Dyeing mechanism and photodegradation kinetics of gardenia yellow natural colorant

In this study, gardenia yellow solution is used to dye 100% cotton fabric. The dyeing rate curve and adsorption isotherms were recorded to explore the thermodynamic model and to calculate the corresponding parameters. A definite concentration of gardenia yellow solution was placed under the xenon arc lamp for irradiation to test its photodegradability. Absorbance of the solution was measured at different degradation times and the corresponding varying curve of the absorbance was drawn to explore the photodegradation reaction order of the natural colorant and consistent parameters were calculated. The experimental results proved that the dyeing of cotton fabric with gardenia yellow colorant followed the pseudo second order kinetic model whereas adsorption isotherm followed the Langmuir model and the photodegradation process followed the second order kinetic model. Values of different parameters were calculated: reaction rate constant k = 2.26 × 10–3 (mg · L−1)1−m h−1, the correlation coefficient R2 = 0.994, and half decay time t1/2 = 5.82 h.

Preparation and Characterization of Dyed Corn Straw by Acid Red GR and Active Brilliant X-3B Dyes

Corn straw is a kind of biomass material with huge reserves, which can be used in plate processing, handicraft manufacturing, indoor decoration, and other fields. To investigate the dyeing mechanism of corn straw with different dyes, corn straw was pretreated and dyed with Acid Red GR and Brilliant Red X-3B. The dyeing properties and light resistance of the two dyes were analyzed by dyeing rate, photochromaticity, FTIR, SEM, and water-washing firmness. The results showed that the structure and stability of the dyes were the main factors which influenced fading. A bleaching pretreatment could remove the waxiness of the corn straw epidermis and increase the porosity on the surface of the straw, which accelerated the photochromic coloring of the corn straw skin. The corn straw dyed with both dyes had good light resistance, but the straw dyed with Reactive Brilliant Red X-3B had higher dyeing rate, brighter color, and higher photochromaticity than the straw dyed with Acid Red GR. FTIR and water-washing firmness showed that Acid Red GR mainly bound to lignin, while Reactive Brilliant Red X-3B mainly bound to cellulose, hemicellulose, and lignin in corn straw through covalent bonds, which increased the coloring rate.

Dyeing Kinetics of Collagen Modified PAN Fiber

PAN fiber is one that contains at least 85% by mass of acrylonitrile co-monomer in the polymer chain. It has low moisture-absorbency and electrostatic tendency. The moisture regain of collagen modified PAN fiber is increased. Dyeing kinetics of collagen modified PAN fiber was studied using Cationic Red X-GRL dyes, including dyeing rate curve, equilibrium dyeing uptake, half dyeing time, dyeing rate constant and diffusion coefficient. The results show that: compared with PAN fiber, the equilibrium dye uptake decreased, half dyeing time, dyeing rate constant and diffusion coefficient reduced, and the dyeing behavior of collagen modified PAN fiber become worse than that of PAN fiber.

Dyeing of Silk with Anthocyanins Dyes Extract from Liriope platyphylla Fruits

A new source of natural anthocyanins dyes, from Liriope platyphylla fruit, is proposed. This paper analyzes the dye extracts, the primary color components of the extracts, the color features of the extracts under different pH conditions, and their application in silk dyeing. The research shows that, nine anthocyanins are found in L. platyphylla fruits by analyzing the results of the HPLC/DAD, MS, and MS/MS spectra. The five major anthocyanins related to delphinidin, petunidin, and malvidin derivatives take up 91.72% of total anthocyanin contents. The color of the solution is red under acidic condition (pH < 3.0) and stays in yellow under alkaline condition with pH values above 7.0. The dye extracts applied to silk fabric with mordant free dyeing show different color under different pH conditions, changing between purple, blue, green, and yellow. However, the dyed colors is light and the dyeing rate is low. Metal mordant such as Sn in chelation enhances the dye depth and improves the fastness of the dyed silk fabrics, especially in silk fabrics dyed by premordanting and metamordanting.

Kinetics and Thermodynamics Studies of Monascus Red Dyeing on Wool

The mechanism of monascus red pigment dye on wool fiber was studied by analyzing of dyeing kinetics and thermodynamics. The results showed that the dyeing rate is quite high at the beginning of dyeing at 70°C-100°C.The diffusion coefficient rise while half-dyeing time decrease With the temperature rise. Its adsorption accords with the combination of Nernst and Langmuir adsorption model. Its enthalpy and entropy of dyeing was 15.21kJ/mol and 46.87J / (mol·K) respectively, which show that wool dyeing with monascus red is a endothermic process. This theoretical is useful to built dyeing process for wool fiber with monascus red.

Research of Salt-Free Dyeing of Reactive Dyes on Chitosan Quaternary Ammonium Salt Treated Bombyx mori Silk Fabric

Chitosan quaternary ammonium salt (short for HTCC) was a strong cationic water-soluble polymer. The bombyx Mori silk fabric was treated by HTCC solution and the salt-free reactive dyeing process and properties of modified silk fabric were investigated in this paper. The results showed that salt-free dyeing effect of silk fabric treated with Cibacron Blue FN-G was better when HTCC concentration was 8g/L, the processing temperature was 60°C and the processing time was 35min; the optimum salt-free reactive dyeing process of silk fabric treated by HTCC was: dyeing pH was 8.0, dyeing temperature was 90°C and dyeing time was 70 min; HTCC had obviously promoted dyeing effect, after salt-free dyeing, the dyeing rate, the color fixing rate and the dyeing depth of silk fabric modified by HTCC solution were all increased obviously, and the washing fastness and rubbing fastness were both improved slightly; the smaller molecular weight of chitosan was used to modify to HTCC, the higher dyeing rate and color fixing rate of the treated silk fabric were obtained.

Plasma Modification of Kapok Fiber and its Properties

Kapok fiber has a unique large thin-walled hollow structure, lightweight and water repellent oil of excellent features, and is not yet fully exploited the small breed natural fibers. In the development process of the use of kapok fiber, there is a problem of dyeing, finishing, dyeing rate, dyeing and poor. Plasma processing technique is a modification to the fiber surface, non-polluting promising new technologies and has energy efficient. The research kapok fiber after plasma surface modification, found kapok modified staining rate has been significantly improved absorbent; Modified kapok fiber mechanical properties are not changed significantly; While exploring the plasma modified kapok fiber optimum.

Influence of Chitosan Finishing on Dyeing Effect

Treatment methods of silk fabric with chitosan and the dyeing of tussah silk fabric on low-salt condition were the subject of this study. The different treatment methods were used to find the influence of treatment methods on the dye ability. It was clear from the results that the color depth of the dyed fabric, the fixation ratio and dyeing rate of reactive dyes on silk fabric could be improved efficiently by the crosslinkling after the fabric was treated with chitosan.The optimal concentration of chitosan was 0.7% (w/v). The finishing effect of pretreatment was the best and the effect of post treatment was better than simultaneous treatment. The salt concentration could be reduced when the fabrics were treated with chitosan, but the degree of salt concentration reduction was not obvious.