Innovative Scouring for Cotton‐Based Textiles

An innovative approach addressing ecological problems associated with scouring of cotton‐based textiles was developed. The innovative scouring method is based on the use of β‐cyclodextrin in the presence of a wetting agent. β‐cyclodextrin is able to accommodate the wax in its cavity, complex with it and dissolve it together with other cotton impurities by the aid of a wetting agent, thereby effecting their removal. The work comprises treatment of desized cotton and polyester/cotton fabrics with β‐cyclodextrin and a wetting agent under a variety of conditions. Variables studied include concentration of β‐cyclodextrin, chemical nature and concentration of the wetting agent, pH of the scouring bath, and temperature and time of scouring. The samples were monitored for the residual wax percent and wettability. The scouring performance of the innovative method was compared with that of the conventional method. Chemical oxygen demand, total dissolved solids and conductivity of the wastewater effluent discharged by the two methods were also determined and compared. The comparison reveals the advantages of the new method in minimizing the degradation of the cotton and polyester/cotton fabrics, which occur during conventional scouring and the persistence of such advantage even after bleaching. The mode of wax removal during the innovative scouring and the impact of the latter on the environment were discussed.     

Analysis of the products from enzymatic scouring of cotton

This article discusses the analysis of the hydrolysis products from one-step scouring of cotton using pectinase and two-step scouring of cotton using lipase then cellulase, protease then cellulase, or lipase/protease then cellulase, to improve water absorbency of cotton. UV spectrophotometric analysis indicated that the pectinase scouring process produced approximately 18-fold higher amounts of reducing sugars and galacturonic acid than any of the two-step scouring processes. The production rate of reducing sugars and galacturonic acid from most of the scouring processes showed a decrease with an increase in time. HPLC analysis revealed that the lipase/protease/cellulase scouring processes produced approximately 5-fold higher amounts of 17 amino acids than the pectinase scouring process. GC analysis for 18 fatty acids (C(8)-C(24)) revealed that three major fatty acids, palmitic acid, stearic acid, and behenic acid, were found on both the scoured and the unscoured fabrics. Scoured fabrics were tested for content of proteins, extractable components, waxes, and anionic components including pectins, and some differences among the fabric scoured with different enzyme combinations were found.     

Nano photo scouring and nano photo bleaching of raw cellulosic fabric using nano TiO2

Photo catalytic action of nano TiO(2) for decomposing of some organic compounds is a well known phenomenon. This can be extended to the application on nano TiO(2) on the desized cotton fabric to decompose the hydrophobic impurities and coloring matters of the fabric. This can be nominating as a replacement for the conventional scouring and bleaching processes on cotton fabric producing the hydrophilic white cotton fabric. The photo activities of the nano TiO(2) on the desized cotton through decomposition of the cotton impurities compared for two different light exposures: UV rays and daylight. The desized cotton fabrics treated in the ultrasonic bath containing a colloidal aqueous solution of nano TiO(2)/citric acid (CA)/sodium hypophosphite (SHP). Incorporating CA in the treatment bath enhanced the treatment durability against washing, created a durable hydrophilic white cotton fabric even after several successive washings. Increasing the nano TiO(2) content enhanced the fabric hydrophilicity and whiteness features. Overall, the nano photo scouring and nano photo bleaching on the cotton fabric introduced and thoroughly discussed. This gains the application of nano TiO(2) on textile materials besides the other well known characteristics obtained on the textiles including self-cleaning, antibacterial and UV protection.     

Wax removal for accelerated cotton scouring with alkaline pectinase

A rational approach has been applied to design a new environmentally acceptable and industrially viable enzymatic scouring process. Owing to the substrate specificity, the selection of enzymes depends on the structure and composition of the substrate, i.e. cotton fibre. The structure and composition of the outer layers of cotton fibre has been established on the basis of thorough literature study, which identifies wax and pectin removal to be the key steps for successful scouring process. Three main issues are discussed here, i.e. benchmarking of the existing alkaline scouring process, an evaluation of several selected acidic and alkaline pectinases for scouring, and the effect of wax removal treatment on pectinase performance. It has been found that the pectinolytic capability of alkaline pectinases on cotton pectin is nearly 75% higher than that of acidic pectinases. It is concluded that an efficient wax removal prior to pectinase treatment indeed results in improved performance in terms of hydrophilicity and pectin removal. To evaluate the hydrophilicity, the structural contact angle (theta) was measured using an auto-porosimeter.     

Thermostable beta-glycosidase-CBD fusion protein for biochemical analysis of cotton scouring efficiency

Multidomain proteins for the biochemical analysis of the scouring efficiency of cotton fabrics were constructed by the fusion of a reporter moiety in the N-terminal and the cellulose binding domain (CBD) in the C-terminal. Based on the specific binding of the CBD of Cellulomonas fimi exoglucanase (Cex) to crystalline cellulose (Avicel), the reporter protein is guided to the cellulose fibers that are increasingly exposed as the scouring process proceeds. Among the tested reporter proteins, a thermostable beta-glycosidase (BglA) from Thermus caldophilus was found to be most appropriate, showing a higher applicability and stability than GFP, DsRed, or a tetrameric beta-glucuronidase (GUS) from Escherichia coli, which were precipitated more seriously during the expression and purification steps. When cotton fabrics with different scouring levels were treated with the BglA-CBD and incubated with X-Gal as the chromogenic substrate, an indigo color became visible within 2 h, and the color depth changed according to the conditions and extent of the scouring.     

Effects of Thermobifida fusca cutinase-carbohydrate-binding module fusion proteins on cotton bioscouring

Previously, we presented a novel approach for increasing Thermobifida fusca cutinase adsorption on cotton fibers by fusing cutinase with a carbohydrate-binding module (CBM). A preliminary study showed that two fusion proteins, namely cutinase-CBM_Cel6A and cutinase-CBM_CenA, with similar stabilities and catalytic properties, had potential applications in bioscouring. In the present study, an indepth analysis of both cutinase-CBMs in bioscouring was explored. Effects of cutinase-CBMs on cotton bioscouring were investigated by characterizing the chemical and physical surface changes in enzyme-treated cotton fabrics. Gas chromatography/mass spectrometry was used to analyze the degradation of the cotton fabric cuticle; Fourier transform infrared microspectroscopy was used to study changes in the chemical composition of the cotton fabric epidermal layer; and scanning electron microscopy was used to monitor minor changes in the morphology of the fiber surface. Our results indicated that cutinase-CBMs in combination with pectinase had a greater effect on cotton fabric than did cutinase. Following scouring with cutinase-CBMs and pectinase, the performance of cotton fabric in terms of its wettability and dyeability was similar to that following alkali scouring. Our study provides a foundation for the further application of cutinase-CBM to bioscouring.     

Characterization of cotton fabric scouring by FT-IR ATR spectroscopy

FT-IR attenuated total reflectance (ATR) spectroscopy has been used for the fast characterization of cotton fabric scouring process. The greige and the scoured cotton fabrics showed very similar FT-IR spectrum in transmission mode because the bulk composition of the fabrics are similar. However, FT-IR ATR spectroscopy can provide information about the surface of a fabric. By examination of C–H stretching region at 2800–3000 cm⁻¹, the amount of waxes left on the fabric can be estimated. The presence of pectins and/or waxes can also be probed by observation of carbonyl peak induced by the HCl vapor treatment on the fabric. Based on these changes of FT-IR ATR spectra, the scouring process has been characterized.     

Discovery of pectin-degrading enzymes and directed evolution of a novel pectate lyase for processing cotton fabric

There is a growing need in the textile industry for more economical and environmentally responsible approaches to improve the scouring process as part of the pretreatment of cotton fabric. Enzymatic methods using pectin-degrading enzymes are potentially valuable candidates in this effort because they could reduce the amount of toxic alkaline chemicals currently used. Using high throughput screening of complex environmental DNA libraries more than 40 novel microbial pectate lyases were discovered, and their enzymatic properties were characterized. Several candidate enzymes were found that possessed pH optima and specific activities on pectic material in cotton fibers compatible with their use in the scouring process. However, none exhibited the desired temperature characteristics. Therefore, a candidate enzyme was selected for evolution. Using Gene Site Saturation Mutagenesistrade mark technology, 36 single site mutants exhibiting improved thermotolerance were produced. A combinatorial library derived from the 12 best performing single site mutants was then generated by using Gene Reassemblytrade mark technology. Nineteen variants with further improved thermotolerance were produced. These variants were tested for both improved thermotolerance and performance in the bioscouring application. The best performing variant (CO14) contained eight mutations and had a melting temperature 16 degrees C higher than the wild type enzyme while retaining the same specific activity at 50 degrees C. Optimal temperature of the evolved enzyme was 70 degrees C, which is 20 degrees C higher than the wild type. Scouring results obtained with the evolved enzyme were significantly better than the results obtained with chemical scouring, making it possible to replace the conventional and environmentally harmful chemical scouring process.     

Enzyme processing of textiles in reverse micellar solution

Scouring of cotton using pectinase enzyme, bioscouring, in reverse micellar system was studied. The effectiveness of bioscouring was evaluated by measuring weight loss of cotton, analyzing pectin and cotton wax remaining and by wetness testing. Pectinase enzyme showed excellent activity even in organic media, and the effectiveness of scouring was equivalent or better than that achieved by conventional alkaline process or bioscouring in aqueous media. Enzymatic modification of wool using protease enzyme in the same system was also studied. It has found that felting property and tensile strength of wool fabrics treated by protease in reverse micellar system were superior to those in aqueous media. Possibilities of utilization of the same system for the subsequent textile dyeing process were also investigated. It was found that cotton and polyester fabrics were dyed satisfactorily by reverse micellar system compared to conventional aqueous system.     

Scouring of cotton using marine pectinase

Bioscouring refers to the enzymatic removal of impurities from cotton fibre, which endows it with improved hydrophilicity for further wet processes. In this study, the efficacy of pectinase from newly isolated marine bacteria Bacillus subtilis, isolated from marine sediment; collected from Chinchani beach, Tarapore, India has been evaluated for scouring of cotton fabric and compared with conventional alkaline scouring of cotton. Use of Citrus limetta peel powder as pectin substrate for enzyme production renders pectinase production process more economically viable. Scouring carried out with pectinase dose of 10% (2.8 IU/g of the fabric) on the weight of the fabric at pH 7, 60 °C for 120 min yielded hydrophilic fabric. Physicochemical and mechanical properties of the pectinase scoured fabric were similar to alkaline scoured fabric. Scouring with pectinase preserves fiber's structure and prevents it from deterioration as observed from tensile strength, FTIR and SEM studies against alkaline scoured fabric. Enhanced dye uptake was also observed in case of pectinase scoured cotton fabric as compared to alkaline scoured fabric.     

Ultrasound-boosted enzymatic cotton scouring process with cutinase and pectate lyase

Abstract

The synergistic effect between power ultrasound and enzymes in an enzymatic scouring process has been studied. The scouring enzymes were Fusarium solani pisi cutinase (EC 3.1.1.74) and pectate lyase (EC 4.2.2.2). In different stages of the scouring process, power ultrasound with a pre-optimized power of 0.57 W cm^?2 and a frequency of 30 kHz was applied. It was found that ultrasound shortens the enzymatic scouring process time dramatically; less than 5 min was required to achieve the desired scouring expressed in terms of hydrophilicity of the cotton fiber. The results obtained have been explained in terms of mass transfer intensification by ultrasound (so-called ‘sono-mechanics’) and its effect on the enzyme kinetics (so-called ‘sono-chemistry’). This latter effect has been found by applying ultrasound in a homogeneous enzymatic reaction in which mass transfer did not play any role. The kinetics of product formation in a homogeneous system was carried out using poly-d-galacturonic acid as a model substrate.     

Degradation kinetics of pectins by an alkaline pectinase in bioscouring of cotton fabrics

Alkaline pectinases have been proven to be effective as bioscouring agents of cotton fabrics. In order to monitor the scouring degree of cotton fabrics quantificationally, a kinetic study of the degradation of pectins in cotton by an alkaline pectinase ‘Bioprep 3000L’ was performed and the influences of initial pectinase concentration and treatment time on bioscouring were evaluated quantitatively. The results showed that although the degradation products increased as pectinase concentration grew higher at same incubation time, the growth multiples of the maximum degradation rate which was used as the starting degradation rate were less than those of initial enzyme concentration. The degradation kinetics of pectins in cotton fibers with a pectinase could be described by modified Ghose–Walseth kinetic empirical equations which had been previously applied to the degradation reaction of cellulose.     

Enzymes and chelating agent in cotton pretreatment

Desized cotton fabric and cotton seed-coat fragments (impurities) have been treated with commercial cellulase (Celluclast 1.5 L), hemicellulase–pectinase (Viscozyme 120 L) and xylanase (Pulpzyme HC) enzymes. Seed-coat fragments hydrolyzed much faster than the cotton fabric itself. This relative difference in hydrolysis rates makes possible a direct enzymatic removal of seed-coat fragments from desized cotton fabric. Addition of chelating agents such as ethylenediamine-tetra-acetic acid (EDTA) markedly enhanced the directed enzyme action. Pretreatments carried out in acidic solution at pH 5 increased the lightness of seed-coat fragments, contrary to the samples treated in neutral medium at pH 7. Alkaline scouring resulted in darker seed-coat fragments except for the samples pretreated with Pulpzyme HC plus EDTA. This effect is similar to that observed in the biobleaching process in pulp and paper industry.     

Degradation of Lignin-Containing Materials by Xylanase in Biopreparation of Cotton

Solubilization of lignin and carbohydrates from the lignin-holocellulose structure of cotton seed-coat fragments was investigated by UV/VIS spectrometry. Xylanase (Pulpzyme HC) pre-treatment partially destroyed the lignocellulosic structure of the seed-coat fragments, producing reducing sugars and soluble lignin in the supernatant. Furthermore, the pre-treatment by enzyme enhanced the delignification in the subsequent alkaline scouring process and increased the lightness of the substrate.     

A new method for measuring scouring efficiency of natural fibers based on the cellulose-binding domain-beta-glucuronidase fused protein

Cellulose-binding domains (CBDs) are characterized by their ability to strongly bind to different forms of cellulose. This study examined the use of a recombinant CBD fused to the reporter enzyme beta-glucuronidase (CBD-GUS) to determine the extent of removal of the water-repellent waxy component of cotton fiber cuticles following hydrolytic treatment, i.e., scouring. The CBD-GUS test displayed higher sensitivity and repeatability than conventional water absorb techniques applied in the textile industry. Increases in the levels of CBD-GUS bound to the exposed cellulose correlated to increases in the fabric's hydrophilicity as a function of the severity of the scouring treatment applied, clearly indicating that the amount of bound enzyme increases proportionally with the amount of available binding sites. The binding of CBD-GUS also gave measurable and repeatable results when used on untreated or raw fabrics in comparison with conventional water drop techniques. The quantitative response of the reaction as bound enzyme activity was optimized for fully wettable fabrics. A minimal free enzyme concentration-to-swatch weight ratio of 75:1 was found to be necessary to ensure enzyme saturation (i.e., a linear response), corresponding to a free enzyme-to-bound enzyme ratio of at least 3:5.     

Non-Cellulosic Polysaccharides from Cotton Fibre Are Differently Impacted by Textile Processing

Cotton fibre is mainly composed of cellulose, although non-cellulosic polysaccharides play key roles during fibre development and are still present in the harvested fibre. This study aimed at determining the fate of non-cellulosic polysaccharides during cotton textile processing. We analyzed non-cellulosic cotton fibre polysaccharides during different steps of cotton textile processing using GC-MS, HPLC and comprehensive microarray polymer profiling to obtain monosaccharide and polysaccharide amounts and linkage compositions. Additionally, in situ detection was used to obtain information on polysaccharide localization and accessibility. We show that pectic and hemicellulosic polysaccharide levels decrease during cotton textile processing and that some processing steps have more impact than others. Pectins and arabinose-containing polysaccharides are strongly impacted by the chemical treatments, with most being removed during bleaching and scouring. However, some forms of pectin are more resistant than others. Xylan and xyloglucan are affected in later processing steps and to a lesser extent, whereas callose showed a strong resistance to the chemical processing steps. This study shows that non-cellulosic polysaccharides are differently impacted by the treatments used in cotton textile processing with some hemicelluloses and callose being resistant to these harsh treatments.     

Interaction of Anthonomus grandis and cotton genotypes: biological and behavioral responses

The boll weevil, Anthonomus grandisBoheman (Coleoptera: Curculionidae), is a key pest of cotton, Gossypium hirsutumL. (Malvaceae). Knowledge about boll weevil feeding and oviposition behavior and its response to plant volatiles can underpin our understanding of host plant resistance, and contribute to improved monitoring and mass capture of this pest. Boll weevil oviposition preference and immature development in four cotton genotypes (CNPA TB90, TB85, TB15, and BRS Rubi) were investigated in the laboratory and greenhouse. Volatile organic compounds (VOCs) produced by TB90 and Rubi genotypes were obtained from herbivore‐damaged and undamaged control plants at two phenological stages – vegetative (prior to squaring) and reproductive (during squaring) – and four collection times – 24, 48, 72, and 96 h following herbivore damage. The boll weevil exhibited similar feeding and oviposition behavior across the four tested cotton genotypes. The chemical profiles of herbivore‐damaged plants of both genotypes across the two phenological stages were qualitatively similar, but differed in the amount of volatiles produced. Boll weevil response to VOC extracts was studied using a Y‐tube olfactometer. The boll weevil exhibited similar feeding and oviposition behavior at the four tested cotton genotypes, although delayed development and production of smaller adults was found when fed TB85. The chemical profile of herbivore‐damaged plants of both genotypes at the two phenological stages and time periods (24–96 h) was similar qualitatively, with 30 identified compounds, but differed in the amount of volatiles produced. Additionally, boll weevil olfactory response was positive to herbivory‐induced volatiles. The results help to understand the interaction between A. grandis and cotton plants, and why it is difficult to obtain cotton genotypes possessing constitutive resistance to this pest.     

Green bioprocess of degumming of jute fibers and bioscouring of cotton fabric by recombinant pectin methylesterase and pectate lyases from Clostridium thermocellum

Enzymatic processes are emerging as important green biotechnological processes in textile industry. The application of recombinant pectin methylesterase (CtPME) and pectate lyase (CtPL1B) from Clostridium thermocellum for enzymatic degumming of jute or bioscouring of cotton was evaluated. The effectiveness of processes by combination of two enzymes were evaluated that effective degumming of jute and bioscouring of cotton as compared with individual enzyme. The optimum concentrations of two enzymes mixture for both processes, degumming of jute and bio scouring of cotton were 5 mg/mL (2.1 U/mL) of CtPME and 5 mg/mL (3.0 U/mL) of CtPL1B under optimized conditions of 60 min, 100 rpm and 50 °C. FESEM images showed more effective removal of pectin from jute fiber and cotton fabric by enzyme mixture, nevertheless similar to NaOH treatment. Wettability analysis showed mixture of enzymes and NaOH treated cotton fabric absorbed a water drop in 10 s and 8 s, respectively. UTM analysis showed higher tensile strength and Young’s modulus for jute fiber and cotton fabric treated with enzyme mixture than untreated and were similar to those of NaOH treated. These results showed that the CtPME and CtPL1B mixture can be used for replacing the chemical process by green bioprocess in textile industry.     

Application of Thermostable Xylanase of Bacillus pumilus in Textile Processing

Desizing of cotton and micropoly fabrics was done using thermostable xylanase from Bacillus pumilus ASH. Micropoly fabric showed better desizing than cotton under same conditions. Violet scale readings from the TEGEWA test after enzymatic desizing for 90 min at pH 7.0 and at 60°C showed the readings falling in the range of 4–5, indicating good desizing efficiency. During bioscouring the weight loss values and liberation of reducing sugars were highest when EDTA was used along with xylanase. The weight loss value of 1.5% was observed for dry cotton fabric after 1 h in case of agitated system at pH 7.0 and at an optimal enzyme dosage of 5 IU/g. The weight loss values and the liberation of reducing sugars were higher in case of cotton fabrics. Wetting time of fabrics was lowered significantly after 60 min of bioscouring using xylanase. Increase in temperature or concentration of surfactant led to further reduction in the wetting time. The whiteness values of fabrics after bioscouring were 0.9% higher than the chemically scoured fabrics indicating good efficacy of xylanase during the scouring process.