In this paper, modelling of dyeing, i.e. adsorptive behaviour of disperse dyes on polyester fibres (dyeing), under the influence of ultrasound has been considered with the aim of getting the data about mechanisms of binding the dyes and defining the conditions of dyeing process of this synthetic fibres along with additional energy source without the use of carriers, compounds that increase permeability of the fibres and help dyeing. Dyeing - adsorption is conducted under different conditions, and the concentration of dyes, mass of the substrate, recipes and time of dyeing were being varied. It has been established that ultrasound allows dyeing without carriers and the efficiency of dyeing depends on the time of contact, initial concentration of the dye and the amount of absorbent - material. There is the continuity of growth of the amount of bound dye to the mass of the absorbent. Characteristic graphs, obtained from Langmuir isotherm, have confirmed that this model ensures precise description of polyester dyeing by disperse dye. Kinetic of dyeing has been remarkably interpreted by pseudo second-order in regards to the high functionality.
This article discusses the process of modification of the polyester knitted fabric as a prerequisite for successful dyeing at a lower temperature and without the presence of the carrier. The processing preceding dyeing, alkali-alcohol hydrolysis with ultrasound, changes the surface morphology causing the peeling and cracks on the surface of polyester fibres of the knitted fabric, decreases the mass and thickness of the knitted fabric, improves the sorption features, capillarity and absorption of water and soaking. The process of dyeing of the modified polyester knitted fabric in the presence of ultrasound at the lower temperature gives much better results than dyeing without ultrasound, and it is very close to the standard process of dyeing of a raw sample at the higher temperature. By increasing the concentration, the level of dye exhaustion per mass unit of the knitted fabric decreases. At the highest applied dye concentrations and the longest dyeing, the biggest dye adsorption happens.
Water pollution has already become a significant worldwide problem, especially in the textile dyeing industry. This paper describes decolorization of dye water modelled by textile dye wastewater. Decolorization was performed on an adsorbent made from physicochemically modified waste hemp fibers, obtained as a by-product from the production of ropes. The adsorbent is relatively dispersive and contains heterogeneous porous particles, with carbon as a dominant element. Obtained results have shown that the positive effect of adsorption directly depends on contact time, pH, temperature, and initial dye concentration. Dye concentration decreases in time, especially when the used concentration is the initial one. The effect of temperature below 40 ?C is not significant, but adsorption gets more intensive when performed at 60 ?C. The higher degree of decolorization is achieved at lower initial dye concentrations, although the highest initial dye concentration leads to higher dye adsorption. The experimental results of adsorption were described by using the Langmuir model. The maximum adsorption capacity ranges from 1.98 to 2.13 mg g-1 for linear and 2.03 to 2.12 mg g-1 for nonlinear form.
This article discusses the process of polyester dyeing through the modelling process, i.e. the ability of adsorption of dyes for chemically modifi ed polyester fi bres of knitted fabrics in aqueous environment in the presence of ultrasound waves, at lower temperature and without carrier. Previous processing before dyeing, i.e. the alkali-alcohol hydrolysis with ultrasound, changes the surface morphology, decreases the mass and thickness of knitted fabric, improves the sorption features, capillarity and absorption of water, and wetting. The process of dyeing a modifi ed polyester knitted fabric in the presence of ultrasound at lower temperature gives much better results than dyeing without ultrasound and it is very close to the standard process of dyeing a raw sample at higher temperature. By modelling the system, it has been found that the Freundlich non-linear and linear isotherm are the most effi cient in simulating the isothermal adsorption of disperse dye on polyester knitted fabric, whereas Langmuir and Nernst give weaker results.
The study deals with modeling of linen fabric dyeing after previous scouring and bleaching. The results reveal the process of the direct dye adsorption on the fabric, as well as the capacity and energy of adsorption based on which the optimization of the dyeing process with maximum performance and minimal costs can be done. With the increase of the dye concentration during dyeing, the degree of exhaustion decreases while the longer dyeing time gives a higher degree of dye exhaustion. Variation in the adsorbed amount of adsorbate increases with the increased initial concentration and time, i.e. a bigger amount of the dye or a longer time period of dyeing causes a bigger quantity of the adsorbed dye per mass unit of the linen fabric. The advantage in results processing is given to Freundlich-s model since the maximal value of the determination coefficient can be obtained.
This research work describes the advantages of dyeing wool fibers at 60 °C after pre-treatment with alcohol. Wool is a natural fiber. This fiber can be dyed with acid, metal-complex and other dyes. Acid dyes should be soluble in water and most commonly used for dyeing wool, silk and nylon. Wool fibers with 100 % chemical composition were used in this study. The wool fiber was pre-treated in alcohol (npentanol) at a temperature of 60 °C for 30 minutes. Pre-treated wool fibers were dyed with Supramin Blau acid dye. The time for dyeing samples of wool fibers was 5, 10, 20, 30, 40, 50 and 60 minutes. The process of dyeing wool fibers with acid dye at 60 °C showed a higher degree of exhaustion and adsorption capacity when wool was pre-treated with n-pentanol compared to wool that was not pre-treated with n-pentanol. A constant increase in the degree of dye exhaustion on the pretreated wool fiber was observed during the increase in initial dye concentration. A longer dyeing time for pre-treated wool results in a higher degree of dye exhaustion. Models Weber-Morris and Elovich are applicable for describing the adsorption flow because there is very little scatter around the ideal curve, so functional straight lines cover most points very well.
The results of the research on the ability of adsorption of dye on polyester fibers at a temperature of 98?C are presented in this paper. The fibers were previously modified in aqueous solutions of NaOH, KOH or Al(OH)3. Typically, the dyeing of the fibers takes place at high temperatures and under pressure in the presence of the carrier. Previous processing before adsorption-dyeing, alkali hydrolysis, changes the surface morphology of polyester fibers. Based on dye exhaustion results, it was found that the dye adsorption on modified polyester fibers (degree of exhaustion 18.2 %, for a dye concentration of 200 mg?dm-3 and adsorption time of 5 min) has been bigger than adsorption to unmodified fibers (degree of exhaustion 10 %, for a dye concentration of 200 mg?dm-3 and adsorption time of 5 min). The five-parameter nonlinear model of Fritz-Schlunder is the most efficient in simulating isothermal adsorption of disperse dye on polyester fibers (the correlation coefficient is 0.995). Other adsorption models, Dubinin-Radushkevich, Marczewski-Jaroniec and Hill give poorer results and cannot be used to explain the adsorption of the disperse dye for polyester fibers (the correlation coefficients are 0.891, 0.922 and 0.973, respectively).
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