.0; MgSO4 ·7H2 O, 0.2; KH2 PO4 , 1.0 supplemented with wheat bran, 5.0 and peptone, 5.0; pH 8.0. The flasks were inoculated with 2% (O.D. ∼ 0.5) of the overnight grown inoculum and incubated at 37 ◦ C under shaking conditions (200 rpm). The enzyme was harvested by centrifuging at 10,000 × g for 15 min [15]. 2.3. Xylanase assay Xylanase activity was assayed according to the method of Bailey et al. [16] by using 1% birchwood xylan (Sigma–Aldrich, USA) dissolved in 0.1 M sodium phosphate buffer (pH 7.0). The enzymatic reaction was carried out at 60 ◦ C for 10 min. The enzyme activity was determined by estimating the amount of reducing sugars released during the enzyme substrate reaction using Miller’s method [17]. One unit (IU) of xylanase activity is defined as the amount of enzyme that catalyzes the release of 1 mol of reducing sugar equivalent to xylose per min under the specified assay conditions. Similarly assay for cellulase was carried out using CM – cellulose and cellulose as substrate. 2.4. Pretreatment of raw jute Greige jute – plain weave, epi (ends per inch) × ppi (picks per inch) – 16 × 16, GSM (g/m2 ) – 250 was used in the investigation. Fabric was washed with distilled water for 30 min (at ambient temperature) in order to extract water soluble constituents followed by drying in oven at 50 ◦ C till constant weight was obtained. This oven dried fabric was used for further studies. All the experiments were performed in triplicate and the standard deviation was calculated on the mean value. 2.5. Bioscouring of jute fabric 2.5.1. Optimization of different variables Optimization of different independent variables for treatment of jute fabric was carried out at moisture ratio of 1:30. For the optimization of different reaction parameters such as pH, buffer molarity, enzyme dose, temperature, retention time and rpm, 2 g of washed oven dried jute fabric was taken in dry flask. Experiments were conducted over a broad range of buffers pH 6.5–9.0 and different buffer molarity from 10 to 100 mM of optimized pH. Enzyme dose was varied ranging from 1 to 12.5 IU/g oven dried fabric. Optimization of retention time and temperature was carried out by treating the moistened jute fabric at different retention time ranging from 20 to 160 min at temperatures varying from 40 to 65 ◦ C. The jute fabric was treated at static as well as under shaking conditions (50–80 rpm). To determine the effectiveness of different treatment processes, the supernatant obtained after treatment was
used for the determination of reducing sugars and the jute fabric was washed in tap water, rinsed with distilled water and dried in an oven at 50 ◦ C for 24 h for determination of its different properties viz. brightness, whiteness, yellowness, and weight loss.
2.5.2. Optimization of chelating agent Ethylene diamine tetra acetate (EDTA) was used as chelating agent. The concentration of chelating agents was varied between 0.5 and 25 mM in combination with enzyme. To determine the effect of different concentrations of EDTA, the effluent after the treatment was used for the determination of reducing sugars and the jute fabric was washed in tap water, rinsed with distilled water and dried in an oven at 50 ◦ C for 24 h for determination of its different properties viz. brightness, whiteness, yellowness, and weight loss.
2.5.3. Optimization of wetting agent Different wetting agents like lissapol D, triton X-100 and Tween-20 were used to evaluate their effect on jute properties in combination with enzyme. The optimization of wetting agent concentration was performed at the conditions optimized for the enzyme treatment. For the optimization, the concentration of different wetting agents was varied between 0.1 and 2.0% (v/v). The effect of different wetting agents and their concentrations was determined in the same way as mentioned above for chelating agent in addition to wettability drop test.
2.6. Scouring of jute fabric Chemical treatment of fabric was carried out by method of Sharma [18] and Chattopadhyay et al. [19] with some modifications. For chemical treatment, jute sample 2 g was dipped in 0.6% (w/v) NaOH at 1:30 fabric to liquor ratio with 0.1% (v/v) wetting agent i.e. Tween 20. The scouring was done at 95 ◦ C for 60 min. After the treatment, the effluent was used for the determination of reducing sugars and the jute fabric was washed in tap water, followed by rinsing in distilled water and then subjected to oven drying at 50 ◦ C for 24 h. The dried fabric was further analyzed for its different properties. At the optimized conditions of bioscouring, different sets of experiments were performed to evaluate the effect of each component individually as well as in combination on removing non-cellulosic impurities and water absorbency property of the fabric. Ten sets of treatment were applied on the fabric: (a) buffer only, (b) buffer and enzyme, (c) buffer and chelating agent, (d) buffer, chelating agent and enzyme, (e) buffer and wetting agent, (f) buffer, wetting agent and enzyme, (g) buffer, wetting agent and chelating agent, (h) buffer, wetting agent, chelating agent and enzyme, (i) chemical control and (j) chemical treatment.
2.7. Bleaching The enzyme control, xylanase treated, chemical control and chemically treated jute fabric were subjected to bleaching chemicals such as hydrogen peroxide (H2 O2 ) 5 g/L, sodium silicate 2.5 g/L, EDTA 1 mM, soda ash (Na2 CO3 ) 1 g/L. The fabric to liquor ratio for effective bleaching process was 1:100 at pH 10.5 [20]. The jute fabric for bleaching was incubated in water bath at 85 ◦ C for 90 min. After bleaching, the fabric was thoroughly washed in tap water, followed by rinsing in distilled water and dried in an oven at 50 ◦ C for 24 h. The dried fabric was further used for the determination of various fabric properties like brightness, whiteness, yellowness and tenacity.
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2.8. Evaluation of fabric properties 2.8.1. Reducing sugars Reducing sugars was measured by a Dinitro salicylic acid reagent [17] after each treatment. The supernatant obtained after the treatment was used for the determination of reducing sugar. The reducing sugars were measured in mg/g. 2.8.2. Wettability drop test Wettability of the fabric was measured by means of the drop test before and after the scouring process to check the bioscouring efficiency for subsequent finishing treatments. Water absorbency was evaluated according to an AATCC (American Association of Textile Chemists and Colourists) Test method 39-1980 evaluation of wettability [21] at room temperature. The time between the contact of water drop with the fabric and the disappearance of the water drop into the fabric was counted as the wetting time. Average values of three determinations were taken. Wetting time of less than 1 s is considered as an indicator of adequate water absorption efficiency of the fabric [8,22]. 2.8.3. Weight loss (%) The weight loss of jute fabric after treatment was assessed by using gravimetric approach. The oven dried fabric sample was weighed before and after the treatment and the weight loss was calculated according to the following relationship: weight loss (%) =
W1 − W2 × 100 W1
where, W1 and W2 are the weights of oven dried fabric before and after the treatment respectively [10]. 2.8.4. Whiteness index, yellowness index and brightness index The whiteness index [23], yellowness index [24] and brightness [25] of the samples were measured after treatment using a Macbeth Color-Eye® spectrophotometer. 2.8.5. Tenacity The tenacity of the samples was measured after bleaching using the Goodbrand tensile strength tester in lbs (pounds). 3. Results and discussion In order to explore the potential of cellulase-free xylanase produced by B. pumilus ASH in textile industry, various factors like buffer pH, molarity of buffer, enzyme dose, temperature, time period, rpm, chelating and wetting agent dose, etc. were tested in order to choose the best condition for the effective bioscouring of jute fabric. The detailed properties of the jute were studied to determine the effect of xylanase treatment. Different ranges of buffer pH and molarity were tested to find the best condition at which enzyme shows the maximum activity. Phosphate buffer of pH 7.5 and molarity 75 mM was found to be the optimum for the treatment of jute fabric with xylanase (Tables 1 and 2). The molarity of buffer has strong effect on enzyme activity as ionic strength of buffer system differs considerably at any one molarity and pH. Increase in xylanase activity with increase in molarity with maximum activity at 100 mM sodium phosphate buffer (pH 7.0) has been reported by Sharma et al. [26]. Maximum bioscouring efficiency was observed at an enzyme dose of 5 IU/g of oven dried fabric (Table 3) whereas enzyme dose of 4% was reported by Vigneswaran and Jayapriya [11]. Further increase in enzyme dose has no significant effect on bioscouring efficiency. Xylanase enzyme showed the best result when the jute fabric was incubated at 55 ◦ C for 120 min as shown in Tables 4 and 5. Samanta et al. reported that brighter jute fiber was obtained at 4% of mixed enzyme when incubated at 55 ◦ C
45
for 120 min at pH 4.8 [27]. Agitation at slow speed of 60 rpm was found to be the best in comparison with static condition (Table 6). Reducing sugars of 2.09 mg/g of dry jute fabric were obtained after optimized condition where as 0.55 mg/mL of reducing sugars were reported when combination of xylanase, cellulase and pectinase was used in case of jute/cotton blended fabric [28]. Any variation in the optimized condition resulted in deterioration in fabric properties. For the optimization of chelating agent and wetting agent, the fabric was treated with their different concentrations in the presence of enzyme at the conditions optimized for enzyme treatment. A concentration of 1.0 mM of EDTA gave the best results when applied in combination with enzyme as shown in Table 7. Among the various wetting agents, Tween-20 at the concentration of 0.5% (v/v) was found to be the best for the effective bioscouring (Table 8). Jute fabric was subjected to ten different treatments conditions as shown in Table 9. Addition of enzyme to buffer resulted in an increase of 3.93 and 10.19% in whiteness and brightness respectively and a decrease of 5.57% in yellowness in comparison to buffer only (Table 9). Improvement in whiteness is mainly due to the delignification of the jute fabric which results in the uniform surface of the fabric because of enzymatic hydrolysis (Vigneswaran and Jayapriya [11]). As reported by Vigneswaran and Jayapriya, the brightness of mixed enzyme treated (xylanase, cellulase and pectinase) jute fabric was more in comparison to the raw jute [11]. Addition of EDTA further to buffer and enzyme solution resulted in an increase in brightness and whiteness. Addition of EDTA facilitates the removal of water extractable impurities and calcium ions from the region that connect the macromolecule in pectin to one another or pectin to other polysaccharides [29]. Similarly, Csiszar et al. reported that EDTA markedly enhanced the apparent activity of commercial xylanases and pectinases in cotton bioscouring, accelerating the degradation and removal of impurities [30]. The result is in contradiction to the results of Losonczi et al. who demonstrated that application of EDTA in different concentration neither inhibited nor increased the activities of xylanase in pure xylanase preparation [31]. Wetting agent in combination with enzyme resulted in an increase of 5 and 13.61% in whiteness and brightness respectively (Table 9). Wetting agent reduces the surface tension of water thereby enabling in the better penetration of enzyme to the jute fabrics. Maximum bioscouring was obtained when buffer in combination with enzyme, wetting agent and chelating agent was used. It resulted in 4.19 and 12.52% increase in whiteness and brightness compared to buffer in combination of wetting agent and chelating agent respectively. Chemical treatment of jute fabric resulted in 9.96 and 30.97% decrease in whiteness and brightness respectively as compared to control. Whereas for bioscouring the decrease was 15.56 and 42.12% for whiteness and brightness respectively compared to chemical scouring. Similarly a decrease in whiteness and brightness of chemically scoured jute had been reported earlier [19,27]. The wetting time of the bioscoured fabric was lower to that of chemically scoured fabric which indicates the suitability of enzyme in the scouring process. The maximum reducing sugars released were 2.39 mg/g of oven dried jute when treated with enzyme, wetting agent and chelating agent whereas chemical treatment resulted in release of 2.18 mg/g of reducing sugars as shown in Fig. 1. Maximum weight loss was observed in chemical treatment process in comparison to all other treatment processes (Fig. 2). 3.1. Bleaching of jute fabric After treatment, controls, enzyme treated and chemical treated jute fabric were subsequently bleached. Bioscouring of jute fabric resulted in an improvement of various physical properties of jute fabric after bleaching. Whiteness and brightness of enzyme treated bleached fabric increased 10.96 and 15.64% respectively compared
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Table 1 Effect of different buffer pH on fabric properties. pH
Buffer
Reducing sugar (mg/g)
DW 6.5 7.0 7.5 8.0 8.5 8.5 9.0
– Phosphate Phosphate Phosphate Phosphate Phosphate Glycine NaOH Glycine NaOH
1.59 1.66 1.77 1.97 1.80 1.70 1.77 1.68
± ± ± ± ± ± ± ±
Weight loss (%)
0.06 0.07 0.06 0.10 0.09 0.05 0.04 0.16
0.78 0.79 0.85 0.92 0.89 0.86 0.84 0.82
± ± ± ± ± ± ± ±
0.02 0.04 0.03 0.02 0.03 0.01 0.02 0.01
Whiteness (hunter) 44.07 44.51 44.77 45.09 44.71 44.56 44.36 44.29
± ± ± ± ± ± ± ±
0.15 0.20 0.10 0.06 0.05 0.12 0.10 0.09
Yellowness (ASTM-E-313) ± ± ± ± ± ± ± ±
40.53 40.39 39.61 38.83 38.96 39.13 39.67 40.26
0.13 0.12 0.11 0.11 0.10 0.13 0.15 0.22
Brightness (ISO 2470) 15.09 15.49 15.70 15.97 15.68 15.61 15.39 15.28
± ± ± ± ± ± ± ±
0.15 0.16 0.13 0.14 0.07 0.05 0.11 0.10
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at retention time of 120 min, at 55 ◦ C at 100 mM buffer molarity. Table 2 Effect of different buffer molarity on fabric properties. Buffer (mM)
Reducing sugar (mg/g)
10 25 50 75 100
1.76 1.81 1.91 1.99 1.91
± ± ± ± ±
0.04 0.02 0.06 0.05 0.05
Weight loss (%) 0.80 0.86 0.90 0.98 0.91
± ± ± ± ±
Whiteness (hunter)
0.02 0.04 0.03 0.04 0.02
44.63 45.16 44.88 45.25 45.05
± ± ± ± ±
0.23 0.15 0.21 0.14 0.15
Yellowness (ASTM-E-313) 40.00 39.66 39.31 38.64 38.97
± ± ± ± ±
0.21 0.15 0.19 0.09 0.14
Brightness (ISO2470) 15.49 15.91 15.75 16.06 15.79
± ± ± ± ±
0.12 0.09 0.15 0.18 0.11
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at retention time of 120 min, at 55 ◦ C at buffer of pH 7.5. Table 3 Effect of different enzyme dose on fabric properties. Enzyme dose (IU/g)
Reducing sugar (mg/g)
0 1 2.5 5.0 7.5 10.0 12.5
1.05 1.56 1.84 1.99 1.98 1.96 1.96
± ± ± ± ± ± ±
Weight loss (%)
0.06 0.08 0.10 0.05 0.05 0.03 0.01
0.60 0.79 0.87 0.99 0.95 0.91 0.85
± ± ± ± ± ± ±
0.03 0.06 0.04 0.03 0.03 0.02 0.03
Whiteness (hunter) 43.70 44.08 44.79 45.17 45.09 45.08 44.92
± ± ± ± ± ± ±
0.16 0.14 0.17 0.11 0.09 0.03 0.12
Yellowness (ASTM-E-313) 40.91 39.94 39.74 38.86 38.92 38.53 39.19
± ± ± ± ± ± ±
0.15 0.13 0.10 0.16 0.19 0.11 0.14
Brightness (ISO2470) 14.78 15.15 15.52 15.98 15.20 16.25 15.06
± ± ± ± ± ± ±
0.12 0.13 0.08 0.15 0.20 0.16 0.13
All the experiments were performed at retention time of 120 min, at 55 ◦ C at buffer pH 7.5 of molarity 75 mM. Table 4 Effect of different incubation temperature on fabric properties. Incubation temperature (◦ C)
Reducing sugar (mg/g)
40 45 50 55 60 65
1.62 1.78 1.96 2.01 1.77 1.65
± ± ± ± ± ±
Weight loss (%)
0.02 0.09 0.10 0.05 0.09 0.07
0.87 0.89 0.96 1.06 0.95 0.89
± ± ± ± ± ±
0.02 0.06 0.04 0.07 0.04 0.08
Whiteness (hunter) 44.15 44.24 44.90 45.22 44.99 44.26
± ± ± ± ± ±
0.09 0.11 0.16 0.15 0.13 0.14
Yellowness (ASTM-E-313) 40.15 40.05 39.69 38.80 38.92 39.24
± ± ± ± ± ±
0.08 0.11 0.16 0.09 0.11 0.19
Brightness (ISO2470) 14.89 15.20 15.72 16.10 15.95 15.40
± ± ± ± ± ±
0.23 0.15 0.11 0.12 0.16 0.13
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at retention time of 120 min, at buffer pH 7.5 of molarity 75 mM. Table 5 Effect of different incubation time on fabric properties. Incubation time (min)
Reducing sugar (mg/g)
20 40 60 80 100 120 140 160
1.51 1.78 1.94 1.96 2.00 2.01 1.97 1.90
± ± ± ± ± ± ± ±
0.09 0.09 0.03 0.06 0.05 0.03 0.04 0.03
Weight loss (%) 0.87 0.95 1.01 1.03 1.04 1.06 0.97 0.92
± ± ± ± ± ± ± ±
0.10 0.06 0.05 0.04 0.02 0.03 0.04 0.02
Whiteness (hunter) 43.70 43.75 44.25 45.05 45.17 45.22 45.05 44.81
± ± ± ± ± ± ± ±
0.05 0.04 0.16 0.12 0.05 0.04 0.11 0.13
Yellowness (ASTM-E-313) 40.37 40.52 39.73 39.42 38.94 38.80 39.04 39.45
± ± ± ± ± ± ± ±
0.23 0.15 0.19 0.11 0.13 0.09 0.16 0.13
Brightness (ISO2470) 14.58 14.79 14.83 15.27 15.87 16.10 15.97 15.89
± ± ± ± ± ± ± ±
0.15 0.19 0.11 0.21 0.23 0.09 0.13 0.11
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM. Table 6 Effect of agitation on fabric properties. Agitation (rpm)
Reducing sugar (mg/g)
0 50 60 70 80
1.68 1.97 2.09 1.98 1.92
± ± ± ± ±
0.06 0.11 009 0.12 0.06
Weight loss (%) 0.89 1.08 1.20 1.04 0.95
± ± ± ± ±
0.09 0.05 0.03 0.08 0.06
Whiteness (hunter) 43.07 43.92 45.23 45.20 45.14
± ± ± ± ±
0.18 0.21 0.17 0.11 0.16
Yellowness (ASTM-E-313) 40.44 40.27 38.65 39.00 39.53
± ± ± ± ±
0.14 0.15 0.16 0.17 0.11
Brightness (ISO 2470) 14.34 14.94 16.21 15.99 15.88
± ± ± ± ±
0.15 0.13 0.14 0.11 0.09
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min.
G. Garg et al. / Journal of Molecular Catalysis B: Enzymatic 85–86 (2013) 43–48
47
Table 7 Effect of different concentration of chelating agent (EDTA) on fabric properties. EDTA (mM)
Reducing sugar (mg/g)
0 0.5 1.0 2.5 5.0 10.0 15.0 20.0 25.0
2.09 2.21 2.24 2.22 2.19 2.15 2.15 2.13 2.11
± ± ± ± ± ± ± ± ±
Weight loss (%)
0.06 0.11 0.05 0.06 0.04 0.05 0.08 0.03 0.03
1.22 1.48 1.54 1.50 1.49 1.45 1.37 1.34 1.25
± ± ± ± ± ± ± ± ±
0.10 0.05 0.04 0.03 0.02 0.04 0.03 0.02 0.08
Whiteness (hunter) 45.19 46.20 46.27 46.25 46.19 46.15 46.13 46.18 46.17
± ± ± ± ± ± ± ± ±
Yellowness (ASTM-E-313)
0.12 0.15 0.05 0.04 0.05 0.02 0.02 0.12 0.15
38.79 38.15 38.07 38.20 38.37 38.42 38.61 38.67 38.71
± ± ± ± ± ± ± ± ±
0.09 0.15 0.11 0.14 0.13 0.08 0.11 0.12 0.15
Brightness (ISO2470) 16.13 17.36 17.56 17.39 16.83 16.54 16.41 16.32 16.19
± ± ± ± ± ± ± ± ±
0.11 0.09 0.15 0.16 0.15 0.14 0.18 0.09 0.11
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min.
Table 8 Effect of different wetting agents on fabric properties. Wetting agent
Concentration (%, v/v)
Reducing sugar (mg/g)
Control Lissapol D Lissapol D Lissapol D Lissapol D Lissapol D Lissapol D Triton X-100 Triton X-100 Triton X-100 Triton X-100 Triton X-100 Triton X-100 Tween-20 Tween-20 Tween-20 Tween-20 Tween-20 Tween-20
– 0.1 0.25 0.5 1.0 1.5 2.0 0.1 0.25 0.5 1.0 1.5 2.0 0.1 0.25 0.5 1.0 1.5 2.0
2.09 2.11 2.12 2.14 2.16 2.19 2.17 2.12 2.16 2.18 2.16 2.16 2.15 2.15 2.20 2.22 2.20 2.17 2.15
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.02 0.03 0.02 0.03 0.01 0.05 0.03 0.06 0.04 0.01 0.03 0.02 0.03 0.01 0.04 0.03 0.02 0.04 0.02
Weight loss (%) 1.23 1.27 1.29 1.34 1.38 1.41 1.39 1.22 1.31 1.37 1.35 1.34 1.34 1.28 1.37 1.49 1.41 1.38 1.35
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.02 0.01 0.03 0.04 0.02 0.01 0.03 0.04 0.02 0.03 0.01 0.02 0.03 0.05 0.01 0.03 0.01 0.02 0.05
Water drop
Whiteness (hunter)
23 ± 1 5 ± 0.57 4±1 4 ± 0.57 3 ± 0.57 2±1 2 ± 0.57 2 ± 0.57 2±1 1 ± 0.57 <1 <1 <1 1 ± 0.57 1 ± 0.57 <1 <1 <1 <1
45.12 45.22 45.31 45.52 45.79 46.11 45.72 45.40 45.79 45.94 45.68 45.31 45.28 45.52 45.97 46.24 45.68 45.33 45.30
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
Yellowness (ASTM-E-313)
0.10 0.06 0.08 0.13 0.16 0.21 0.19 0.16 0.11 0.13 0.22 0.06 0.05 0.09 0.16 0.14 0.09 0.11 0.15
38.88 38.50 38.46 38.34 38.24 37.98 38.10 38.73 38.38 38.11 38.16 38.36 38.38 38.60 38.14 37.97 38.27 38.37 38.40
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.11 0.03 0.05 0.18 0.17 0.14 0.09 0.23 0.26 0.04 0.05 0.09 0.15 0.10 0.08 0.16 0.14 0.05 0.04
Brightness (ISO 2470) 15.97 16.00 16.22 16.24 16.63 16.78 16.73 16.04 16.27 16.52 16.45 16.28 16.26 16.27 16.57 17.27 16.80 16.61 16.57
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.05 0.07 0.15 0.03 0.13 0.04 0.05 0.17 0.19 0.05 0.07 0.03 0.02 0.16 0.14 0.15 0.21 0.18 0.16
All the experiments were performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min.
Table 9 Effect of different treatment mode on fabric properties. S no.
Treatment mode
Water drop (s)
Whiteness (hunter)
A B C D E F G H I J
Buffer Buffer + enzyme Buffer + EDTA Buffer + enzyme + EDTA Buffer + Tween-20 Buffer + enzyme + Tween-20 Buffer + Tween-20 + EDTA Buffer + enzyme + EDTA + Tween-20 Control (chemical treatment) Chemical treatment
30 ± 2 26 ± 2 27 ± 3 24 ± 1 1 ± 0.57 <1 1 ± 0.57 <1 28 ± 1 2 ± 0.57
43.52 45.23 44.42 46.15 43.97 46.17 45.08 46.97 44.05 39.66
± ± ± ± ± ± ± ± ± ±
0.21 0.12 0.09 0.11 0.12 0.15 0.11 0.13 0.15 0.09
Yellowness (ASTM-E-313) 40.93 38.65 40.18 38.17 40.20 37.85 39.23 37.11 40.26 43.25
± ± ± ± ± ± ± ± ± ±
0.09 0.16 0.15 0.23 0.03 0.11 0.18 0.17 05 0.12
Brightness (ISO2470) 14.71 16.21 15.32 17.61 15.28 17.36 15.97 17.97 15.01 10.36
± ± ± ± ± ± ± ± ± ±
0.15 0.12 0.11 0.15 0.19 0.21 0.14 0.16 0.14 0.19
Enzymatic treatment was performed at an enzyme dose of 5 IU/g of oven dried fabric, at 55 ◦ C, at buffer pH 7.5 of molarity 75 mM at retention time of 120 min. Tween-20 (0.5%, v/v), EDTA (1.0 mM).
with chemically treated bleached jute (Table 10). Enzyme treatment resulted in decrease in tenacity of the fabric as compared to control which is mainly due to the partial surface hydrolysis of fibers due to enzyme as reported by Vigneswaran and Jayapriya [11]. The decrease in tenacity is more in case of chemically treated fabric (7.5%) than enzyme treated fabric (2.7%) which may be due to
release or dissolution of different extent of hemicelluloses, waxes, fats and other impurities which give strength to the fabric [10]. Alkali pretreatment is mainly responsible for reduction in whiteness index after bleaching [32]. The enzyme treatment can be conducted before or after the bleaching process [33]. It has been reported that if enzyme treatment was given before bleaching, it
Table 10 Effect of different treatment on fabric properties after bleaching. Jute fabric sample
Whiteness (hunter)
Control Bioscoured (enzyme treated) Chemical control Scoured (chemical treated)
76.64 78.46 77.12 70.71
± ± ± ±
0.26 1.03 0.24 0.51
Yellowness (ASTM-E-313) 18.12 16.41 17.85 22.42
± ± ± ±
1.15 0.95 0.15 0.26
Brightness (ISO2470) 55.63 57.22 56.05 49.48
± ± ± ±
0.34 0.35 0.13 0.24
Tenacity (lbs) 73 71 72.5 67
± ± ± ±
1.5 0.57 0.21 0.51
48
G. Garg et al. / Journal of Molecular Catalysis B: Enzymatic 85–86 (2013) 43–48
1.0 mM of EDTA as chelating and 0.5% Tween-20 as wetting agent imparts optimal improvement to the jute properties like whiteness, brightness and yellowness thereby making it finer, softer, cleaner and brighter than the chemical process. The approach described in the present work seems to be convincingly reproducible and environment friendly which can be easily adopted by the textile industry. Acknowledgement The authors gratefully acknowledge Kurukshetra University, Kurukshetra, India for providing laboratory facilities during the course of investigation.
Fig. 1. Effect of different pretreatment mode on reducing sugars (mg/g) in jute fabric.
Fig. 2. Effect of different pretreatment mode on weight loss (%) in jute fabric.
resulted in increase of whiteness index, whereas whiteness index decreased if enzyme treatment was done after bleaching of fabric which may be due to the back staining of the fabric [33]. Enzyme treatment before bleaching resulted in an increase in pore volume and increase in the amount of exposed lignin to the bleaching chemicals which might be responsible for enhancement of bleaching process [29]. As compared to chemical treatment, enzymatic treatment consumes less energy and gives cleaner technology with better fabric quality [34]. 4. Conclusions An attempt has been made to replace the harsh chemicals used during scouring of jute with xylanase enzyme produced from B. pumilus ASH which can specifically target the non-cellulosic impurities. Bioscouring is a cost effective and environment friendly process. It has been observed that the xylanase in combination with chelating and wetting agent is more effective for bioscouring process to remove hemicelluloses to make the fabric softer. Application of 5 IU/g enzyme dose at 55 ◦ C for 120 min at buffer pH of 7.5 with
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