Vat Dyes Research Articles

Ionic Liquid‐Supported Vat Dye (Congo Red)‐Based Donor–Acceptor Type Conjugated Polymeric Material as Photosensitizer for Dye‐Sensitized Solar Cells

The greatest candidates for organic dyes that exhibit redox activities are vat dyes. Polymers based on vat dyes become effective sensitizer material for dye‐sensitized solar cells (DSSCs) because of their higher absorption coefficient and redox properties by reducing the polymeric film thickness. Herein, an ionic liquid (IL)‐supported D–A type conjugated polyimide sensitizer based on vat dye Congo red and pyromellitic dianhydride is synthesized via condensation polymerization technique. This polymeric material is doped with BF3 and supported with a minimal quantity of IL for better conductivity results and interface creation. The synthesized polyimide shows altruistic oxidoreduction properties with a narrow bandgap of 1.96 eV. Additionally, it comprises conjugated electrons having a backbone system that shows good electrical conductivity (>10−4 S cm−1) and becomes a semiconducting material. To determine the photovoltaic characteristics of the synthesized polymeric material, electrode fabrication and DSSC are carried out. The estimated photovoltaic characteristics are Jsc = 0.2324 mA cm−2, fill factor = 0.6906, and Voc = 0.2380 V. The power conversion efficiency of the device is obtained at 0.04%. The film‐forming property of polymeric sensitizer can reduce electron passivation in the cell. These observed properties of polymeric sensitizer material hardly claim their suitability for DSSCs applications.

A green approach of vat dyeing of cotton fabric with natural reducing agents

This study focuses on an eco-friendly approach to vat dyeing of cotton fabric using natural reducing agents and compare their performance with a conventional reducing agent. Natural reducing agents derived from pineapple barks, watermelon, and carambola extracts were investigated as alternatives. The reduction potential and FTIR of these natural extracted reducing agents were evaluated to assess their dyeing capability. Different colorimetric properties, color strength, colorfastness, bursting strength and pilling resistance of the dyed fabrics were analyzed. The environmental impact of the dyeing process was assessed by measuring parameters such as BOD, COD, TDS, DO and pH values. The results indicated that the natural reducing agents exhibited comparable reduction potential to sodium dithionite. Colorimetric analysis revealed that the optimal concentrations of the reducing agents for dyeing were 500–600 ml/l. The carambola extract showed the best colorimetric properties among the three reducing agents tested. The study demonstrates the potential of natural reducing agents as eco-friendly alternatives for vat dyeing of cotton fabric, contributing to sustainable and green textile dyeing processes.

Production scale test for indirect cathodic reduction of indigo opens a route for greener denim

Textile and garment industry is one of the biggest industrial consumers of high quality water and belongs to most polluting industries worldwide. Development of textile chemical processes which allow reuse of chemicals and water thus is an imperative. Cathodic reduction of vat dyes e.g. indigo is a promising technology to replace non regenerable reducing agents in dyeing processes. Experiments at laboratory scale are not sufficient to achieve scalable results. In this study a full scale production test for replacement of dithionite based indigo reduction in denim production by cathodic dye reduction has been performed to demonstrate the potential of the technology. A 1000 A electrolyser was coupled to a open width yarn dyeing unit and 11,000 m (3,600 kg) of warp yarn was dyed with use of a cathodically regenerated iron-triethanolamine complex as reducing agent instead of a continuous dosage of dithionite into the dyebath. A time constant production was achieved over the full duration of the 5.5 h production. The dyed warp then was woven into denim fabric and only very minor colour deviations were observed between the electrochemically dye fabric and the reference quality, which demonstrates the ability of the technology to reproduce shade and ring-dying of a denim yarn. Model calculations to compare the chemical consumption of an electrochemical dye reduction with standard chemical processes indicate the importance of a recycling of the waste water by membrane filtration. Compared to a typical indigo range which consumes 100 g min−1 dithionite the chemical consumption of the new process falls below to 30% when 60% of the iron-complex therein is recovered. The demonstration of the technology in a full scale test can be understood as a relevant break through for future introduction of indirect cathodic dye reduction as cleaner technology in denim production.

Physicochemical parameters optimization and peroxidase characterization from Aspergillus niger native strain by solid-state fermentation for improved dye decolorization

The hyper yield of peroxidase (POX) was investigated for a novel native Aspergillus niger strain identified by 18S RNA analysis. A. niger strains sequences were submitted to GenBank; IDs allotted were MN611114.1 (BMB 17) and MN559756.1 (BMB-18). The identified Aspergillus strains in combination showed enhanced (POX) activity (601.5 U/mL) by solid-state fermentation in comparison to their individual activities. POX was purified by ammonium sulfate, and size exclusion gel chromatography exhibited a 7.83-fold increase in POX concentration (13.3 U/mg) in comparison to BMB17 and BMB 18 (11.8 & 7.6 U/mg respectively). The best POX activity was obtained with pH 6.5, 37 °C, and 5 days of incubation. Using guaiacol as substrate, POX showed maximum activity (Vmax) of 537 U/mL with a corresponding Michaelis constant (Km) value of 126 µM. Calcium chloride worked as a POX activator at 300 & 400 mM. Zinc sulfate (500 mM), EDTA (5 mM); ethanol, propanol, and acetonitrile (50%) inhibited (18-30%) POX. Urea (1M), and copper sulfate (500 mM) strongly inhibited POX up to 40%. Polysorbate-80 (1%) slightly reduced the POX by 10% to 15%. BMB17+18-induced promising dye decolorization (88-98%) against all vat dyes, methylene blue, and phenol red.

Impact of Different Modern Chemical Finishing on Cotton Knitted Fabrics Dyed with Anthraquinone Vat Dye

Impact of Different Modern Chemical Finishing on Cotton Knitted Fabrics Dyed with Anthraquinone Vat Dye

Improved pollutant management by kinetic and Box-Behnken design analysis of HDTMA-modified bentonite's adsorption of indigo carmine dye

The optimal performance characteristics of hexadecyltrimethylammonium-modified bentonite (HDTMA-B) for the removal of indigo carmine (IC, vat dye) from aqueous solution require a process parameter study. Using batch mode experiments and kinetic models, the study evaluated the adsorption behavior and dye-adsorbent interaction at different temperatures, adsorbent dosages, and initial dye concentrations. The rating mechanism for adsorption in ICs was found to be quite similar to the pseudo-second-order model. All of these IC dye removal adsorption parameters were optimized using a Box-Behnken surface statistical design with a pH of 6.6 as the starting point (as a fixed input parameter). At the 95% confidence level, the main effects of starting dye concentration and adsorbent dosage were both statistically significant, as was the square impact of initial dye concentration (ANOVA). There was a negative interaction between the adsorbent dose and the initial dye concentration, and this led to the discovery of a substantial detrimental effect. The primary factor in IC elimination was the initial dye concentration component (PC = 48.36%). At 34.28 °C and a starting dye concentration of 53.3 mg L-1, 0.97 g L-1 of adsorbent was optimal for removing 96.40% of IC from aqueous solutions, yielding a desirability of 1.00. The removal effectiveness of IC dye by HDTMA-modified bentonite could be predicted and the experimental parameters optimized using the simulated polynomial function. The regeneration capacity of the HDTMA-B adsorbent proves its importance in industrial wastewater treatment.

Removal of different vat dyes by Aspergillus niger: A comparative study focusing on the molecular structure

Vat dyes are the most commonly used dyes in the denim industry. Since the pollution of the textile industry is a worldwide problem, Aspergillus niger was used in this study, to treat vat dye wastewater by pre-culture and simultaneous-culture methods. A comparison between the two biosorption techniques used showed that pre-culture was about 30% more efficient than simultaneous culture. The adsorption capacity was determined using the Langmuir and Freundlich adsorption models, with Langmuir proving to be the most suitable model. The high saturation capacity of 121.35 mg/g for C.I. Vat Brown 1 calculated with the Langmuir adsorption model indicated that A.niger is a suitable sorbent for vat dye wastewater.To investigate the influence of dye structure on biosorption efficiency, eight vat dyes with different chemical characteristics were used. The results showed that the complete decolorization time was reduced by 200 and 150 min for planar and non-planar structures, respectively, due to the reduction of molecular mass, indicating that molecular mass is probably the dominant factor in vat dye removal. In addition, planar structures resulted in a 50-min reduction in biosorption time. The possible adsorption sites were analyzed by Fourier transfer infrared analysis. The results showed that the amino and carboxyl groups of the fungus could serve as sorption sites for vat dyes through hydrogen bonding.”

MIL53 Based Metal Organic Framework for Removal of Dye from Waste Water by Adsorption

To treat wastewater containing vat dyes, a newly method of based on MIL 53 (Al-Fe) @SiO2 was created and used in a combine to desegregated process toward off followed by adsorption. Coal fly ash was used in the synthesis of MIL 53 (Al-Fe) @SiO2. As compared to raw fly ash obtained by coal, the newly synthesized material, MIL 53 (Al-Fe) @SiO2, present remarkable changes in physical and chemical properties, which improve and become greater its adsorption capacity by three times. In adding, the FTIR examination and analyzed investigation shows that the Compared to MIL 53 (Al) and MIL 53 (Fe)@SiO2, freshly synthesis MIL 53 (Al-Fe) @SiO2 exhibits a reduced electron-hole recombination rate. 53 (Al)@SiO2. The highest adsorption capacity of the MIL 53 (Al-Fe) @SiO2 was 692.942 mg g1 and highest degradation of 89.89 and 99.98% when exposed to visible and UV light subjection, separately This study demonstrates that suggested MIL 53 (Al-Fe) @SiO2 outperforms the traditional materials in the removal of hazardous contaminants from industrial effluents. KEY WORDS: Vat dyes, MIL53(Al-Fe) @SiO2, Adsorption.

Colouration and Performance Evaluation of Ethiopian Kusha Fibres

ABSTRACT Bast fiber dyeing process is common practice as the value addition of most bast fibers demanded for various commercial and household applications. In this research work, kusha fiber (extracted previously) was subjected to dyeing using direct, reactive, vat and cationic dyes for the first time. Dyeing process was perfrmed using concentrations 0.5%, 1%, & 3% (W/W) dye to fiber with MLR 1:20. After dyeing process, performance of dyed fiber and tensile tests were conducted. The results revealed that K/S value of all dyed kusha fiber samples increases as the concentration of dyes applied increases. The dyed fibers color fastness to washing was found good both in dry and wet rubbing fastness. Reactive dyed samples have shown good rubbing fatness performance over the others. Regarding light fastness, the result shows there was good performance for all samples according to blue wool light fastness standard that exceeds 6. The tensile strength and elongation of dyed samples showed slight decrement both in vat and direct dyed samples; whereas, considerable decrement was observed both in reactive and basic dyed samples due to formation of covalent bond and acid processing medium.

Front Cover: From Textile Coloring to Light‐emitting Electrochemical Devices: Upcycling of the Isoviolanthrone Vat Dye (Chem. Asian J. 6/2023)

Produced at a ton scale for textile industries, vat dyes have a significant environmental impact as they are considered major water contaminants. Hence, as a contribution to the current ecological transition, we demonstrate the valorization/upcycling of wastewaters, generated during the staining process, through the functionalization and use of the reduced (leuco) form of a vat dye, namely, violet 10, also known as isoviolanthrone. The resulting readily soluble large π-conjugated platform was indeed successfully embedded in light-emitting electrochemical cells as active material. More information can be found in the Research Article by Clément Cabanetos, Dominik Lungerich, Pierre Josse, Eunkyoung Kim et al.

From Textile Coloring to Light-emitting Electrochemical Devices: Upcycling of the Isoviolanthrone Vat Dye.

Produced at ton scale, vat dyes are major environmental pollutants generated by the textile industry. However, they represent ideal and accessible candidates for chemical upcycling since they are usually composed of large π-conjugated scaffolds. Based on the valorization of "old" products, waste or even contaminant into high-added value goods, this concept can be easily transposed to the laboratories. As a contribution to the current environmental and ecological transition, we demonstrate herein the valorization/upcycling of wastewaters generated during the dyeing procedure. To do so, the reduced (leuco) form of vat violet 10, also known as isoviolanthrone, was functionalized to afford a readily soluble derivative that was subsequently and successfully used as active material in operating solution processed light-emitting electrochemical cells, that is, from textile dyeing to high-tech application.

Manipulating Indigenous Vegetable-Tanned Leather for Use in Crocheting Art

The study explores techniques and methods used in converting indigenous vegetable-tanned leather into yarns that can serve as an alternative material and convert the locally made yarns into crocheted ladies containers and footwear using different stitches. It embraces a qualitative research of which the approach implements two various approach’s (Descriptive and Studio-based research). The novelty of the study came from sampling, which consisted of Crochet Artisans, Leatherworks Teachers, and Leather Technologists within the above areas. The Crocheting Artisans were selected through the snowball sampling technique, whereas the Leatherwork Teachers and Leather Technologists were selected using the purposive sampling technique. The results from data gathered via the project experiments involved studio activities in converting the local vegetable-tanned leather into yarns and crocheting the yarns into ladies containers and footwear using different stiches were analysed and discussed. The study concludes that indigenous vegetable-tanned leather is suitable for use in making crocheting yarns and crocheting artefacts due to its strength, flexibility, and hook construction. Moreover, spiral cutting techniques came out to be the most appropriate technique for cutting leather into yarns for use in crocheting art. The study recommends that the use of leather in making crocheting yarns should follow these steps - the cutting of leather, softening of leather (wet pounding) and dyeing of leather (vat dye and the mixture of suede and insoluble dye). In addition, the study suggests that to create diversity in crocheting yarns, crocheting artefacts and expand leather usage, the potential leather should be tapped by both Crocheting and Leather Artisans.

A comparative Studies of Physio Chemical Properties of Linen Yarn Dyed Fabric Dyed with Reactive & Vat Dye

A comparative Studies of Physio Chemical Properties of Linen Yarn Dyed Fabric Dyed with Reactive & Vat Dye

Flame retardancy and aspects of the vat dyes application on inherently flame retardant fabrics

The paper presents research on the application of vat dyes to inherently flame resistant fabrics, using the conventional screen-printing method. The composition of the fabrics are defined within a scope of a project conducted in partnership of Croatian textile factory Cateks d.d. and University of Zagreb Faculty of Textile Technology. Fabrics are screen printed by using a vat dye Indanthren® Olive R (DyeStar, Germany) in two concentrations. After printing, a coloristic analysis of the obtained colouration is performed, based on instrumental spectrophotometric measurement and objective evaluation of the colouristic parameters (L*, C*, h°) and colour depth (K/S). The samples are tested for resistance to surface burning, and the colour fastness to dry/wet rubbing and light exposure are also tested. Excellent results of fire resistance and dry/wet rubbing resistance are achieved, while resistance to light exposure is lower to optimal.

Electrocatalytic hydrogenation of indigo by NiMoS: energy saving and conversion improving.

An NiMo alloy bonded with sulfur (NiMoS) exhibits enhanced surface affinity toward water and organic molecules, thereby enhancing electrocatalytic hydrogenation (ECH) reactions through synergistic effects. In industrial processes, indigo, an ancient dye employed in the denim industry, is typically chemically reduced using sodium dithionite. However, this process generates an excess of toxic sulfide, which heavily contaminates the environment. ECH is a sustainable alternative for indigo reduction due to its reduced reliance on chemicals and energy consumption. In this study, carbon-felt (CF)-supported NiMoS was synthesized in a two-step process. First, the NiMo alloy was electrodeposited onto the CF surface, followed by sulfidation in an oven at 600 °C. NiMoS exhibits a larger electrochemically active surface area and a smaller charge transfer resistance compared to pure Ni and NiMo. Furthermore, NiMoS demonstrates excellent thermodynamic and kinetic properties for water splitting in strong alkaline solutions (1.0 M KOH). Additionally, optimal reaction conditions for the ECH of indigo were explored. Under the conditions of a 1.0 M KOH hydroxide medium with 10% methanol (v/v), an indigo concentration of 5 g L-1, a reaction temperature of 70 °C, and a current density of 10 mA cm-2, NiMoS/CF achieved remarkable improvements in both conversion (99.2%) and Faraday efficiency (38.1%). The results of this experimental work offer valuable insights into the design and application of novel catalytic materials for the ECH of vat dyes, opening up new possibilities for sustainable and environmentally friendly processes in the dye industry.

Application issue of anthraquinonoid vat dyes on inherently flame‐resistant fabrics

AbstractThe vat dyeing process of specific fabrics with protective, inherently fire retardant properties that have a high content of aramid fibres in their composition, is presented. The research was performed on fabric samples that differ in raw material composition and aramid content. The samples were dyed in raw form (group 1) as well as after pretreatment with alkaline scouring (group 2). Measured limiting oxygen index (LOI) values showed that the selected fabrics meet the properties of inherently fire retardant fabrics. Dyeing was performed with Indanthren® Olive Green HB (manufactured by DyStar) vat dye, in exhaustion process, with a bath ratio of 1:30. The dye concentration was 3%, and sodium‐hydrosulphite (Na2S2O4) was used as a reducing agent. The colouristic analyses were performed based on spectrophotometric measurement and results interpretation according to CIELab system. The evaluation of primary tactile properties was performed which show an increase of smoothness and softness after scouring and dyeing. Also, wash fastness as well as light fastness tests have shown satisfactory fastness properties.

Cyclohexane and n-hexane adsorption studies on novel hex-star antimonene nanosheets – A first-principles outlook

• The geometrically stable hex-star antimonene nanosheets possesses an energy band gap of 0.862 eV. • Cyclohexane and n-hexane molecules are adsorbed on hex-star antimonene nanosheet. • Both cyclohexane and n-hexane are physisorbed on hex-star antimonene. • Hex-star antimonene nanosheets exhibits chemi-resistive nature upon adsorption of cyclohexane and n-hexane. The presence of acetic acid, nitrates, vat dyes, and heavy metals all collectively produce highly toxic effluent from the textile industry. The aliphatic hydrocarbons, namely cyclohexane, and n-hexane are the common toxic volatiles emitted from the various textile industry in worldwide leading to environmental degradation and human illnesses. Hence, there is a requirement for high sensitivity and a stable chemical sensor for detecting these toxic molecules to safeguard human health and the air atmosphere. In this research, we used hex-star antimonene as a leading sensing material to detect cyclohexane and n-hexane molecules at ambient temperature. Originally, the structural firmness of hex-star antimonene is validated with the influence of cohesive formation energy. Furthermore, the band structure and projected density of states spectrum provides the fingerprint for electronic properties of hex-star antimonene. The band gap of hex-star antimonene is calculated to be 0.862 eV. Significantly, the adsorption properties of cyclohexane and n-hexane on the base substrate are investigated by the deciding factors, such as Bader charge transfer, adsorption energy, and relative band gap variations. The scope of adsorption energy (−0.115 eV to −0.502 eV) confirms that both cyclohexane and n-hexane are physisorbed on hex-star antimonene. The outcome recommended that hex-star antimonene can be utilised as a chemical sensor to monitor the cyclohexane and n-hexane emitted from textile industries.

Enhancing the Fabric Printability with Vat and Direct Dyes via Treatment Using Chitosan and Chitosan Nanoparticles

Enhancing the Fabric Printability with Vat and Direct Dyes via Treatment Using Chitosan and Chitosan Nanoparticles

Synthetic Dyes for Textile Colouration: Process, Factors and Environmental Impact

Dyes are substances that enhance the appearance of finished goods by providing uniform colour. Dyeing is the application process of dyes that are fixed in textile fibers. The dyeing process uses various steps, including pre-treatment, desizing, scouring, bleaching, carbonizing, degumming, and mercerization. Water is considered the primary medium for applying dyes and other chemicals for this treatment in the dyeing process. The dyeing process contains many toxic chemicals, metals and non-soluble substances, such as wastewater, which is thrown into the environment. It is noted that, during dyeing , around 50-300 liters of water is required for 1 kg of fiber. On the other hand, 1-2 million liters of water are needed every day for 50,000 meters of daily production. This massive amount of toxic wastewater is highly harmful to the environment, human health, aquatic system, soil, air, water, plants, and animals. This review paper states various dyeing processes with different dyes, including acid dye, direct dye, sulfur dye, reactive dye, vat dye, metal complex dye, azo dye, disperse dye, and basic dye. In contrast, it also describes the influencing factors of dyeing processes and methods. Moreover, this review demonstrates the impacts of textile dyes on the environment (water, soil, air emissions, human health) and illustrates possible remedial actions regarding wastewater.

Electrodeposited NiMoP catalysts on carbon felt for hydrogenation of indigo during electrocatalytically splitting water

Electrochemical hydrogenation is an environmentally favorable alternative to chemical reduction of indigo because it performs under ambient conditions using water as the donor of hydrogen. The purpose of this work is to fabricate electrocatalysts with high activity and durability for electrocatalytic hydrogenation of indigo. This work compares the performances of a series of Ni based catalysts (Ni, NiMo, NiP and NiMoP) on the substrate of carbon felt (CF) for electrolyzing water. Both the overpotential and Tafel slop are decreased as a function of the components as Ni > NiMo > NiP > NiMoP. Hence, NiMoP/CF shows the excellent performance based on the thermodynamics (η10 = 239 mV) and kinetics (Tafel slope = 89.7 mV·dec−1) for splitting water. Further, the electrode of NiMoP/CF was used for the electrocatalytic hydrogenation of indigo. The conversion efficiency and Faradic efficiency can be improved as 26.2% and 10.7% respectively. Furthermore, the dyeing behavior of the electrohydrogenated indigo is similar to that of conventional reduction methods. Thus, the present work offers foundational results and paves the way for the design of new catalytic materials for the reduction of vat dyes.