Petra Forte Tavčer

Low Water and Energy Saving Process for Cotton Pretreatment

Cotton fabric was alkaline scoured with sodium hydroxide and bioscoured with acid or alkaline pectinases. In addition, the scoured fabrics were bleached with hydrogen peroxide (HP) or peracetic acid (PAA). The cotton fabric was treated simultaneously with pectinases and PAA in a one-bath process. The CIE whiteness, water absorbency, weight loss, tenacity at maximum load, and dyeability with a reactive dye were evaluated on differently pretreated samples. The remaining scouring and bleaching baths were analyzed for ecological parameters including pH, total organic carbon (TOC), chemical oxygen demand (COD), and biological oxygen demand (BOD5). The quantity of water and energy used for different processes was estimated. The water absorbency of all scoured fabrics was satisfactory. The degree of whiteness of all bleached fabrics was improved. The highest degrees of whiteness were from HP bleached samples. Less whiteness was achieved in PAA bleached samples. The whiteness was greater in the alkaline scoured fabrics relative to the enzymatic scoured fabrics. One-bath processes produced whiteness values comparable to alkaline scouring and bleaching with PAA. Neither of the processes had little effect on the tenacity at maximum load. All samples were evenly dyed with reactive dye. There was a remarkable color difference between samples that were alkaline or enzymatically scoured before dyeing and between differently bleached samples. On the other hand, there was no noticeable color difference between samples that were scoured and bleached in two-bath or one-bath processes before dyeing. In comparison to conventional pretreatment, less energy and water is used in enzymatic and/or PAA treatments since they proceed at 60°C and at a pH between 6 and 8. Therefore, neutralization is unnecessary. The remaining baths are biodegradable. During the one-bath scouring/bleaching process, the consumption of water and energy was even lower and the production time was shorter.

Dye-Surfactant Interactions Studied Using Job's Method:

Interactions between the anionic dye Acid Orange 7 and two cationic surfactants N- cetylpyridinium chloride (CPC1) and cetyltrimethylammonium bromide (CTMABr) in aqueous solutions far below the CMC are studied using the method of continuous variations, also called Jobs method. Light absorbance in the visible spectral range is measured. Both surfactants form stable associates with the acid dye. Jobs method is suitable for determining the stoichiometric composition and equilibrium association constants of the associates studied. The molar binding ratio of both surfactant/dye associates is 1:1. The calculated equilibrium constants are high (about 106), indicating strong interactions. From the constants calculated at different temperatures ( 15, 25, and 35°C), the corresponding thermodynamic functions ΔG 0, ΔH 0, and ΔS 0 are ob tained. We have concluded that strong interactions between cationic surfactants and anionic dyes are the result of attractions between oppositely charged ions combined with hydrophobic and dispersive forces.

Complete enzymatic pre-treatment of cotton fabric with incorporated bleach activator

The feasibility of a complete enzymatic one-bath pre-treatment of the cotton fabric at low temperature was investigated in this study. The cotton fabric was enzymatically desized, scoured and bleached with an enzyme mixture of starch-degrading enzymes, pectinases and glucose oxidases, respectively. Starch-degrading enzymes hydrolyzed the sizing agent into glucose. Glucose oxidases catalyzed the oxidation of β-D-glucose to D-glucono-ω-lactone and simultaneously generated hydrogen peroxide. The desizing and hydrogen peroxide generation each took one hour. For bleaching, hydrogen peroxide was converted into peracetic acid by incorporating the bleach activator tetra acetyl ethylene diamine (TAED). Bleaching took place at 50°C and neutral pH, where peracetic acid is most effective. Pectinases were added into the pre-treatment bath to remove pectins from fibers and improve their wettability. Whiteness values, water absorbency, polymerization degree and tenacity at maximum load were measured on pre-treated samples. The total organic carbon, pH and biodegradability were measured on residual pre-treatment baths. It was established that hydrogen peroxide can be efficiently enzymatically produced from the sizing agent and converted with TAED to form peracetic acid to bleach the cotton fabric. Cotton fabrics with a medium degree of whiteness, W = 51, and good water absorbency can be obtained at low water and energy consumption.

Impregnation and Exhaustion Bleaching of Cotton with Peracetic Acid

Cotton fabric was bleached with equilibrium peracetic acid in an exhaustion process and in cold pad-batch, hot pad-batch, and pad-steam bleaching processes. Exhaustion bleaching proceeded for 40 minutes at 60 °C and pH 7.5 with different concentrations of Persan S15 (peracetic acid produced by Belinka, Slovenia). Pad-batch processes were conducted with storage for different times at room temperature or at 60 °C. Two bleaching baths with 15 and 60 ml/l of Persan S15 were used for the impregnation processes. Pad-steam bleaching was also performed; the samples were steamed immediately after padding with bleaching solution or after cold/hot storage. The degree of whiteness achieved with elongation of storage time was measured. The influence of different bleaching conditions on damage to the cotton fabrics was evaluated by measurements of the degree of polymerization and the breaking strength of the fabrics. It was established that the achieved whiteness values depend on the concentration of the bleaching agent, temperature, and time of treatment. The exhaustion bleaching and both types of pad-batch bleaching with low concentration bleaching solution are very convenient processes for bleaching of cotton fabric with peracetic acid. The pad-steam process did not prove appropriate. The breaking strength of the fabric did not deteriorate remarkably with any of the processes, but the degree of polymerization of the fibers revealed that damage occurred at high concentrations of bleaching agent.Cotton fabric was bleached with equilibrium peracetic acid in an exhaustion process and in cold pad-batch, hot pad-batch, and pad-steam bleaching processes. Exhaustion bleaching proceeded for 40 minutes at 60 °C and pH 7.5 with different concentrations of Persan S15 (peracetic acid produced by Belinka, Slovenia). Pad-batch processes were conducted with storage for different times at room temperature or at 60 °C. Two bleaching baths with 15 and 60 ml/l of Persan S15 were used for the impregnation processes. Pad-steam bleaching was also performed; the samples were steamed immediately after padding with bleaching solution or after cold/hot storage. The degree of whiteness achieved with elongation of storage time was measured. The influence of different bleaching conditions on damage to the cotton fabrics was evaluated by measurements of the degree of polymerization and the breaking strength of the fabrics. It was established that the achieved whiteness values depend on the concentration of the bleaching agen...

Combined Bioscouring and Bleaching of Cotton Fibres

SUMMARY Cotton fibres were scoured with acid and alkaline pectinases and bleached with peracetic acid. Because of similar treatment conditions of both processes, they were combined in one bath as one-step and two-step processes. At the beginning of the treatments, pH 5 was set for acid pectinases and pH 8 for alkaline pectinases. To activate the peracetic acid, pH was also adjusted during the process. Tetrasodium pyrophosphate was added to improve the effects of bleaching and scouring. The highest CIE whiteness values and water absorbencies were obtained in a one-step process with alkaline pectinases and peracetic acid.

Low-temperature bleaching of cotton induced by glucose oxidase enzymes and hydrogen peroxide activators

Glucose oxidase enzymes were used to produce hydrogen peroxide from glucose and oxygen in aqueous solutions. Different working conditions, that is, temperature, aeration with liquefied air, presence of cotton fibre and time of enzyme activity, were tested in order to obtain a solution with the highest possible concentration of hydrogen peroxide. The hydrogen peroxide produced was transformed into different peracids which could bleach the cotton fabric under mild conditions, at a pH between 7 and 8 and at a temperature of around 60°C. The conversion or activation of hydrogen peroxide was conducted with the bleach activators TAED, NOBS and TBBC. The concentrations of hydrogen peroxide and peracids in the solutions were measured with sodium thiosulphate titrations. The results indicated that the formation of hydrogen peroxide with glucose oxidase was effective under optimal conditions, which are 50°C, pH 4.6 and aeration. Convenient activators for the conversion of hydrogen peroxide into peracids were TAED and TBBC, which enabled attainment of a relatively high degree of whiteness at pH 7.5 and temperature 50°C. Using the activator NOBS under these conditions did not provide enough peracid to markedly improve whiteness.

Low-temperature bleaching of knit fabric from regenerated bamboo fibers with different peracetic acid bleaching processes

The bleaching of textile fibers with peracetic acid (PAA) results in adequate whiteness at low temperature and neutral pH media. PAA can be added to the bleaching bath in the form of a commercial solution or can be produced in situ in the presence of hydrogen peroxide (H2O2) with the addition of a bleach activator, tetraacetylethylenediamine (TAED), or arylesterase enzymes. In the present study, a knit fabric from regenerated bamboo fibers was bleached with four different PAA bleaching processes: with only PAA, with PAA or H2O2 in combination with TAED, and with H2O2 in combination with arylesterase enzymes. The knit fabric was also bleached conventionally with H2O2 for comparison purposes. Whereas the conventional H2O2 process was carried out at 90℃ and in highly alkaline pH media, the bleaching processes with PAA were carried out at 65℃ and in neutral to slightly alkaline pH media. The bleaching processes with PAA have a strong whitening ability that is comparable to that of the conventional bleaching process with H2O2. The highest whiteness index of the bamboo knit fabrics bleached by different processes was measured after the bleaching process with PAA in combination with TAED (WI 71.2). Overall, with PAA bleaching processes, bamboo knit fabrics with a high degree of whiteness, high water absorbency, and high tenacity can be obtained with low water and energy consumption.

Enzymatic scouring and low-temperature bleaching of fabrics constructed from cotton, regenerated bamboo, poly(lactic acid), and soy protein fibers

In the present study, fabrics constructed from cotton, regenerated bamboo, poly(lactic acid), and soy protein fibers were scoured with pectinase enzymes, bleached with different bleaching processes using peracetic acid (PAA), and conventionally bleached with hydrogen peroxide (HP). The enzymatic scouring and bleaching with PAA have been chosen in order to minimize fiber damage and to perform the processes in more benign conditions. PAA was added to the bleaching bath in the form of a commercial solution or it was produced in situ in the presence of HP with the addition of a bleach activator, tetraacetylethylenediamine (TAED), or arylesterase enzymes. The conventional process was performed at 90 °C in highly alkaline pH media, and the bleaching processes with PAA were performed at 65 °C in neutral to slightly alkaline pH media. The results revealed that after the enzymatic scouring, the hydrophilicity of the fabrics is adequate. Compared with the cotton fibers, the regenerated bamboo and especially the poly(lactic) acid and soy protein fibers are significantly damaged during conventional HP bleaching. By contrast, bleaching with PAA revealed a strong whitening ability that is comparable to that of conventional bleaching with HP but with substantially reduced fiber damage.

Environmentally Sustainable Apparel Acquisition and Disposal Behaviours among Slovenian Consumers

Abstract Fibre production and textile processing comprise various industries that consume large amounts of energy and resources. Textiles are a largely untapped consumer commodity with a strong reuse and recycling potential, still fibres and fibre containing products ends up in landfill sites or in waste incinerators to a large extent. Reuse and recycle of waste clothing results in reduction in the environmental burden. Between 3% and 4% of the municipal solid waste stream in Slovenia is composed of apparel and textiles. This exploratory study examines consumer practices regarding purchase and the disposal of apparel in Slovenia. Data were collected through structured online survey from a representative random sample of 535 consumers. Responses to online questionnaire indicated the use of a variety of textile purchase and disposal methods. The influence of different sociodemographic variables on apparel purchase, disposal and recycling behaviour was examined. Moreover, the differences in the frequency of apparel recycling between consumers with and without an apparel bank available nearby were explored. This research was conducted, since it is crucial to analyse the means by which consumers are currently disposing their textile waste in order to plan the strategies that would encourage them to further reduce the amount of apparel sent to landfills.

Visual and Functional Properties of Digital Printed and Finished Anaglyph Pictures on Cotton Fabric

The aim of the study was to examine the infl uence of various protective fi nishes on the visual properties of anaglyph images and CMYK primary colours digitally printed on a cotton fabric. Using the impregnation process, one-component waterand oil-repellent, and fl ame retardant fi nishes, as well as their combination were subsequently applied on the printed samples. A visual evaluation was determined for the 3D visual eff ect of printed samples before and after the fi nishing, one and fi ve washings, and after seventy-two hours of exposure to artifi cial light. The colour fastness of prints after repeated washing, exposure to artifi cial light, dry and wet rubbing was determined. The repellence properties of studied fi nishes were studied by measuring the contact angles of water and n-hexadecane, while the vertical fl ammability test was used for the determination of fl ame retardancy. The wash fastness of the studied fi nishes was also taken into observation. The results showed that the presence of fi nishes changed the colour properties of prints; however, it did not impair the 3D eff ect of the anaglyph image, which was maintained even after repeated washings and exposure to artifi cial light. The presence of fi nishes improved the wash fastness of the M and Y colour, and impaired the wash fastness of the C and K colour. The light fastness of unfi nished printed samples was poor, but it improved for the M, Y and K colours after the application of fi nishes. The prints did not infl uence the functional repellent and fl ame retardant properties. However, the impaired wash fastness of fi nishes was observed.