Search

Trials have been carried out to investigate the efficiency of ozone treatment in the colour stripping of reactive-dyed cotton fabrics. The trials were performed on a specially designed apparatus to inject ozone gas into the liquor passing through a perforated beam with fabric rolls on it, just like a beam dyeing machine with ozone venturi injection. Conventional reductive colour stripping was applied as the control treatment, and ozone treatment was applied for three different application times (15, 30, and 45 min). Trials were performed with seven selected reactive dyes having various chromophores and reactive groups. The results indicate that 45 min ozone treatment yielded the best colour stripping results among the three application times. Furthermore, the colour stripping percentages of the 45 min ozone treatment were higher for four of the tested dyes, the same for one of the tested dyes, and lower for two of the tested dyes compared with the control treatment, which consisted of conventional reductive colour stripping. Colour stripping of 90% and above was achieved for all samples of the 45 min ozone treatment. The chemical oxygen demand values of the colour stripping baths were compared: the average value of the 45 min ozone application baths was 105 mg l(-1), and it was 1993 mg l(-1) for the conventional reductive treatment baths. Consequently, a reduction in chemical oxygen demand of almost 94% was achieved by ozone treatment compared with conventional reductive treatment. The strength values of the fabrics after the respective treatments were similar, with a difference of only 3%.

In this study, a novel process utilizing ozone was carried out for colour stripping of fabrics misprinted with reactive dyes in ink-jet machines. The results of ozone applications were compared with conventional colour stripping process performed by thiourea dioxide (TUDO) and soda ash. In trials, cotton-based and viscose-based woven fabrics were used as these fabrics were the most utilized at the textile mill in which this study was performed. Different ozone treatment times (30, 45, 60 or 90 min) were tested to find optimum process time and it was found that process times depended on fabric type. Particularly, colour stripping on high density and thick fabrics were harder than low density and thin fabric types. Fabric strengths, whiteness indexes and chemical oxygen demand (COD) values were measured. Also energy, chemical and water consumptions were calculated. Consequently, it was found that the reduction of the COD value of effluent was up to 98%. The calculations showed that the savings in time and cost in ozone treatment were up to 77%. Satisfactory colour stripping and tensile strengths were achieved. Akbaşlar Tekstil Enerji San. ve Tic. A.Ş.

In this study, the effects of ultrasound on the bioscouring of cotton by alkaline pectinase were examined. Conventional alkaline scouring was considered as the control treatment, and two different sources of ultrasound, an ultrasonic bath and an ultrasonic homogeniser, were tested, along with the enzymatic scouring process. Results indicated a clear increase in the efficiency of the enzymatic scouring process when the ultrasonic homogeniser was used: wettability time and wicking distance after ultrasonic homogeniser-assisted bioscouring were much better than for enzymatic scouring without the use of ultrasound energy and almost the same as when conventional alkaline scouring was employed. Ultrasonic bath-assisted enzymatic bioscouring gave slightly better results than enzymatic scouring without sonication. Reasons for the difference in efficacy of the ultrasound sources were postulated. Weight loss was increased by the use of ultrasonic equipment during enzymatic scouring. Fabric thickness and fabric strength was not significantly affected by the scouring processes. The environmental impact of the processes was also monitored by chemical oxygen demand measurement of the treatment liquors. Conventional alkaline scouring resulted in the highest environmental impact. Ultrasonic homogeniser-assisted bioscouring also led to slightly higher chemical oxygen demand loads than other enzymatic processes owing to the more efficient removal of impurities.

17th World Textile Conference of the Association-of-Universities-for-Textiles (AUTEX) - Shaping the Future of Textiles --MAY 29-31, 2017 -- GREECE, WOS: 000417214900098, The aim of this study is decolorisation of CI Disperse Dark Blue 148 dye by ozone treatment which is one of the most attractive alternatives for solving the problem of color in textile dyeing effluents. A venturi injection system added dyeing chamber for getting ozone from the ozone generator. And additive (acetic acid and dispersing agent) put in the dyeing. After the coloration, the experimental color, chemical oxygen demand (COD), pH, temperature (degrees C) and conductivity (mu S/cm) were measured. The results encourage the use of the system for decolorisation trials as well as dyebath effluent recycling., Assoc Univ Textiles

The objective of this study was to develop a new process to desize, bleach, and dye starch-sized cotton fabrics in one bath using enzymes. Desizing was performed with an amyloglucosidase/pullanase enzyme (Dextrozyme DX, manufactured by Novozymes) instead of a conventional amylase enzyme in order to hydrolyze starch into single glucose units. Multifect GO 5000L (Genencor) glucose oxidase enzyme was used to yield hydrogen peroxide from the glucose generated during desizing; bleaching was performed by this enzymatically generated hydrogen peroxide. Decomposition of hydrogen peroxide after bleaching was done with Terminox Ultra 10L (Novozymes) catalase enzyme. The fabric was dyed in the same bath with the selected monochlortriazine reactive dyes (DyStar). The amount of glucose generated during desizing was 4000 ± 135 mg/l and it yielded 765 ± 15 mg/l hydrogen peroxide during glucose oxidase enzyme treatment. The whiteness index of the enzymatically bleached fabric was 71.0 ± 1.2 stensby degree. The color yields of the enzymatically treated samples were comparable to the conventionally treated samples. All enzymes used in this study were commercial grades having the advantages of easy storage and supply compared to the pure enzymes used in earlier studies. The advantages of the new one-bath process were: less auxiliary demand; lower environmental impact; and energy and water savings compared to the conventional desizing, scouring, bleaching, and dyeing sequence.

In this study, the effects of ultrasound on the enzymatic treatment of cotton fabrics with laccase were investigated. The laccase enzyme treatment of cotton fabric samples was carried out with the support of an ultrasonic homogeniser (UH) and an ultrasonic bath (UB). Optimum enzyme concentration, application time, and enzyme application temperature conditions were first determined. The ultrasound-supported treatments were performed with the obtained optimum conditions. Whiteness, yellowness, weight loss, fabric thickness, tensile strength, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analysis, as well as COD measurement of the process effluents, were carried out. The whiteness of the cotton fabric slightly increased after the laccase enzyme treatment. The effect of the enzyme was intensified with the help of ultrasonic energy leading to up to a 9.2% whiteness improvement. Results indicated that the laccase enzyme treatment processes had no significant degradative damage or effect and/or did not lead to any drastic detrimental change to the surface morphology of the cotton fibre.

The nettle plant is an industrial crop, different parts of which can be used as food, fodder, and as a raw material for different product purposes in cosmetics, medicine, industry, biodynamic agriculture, and textiles. Nettle fibre usage provides bio-degradable, renewable, sustainable, and eco-friendly textile production and requires low energy consumption during production. However, the natural colour of nettle fibre is beige, cream, or light-brown. In this study, bleaching of 100% natural nettle fibre fabric with ozonation was explored. Apart from ozonation alone, ozonation in the presence of ultrasonic homogeniser activation, conventional bleaching with various bleaching agents, bleaching with a laccase enzyme, and their sequential applications with ozonation (conventional bleaching, then ozonation, followed by laccase enzyme bleaching, and then ozonation) were also investigated. Whiteness, tensile strength, hydrophilicity, and chemical oxygen demand (COD) values were determined and compared. Ozone bleaching led to less strength loss in comparison to hydrogen peroxide bleaching. Higher oxycellulose formation resulted in higher strength loss in the case of peroxide bleaching in comparison to ozone bleaching. Ozone bleaching for nettle fibre fabrics could be used as a viable alternative to hydrogen peroxide bleaching due to its effectiveness, lower application temperature, lower application time, and less environmentally harmful nature. Pamukkale Üniversitesi - 2010 FBE 035

A set of trials has been conducted to examine the efficiency of ozonation afterclearing on poly(ethylene terephthalate) fibres dyed with disperse dyes. The afterclearing process was performed in neutral distilled water at room temperature with 12.8 +/- 0.3 mg/min ozone at 400 ml/min ozone gas flow rate. The results indicate that 1 min ozonation time is adequate to achieve wash fastness results comparable with conventional reduction clearing without significant colour yield losses. Ozonation periods greater than 1 min not only caused significant colour yield losses, but also caused a severe decrease of the breaking load of the fabric. The advantages of ozonation afterclearing are: savings in energy and time, as it is performed at room temperature for only 1 min, and decrease of environmental load as it avoids the use of the harsh chemicals used in conventional reduction clearing.

In this study, the effects of ultrasound on ozone treatment processes for bleaching cotton fabrics were investigated and compared with the conventional hydrogen peroxide bleaching process (60 °C over 90 min). Two ultrasonic + ozone treatments of cotton fabric samples were carried out: (1) ozone in an ultrasonic homogenizer (UH) and (2) ozone in an ultrasonic bath. Ozone dosages, temperature and time variations were determined with both ozone-ultrasonic bleaching processes. Whiteness, yellowness, weight, tensile strength properties, FTIR (ATR) spectra and visual appearance, via scanning electron microscopy of treated cotton fabrics as well as chemical oxygen demand (COD) of bleaching effluents, were investigated. It was concluded that the ozone + UH process, conducted for 30 min at 30 °C, produced closely equivalent values of cotton fabric whiteness and yellowness to the classic peroxide bleaching process, with slightly less weight loss, dramatically less COD in the process effluent (29 mg/l for ozone-UH vs. 4,316 mg/l for classical peroxide treatment), and without causing any adverse and/or detrimental effects on loss of fabric strength or elongation of the cotton fabrics. The ozone-UH process also leads to time and energy savings with much less environmental impact. Consequently, the combination of ozonation plus UH carried out at 30 °C over 30 min can be used successfully for cotton bleaching instead of the classic hydrogen peroxide bleaching process. © 2014, Springer Science+Business Media Dordrecht.

In this study, the effect of ultrasound on the activity of the glucose oxidase (GOx) enzyme for bleaching of the cotton fabrics was investigated. Hydrogen peroxide generation with the GOx enzyme from glucose was carried out under ultrasonic homogenizer (UH) and ultrasonic bath support. The aim of using ultrasonic support was to increase the yield of the enzyme reactions. The enzymatically generated hydrogen peroxide was used for bleaching of cotton fabrics. The bleaching process was performed at 90 °C and pH 11 (with NaOH) for 60 min, followed by rinsing at 70 and 50 °C then cold washing. The whiteness degrees of the cotton samples that were bleached by the generated peroxide were compared to the whiteness degrees of the conventionally bleached cotton fabrics. Sufficient whiteness degrees in cotton fabrics could be obtained by enzymatically generated hydrogen peroxide by UH support. The initial whiteness degree of the cotton fabric was 59.9 Stensby degrees; the whiteness was increased to 75.6 Stensby degrees by the GOx enzyme under UH support where the conventional bleaching process yielded a whiteness value of 76.7 Stensby degrees. For efficient cotton bleaching by the GOx enzyme, UH support contributed to the concentration of enzymatically generated hydrogen peroxide by the GOx enzyme. Bleaching of cotton by the GOx enzyme was approved as a more environmentally friendly process compared to the conventional bleaching method in respect of the results of chemical oxygen demand tests. © 2014 Springer Science+Business Media Dordrecht.

In this study, decolorization of three disperse dyes by ozonation was evaluated. The dyes assessed represent low (CI Disperse Blue 56), medium (CI Disperse Blue 60) and high (CI Disperse Blue 79) energy level dyes. UV-visible spectroscopy, HPLC-DAD and COD analysis were performed to follow the removal of color from effluent. The results indicated that color removal rates up to 100% and COD removal rates up to 68% could be achieved via ozonation. HPLC analysis and UV-vis analysis were performed for all of the dyes, and a degradation mechanism was proposed for CI Disperse Blue 79.

In this study, the effectiveness of the ozonation process, in neutral distilled water at room temperature, as a clearing process for disperse-dyed poly(lactic acid) fibre fabrics is investigated. The efficiency of simultaneous decolorisation of dyebath effluent and clearing of dyed poly(lactic acid) in the cooled dyebath after completion of the poly(lactic acid) dyeing cycle is also explored. Conventional alkaline reduction clearing with sodium dithionite was chosen as a control clearing process for comparison. Wash fastness, colour difference, colour removal (in Hazen) and chemical oxygen demand values were determined and compared. Long ozone treatment times at high ozone dose resulted in unacceptable colour differences. The colour difference problem was solved by use of lower ozone dose; however, a warm soaping step had to be added to the after-clearing sequence in order to achieve the desired fastness properties. A 33% reduction on the chemical oxygen demand load of the total process (dyeing + after-clearing) could be achieved by ozone after-clearing instead of using a conventional reduction clearing treatment. The addition of the warm soaping step to improve the fastness properties of the ozonated samples increased the total chemical oxygen demand of the process (dyeing + ozonation in water + warm soaping), but a 12–18% reduction on the chemical oxygen demand load of the total process was observed when compared with the conventional treatment sequence (dyeing + reduction clearing).

The efficiency of ozone treatment for the clearing of disperse dyed polyethylene terephthalate fibres has been examined. The ozone treatment for the clearing of the dyed samples was performed by blowing the ozone gas from the ozone generator on to the wet fabric samples. The results indicated that 3- and 5-min ozonation times were appropriate to achieve comparable wash fastness results with conventional reduction clearing without significant colour differences (ΔE* value) for the samples dyed with CI Disperse Yellow 23 and CI Disperse Blue 79, respectively; however, the ozonation time had to be increased to 15 min for CI Disperse Red 82. Tensile strength tests and scanning electron microscopy analysis indicated that the ozone treatment did not cause any severe damage to the fabrics. Ozone treatment for the afterclearing of disperse dyed polyester fabric can lead to energy and time savings and environmental load reduction when compared with conventional reduction clearing. This study tested a new method of ozone application for clearing of disperse dyed polyester by blowing ozone directly on to the fabric samples. This new method of application has the advantage of being readily adoptable for continuous treatment lines and lower water consumption.

In this study, the effects of ozonation, ozonation with ultrasonic bath and ozonation with ultrasonic homogeniser processes on colour and chemical oxygen demand removal properties of disperse (CI Disperse Red60, CI Disperse Blue337) and reactive (CI Reactive Blue171 and CI Reactive Blue19) dyebath solutions with and without dyeing auxiliaries were investigated. Chemical oxygen demand (in mg/l) and colour (in Hazen) measurements of the studied dyebath solutions were determined. The ozonation process caused simultaneous chemical oxygen demand removal during decolorisation. However, the improvement in chemical oxygen demand reduction was less than of that on decolorisation. The application of the combination of ozonation with ultrasonic homogeniser is the most efficient process and creates a great time advantage over the other process types studied (ozonation alone and ozonation with ultrasonic bath) to reach the same colour and levels of chemical oxygen demand removal. © 2012 The Authors. Coloration Technology © 2012 Society of Dyers and Colourists.

A set of knitted fabrics comprising soybean fibers was ozonated at room temperature for periods ranging from 2.5 to 300 minutes to identify any accompanying effects on either physical properties (specifically whiteness and burst-strength), fiber surface integrity or microstructure. A hydrogen peroxide treatment was applied to some of the fabric in order to provide a comparison. Ozonation was found to produce a promising increase in whiteness which, after the maximum exposure time, was significantly higher than was achieved using hydrogen peroxide. © 2012 International Ozone Association.

Ozone is a strongly oxidative gas that is generally used in medical sterilization and decolorization of the effluent of textile spent dyebaths. Recent studies have reported the use of ozone to bleach textile fabrics. In this study, ozone was utilized in cotton preparation for greige, desized and scoured 100% cotton fabrics. Hydrogen peroxide bleaching was performed as the control treatment. The degree of whiteness of cotton increased after prolonged ozonation times. The scoured samples reached the whiteness level of the control (hydrogen peroxide bleached) samples. The whiteness of the hydrogen peroxide bleached, 60-min ozonated and 90-min ozonated samples all had a Stensby degree of whiteness of 81 for the scoured fabric samples. The strength loss after prolonged ozonation times was negligible. Ozonation increased the starch-size removal of the greige cotton samples and the water absorbency of the greige and desized cotton samples.

A set of knitted poly(lactic acid) (PLA) fabrics was ozonated at room temperature for periods ranging from one to 60 minutes in order to identify any accompanying effects on physical properties (specifically whiteness, water-absorbency, flexural rigidity and burst strength), fiber surface integrity or internal microstructure. A significant (ca. 6% after 10 minutes of treatment) initial increase in whiteness was observed, with longer treatment times producing little further change. The fabric’s absorbency and flexibility both increased, the time of wetting having fallen by ca. 20% and the flexural rigidity by ca. 16%, respectively, after 10 minutes of treatment. Fabric strength remained virtually unaffected for short times (up to 10 minutes) of ozonation, although longer treatments caused a measurable drop (ca. 10% after 60 minutes). SEM imaging showed virtually no evidence for surface damage, even after 60 minutes of treatment, whereas peroxide treatment caused massive pitting of the fiber surface. Raman spectroscopy of the ozonated PLA fabrics indicated that the treatment had not affected the internal microstructure of the fibers. Our conclusion is that brief (no more than 10 minutes) room-temperature ozonation is potentially an effective, safe and low-energy alternative to conventional higher temperature peroxide treatment. © 2011, SAGE Publications. All rights reserved.

The oxidative ozone treatment of poly (ethylene terephthalate) fibers after dyeing was recently proposed as a novel afterclearing method. High fastness properties, energy and time savings, and environmental benefits were reported by the ozone treatment compared to the conventional reduction clearing. This study investigated the efficiency of the ozone treatment afterclearing process on the surface trimer removal of poly(ethylene terephthalate) fibers. Results indicated similar cyclic trimer [(GT)3] removal rates after 1 min ozone treatment when compared to the conventional reduction clearing; the removal rates increased at 3 min ozone treatment time. The migration rate of the cyclic trimers [(GT)3] out of the fibers was also investigated as a function of temperature and a sudden increase was observed after second glass transition temperature of poly (ethylene terephthalate) fibers rather than a linear increase.

Bu çalışmada, oksidatif bir madde olan ozonun lakkaz enzimleriyle ağartmaya etkisi, enzim aktivitesi ve beyazlık açılarından incelenmiştir. Beyazlık ölçüm sonuçları, tek başına lakkaz kullanımının beyazlıkta kayda değer bir artış sağlamadığını göstermiştir. 40°C’daki lakkaz ağartma banyosuna ozon gazı beslenmesi durumunda beyazlık değeri (Stensby) 61’den 69’a çıkmıştır. Ozon oksidatif özelliği nedeniyle enzim aktivitesini düşmüştür. Ozon tek başına kullanıldığında beyazlık değeri (Stensby) 71’e çıkmıştır. Enzim ve ozon ile işlem görmüş numunelerin beyazlıklarını artırmak için ilave peroksit ağartması yapılmış ve beyazlıklarda ciddi artışlar sağlanmıştır. Ozon ile işlem görmüş numunenin beyazlık değeri ilave peroksit ağartması sonrasında (Stensby) 83’e kadar çıkarak klasik peroksit ağartmasında ulaşılan değerleri yakalamıştır. The effects of ozone on the enzyme activity and bleaching effect of laccase have been examined in this study. Laccase treatment at 40 degrees C did not increase the whiteness of the fabric alone. However, ozone feed into the bleaching bath prepared with laccase increased the Stensby whiteness degree of the fabric from 61 to 69, ozonation alone resulted in a whiteness degree of 71. Ozone decreased the enzyme activity because of its oxidative effect. A post bleaching process with hydrogen peroxide was conducted to improve the whiteness degrees of the treated fabrics, and this resulted in increases in the whiteness degrees. The whiteness degree of the sample treated with ozone increased upto 83 (stensby) after post bleaching and reached the whiteness Value of the conventionally bleached sample.

The objective of this study was to substitute cotton pretreatment chemicals with enzymes to create an environmentally friendly process for water and energy savings. In this study, enzyme selection and process optimisation was made in order to increase the glucose content of the desizing liquor of a starch-sized cotton fabric. Results indicated that commercial desizing enzyme formulations of a-amylase enzymes were not appropriate to produce a large quantity of glucose in the desizing bath; the glucose amounts obtained were about 200 mg/l. However the food market enzyme used, an amyloglucodidase/pullanase mixture (amyloglucosidase 186 Units/g, pullanase 395 Units/g), produced approximately 4000 mg/l glucose in the desizing bath after process optimisation. The desizing effect of the amyloglucodidase/pullanase enzyme mixture was compatible with those of commercial desizing enzymes. The results of peroxide generation from glucose and bleaching trials are reported in the second part of the study.

Dyeing of polyester/cotton fabrics with one-step processes leads to substantial savings in process time, water, and energy pollution. Alkaline dyeing is one alternative for one-step dyeing of polyester/cotton fabrics, but dye selection is a critical factor affecting the success of the process. Reactive dyes must be stable at high temperatures and disperse dyes must be stable in alkaline media and in the presence of electrolyte. In this study, the alkaline one-step dyeing process and the selection of appropriate reactive and disperse dyes have been discussed.

Although the properties of blended fabrics such as economy, durability, easy care, attractive appearance, and hand satisfy customer demands, increased process steps and costs negatively impact textile finishing mills. Combining the processes provides great advantages, especially in today's competitive market. Mononicotinatetriazine reactive dyes enable the dyeing of polyester/cotton blends in one bath due to their ability to dye cotton at neutral baths and to resist high temperatures. Eliminating reduction clearing in the one-step dyeing process leads to poor fastness properties of dark shades. An oxidative clearing method seems to solve this problem.