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11.
Effects of plasma treatment on water sorption in viscose fibres
Miha Devetak, Nejc Skoporc, Martin Rigler, Zdenka Peršin, Irena Drevenšek Olenik, Martin Čopič, Karin Stana-Kleinschek, 2012, original scientific article

Abstract: We investigated water sorption in viscose nonwoven fibres manufactured by Tosama d.d. with the surface density of 175 g/m2. A comparison between untreated fibres and by oxygen plasma treated fibres was made using optical polarization microscopy. Plasma treatment was done for 10 minutes at pressure of 75 Pa at current of 250 mA at the power of 500 W. Swelling was characterized by measurements of fibre diameter. Modifications of intensity of the polarized light transmitted through the fibre were measured as a function of time of exposure to water. Characteristic swelling and intensity modification times were resolved for untreated and oxygen plasma treated fibres. The swelling time of oxygen plasma in comparison to untreated plasma is reduced by the factor of 0.54 and intensity change time by the factor of 0.4. From the characteristic swelling and intensity change times it was concluded that oxygen plasma treatment of viscose increases the speed of water sorption.
Keywords: plasma treatment, viscose, optical polarization microscopy
Published: 01.06.2012; Views: 939; Downloads: 29
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12.
The impact of corona modified fibres' chemical changes on wool dyeing
Darinka Fakin, Alenka Ojstršek, Sonja Čelan Benkovič, 2009, original scientific article

Abstract: The main contribution of the present work was to study the impact of Corona-treated wool fabricsć induced surface properties on dye-bath exhaustion, in order to optimize different dyeing systems. Firstly, the differing chemical aspects of a woven wool fabricćs surface were determined using two dissimilar analytical skills (XPS and polyelectrolyte titration). With the intention of establish the ability of low-temperature plasma treatment to change wool fibre morphology which could have an impact on sorption properties, fabrics were dyed with blue acid and blue metal-complex dyes, and dyeing behaviour were studied by means of on-line VIS spectrophotometry. Finally, dyed samples were colourimetricaly evaluated and colour differences calculated. The results provided evidence that the overall carbon C 1s content was decreased while oxygen and nitrogen atoms were increased when using ionized air for fabric modification. It has also been noted that the amount of positive-charged functional groups in various pH ranges are higher for Corona-treated wool fabric in comparison with the untreated that improves hydrophylity and dyeing properties.
Keywords: Corona treatment, wool, metal-complex dye, acid dye, sorption, colourimetry
Published: 01.06.2012; Views: 1199; Downloads: 59
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13.
Effect of testing temperature on corrosion behaviour of different heat treated stainless steels in the active-passive region
Mojca Slemnik, 2008, original scientific article

Abstract: Purpose - This paper aims to focus on the effects of temperature of the immersion media on the corrosion behaviour of differently heat-treated X20Cr13 stainless steel. Design/methodology/approach - Specimens, quenched on air, quenched in oil and quenched in oil and then tempered, were tested during exposure in 0.1?M H2SO4 at 30, 40 and 50°C. The results were interpreted on the base of potentiodynamic and impedance measurements. Findings - From the impedance spectra a reaction mechanism can be determined: after samples had reached and passed the active peak, expressed as the highestpeak on the potentiodynamic curve, corrosion products at interfaces, which were adsorbed at metal surface, led to an increase in the charge transfer resistance. Elevated temperature of immersion media has had appreciable influence on the corrosion rate and adsorption of products, but atthis temperature level did not affect the principle of corrosion reactions. Activation energies were calculated to exhibit temperature dependence of current density, which was the highest for the oil- and the lowest for the air-quenched sample. Originality/value - The paper provides further research on stainless steel, the corrosion behaviour of which can be controlled already by heat treatment.
Keywords: corrosion, stainless steel, heat treatment, temperature
Published: 01.06.2012; Views: 896; Downloads: 74
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14.
Case study of the sonochemical decolouration of textile azo dye Reactive Black 5
Simona Vajnhandl, Alenka Majcen Le Marechal, 2007, original scientific article

Abstract: The decolouration and mineralization of reactive dye C.I. Reactive Black 5, a well-known representative of non-biodegradable azo dyes, by means of ultrasonic irradiation at 20, 279 and 817 kHz has been investigated with emphasis on the effect of various parameters on decolouration and degradation efficiency. Characterization of the used ultrasound systems was performed using calorimetric measurements and oxidative species monitoring using Fricke and iodine dosimeter. Experiments were carried out with low frequency probe type, and a high-frequency plate type transducer at 50, 100 and 150 W of acoustic power and within the 5-300 mgžL initial dye concentration range. Decolouration, as well as radical production, increased with increasing frequency, acoustic power, and irradiation time. Any increase in initial dye concentration results in decreased decolouration rates. Sonochemical decolouration was substantially depressed by the addition of 2-methyl-2-propanol as a radical scavenger, which suggests radical-induced reactions in the solution. Acute toxicity to marine bacteria Vibrio fischeri was tested before and after ultrasound irradiation. Under the conditions employed in this study, no toxic compounds were detected after 6 h of irradiation. Mineralization of the dye was followed by TOC measurements. Relatively low degradation efficiency (50% after 6 h of treatment) indicates that ultrasound is rather inefficient in overall degradation, when used alone.
Keywords: textile industry, wastewater treatment, textile dyeing, reactive dyes, azo dyes, decoloration, ultrasound, degradation, decoloration kinetics, oxidizing species
Published: 01.06.2012; Views: 1276; Downloads: 57
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15.
Residual dyebath purification using a system of constructed wetland
Alenka Ojstršek, Darinka Fakin, Danijel Vrhovšek, 2007, original scientific article

Abstract: A constructed wetland model, comprising two different substrate mixtures, was used to purify textile dyebath wastewater. Three laboratory prepared wastewaters containing three commercial dyes of different classes and chemicalconstitution (one vat and two reactive dyes), different chemicals (NaOH, NaCl) and auxiliaries (migration inhibitor, sequestering, defoaming andwetting agents) were employed. Purifying efficiency was verified by measuring pollution parameters, such as absorbance, pH, total organic carbon (TOC), chemical oxygen demand (COD) and electrical conductivity (EC). It was found that the constructed wetland model reduced dye concentration by up to 70%, lowered the TOC and COD values up to 88%, electrical conductivity up to 60% and pH from 12 to 7.6.
Keywords: textile dyeing, reactive dyes, vat dyes, wastewater treatment, constructed wetland model, biological treatment, purification
Published: 01.06.2012; Views: 1188; Downloads: 56
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16.
Influence of magnetic field on the aragonite precipitation
Lucija Črepinšek-Lipuš, Danijela Urbancl, 2007, original scientific article

Abstract: Many laboratory investigations of magnetic water treatment (MWT) for scale control explained the formation of less compact scales by raised portion of aragonite, which is needle-like and less adhesive than rhombohedral calcite crystals, while our experiment was conducted with tap water, which contains Mg+2 and Fe+2 ions in concentrations exceeding thresholds for calcite inhibition, common for major tap waters. MWT efficiency was evaluated by amounts of scale precipitated in boilers and pipes during three-weeks run of two parallel experimental lines-one with and another without magnetic treatment. All scales were identified by X-ray diffractometer to be aragonite,but in the case of magnetic treatment, scales occurred in much smaller amounts: the scale on heating copper-pipe spiral was 2.5-times thinnerdue to MWT and in zinc-coated steel pipe occurred as very thin powder-like coating, while in the line without the treatment abundant hard lining was formed. The scalesć morphology was observed by scanning electron microscope: the husks from both lines consisted of parallel distributed needles, but these crystals were about four times thinner in the case of MWT. The present work demonstrates that hard scale deposits can form even under conditions where aragonite precipitates predominantly, and that MWT can also affect the crystallization of this polymorph in a manner conducive to scaling control.
Keywords: water, magnetic water treatment, scale, aragonite, cristallization, water supply pipes
Published: 01.06.2012; Views: 1221; Downloads: 64
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17.
X-ray study of pre-treated regenerated cellulose fibres
Majda Sfiligoj-Smole, Zdenka Peršin, Tatjana Kreže, Karin Stana-Kleinschek, Volker Ribitsch, Susanne Neumayer, 2003, original scientific article

Abstract: Regenerated cellulose fibres have had an important role to play in the man-made fibre field. The very special characteristics of different types of regenerated cellulose fibres, e.g. mechanical properties, sorption characteristics, and aesthetics were conditioned by the differences in their fine structure due to fibre formation processes. Additionally, the finishing processes could influence the fibre structure. A study was done of the crystalline structures of a solvent-spun cellulose fibre type (Lenzing Lyocell), made according to the NMMO process, and two conventional cellulosic fibre types, made by the viscose process (Lenzing Viscose and Lenzing Modal). The fibres were pre-treated (bleached and slack mercerised) and structural changes were followed by wide angle and small angle x-ray scattering (WAXS and SAXS), respectively. The periodical structure, determined by long spacing, was nearly the same in all the different types of fibres. A slight increase was observed after the treatment of viscose and modal fibres, but an unpronounced fall of a long period accompanied the pre-treatment of lyocell fibres. Some changes in crystallinity and crystalline orientation occurred due to the treatment conditions. The structural changes were correlated to the iodinesorption and mechanical properties.
Keywords: regenerated cellulose fibres, fibre structure, fibre properties, x-ray analysis, WAXS, SAXS, cellulose pre-treatment
Published: 01.06.2012; Views: 1227; Downloads: 50
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18.
Best available techniques for developing countries
Peter Glavič, 2003, published scientific conference contribution abstract

Keywords: environmental protection, cleaner technologies, waste oil treatment, Slovenia
Published: 01.06.2012; Views: 1289; Downloads: 10
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