Acid Dyebath Research Articles

Adsorption kinetics and thermodynamics of metal complex acid dyes on silk fabric

This study reports the adsorption phenomena of metal complex acid dyes onto silk fabric. Two commercial metal complex acid dyes namely Bestalan Yellow SF and Bestalan Navy SF were adsorbed onto degummed silk fabric. The functional properties and surface morphology of silk fabric were investigated with FT-IR spectroscopy and FE-SEM respectively. The typical absorption band of C = O stretching was found at 1620 cm−1 indicating amide I structure and C-N stretching as well as N-H bending vibrations were observed at 1510 cm−1 suggesting the β-sheet crystallites of amide I and amide II silk proteins. The effectiveness of degumming performance was confirmed by SEM images. The adsorption of dyes by silk fabric was investigated with respect to pH, initial dye bath concentration, and contact time. It was found that the adsorption of dye onto silk fabric was highly influenced by the dye bath pH, initial dye concentration, and contact time. The higher dye adsorption was observed at acidic dye bath condition (pH = 3.5). The adsorption of dye was also increased with the increase of the initial dye bath concentration. The dyes adsorption reached at equilibrium condition after 80 min. The adsorption isotherm and kinetics were also evaluated based on the experimental results. The adsorption pattern fitted well to the Langmuir adsorption isotherm with high correlation coefficient (R 2>0.97) for both dyes. The kinetic parameters suggested that the pseudo-second-order model is more suitable compare to the pseudo-first-order model considering the higher regression coefficients ( R 2 = ∼ 0.99 ) . The maximum adsorption of Bestalan Yellow SF and Bestalan Navy SF was found to be 232.5 and 222.2 mg/g respectively. The thermodynamic data were studied at 25, 40 and 60 °C. The change of Gibbs free energy of the system was positive indicating the spontaneous nature of the adsorption. The values of ΔH (-4.68 kJ/mole −3.65 kJ/mole) suggested the exothermic environment and the negative values of ΔS (-0.035 and −0.034 kJ/mole/k) advocated the good interaction between the metal complex acid dyes and silk fabric. The Langmuir adsorption model and pseudo-second-order kinetic suggested that the dyeing of metal complex acid dyes on silk fabric was controlled by ion-exchange chemical reaction.

Effect of dye bath pH in dyeing of cotton knitted fabric with reactive dye (Remazol Yellow RR) in exhaust method: impact on color strength, chromatic values and fastness properties

The significance of textile coloration is inevitable as coloration is a critical process and it can be affected by several parameters i. e. time, temperature, pH, and liquor ratio (M:L). This research reveals the behavior of different dye bath pH (2 to 12) on the basis of spectrophotometric characteristics and colorfastness using the most useable brand of reactive dye in Bangladesh i. e. Remazol Yellow RR. Earlier researches were performed on the basis of other coloration controlling factors i. e. temperature, time and liquor ratio (M:L) where pH acts as the dependent variable. However in this study, pH was taken as an independent variable where lower pH (2, 4 and 6), medium pH (8 and 10) and higher pH (12) were taken into consideration for verifying the dyeing performance. Meanwhile, the mentioned pH was achieved by adding acetic acid, soda ash and caustic soda respectively. In this study, the impact of pH is analyzed on the basis of color strength, chromaticity, hue angle, CIELAB color space, spectrophotometric image, reflectance percentage and color fastness tests i. e color fastness to rubbing, color fastness to wash, color fastness to perspiration, color fastness to light. Gradually elevated pH boosts up the color strength and chromaticity, at the same time downgrades of hue angle results orangish tone in the dyed fabric. Even more, the lightness of dyed fabric decreases and redness rises with the increment of dyebath pH which results in orangish red darker tone of dyed fabric. Consequently, fabric dyed at acidic dye bath pH exhibits higher resistance in case of color change and color staining from the dyed fabric and multifiber fabric respectively and vice versa.

Studies on Dyeing Parameters of Colourants Extracted from Camellia sinensis

Wool and silk fibres have been effectively dyed with an aqueous extract of C. sinensis from an acidic dye bath (pH ~ 4.0). Methanol extract of the dye has been used for measuring different kinetic and thermodynamic parameters. The results indicate that the dye has an affinity for wool and silk. The standard affinity value of C. sinensis for wool fibre is greater than that for the silk fibre and it increases with the increase in temperature. Rate of dyeing for wool is lower as compared to that of silk. Studies on adsorption isotherm indicate that this dye is adsorbed on protein fibres chiefly following Langmuir adsorption mechanism.

Microwave-assisted sustainable dyeing of wool fabric using cochineal-based carminic acid as natural colorant

ABSTRACTThe revival of natural dyes in textiles is gaining popularity due to their sustainable nature. The current study has been undertaken to improve the dyeing behaviors of cochineal-based natural dye (carminic acid) for wool dyeing under the influence of microwave treatment. For the purpose, wool fabric and extract obtained from cochineal insects (Dactylopius coccus costa) were irradiated for 1–6 min. The nature of dye bath (pH) and dyeing temperature were optimized using optimal irradiation conditions. To make dyeing process more sustainable and eco-friendly, bio-mordants and chemical mordants have been employed at optimal conditions. It is found that microwave treatment of extraction for 5 min is suitable to get darker shades with acceptable color characteristics using unirradiated wool fabric. K/S was found using acidic dye bath of cochineal insect of pH 1 for dyeing unirradiated fabric at 70°C using acidic extract of Cochineal bugs. Suggested ISO standards for color fastness revealed that 5% of henna and 3% pomegranate as bio-mordant have not only given high color depth but also rated excellent fastness properties as compared to chemical mordants used. It is found that MW treatment has not only improved the dyeing behavior of carminic acid but also enhanced the color characteristics.

Eco-friendly salt-free reactive dyeing of cotton (muslin) fabric after cationization with amino acid from soya

Bleached cotton fabric was chemically modified (cationized)with natural amino acids extract obtained by acid hydrolysis (6N HCL) from soya bean seed waste, adding MgCl2 as an acid donor in the pad-dry-calendaring process to investigate the changes in textile properties and its dyeability with reactive dye in both a conventional alkaline dye bath and salt-free acidic dye bath. This modified cotton incorporates new functional groups producing [Formula: see text] in acid bath to obtain cationized cotton, rendering it to eco-friendly salt-free reactive dyeing at acceptable shade depth without much sacrifice of other textile-related properties. Bi-functional high exhaustion-type reactive dye shows better dye uptake than mono-functional cold brand as well as hot brand reactive dye. Moreover, the application of a specific dye fixing agent further improves surface color depth ( K/ S) of the soya-modified cotton fabric. The study of surface morphology of said chemically modified cotton substrate indicates a higher degree of surface deposition, that is, more anchorage of soya extracted amino acids on cotton fabric. Chemical anchorage as per the reaction scheme postulated for such modifications is verified with Fourier transform infrared spectroscopy. Finally, it is revealed that cotton treated with soya extract provides a new route of eco-friendly salt-free reactive dyeing with high exhaustion-type reactive dyes showing much higher dye uptake than the control cotton fabric.

Advanced treatment of spent acid dyebath and reuse of water, salt and surfactant therein

Abstract In this research, a facile process combined chitosan adsorption and UV-Fenton advanced oxidation process (CAAOP) has been developed for the treatment and reuse of spent acid dyebaths. The acid dyes in the spent dyebaths are completely removed through the adsorption column filled with chitosan, while most of sodium sulphate and Peregal O-25 (nonionic organic surfactant) can pass through the adsorption column with the water. Although the resulting recycled spent acid dyebaths are reused over ten times as new dyebaths for dyeing with C.I. Acid Red 1, the changes of the color differences and the relative unlevelness properties on dyed fabrics are still remained within the acceptable levels. That is also true for the other shade dye, namely C.I. Acid Yellow 11, in the 11th recycling cycle. As a result, an average saving of 87.4%, 91.7% and 50.1% for water, sodium sulphate and Peregal O-25, respectively, is achieved with the reuse process for the total eleven dyebaths. The exhausted chitosan can be easily recovered by dilute alkali as a desorbing agent, and the emissions from the two eluted concentrates treated with UV-Fenton are found to meet the most stringent emission standards for both COD and color in China. Results reveal that CAAOP is a promising process for the treatment and reuse of textile dyeing wastewaters, which can benefit the environment and reduce the operating cost.

Parmotrema austrosinence(지의류)를 이용한 직물염색과 키토산 처리에 의한 염색성 향상

국내에서 자라는 지의류의 한 종류인 Parmotrema austrosinence를 채취하여 염액을 제조하고, 제조된 염액을 사용하여 견직물, 나일론직물과 면직물을 염색하였다. Parmotrema austrosinence를 암모니아수에 넣고 발효시켜 얻은 염액을 사용하여 pH를 4, 7, 10으로, 염색온도를 <TEX>$30^{\circ}C$</TEX>, <TEX>50^{\circ}C$</TEX>, <TEX>$80^{\circ}C$</TEX>로 각각 조절한 후 염색을 하였다. 면직물은 견직물과 나일론직물에 비해 염색성이 낮게 나타났다. 면직물의 염색성 향상을 위해 키토산 액으로 처리하고 염색성과 염색견뢰도의 변화를 검토하였다. 염색된 시료들의 염색성은 K/S값, <TEX>${\Delta}E$</TEX>와 Munsell값을 측정하여 평가하였다. 염색된 시료들의 K/S값은 견직물의 경우에는 520nm에서, 나일론직물과 면직물은 480nm에서 최대 흡광파장을 나타냈다. 견직물 염색포의 K/S값은 <TEX>$4.6{\sim}9.3$</TEX>으로 <TEX>$1.0{\sim}2.7$</TEX>인 나일론직물이나 <TEX>$0.8{\sim}1.6$</TEX>인 면직물에 비해 매우 높게 나타나 견직물이 Parmotrema austrosinence 염액에 대해 우수한 염색성을 가짐을 확인하였다. 염색온도가 높아질수록 먼셀 색상값이 red나 yellow red에서 yellow쪽으로 이동하는 색상변화가 나타났다. 견직물의 경우, 염색온도가 <TEX>$50^{\circ}C$</TEX>와 <TEX>$80^{\circ}C$</TEX>일 때의 염색성이 비슷하였으며, 다른 직물의 경우에는 염색온도 상승에 따라 K/S값도 높아졌다. 따라서 지의류를 사용한 적정 염색온도는 견직물의 경우 <TEX>$50^{\circ}C$</TEX>, 다른 직물의 경우 <TEX>$80^{\circ}C$</TEX>임을 확인하였다. 염색된 시료의 먼셀 색상은 견직물에서는 R(red) 영역에서, 나일론 직물에서는 YR(yellow red)-R 영역에서, 면직물은 YR 영역으로 나타났다. 면직물과 나일론직물은 중성 또는 산성염액에서 염색이 잘 되었고, 견직물의 경우는 중성 염액에서의 염색성이 가장 우수하였다. 염색성이 낮게 나타난 면직물은 키토산 가공에 의해 염색성과 염색견뢰도를 향상시킬 수 있음을 확인하였다 염색된 시료들의 일광견뢰도와 세탁견뢰도는 대체로 낮게 나타났으나 드라이크리닝 견뢰도는 4-5급 또는 5급으로 모두 우수하였다. Three fabrics, 100% silk, nylon and cotton each, were dyed with a lichen dye solution prepared by a fermentation method under conditions of varying dyebath pH and temperature. To verify the effect of chitosan on fabric dyeing, the 100% cotton fabric was treated with a chitosan solution before dyeing. The K/S, CIE <TEX>$L^*$</TEX>, <TEX>$a^*$</TEX>, <TEX>$b^*$</TEX>, <TEX>${\Delta}E$</TEX> and Munsell values of the dyed samples were measured. Colorfastness of each sample was also investigated. The maximum K/S value was measured at 520nm wavelength for the dyed silk fabric and at 480nm for the dyed cotton and nylon. The K/S values for the dyed silk fabric were much greater than those of the other fabrics. The dyed silk fabric showed a red tone on the Munsell color system, and the dyed nylon and cotton fabrics a yellowish red tone. Dye affinity to fabrics was better in a neutral or acidic dyebath. As dyeing temperature increased, K/S values increased for the dyed nylon and cotton fabrics but not for the silk. Dyeability of cotton fabrics could improve by Chitosan treatment. As for most natural dyes, colorfastness of all dyed samples was poor. The silk fabric showed an excellent dry cleaning fastness of Grade 5.

Effect of Operating Parameters on the Electrocoagulation of Simulated Acid Dyebath Effluent

The present study investigates the influence of operating parameters (electrolyte concentration, applied electrical current, initial reaction pH) on color and COD removals from a simulated acid dyebath effluent employing electrocoagulation with aluminum (Al) and stainless steel (SS) electrodes. Our results indicated that almost complete (100% for EC with SS electrodes) color and partial (around 50% for EC with SS electrodes) COD removal could be achieved via electrocoagulation using Al as well as SS electrodes once working conditions were optimized. The study also revealed that electrocoagulation with SS electrodes was more attractive both in terms of treatment performance as well as electrical energy and sludge handling costs; the electrical energy requirement and sludge production rate were 17 kWh/(m 3 wastewater) and 8200 g/(m 3 wastewater) for electrocoagulation with Al electrodes, instead of 8 kWh/(m 3 wastewater) and 700 g/(m 3 wastewater) for electrocoagulation with SS electrodes to achieve the same treatment efficiency.

Effect of Fenton's treatment on the biodegradability of chromium-complex azo dyes

Pretreatment of an acid dyebath effluent bearing a new generation chromium complex azo dyestuff (C0 = 350 mg/L) with Fenton's reagent was investigated. Preliminary optimisation (baseline) experiments were conducted to determine the Fe2+, H2O2 concentrations and pH required to the highest possible COD and colour removals. Kinetic studies were carried out at varying temperatures (20 degrees C < T < 70 degrees C) to establish a relationship between COD abatement and H2O2 consumption. The activation energy found for catalytic H2O2 decomposition (Ea = 9.8 kJ/mol) appeared to be significantly less than that of fermentative (Ea = 23 kJ/mol) and of thermal (Ea = 76 kJ/mol) H2O2 decomposition, implying that H2O2 decomposition during the Fenton's reaction occurs more spontaneously. The experimental studies indicated that approximately 30% COD and complete colour removal could be achieved under optimised Fenton pretreatment conditions (Fe2+ = 2 mM; H2O2 = 30 mM; pH = 3; at T = 60 degrees C). Long-term activated sludge experiments revealed that although the raw and pretreated acid dyebath effluent contained practically the same amount of "readily biodegradable" COD (inert COD fraction < or = 10%), biodegradation of the chemically pretreated acid dye effluent proceeded appreciably faster than that of the untreated acid dyebath effluent.

Potential of a Pycnoporus sanguineus laccase in bioremediation of wastewater and kinetic activation in the presence of an anthraquinonic acid dye

In the frame of the development of a bioprocess using the competences of White Rot Fungi to decolourise and detoxify dye contaminated effluents, laccases were produced by the strain Pycnoporus sanguineus MUCL 41582 in a malt extract medium. Two isoenzymes were detected among which LAC-1 was concentrated. A survey of the composition of industrial effluents showed that wastewaters from textile industry usually contain high concentrations of Na 2SO 4 or NaCl. Regarding the activity profile of the biocatalyst against pH, salts, temperature and target substrates, LAC-1 appears to be a good candidate for application in acid dye bath treatments. Studying the model anthraquinonic dye ABu62 decolourisation, we proved that this dye was a good substrate for LAC-1. Furthermore, unusual kinetic behaviour was observed suggesting that LAC-1 was activated in presence of ABu62. On the contrary, a classical Michaelis-Menten behaviour was observed for the oxidation of ABTS and LAC-1 showed a high affinity for this substrate as compared to data available for other laccases. To our knowledge, this is the first report showing this atypical behaviour of a laccase in the presence of dyes.

Reclamation of acid dye bath wastewater: Effect of pH on nanofiltration performance

This paper describes the effect of pH on the selection of the best treatment scheme for the reclamation of acid dye bath wastewaters (ADBW) of carpet manufacturing industry. ADBW, having acidic pH (5.0–5.9) originally, was subjected to pre-filtration through 1.0 μm microfiltration (MF) media prior to nanofiltration (NF). Three treatment alternatives were adopted: (1) single NF without pH neutralization; (2) sequential NF without pH neutralization; (3) single NF with pH neutralization. Color was removed completely and turbidity was rejected by 79–92% in all alternatives. However, COD, total solids, total hardness and conductivity were partially removed in single NF without pH neutralization. The inadequate rejection of pollutants lead to the implementation of sequential NF consisting of three stages, where COD rejection increased from 55%–77% to 94% at the end of the third stage. Finally, the wastewater pH was neutralized by adjusting to 7.0, which provided COD rejection efficiency as high as 97% in single NF. The flux decline in single NF at acidic pH was 14–23%. In sequential NF, the flux decline decreased from 21% to 9% in three stages. The flux declines increased up to 25% due to pH neutralization, however chemical cleaning was found to be effective in restoring the fluxes. Besides, the main cause of flux decline, which was fouling at acidic pH became concentration polarization at neutral pH. Therefore, the best treatment scheme for the recovery of ADBW came out to be single NF with pH neutralization preceded by 1.0 μm MF. These results revealed that pH is an important operational parameter affecting the selection of the best treatment scheme for ADBW.

Membrane based strategies for the pre-treatment of acid dye bath wastewaters

This paper, as part of a study carried out for the recovery of the acid dye bath wastewaters of a carpet manufacturing industry by membrane processes, describes the evaluation of alternative strategies for the pre-treatment of acid dye bath wastewaters. Dead-end microfiltration (MF) simulating sand filtration with MF media having pore sizes of 2.5, 1.0, 0.45 and 0.2 μm and ultrafiltration (UF) with an UF membrane having a molecular weight cut off (MWCO) of 50,000 Da were tested in single and sequential stages in order to achieve the best treatment efficiency. Four alternative process trains were tested; single MF, sequential MF, single UF, and MF followed by UF. For both MF and UF, application of sequential filtration did not provide any significant benefit over single processes. In addition, chemical oxygen demand (COD) removal performance of all the alternative processes was similar where the highest removal was only 5%. On the other hand, color removals were much better; ranging from 15 to 100%, even with single MF. Comparison of all the process alternatives revealed that, single MF (0.45 μm), as the simplest process, is the most suitable pre-treatment method for the acid dye bath wastewaters.

Acid dyebath effluent pretreatment using Fenton's reagent: Process optimization, reaction kinetics and effects on acute toxicity

Fenton's reagent (Fe 2+/H 2O 2) is known as one of the most effective and most often employed advanced oxidation process (AOPs) for the treatment of textile dyes and dyehouse effluent. In the present study, a synthetic acid dyebath effluent (SADB) bearing two azo and one anthraquinone dye together with two dye auxiliaries was subjected to pretreatment with Fenton's reagent. Firstly, initial Fe 2+ and H 2O 2 concentrations as well as pH were optimized to achieve highest COD and color removals during Fenton's treatment of SADB. In the second stage of the experimental work, kinetic studies were conducted to elucidate the effect of operating temperature (20 °C < T < 60 °C) on COD, color abatement and H 2O 2 consumption kinetics. Obtained results indicated that 30% COD and practically complete color removal (99%) could be achieved at T = 50 °C. The kinetic studies revealed that a strong correlation existed between COD removal and H 2O 2 utilization rates. In the final part of the study, the acute toxicity of raw (untreated) and pretreated SADB on heterotrophic biomass was investigated employing a modified (COD-balanced), activated sludge inhibition test. The toxicity experiments demonstrated that the inhibitory effect of SADB towards sewage sludge could be completely eliminated when the effluent was pretreated with Fenton's reagent.

Reduction of colorants in nylon flock dyeing effluent

The batch dyeing of fiber materials such as staple fibers and flock is usually carried out by exhaustion methods. However, the dyeing of flock fibers, either nylon, PET or acetate, with acid or disperse dyes is not 100% efficient in terms of dye utilization. Therefore, the remaining dyes in the spent dye bath are generally not reused, and are usually discharged with minimum treatment, together with the dyeing chemicals into the sewage wastewater system causing environmental pollution. We found that the colorants and chemical auxiliaries in the fiber dyeing effluents can be reduced by: (1) optimizing the acid dyeing conditions such as salt addition and pH control; (2) reuse of the spent dye bath that remain after the original dyeing process. In the lab scale trials, we have successfully raised the acid dye exhaustion to over 90% by optimizing the dyeing conditions. The reuse of the spent acid dye bath also showed promising results with dye exhaustion ranging from 91 to 93% after four times of reuse.

PH control for dyeing polyamide in a reused acid dyebath

The pH control that can be achieved in a reused dyebath was investigated. The study involved a phosphate buffer system and four pH sliding systems, including ammonium sulphate and three hydrolysable organic esters. Instead of discharging the dyebath after each dyeing cycle, the residual dyebath was analysed using a UV‐Vis spectrophotometer and reconstituted to the required concentration of dyes, auxiliaries and acid donors. The dyebath was reused for 10 cycles and colour reproducibility, levelness and fastness of the dyed samples were measured after each recycling. In comparison with ammonium sulphate and sodium dihydrogen phosphate, hydrolysable organic esters gave a stable and effective pH shifting in the dyebath reuse system. In addition, hydrolysable organic esters resulted in a very low amount of salt in residual dyebath. No deterioration in colour fastness of the dyed fabrics over 10 cycles of dyebath reuse was evident.

Water Reclamation in the Textile Industry: Nanofiltration of Dye Baths for Wool Dyeing

The textile industry is a large water consumer: dyeing, rinsing, and follow-up treatment of textiles use large amounts of freshwater. As regulations become more and more stringent and the cost of freshwater increases, reclamation of wastewater becomes more and more attractive. This paper explores the possibility of using nanofiltration to improve the wastewater quality to the standards that are used for the dyeing of wool. Four different samples from the wastewater treatment sequence of a textile factory were filtrated with three different nanofiltration membranes (NF70, UTC-20, and NTR 7450). The samples were a used and untreated metal complex dye bath, a used and untreated acid dye bath, a sample from the storage tank (containing a diluted mixture of the previous baths), and the effluent of the biological treatment. Nanofiltration was possible for all samples, but the biologically treated dye baths showed a more efficient color removal. For direct nanofiltration of used dye baths, two membrane passages...

Acid‐dyeable acrylic fibres copolymerised with amino alkyl methacrylates for differential cross‐dyeing

The equilibrium adsorption of acid dyes on acrylic fibres copolymerised with dimethyl amino ethyl methacrylate has been investigated. A typical characteristic of this type of fibre is its excellent stable dyeability over a wide pH range. This is due to the strong basicity of alkylamino groups in the copolymerised component, which makes it possible to dye the fibre thoroughly even in a weakly acidic dyebath using a normal dyeing processes of acrylic fibre with cationic dye. Consequently it is useful for differential cross‐dyeing in a single dyebath.

Synthesis and properties of disazo dyes derived from 4-amino-2′-nitrodiphenylamine

A series of black and navy-blue disazo acid dyes, derived from 4-amino-2′-nitrodiphenylamine and 1- N-phenylaminonaphthalene-8-sulphonic acid, were synthesized. The dyes were suitable for dyeing polyamide fibres and wool from a weakly acidic dyebath without electrolytes. Spectroscopic data for these dyes were estimated. Their application properties are characterized by a high tinctorial power and a very high degree of exhaustion from the dyebath.

Synthesis and properties of 1:1 copper-azo dye complexes derived from 1-Phenyl-3-Methyl-5-Pyrazolone

A series of orange and red 1:1 copper-azo dye complexes, derived from 1- (3'-N-benzenesulphonamido)phenyl-3-methyl-5-pyrazolone, have been synthesized. The dyes were evaluated with respect to application, fastness and spectroscopic properties. Due to the presence of sulphonamide groups the dyes are suitable for dyeing polyamide fibres and wool from a weakly acidic dye bath; they have good application and end-use properties.

Synthesis and properties of acid dyes derived from 1-phenyl-3-methyl-5-pyrazolone

A series of yellow dyes, derived from 1-phenyl-3-methyl-5-pyrazolone and containing one or two arylsulphonamide groups were synthesized. The dyes were suitable for dyeing polyamide fibres and wool from a weakly acidic dye bath. Spectroscopic data for the dyes were evaluated and their application and fastness properties studied. The beneficial influence of the sulphonamide group on some application and fastness properties was concluded.