Emilia Csiszar

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.

Combining Traditional Cotton Scouring with Cellulase Enzymatic Treatment

The action of a cellulase enzymatic pretreatment in the efficient alkaline scouring of cotton fabrics is studied and reported in this work. Improved removal of seed-coat fragments is the primary goal of the experiments, and spinning blowroom waste, rich in seed-coat fragments, is the main target substrate for enzymatic studies. Commercially available cellulase enzyme, a complex mixture of cellulase components (endo- and exoglucanases, beta-glucosidase) and accompanying enzymes (e.g., hemicellulases. pectinases ), is used throughout the experiments. Depending on time and enzyme con centration, 28-34% of the spinning blowroom waste can be hydrolyzed by cellulase. With consecutive cellulase treatment and traditional pad-steam scouring, weight loss is as high as 78-86%. Alkaline cotton scouring (control) results in only 66% weight loss. The cellulase enzyme complex makes the residual seed-coat fragments more ac cessible to scouring chemicals. The effect of enzymatic treatment on seed-coat fragment removal from desized cotton fabric is also significant. As photomicrographs show, the tiny fibers that attach the seed-coat fragments to the fabric are hydrolyzed by the enzyme, facilitating removal of these impurities from the fabric surface.

Development of antimicrobial cotton fabrics using herb loaded nanoparticles

In the present work ethanol, methanol, petroleum ether and water extracts of the leaves of Ocimum sanctum were screened for their anti-microbial activity by using the agar diffusion method. The minimum inhibitory concentration of the extracts was also measured. The methanol extracts O. sanctum proved to have the maximum antimicrobial effect were loaded inside the sodium alginate chitosan nanoparticles by cation induced controlled gelification method and finished on cotton fabric by pad dry cure method. The average particle size of the nanoparticles was calculated using dynamic light scattering technique. The antimicrobial activity of the fabrics was assessed by using the standard AATCC technique (AATCC 100). The quantitative tests proved that cotton fabrics finished with the methanol extract of O. sanctum loaded nanoparticles possessed remarkable antibacterial activities with excellent wash durability. The study revealed that the herb encapsulated nanoparticle could act as a biocontrol agent against bacteria in fabrics.

The effect of low-frequency ultrasound on the activity and efficiency of a commercial cellulase enzyme.

A commercial acidic cellulase enzyme complex was chosen in order to gain detailed information about the effect of low-frequency ultrasound (horn at 40 kHz) on the enzyme activity. The performance of the enzyme under sonication was also evaluated in a cellulose-cellulase model reaction. The filter paper activity of the enzyme and the yield of the enzyme catalysed hydrolysis were determined as a function of the parameters of the sonicated environment (treatment time, amplitude, with and without a reflector) and compared with the data measured in a non-sonicated bath. Depending on the parameters of the sonication, the enzyme is susceptible to ultrasound and its activity can significantly decrease. Despite the serious reduction of the enzyme activity, the outcome of the enzyme catalysed hydrolysis was always positive, implying that the advantageous effects of sonication impressed on the heterogeneous enzyme reaction always overcome the undesirable enzyme modifying effect of ultrasound.

Bleachability and Dyeing Properties of Biopretreated and Conventionally Scoured Cotton Fabrics

Enzymatic (cellulase, pectinase, xylanase) and simple buffer treatments in the presence of a nonionic surfactant improve water wettability of fabrics to a level equal to conven tional alkaline scouring. Caustic scoured fabric is significantly lighter and less colored than all the biopretreated samples. Application of a hydrogen peroxide bleaching subse quent to the biopretreatment is beneficial because it reduces the great color differences between conventionally scoured and biopretreated samples. Bleachability of the pretreated fabrics is better than that of the conventionally scoured sample. Biopretreated fabrics can be dyed with a reactive dye subsequent to the enzymatic treatment without further oxidative bleaching. At higher dye concentrations (i.e., 1 or 2%), there is no perceptible color difference between the biopretreated and alkaline scoured fabrics in the dyed state. In pale and medium dyeings, however, the color difference is great and perceptible. Bleaching applied subsequent to bioscouring significantly decreases the color difference between the dyed samples pretreated in different ways. None of the pretreatments causes uneven dyeing. Wash fastness of the dyed samples is excellent and unrelated to the pretreatment method.

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.

Microstructure and surface properties of fibrous and ground cellulosic substrates

Cotton and linen fibers were ground in a ball-mill, and the effect of grinding on the microstructure and surface properties of the fibers was determined by combining a couple of simple tests with powerful techniques of surface and structure analysis. Results clearly proved that the effect of grinding on cotton fiber was much less severe than on linen. For both fibers, the degree of polymerization reduced (by 14.5% and 30.5% for cotton and linen, respectively) with a simultaneous increase in copper number. The increased water sorption capacity of the ground substrates was in good agreement with the X-ray results, which proved a less perfect crystalline structure in the ground samples. Data from XPS and SEM-EDS methods revealed that the concentration of oxygen atoms (bonded especially in acetal and/or carbonyl groups) on the ground surfaces increased significantly, resulting in an increase in oxygen/carbon atomic ratio (XPS data: from 0.11 to 0.14 and from 0.16 to 0.29 for cotton and linen, respectively). Although grinding created new surfaces rich in O atoms, the probable higher energy of the surface could not be measured by IGC, most likely due to the limited adsorption of the n-alkane probes on the less perfect crystalline surfaces.

Effect of liquid ammonia on the fine structure of linen fabrics

It has recently been shown that liquid ammonia treatment (water-based process) is very effective in improving the wrinkle recovery, dimensional stability, and resistance to abrasion of the all-linen fabrics. In this study the changes in the fine structure were characterized by measuring the crystallinity and sorption properties of the linen fabrics. In addition, the effect of liquid ammonia on the surface properties of the linen fibers was investigated. X-ray analysis showed that liquid ammonia treatment did not significantly affect the ratio of crystalline and amorphous regions, but a partial recrystallization occurred in the crystalline part, resulting in mixed cellulose I and III lattices in the linen substrates. Although the moisture regain and iodine sorption capacity of the treated linen substrates increased, water retention values, however, were decreased significantly by the intracrystalline swelling treatment.

The effect of low frequency ultrasound on the production and properties of nanocrystalline cellulose suspensions and films

Suspension of nanocrystalline cellulose (NCC) produced from bleached cotton by controlled sulphuric acid hydrolysis was treated with low frequency ultrasound at 20 kHz and 60% amplitude for 0, 1, 2, 5 and 10 min and the effects of sonication on the properties of both the cellulose nanocrystals and their aqueous suspensions were investigated. Furthermore, a series of nanocellulose films were manufactured from the suspensions that were sonicated for different periods of time and tested. Laser diffraction analysis and transmission electron microscopy proved that sonication not only disintegrated the large NCC aggregates (Dv50 14.7 μm) to individual nanowhiskers with an average length and width of 171 ± 57 and 17 ± 4 nm, respectively, but also degraded the nanocrystals and yielded shorter and thinner particles (118 ± 45 and 13 ± 3 nm, respectively) at 10-min sonication. The ultrasound-assisted disintegration to nano-sized cellulose whiskers decreased the optical haze of suspensions from 98.4% to 52.8% with increasing time from 0 to 10 min, respectively. Sonication of the suspensions significantly contributed to the preparation of films with low haze (high transparency) and excellent tensile properties. With the increasing duration of sonication, the haze decreased and the tensile strength rose gradually. Irrespectively of sonication, however, all films had an outstanding oxygen transmission rate in a range of 5.5-6.9 cm(3)/m(2)day, and a poor thermal stability.

Influence of EDTA complexing agent on biopreparation of linen fabric

In this work the ‘EDTA–enzyme–substrate’ interaction was investigated in linen biopreparation. The effect of EDTA on the degradation of non-cellulosic constituents during bioscouring with pectinase enzyme was investigated in detail. Greige linen fabric was treated with pectinase, pectinase supplemented with ethylenediamine-tetra-acetic acid (EDTA), and EDTA pre-treatment followed by pectinase, in a tumble agitated bath. Adding EDTA to the enzyme solution accelerated the degree of hydrolysis and resulted in higher reducing sugar liberation and more efficient calcium ion extraction, indicating a synergistic effect of enzyme and EDTA. However, when EDTA was applied as a pre-treatment, a decrease in the efficiency of the subsequent enzymatic hydrolysis was observed.