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This article focuses on comparing the characteristics of cotton fabric dyed with Diospyros mollis extract (DME) solution and that of cotton fabric dyed with the reactive dye. The parameters of the cotton fabric after dyeing with both types of dyes were assessed, including color strength (K/S), structural morphology, infrared spectrum, antibacterial properties, UV resistance, color fastness to washing, rubbing, light, moisture absorption, breathability, and wastewater indices. The obtained results show that the K/S value of cotton fabric dyed with DME solution is slightly lower than that of cotton fabric dyed with the reactive dye, 18.52 and 19.36, respectively. The cotton fabric dyed with the reactive dye does not exhibit antibacterial activity against Escherichia coli and Staphylococcus aureus, whereas the antibacterial effectiveness against these bacteria for cotton fabric dyed with DME solution is 99.99 %. The UV protection capability of cotton fabric dyed with DME solution is superior to cotton fabric dyed with the reactive dye. The BOD/COD ratio of wastewater from the dyeing process with DME is higher than that of the reactive dye, with values of 0.70 and 0.32, respectively. The findings of this study indicate the superior ability of using DME solution as compared to the reactive dye, which is promising as a natural dye for fabric in medical applications. [ABSTRACT FROM AUTHOR]

This study explores a novel sulfonation method for analyzing blue-dyed fabrics containing reactive, direct and indigo dyes. The proposed method accurately distinguishes indigo fabrics by converting indigo blue into indigo carmine using concentrated H2SO4, resulting in distinct spectral analysis through UVVisible spectrophotometry. Generally, UV-Visible spectroscopy shows absorption peak characteristics influenced by analyte and environmental properties, leading to broadening and wavelength shifts. Therefore, statistical analysis of peak characteristics, including center, centroid, Full Width at Half Maximum (FWHM), height and L/R ratio, was performed on the obtained spectra to facilitate comprehensive quality evaluation of indigo-dyed fabrics. The proposed method demonstrated good precision and accuracy, with %RSD values indicating excellent repeatability and reproducibility, contingent on consistent sample preparation, narrow analyte peaks and minimized background signals. Furthermore, this method was applied to analyze the collected indigo-dyed fabrics from Sakon Nakhon Province, revealing the center value (611.79 nm) as a precise marker for indigo dye, with a narrow control range (607.02 - 616.56 nm) and a low coefficient of variation (CV) of 0.26 %. Moreover, centroid, L/R ratio and FWHM significantly contributed to fabric classification and quality assessment. This research offers valuable insights to improve indigo fabric production in Sakon Nakhon Province, leading to more reliable authentication and quality control of the natural indigo-dyed industry. [ABSTRACT FROM AUTHOR]

Demand for textiles is increasing owing to human population growth, social competition, and fashion trends. This growth in demand is met at the cost of contamination of tons of fresh water with dye. In this study, microwave irradiation was used in dyeing of textiles as a method of minimizing this environmental threat. The microwave works through dielectric heating and realizes its effect on different dye structures. Dyeing was performed on six different reactive red dyes based on an H-acid coupling component with dissimilar substituents. UV–visible spectroscopy measurements revealed that auxochromes do not impart color to the dyes, but still have a great impact on color depth and hue. The zeta potential and temperature rise per minute under microwave irradiation were both affected by changes in the dye concentration and structure. The dyeing of cotton samples was performed by the exhaust microwave dyeing technique with an optimized recipe and conventional dyeing with a standard recipe for comparison. The color strength values obtained from the experiments revealed that the microwave technique provides better results by consuming 86.67% less salt with a lower liquor volume. The exhaustion and fixation values further confirmed this assessment. The color fastness against basic conditions was similar with both techniques; hence, the microwave can be considered to be a better technique in all aspects. Furthermore, the dye D195 was found to be more effective in achieving higher color depths with a less concentrated effluent indicating that the synthesis of high-performance dyes requires care in the selection of substituents. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study is to investigate the feasibility of an alternative Fenton-based advanced oxidation process for the discoloration of reactive-dyed waste cotton as a pre-treatment for textile recycling. For that, pre-wetted dark-colored (black and blue) knitted samples of 300 cm2 are treated in 1200mL Fenton-solution containing 14 mM Fe2+ and 280mM H2O2 at 40 °C. Characterization of the textiles before and after the treatments are performed by UV VIS-spectrophotometry measuring color strength, microscopy, FTIR spectroscopy, thermal analysis and tensile testing measuring tenacity and elongation. Afterwards, the cotton is mechanically shredded for qualitative analysis of the recyclability. The color-strength measurements of the black and blue cotton led to discoloration-efficiencies of respectively 61.5 and 72.9%. Microscopic analysis of discolored textile fabric also showed significant fading of the colored textiles. Mechanical analysis resulted in reduced tensile strength after treatment, indicating oxidation of the cellulosic structure besides the degradation of the dye-molecules, also confirmed by reductions in thermal stability found after thermal analysis. Shredding of the fabric resulted in enhanced opening, but shorter remaining fibers after treatment. The findings of this study provide a proof-of-concept for an alternative color-stripping treatment concerning a Fenton-based advanced oxidation process as a pre-treatment for textile recycling.

The principal goal of this research revolves around imparting antimicrobial activities on printed cotton fabric utilizing silver nanoparticles. Two colorants, dyes, and pigments are used for printing of 100% scoured and bleached cotton, fabric, and both fabrics are assessed to get antimicrobial activity of printed cloth. Screen-printing techniques are used here to apply the pigment and reactive dye onto the fabric. The outcomes of the study reflect that the addition of silver nanoparticles to the reactive dye-printed and pigment-printed fabric significantly decreases bacterial growth up to 99.99%. In addition, Silver nanoparticles increase color intensity by around 25% in pigment printing, however, reduce it in reactive printing. Both methods enhance color fastness by increasing resistance to fading, staining, and rubbing. The scanning electron microscopy (SEM) analysis reveals that the print paste and sodium alginate have an impact on the distribution of nanoparticles. Through X-ray diffraction (XRD), it has been determined that the sample maintains a crystalline form and an average size of 29.185 nm of silver nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) analysis indicates no notable molecular-level alterations. [ABSTRACT FROM AUTHOR]

Dopamine (DA) can undergo complex oxidative self-polymerization to modify the surface properties of cotton fabrics; however, the disordered polymerization of dopamine to polydopamine (PDA) results in poor colorfastness and limits the application of DA to textile fibers. To ensure the ordered polymerization of DA and the growth of PDA and to obtain good colorfastness and depth in the PDA-modified cotton, we used the hot pad-batch (HPB) dyeing method for DA and Reactive Red 239 (RR-239), along with the action of the fabrics squeezing each other. We compared the differences in colorfastness caused by the disordered and ordered polymerization of DA and aluminum ions. We studied the effect of sodium carbonate, DA, and RR-239 concentration on the K/S values of the cotton fabric. We also analyzed the dyeing mechanism of PDA/RR-239 for cotton fibers and the effect of the aluminum ions therein via attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) and determined the UV resistance, mechanical properties, and thermal properties of the cotton fabric. HPB dyeing produced better colorfastness than exhaustive dyeing with a co-bath of DA/RR-239 and enabled ordered polymerization of PDA on the fibers. HPB dyeing accelerated the formation of PDA in the presence of a small amount of aluminum salt. Thus, HPB dyeing is suitable for the modification of cotton fabric with DA and reactive dyes because it is a short dyeing process that can improve the washing and rubbing colorfastness to 4 and 3–4, respectively. [ABSTRACT FROM AUTHOR]

In order to improve the fixational rate of reactive dyes, response surface methodology was used to optimize the dyeing process of cotbon fabric in systatin non-Rueous and less water medium. The interaction among sodium carbonate concentration, Fixation time and fixation temperature was studied, and the optimum process parameters were optimized^ sodium carbonate concentration 48 g/L, fixation time lOmin and fixation temperature 89 °C . According to the optimum process conditions, the predicted fixation rate is 75. 67%. The fixation rate calculated by experiment is 76. 73%, which is consistent with the predicted value [ABSTRACT FROM AUTHOR]

Abstract This article focuses on comparing the characteristics of cotton fabric dyed with Diospyros mollis extract (DME) solution and that of cotton fabric dyed with the reactive dye. The parameters of the cotton fabric after dyeing with both types of dyes were assessed, including color strength (K/S), structural morphology, infrared spectrum, antibacterial properties, UV resistance, color fastness to washing, rubbing, light, moisture absorption, breathability, and wastewater indices. The obtained results show that the K/S value of cotton fabric dyed with DME solution is slightly lower than that of cotton fabric dyed with the reactive dye, 18.52 and 19.36, respectively. The cotton fabric dyed with the reactive dye does not exhibit antibacterial activity against Escherichia coli and Staphylococcus aureus, whereas the antibacterial effectiveness against these bacteria for cotton fabric dyed with DME solution is 99.99 %. The UV protection capability of cotton fabric dyed with DME solution is superior to cotton fabric dyed with the reactive dye. The BOD/COD ratio of wastewater from the dyeing process with DME is higher than that of the reactive dye, with values of 0.70 and 0.32, respectively. The findings of this study indicate the superior ability of using DME solution as compared to the reactive dye, which is promising as a natural dye for fabric in medical applications.

This work focuses on the development of a novel and affordable yellow DS5R polymeric film on the glassy carbon electrode surface (Po-YDS5R/GCE) for the detection of uric acid (UAC). Po-YDS5R/GCE was effectively developed using cyclic potentiodynamic polyme­rization technique. The sweep rate study revealed that the overall electrode reaction is diffusion-controlled. The linear range of 10-60 µM of UAC was used to compute the limit of quantification and limit of detection, and the results yield 3.12 and 0.87 µM, res­pec­ti­vely. The interference of dopamine on the electrooxidation of UAC was tested at the developed sensor. It was discovered that the modified sensor allows selective detection of UAC. These impressive outcomes showed that a simple and less-costly Po-YDS5R/GCE sensor has a significant potential to make significant improvement over current electro­chemical sensor technology.

Wastewater containing reactive textile dyes constitutes a crucial environmental problem as they are permanent and dangerous. The electro-Fenton (EF) method is promising as an effective technique for degrading organic materials such as dyestuffs. In this study, the optimization of influential variables in removing reactive yellow 145 azo textile dye by EF was investigated using response surface methodology (RSM). Central composite design was used to study the combined effects of critical parameters such as voltage (2.5–12.5 V), H2O2 addition (0.1–1.3 mL), pH (1.75–4.75), electrode spacing (0.25–3.25 cm), and treatment time (25–85 min). The optimum values of the variables to ensure the highest dye removal efficiency (approx. 93%) with the lowest energy consumption (approx. 3.4 Wh/L) were approximately 9.4 V voltage, pH 3.7, 2.5 cm electrode spacing, 1 mL H2O2 addition, and a 40-min treatment time. ANOVA analysis of the predicted quadratic polynomial model showed a regression coefficient value of approximately 0.97 for both objective functions; this highlights the model's applicability for navigating the design space. Simultaneous optimization of process parameters using RSM was achieved with a few experiments. [ABSTRACT FROM AUTHOR]

In a traditional water-based dyeing system, large amounts of salts and water are consumed. However, a non-aqueous media dyeing system achieves salt-free and less-water dyeing. In a non-aqueous media dyeing system, a small amount of water is used, which may affect the aggregation morphology of the dyes. The molecular dynamics of reactive dyes on the surface of cotton fibers were investigated. The results showed that the color depth of dyed cotton fabric did not change much when the dosage of salt was below 5.2% o.w.f. However, continuing to increase the amount of salt could influence the dyeing level of dyed fabric. The diffusion coefficient of dye was 0.3044 × 10−5 cm−2/s when there was no salt in dyeing system. But it was decreased by 14.03% and 16.62% when the salt concentration was increased from zero to 5.2% and 13% o.w.f., respectively. When the concentration of sodium sulfate was zero, the dye molecules in the solution displayed in the form of unimolecular molecules and dimers. However, reactive dyes mainly existed in the form of trimers and polymers when the concentration of sodium sulfate was above 5.2%. When there was no salt in the less-water dyeing system, the van der Waal energy between fiber and dye was 131.29 kJ/mol, but it was increased to 382.92 kJ/mol when the dosage of sodium sulfate was 5.2%. Therefore, with the increase of sodium sulfate dosage, the color depth of the dyed fabric changed little, but the level of dyeing property became poorer. [ABSTRACT FROM AUTHOR]

The use of residual microbial biomass from various industries in emerging pollutant removal strategies represents a new area of research in the field. In this case, we examined how to remove reactive dyes from an aqueous solution utilizing a biosorbent made of residual biomass from immobilized Saccharomyces pastorianus (S. pastorianus) in a polymer matrix using a dynamic system. Fluidized bed column biosorption investigations were carried out on a laboratory scale. Brilliant Red HE-3B was chosen as the target molecule. The main parameters considered for this purpose were the flow rate (4.0 mL/min; 6.1 mL/min), initial pollutant concentration (51.2 mg/L; 77.84 mg/L), and biosorbent mass (16 g; 20 g). The experimental data of the fluidized bed study were evaluated by mathematical modeling. The Yoon–Nelson, Bohart–Adams, Clark, and Yan models were investigated for an appropriate correlation with the experimental data. An acceptable fit was obtained for a flow rate of 4 mL/min, an initial pollutant concentration of 51.2 mg/L, and a biosorbent amount of 20 g. The obtained results indicate that the biosorbent can be used efficiently in a dynamic system both for the removal of the studied dye and in extended operations with a continuous flow of wastewater. As a conclusion, the investigated biocomposite material can be considered a viable biosorbent for testing in the removal of reactive dyes from aqueous environments and creates the necessary conditions for the extension of studies toward the application of these types of biosorbents in the treatment of industrial effluents loaded with organic dyes. [ABSTRACT FROM AUTHOR]

In this research, low-priced bio-chars produced from biomass waste (fiddle-leaf fig seed) via physical and chemical activation processes were applied for selective removals of iodine and reactive dyes. The adsorption natures and capabilities were systematically considered from isotherms, kinetic and thermodynamic parameters. As achieved results, activated bio-char (ABC) prepared via phosphoric activation and carbonization at 400 °C for 2 h presented good capabilities for adsorptions of iodine (qmax = 420.47 mg/g) and reactive red 22 (RR22, qmax = 15.17 mg/g). The fast adsorption natures of iodine and RR22 using each adsorbent exhibited monolayer physisorption, which were identified by Langmuir, Dubinin–Radushkevich, Redlich–Peterson, Toth and pseudo-second order, while intra-particle diffusion with 2 steps could be obtained from Weber–Morris model. Thermodynamic nature also displayed that iodine and reactive dye adsorption procedures were endothermic and spontaneous styles, supporting by standard enthalpy/entropy/Gibbs free energy at temperature range about 303–328 K. Moreover, the capability for selective removal of wastewater models (mixed dyes) over all adsorbents was in order of reactive blue 19 (RB19) > RR22 > reactive yellow 3 (RY3). This work methodically focused on adsorption manners of dye molecules using low-priced bio-char and gave possible/green way for wastewater treatment under practical process. [ABSTRACT FROM AUTHOR]

Developing reusable, sustainable and long term storable bioremoval technologies is essential for removal of heavy metals and reactive dyes in industrial wastewater. Clavibacter michiganensis (C. michiganensis) having bioremediation property was selected for attachment, and polysulfone (PSU) was selected as the polymer matrices for the electrospinning of nanofibrous webs. For this approach, polysulfone nanofiber mats (PSU-NFMs) were produced by electrospinning, followed by attachment of bacteria onto nanofiber mats and a subsequent used in the removal of Cr(VI) and reactive dye. The efficient Cr(VI) removal with 100% yield was achieved within 24 hours (10 ppm) with bacteria attached nanofiber mats. Also, nano bio-composite mats decolorized 100% of Reactive Blue (RB, 20 ppm) within 13 h. Furthermore, the prepared bacteria attached to PSU-NFMs showed storage stability at 23 ± 2° and 4° for 30 days with efficient removal yields and PSU-NFMs found as potentially storable for keeping attached bacterial cells alive. Finally, the reusability of bacteria attached to PSU-NFMs were determined after five cycles for both pollutant and 70.3% and 51.8% of the Cr(VI) and dye removal capacities were obtained. It was expected that the bacteria attached to PSU-NFMs could be a potential application in wastewater treatment. [ABSTRACT FROM AUTHOR]

Background: Reactive Red (RR) 141 dye is widely used in various industrial applications, but its environmental impact remains a growing concern. In this study, the phytotoxic and genotoxic effects of RR 141 dye on mung bean seedlings (Vigna radiata (L.) Wilczek) were investigated, serving as a model for potential harm to plant systems. Methods and results: Short-term (14 days) and long-term (60 days) experiments in paddy soil pot culture exposed mung bean seedlings to RR 141 dye. The dye delayed germination and hindered growth, significantly reducing germination percentage and seedling vigor index (SVI) at concentrations of 50 and 100 ml/L. In short-term exposure, plumule and radical lengths dose-dependently decreased, while long-term exposure affected plant length and grain weight, leaving pod-related parameters unaffected. To evaluate genotoxicity, high annealing temperature-random amplified polymorphic DNA (HAT-RAPD) analysis was employed with five RAPD primers having 58–75% GC content. It detected polymorphic band patterns, generating 116 bands (433 to 2857 bp) in plant leaves exposed to the dye. Polymorphisms indicated the appearance/disappearance of DNA bands in both concentrations, with decreased genomic template stability (GTS) values suggesting DNA damage and mutation. Conclusion: These findings demonstrate that RR 141 dye has a significant impact on genomic template stability (GTS) and exhibits phytotoxic and genotoxic responses in mung bean seedlings. This research underscores the potential of RR 141 dye to act as a harmful agent within plant model systems, highlighting the need for further assessment of its environmental implications. [ABSTRACT FROM AUTHOR]

Purpose: The main purpose of this study was to prepare the cotton fibers and cellulose powder by a layer of nano-crystalline-titanium dioxide (TiO2) using the sol-gel sono-synthesis method to clean the wastewater containing reactive dye. Moreover, TiO2 nano-materials are remarkable due to their photoactive properties and valuable applications in wastewater treatment. Design/methodology/approach: In this research, TiO2 was synthesized and deposited effectively on cotton fibers and cellulose powder using ultrasound-assisted coating. Further, tetra butyl titanate was used as a precursor to the synthesis of TiO2 nanoparticles. Reactive dye (red 195) was used in this study. X-ray Diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy were performed to prove the aptitude for the formation of crystal TiO2 on the cotton fibers and cellulose powder along with TiO2 nanoparticles as well as to analyze the chemical structure. Decoloration of the wastewater was investigated through ultraviolet (UV-Visible) light at 30 min. Findings: The experimental results revealed that the decolorization was completed at 2.0 min with the cellulose nano TiO2 treatment whereas cotton nano TiO2 treated solution contained reactive dyestuffs even after the treatment of 2 min. This was the fastest method up to now than all reported methods for sustainable decolorization of wastewater by absorption. Furthermore, this study explored that the cellulose TiO2 nano-composite was more effective than the cotton TiO2 nano-composite of decoloration wastewater for the eco-friendly remedy. Research limitations/implications: Cotton fibers and cellulose powder with nano-TiO2, and only reactive dye (red 195) were tested. Practical implications: With reactive dye-containing wastewater, it seems to be easier to get rid of the dye than to retain it, especially from dyeing of yarn, fabric, apparel, and as well as other sectors where dyestuffs are used. Social implications: This research would help to reduce pollution in the environment as well as save energy and cost. Originality/value: Decoloration of wastewater treatment is an essential new track with nano-crystalline TiO2 to fast and efficient cleaning of reactive dyes containing wastewater used as a raw material. [ABSTRACT FROM AUTHOR]

The efficiency of desalination of reactive dye solutions with the addition of a fixed amount of mineral salt was evaluated using standard ion-exchange membranes in the electrodialysis (ED) process. Five reactive dyes (Reactive Orange 16, Remazol Brilliant Blue R, Reactive Orange 20, Reactive Black 5, Reactive Red 120), varying in molecular weight, were used in the study. The model solutions were prepared by varying the dye concentration (20, 50 and 100 mg/L) and adding mineral salt (2 g/L of NaCl) to each dye solution. It was observed that the salt was successfully separated from dye solutions with the efficiency of 97.6%-98.5%. The migration of dye molecules from diluate to concentrate compartments was negligible. The dye concentration in the concentrate compartments amounted to 0.6-0.85 mg/L, irrespectively of the process parameters. However, significant deposition of dye particles in the membrane matrix was noted. Around 26%-31% of the initial dye mass was adsorbed, and this effect was strongly influenced by the dye reactivity. It can be concluded that the ED process with standard ion-exchange membranes is quite a promising method for reactive dye and mineral salt separation. This will enable further usage of the obtained dye and salt streams in a variety of technological processes. [ABSTRACT FROM AUTHOR]

This study simulated actual dyeing wastewater in dyeing factories with three types of dyeing wastewaters from laboratory cotton fabric dyeing to investigate the effects of catalyst and oxidant peroxymonosulfate (PMS) concentrations, pH level, and temperature on dye degradation in wastewater and determine the optimal conditions for dyeing wastewater treatment accordingly. The results demonstrated that the optimal conditions varied with the reactive dyes. Specifically, the optimal oxidant PMS concentration for degrading Reactive Yellow and Reactive Blue was 0.6 g/L, and that for degrading Reactive Red was 0.4 g/L. The optimal pH level for degrading Reactive Red and Reactive Blue was around 7.0, and that for degrading Reactive Yellow was about 5.0. The activation energy of the degradation and the mineralization degree of the three dyes were also discussed. Reactive Blue showed greater activation energy (47.0 kJ/mol) and a higher mineralization degree (81% chemical oxygen demand removal) than the other two dyes under optimal disposal conditions. The Fe/N-codoped carbocatalyst loaded on carbon cloth exhibited desirable reusability and good stability for the degradation of the three dyes. Mechanisms involved in their degradation were analyzed through X-ray photoelectron spectroscopy, focusing on N species, Fe-N binding, and C=C and C–N active components in the Fe/N-codoped carbocatalyst. Electron paramagnetic resonance experiments demonstrated that both the radical and non-radical pathways were accountable for the degradation of the three dyes, primarily the non-radical pathway. This study may contribute to the application of activated PMS for practical dyeing wastewater treatment. [ABSTRACT FROM AUTHOR]

Reactive dyes exhibit suitable opto-electronic properties, making them promising for dye-sensitized solar cell (DSSC) applications. The present study uses reactive orange 16 dye to design an efficient dye sensitizer for DSSC application using a donor–π–acceptor concept. The sensitizer structures and their electronic and optical properties were investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The molecular electrostatic potential maps, HOMO–LUMO distributions, and density of states plots were obtained for the optimized geometry. The analysis showed that the electronic properties of reactive orange 16 are enhanced due to the π-linkage, responsible for extending the conjugation length of the system. The TD-DFT calculations showed a bathochromic shift in the absorption spectra due to the introduction of the π-linker. The shift confirmed the conjugation's role in enhancing the sensitizers' electronic properties. The transitions were π → π* and n → π*, and the transition with maximum oscillator strength was assigned to the H → L excitation. The study showed that donor–π–acceptor concept-based sensitizers derived from reactive dyes favor DSSC applications. Hence, this study's findings could be used to design and develop more efficient dye sensitizers based on reactive dyes. [ABSTRACT FROM AUTHOR]

This study investigated the performance of different coagulants for the removal of different dye types from synthetic dye solutions. The ability to use each of the following: aluminium sulphate (Al2(SO4)3, aluminium chloride (AlCl3), and ferric chloride (FeCl3) as chemical coagulants were examined for removing reactive red 141 (RR 141) dye and disperse red 13 (DR 13) from dye solution. Coagulation studies determined the optimum pH, mixing time, coagulant dosages, and initial dye concentrations. The maximum efficiency for removing RR 141 was 65.7% by aluminium chloride at the operation condition of pH 8, mixing time 10 min, and dye concentration of 100 mg/L. In contrast, under the same conditions, ferric chloride could remove more than 98% of DR 13. Since the disperse dye type has better colour removal, the maximum volume of sludge was 0.3 kg/m3 which was produced when FeCl3 was used as a coagulant. The results demonstrated that coagulation is a promising technology for dye removal, especially for dispersed dyes as it has some characteristics such as colloidal dispersion and very low water solubility.

At present, organic wastewater containing dyes has become one of the main threats to the environment, and wastewater pollution caused by dyes released from fabrics during home washing also accounts for a large proportion. In this study, Ti/IrO2 electrodes for dye waste degradation were designed and prepared with Reactive Yellow 210 (RY 210), Reactive Blue 19 (RB 19) and Reactive Blue 21 (RB 21) solutions, and a laboratory electrochemical reactor was constructed. Secondly, in the reactor, the effects of current density (20–60 mA cm−2), electrolyte concentration (NaCl, 0.01–0.03 M L−1), and initial dye concentration (30–70 mg L−1) on the COD degradation rate and energy consumption of the dye solution were explored, and the parameters were optimized by the Box-Behnken design, and the equipment was realized in the washing machine. The results showed that the effect of degradation parameters on the degradation of the three groups of dyes was: current density > initial dye concentration > electrolyte concentration. Through parameter optimization, the average COD degradation rates of the three groups of dyes, Reactive Yellow 210 (RY 210), Reactive Blue 19 (RB 19) and Reactive Blue 21 (RB 21), reached 50.71%, 41.65%, and 33.12%, respectively, and the degradation energy consumption decreased by the same trend as 29.91%, 26.49%, and 65.91%, respectively.

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Cold pad–batch dyeing of reactive dyes is low energy consumption and a clean dyeing technique. However, the room dyeing temperature requires strongly active base reactive dyes for dye fixation, bringing about the limitation of dye adaptability. Here, we propose a new technology of hot pad–batch dyeing that has the advantages of higher dye fixation and excellent color fastness. Three blue reactive dyers (C.I. Reactive Blue 19, C.I. Reactive Blue 21, C.I. Reactive Blue 203) that contain β-sulfate ethyl sulfone were used to increase the dye fixation of reactive dyes with cotton fibers. The effects of alkali concentration, dyeing temperature, batching time, and salt concentration on the dyeing performance of cotton fabrics were studied. The effects of post-treatment (soaping and fixation) on the K / S values and color fastness were also investigated. The study showed that the dye fixation rate of the three reactive blue dyes was higher than 87%, and the rubbing and washing color fastness was more than grade 3–4 in the process of hot pad–batch dyeing of cotton fabrics. Furthermore, the dyed cotton fiber was fixed with a fixing agent (polyurethane (PU) and a mixture of PU and an aziridine crosslinker), and the color fastness reached not less than grade 4. Compared with cold pad–batch dyeing, hot pad–batch dyeing has the advantages of higher dye fixation and excellent color fastness for the three reactive blue dyes. Therefore, the dyeing performance of β-sulfate ethyl sulfone types of blue reactive dyes using hot pad–batch dyeing can effectively reduce the burden of post-treatment and the discharge of dyeing wastewater, and has a good application prospect in the dyeing of cotton fabrics. [ABSTRACT FROM AUTHOR]

In the nonaqueous medium dyeing system (decamethylcyclopenta siloxane; D5), the bonding between cotton fiber and reactive dye may be influenced by the dyeing medium. To evaluate the dyeing performance of reactive dye in the D5 dyeing system, the fixing of reactive dyes with different structures was studied. Before and after dyeing, the chemical environment of cotton fiber was investigated by X-ray electron spectroscopy, and compared with the spectroscopic method. Compared with traditional reactive dyeing, the color depth of the dyed cotton fabrics and the final fixation of dyes are much higher in the D5 dyeing system. The elements of the cellulose fiber surface are changed after dyeing. Especially for N element, its content is increased after dyeing. After 30 minutes, the final fixation of reactive dye is about 80% by analyzing the account of N. Compared with the undyed cellulose fiber, the peak area of C–C or C–H is gradually increased after dyeing, but the proportion of C–O is decreased with the fixing time. The proportion of O–C–O is not changed much with the fixation time. Therefore, the C–C or C–H chemical environment on the cellulose fiber surface will be changed after dyeing. Therefore, the bonding of dyes and fibers can be analyzed through the change of the C1s chemical environment or the amount of N element before and after dyeing. This investigation successfully developed a method which could evaluate the fixation process in the D5 dyeing system. [ABSTRACT FROM AUTHOR]

This analysis was extended to optimize the elimination of three mixed reactive colors including yellow 145, red 195, and blue 19 from wastewater using dicyandiamide-formaldehyde (DCD-F) resin. The synthesis of resin was conducted in controlled conditions and Fourier-transform infrared spectroscopy was performed to identify the nature of the synthesized resin structure. The investigation strategy, formulated on the response surface methodology (RSM) by the central composite design (CCD), was applied to optimize the impacts of the three operating factors of the coagulation and flocculation processes together with contact time (30-60 min), pH (5-9), and DCD-F dosage (0.5-1.5 mg/L) on the response, which was color removal (%). In addition, several linear and non-linear kinetic and isotherm models and thermodynamic parameters were used to assess the capacity and behavior of adsorption processes and dye mass transfer on DCD-F resin surface. Using RSM/CCD, the optimized conditions of contact time, pH, and polymer dosage were found to be 30 min, 7.18, and 1.3 mg/L, respectively. Assessing the linear and non-linear kinetic and isotherm models indicated that the dyes adsorption on DCD-F resin was fitted with linear pseudo-second-order type II and non-linear Freundlich models, respectively. In the best fitted isotherm model, the adsorption capacity was 726.3 mg/g and the kinetic study revealed that the adsorption process of reactive dyes on polymer is due to physicochemical interactions between the two phases of DCD-F resin and solute. In addition, the thermodynamic results including entropy, enthalpy and Gibbs free energy disclosed that the adsorption of reactive dyes on the synthesized resin was likely to be influenced by a physisorption mechanism. The results also disclosed that the resin can efficiently eliminate the reactive dye over an extended pH range. Therefore, it can be concluded that the DCD-F resin as an effective flocculant can be used to eliminate reactive dyes from colored wastewater in optimized conditions. [ABSTRACT FROM AUTHOR]

Rice straw is the most abundant agricultural waste material in Thailand. Therefore, this research was interested in utilizing rice straw and adding value by preparing a reactive dye bio adsorbent. The aims of this research were to prepare rice straw nonwovens by the wet-laid process, study chitosan-coated nonwovens by the dip coating method, and evaluate the reactive dye adsorption capacity of the coated nonwovens. The ratio of weight per unit area of the prepared nonwovens was controlled. The nonwovens were dipped in chitosan solutions (0.5, 1, and 1.5 wt% of chitosan) to prepare chitosan-coated nonwovens. Reactive dye adsorption capacity, chemical structure, morphology, and physical properties of the nonwovens were investigated. It was found that rice straw nonwoven coated with chitosan increased in thickness, hardness, and water resistance properties with increasing chitosan concentration. Chitosan-coated nonwoven, at 15% chitosan concentration and a contact time of 72 hours, was able to adsorb 38.40% of the reactive azo dye, C.I. Reactive Blue 194 (50 mg/L). The dye absorbency of the chitosan-coated nonwovens increased with the increase in the chitosan-coated concentration and the contact time. In addition, the chitosan-coated nonwovens could remain on rice straw cellulose nonwoven surfaces under reactive dye immersion for at least 72 hours without change. The results indicated that rice straw nonwovens coated with chitosan by the dip coating method had reactive dye adsorption abilities. [ABSTRACT FROM AUTHOR]

The study tested the use of Viscobleach as a multi-scouring agent for pretreating cellulosic fabrics (cotton, viscose, and linen) instead of using traditional agents (caustic soda, soda ash, and hydrogen peroxide). The results showed an increase in whiteness and absorbency for viscose and linen fabrics pretreated with Viscobleach. The color strength (K/S) increased for all shades of cotton and for medium and dark shades of viscose and linen. The study also showed that the dye pick-up was higher and dye wastage lower with the Viscobleach pretreatment. The color fastness to wash and rubbing was rated 4-5 for all samples. [ABSTRACT FROM AUTHOR]

The galvanising industry's wastewater treatment facilities generate waste metal hydroxide. These sludges have the potential to be used to remove textile dyes from effluents. In this study, three reactive dyes, which are frequently used in cellulosic textile materials' dyeing, Remazol Turquoise Blue G 133% (CI RB21), Remazol Red 3B (CI RR23), and Remazol Red 3BS 133% (CI RR239) were used to investigate the color removal efficiency of aluminum hydroxide sludge (AHS) depending on dye chromophore. Adsorption studies were conducted under varying conditions of pH, initial dye concentrations, and AHS doses. The characteristics of the AHS were examined by SEM (EDX and DX-Mapping), BET, XRD, and FTIR. The maximum dye removal was achieved at pH 3 for CI RB21, and at pH 5 for CI RR239 and CI RR23. Over 90% of dye removal was obtained for CI RR239 and CI RB21, when the adsorbent dosages were 8 g/l and 5 g/l, respectively. For CI RR23, the highest color removal percentage was only 72.7%, when the dosage of adsorbent was 10 g/l. It was also determined that at 500 mg/l initial CI RB21 dye concentration, the removal percentage of CI RB21 reached 95%, while the maximum removal percentages (95% for CI RR239 and 68.3% for CI RR23) were achieved at the 200 mg/l and 100 mg/l initial dye concentrations for CI RR239 and CI RR23, respectively. In the study, it was observed that the number of sulfo groups affecting the ionic charge of dye molecules and molecular weights of the dyes have a significant effect on the dye removal efficiency. Metal hydroxide is produced from treating wastewater from galvanising industry. Aluminium hydroxide sludge is cheap and efficient to remove dyes from textile wastewaters. Number of sulfo groups and molecular weights of dyes are significant for color removal efficiency. The highest dye removal by aluminium hydroxide sludge occurs in acidic conditions and dyes having higher molecular weight and higher number of sulfo groups. [ABSTRACT FROM AUTHOR]

The adsorption performance, kinetics, and thermodynamic parameters of reactive dyes on chitosan-treated cotton fabric are described in this research. The batch experiment was carried out to investigate the influence of pH, time, temperature, dye concentration, and material to liquid ratio of Remazol Red RR and Remazol Yellow RR, two widely used reactive dyes. The adsorption of red and yellow dyes was observed at λmax 517 and 419 nm respectively. For both Remazol Red RR and Remazol Yellow RR reactive dyes with starting dye concentrations of 0.0667 and 40 mg/L, the greatest dye adsorption was reported at pH 11 (0.0009 and 0.1284 mg/g) and pH 4 (0.0004 and 0.1038 mg/g). The adsorption performance was investigated using the Langmuir and Freundlich isotherms. The adsorption behaviours of the two reactive dyes closely matched to the Langmuir adsorption isotherm (R2>0.98) than Freundlich isotherm (R2>0.92). The pseudo-second-order kinetic model (R2>0.99) was followed by the dyeing kinetics of modified cotton sample. Thermodynamic investigation was covered with enthalpy change (ΔH⁰), Gibbs free energy (ΔG⁰) and entropy change (ΔS⁰) where all the values were reported positive confirming that the adsorption process was non-spontaneous, endothermic and the higher affinity of reactive dye on chitosan treated cotton.

The research aims for the simultaneous use of chlorine and UV irradiation (UV/Chlorine) to decolorize and detoxify Navy Blue 250 (NB250) and raw dye wastewater. The UV/Chlorine was the most effective in removing NB250 and color intensity (American Dye Manufacturers Institute, ADMI unit). The UV/Chlorine removed NB250 approximately 1.47-1.50 times faster than chlorination alone. The degradation constants in UV/Chlorine were 0.3317 mM-1min-1 and 0.3384 mM-1min-1 for NB250 and its ADMI color intensity, respectively. The optimum pH for decolorization was between 6 and 7. The UV/Chlorine with a chlorine dose of 1.0-2.0 mM was recommended for decolorization to meet the industrial discharge standard (300 ADMI). Reactive chlorine species (RCS) were more significant oxidants for NB250 removal than HO•. The presence of NB250 inhibited the germination of morning glory (Ipomoea aquatica) seeds, and exposure to raw dye wastewater (color = 6,658 ± 227 ADMI) completely inhibited seed germination. However, the samples treated by the UV/Chlorine were less toxic to seed germination and root growth. Therefore, the UV/Chlorine has a high potential in the decolorization and detoxification of dye wastewater. This is the first study to use the UV/Chlorine to treat industrial dye wastewater. [ABSTRACT FROM AUTHOR]

The use of low-cost adsorbent such as bottom ash has been investigated as a replacement for the current expensive materials for removal dyes from aqueous solution. The adsorbent was obtained from incinerated hospital waste (Mascara, Algeria). The prepared adsorbent was characterized by X-fluorescence, XRD, scanning electron microscopy, specific surface area (BET method) and pH(PZC). The results indicated that the material consisted of silica, carbonates and sodium chloride. The surface area and PZC were 1.29 m2/g and 8.9, respectively. The solid was applied for the removal of synthetic dyes namely Disperse Yellow 3 and Reactive Brillant Blue at various contact time, pH values and solution temperatures. The optimum pH and equilibrium time were 8.3 and 60 min, respectively. The dyes were adsorbed in single and binary solution. The adsorption isotherms show that the reactive dye was better adsorbed (269.36 mg/g) than the dispersive dye (120.64 mg/g). The adsorbed amounts of the dyes onto bottom ash were not affected by the type of system. The adsorption data were fitted with the linear forms of the Langmuir, Freundlich and Dubinin–Radushkevich models. Overall, the Langmuir isotherm showed a better fitting for all adsorptions under investigation in terms of correlation coefficient. Among the kinetic models tested, the adsorption reaction follows the pseudo-second-order kinetic controlled by intra-particle diffusion. In the both systems, the free energy and enthalpy changes obtained revealed that the process was spontaneous and endothermic. The positive entropy change confirms the enhancement of disorder near interface liquid/solid. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A detailed study was carried out to compare the removal of Reactive Blue 221 and Red X-5GN dyes using raw Helianthus Annuus L. seed shell as a natural adsorbent. There is no study in the literature for comparing the treatment of these anionic and cationic dyes using the current seed shell in raw form. Bringing a natural waste to the economy that can compete with adsorbents such as activated carbon commercially used in dye removal, will offer important advantages. The variation of initial pH value, shell dosage, contact time and, initial dye concentration was investigated. Reactive Blue 221 was successfully removed at pH 2 with a treatment efficiency of above 90%, while Red X-5GN was treated at pH 4 with a removal efficiency of 97%. Appropriate adsorbent dosages were 4 and 10 g/L for Reactive Blue 221 and Red X-5GN, respectively. Adsorption data of two dyes fitted very well to the pseudo-second-order reaction model with R2 values of 0.979–0.999. The data were best represented by the Langmuir model for Reactive Blue 221 with an R2 of 0.986. Freundlich isotherm was the most suited model for adsorption of Red X-5GN dye with an R2 of 0.996. The maximum uptake capacities were found to be 27.40 mg/g for Red X-5GN and 30.58 mg/g for Reactive Blue 221. The results showed that the conditions of adsorption for each dye can be significantly different. Besides, the potential of this seed shell as an eco-friendly and low-cost adsorbent was exhibited with perfect treatment results. [ABSTRACT FROM AUTHOR]

Textile wastewater treatment is a critical issue due to its high volume and pollution potential. This study investigates the photocatalytic degradation of red and green active dyes using a newly synthesized ZnO − TiO2 nano-photocatalyst doped with iron ions. The nano-photocatalyst is prepared through a green method using bitter olive seeds and a sol-gel method for doping iron ions. The XRD, FE-SEM, TEM, BET, and EDX characterizations show that the nano-photocatalyst is successful with a particle size of 50 nm and a specific surface area of 157.9 m2 g−1. Response surface methodology and central composite design are used to optimize the photocatalytic degradation of reactive dyes in synthetic and industrial wastewater. The optimal conditions were found to be initial dye concentration of 10 mg L−1, nano-photocatalyst dose of 0.5 mg L−1, contact time of 85 min, and pH of 6. Semi-industrial scale experiments show that the system is effective under both UV and visible radiation with removal efficiencies of more than 75% and 20%, respectively. The novel synthesis method and the high performance of the ZnO − TiO2 nano-photocatalyst doped with iron ions demonstrate the potential for practical application in the treatment of textile wastewater. [ABSTRACT FROM AUTHOR]

As is known, color stripping can be done with oxidizing or reducing agents. Today, reactive dye stripping is conventionally carried out via reductive method using hydrosulfite. However, from an environmental point of view, the use of more ecological chemicals has gained importance. In this study, it is aimed to determine the performances of reducing and oxidizing chemical alternatives to hydrosulfite, depending on the reactive dye chromophore. On the other hand, it was also aimed to provide a color fading effect on reactive dyed cotton fabrics with a treatment applied after dyeing. For this purpose, color stripping and/or fading effect was investigated on cotton knitted fabrics dyed with four different reactive dyes having anthraquinone (Reactive Blue 19), phthalocyanine (Reactive Blue 21), monoazo (Reactive Red 239) and metal azo (Reactive Red 23) chromophores. Studies were carried out with hydrosulfite, sodium hydroxymethane sulfinate and potassium persulfate at five different concentrations. It can be said that sodium hydroxymethane sulfinate and potassium persulfate can be used as an alternative to hydrosulfite in red dyes and blue dyes, respectively. COD and BOD values of wastewater of potassium persulfate treatment was found to be lower than hydrosulfite, which indicates that it is an ecological alternative over hydrosulphite.

Today, innovative productions have gained great importance to meet customer expectations. In this study, color stripping in reactive dyed knitted cotton fabrics with ozone technology was investigated. Furthermore, it was also aimed to obtain vintage effect by fading the color with the ozonation process. For this purpose, fabrics were dyed into three primer colors, namely yellow, red and blue, and also black color, then they were subjected to ozonation at different durations and the resulting stripping efficiency was evaluated in comparison with conventional caustic-hydrosulfite stripping method. From the color fading values (%), it is possible to say that yellow is the hardest and blue is the easiest to fade among the three primer colors. It was observed that as the ozonation time increased, the color lightened, but the actual fading occurred within the first 15 minutes, after which the change in color was smaller. Besides, it has been shown that if the ozonation is done for a very short time such as 5 minutes on reactive dyed fabrics, the vintage effect can be obtained. On the other hand, color stripping can be achieved as an alternative to caustic-hydrosulfite treatment, if the ozonation is performed for 15 minutes or longer.

Al-based waterworks sludge (ABWS) modified by calcination was reused as an adsorbent for the removal two reactive dyes, namely, reactive yellow 176 (RY-176) and reactive red 195 (RR-195) from aqueous solution. 800°C was proved to be the optimal calcination temperature in the range of 200-900°C. A series of static adsorption experiments were carried out using ABWS calcinated at 800°C (ABWS-800) as adsorbent. The results indicated that the adsorption of both the two dyes by ABWS-800 was almost independent of initial solution pH, and the adsorption capacity of ABWS-800 for RR-195 was about 1.4 times higher than that for RY-176. The pseudo-second-order kinetic model was best among the three models to describe the adsorption of the two reactive dyes, and Freundlich isotherm model was better matched than the Langmuir isotherm model to describe the adsorption process. Na2SO4 inhibited the adsorption of the two dyes onto ABWS-800. This work provided the theoretical basis and technical support for the optimization of reaction conditions for the decontamination of dyes wastewater by "waste" ABWS. [ABSTRACT FROM AUTHOR]

Polydopamine polymerization is one of the simplest methods for the functional modification of material surfaces. Because of the high requirements for rubbing and washing color fastness of textile and clothes fabrics during taking, the polydopamine on the fabric surface is a porous, loose, and disordered structure that cannot meet the color fastness requirements. To solve the above problems, we use a hot pad-batch treatment process of dopamine and CI reactive red 239 dye (RR239) that induces the orderly polymerization and growth of dopamine to prepare smooth and orderly polydopamine-modified and dyed cotton fabrics. In this way, the fastness of color is satisfied, and the color of the polydopamine-modified fabric can be enriched. In this paper, we compared the effects of three modification processes on the surface morphology of fibers with cotton fabrics as substrates, investigated the results on the dyeing properties of cotton fibers in the co-presence of dopamine/RR239, explored the role of calcium (Ca2þ) ions in the dyeing process, and the Fourier transform infrared and X-ray photoelectron spectrometer spectra of polydopamine-modified dyed cotton fibers were tested and the mechanism of cotton fiber modification and dyeing was elaborated. The results showed that the hot pad-batch dyeing process with the simultaneous presence of dopamine and reactive dyestuff could improve the polymerization and covalent cross-linking of dopamine, and increase the reaction of reactive dyestuff with fiber fixation. Due to the strong fabric extrusion, the polydopamine is an ordered and smooth structure, with excellent color fastness. [ABSTRACT FROM AUTHOR]

Malachite green (MG) is an organic dye and belongs to triphenylmethane category which is more harmful and toxic carcinogenic compound. In conventional methods for dye treatment, many metal ions and harmful chemicals were used. But in our study, we have proposed completely an eco-friendly method for dye degradation using carbon quantum dots (CQDs) from Spirulina platensis which is purely a natural and novel source of carbon-rich matter. The synthesized CQDs were characterized by TEM, SEM, particle size analyzer and fluorescence spectrophotometer. Sunlight promotes the photocatalytic activity of CQDs and degraded metabolites were analyzed by Gas chromatography–Mass spectrometry (GC–MS). Additionally, small quantity of synthesized CQDs acted as an efficient photocatalyst against 25 ppm concentration of MG dye and degradation was occurred within 3 h. 71% of BOD, 71.6% of COD and 78% of TOC were reduced by charcoal and it also helps to remove the CQDs from treated water by improving the quality of treated water with corresponding optical and physicochemical parameters. Based on the results of MG dye degradation, we have successfully done preliminary work for reactive blue MR and textile effluent degradation. A significant recycling process for degraded water was studied using phytotoxicity test and to prove that it does not possess any hazardous matter. [ABSTRACT FROM AUTHOR]

The use of residual microbial biomass from various industries in emerging pollutant removal strategies represents a new area of research in the field. In this case, we examined how to remove reactive dyes from an aqueous solution utilizing a biosorbent made of residual biomass from immobilized Saccharomyces pastorianus (S. pastorianus) in a polymer matrix using a dynamic system. Fluidized bed column biosorption investigations were carried out on a laboratory scale. Brilliant Red HE-3B was chosen as the target molecule. The main parameters considered for this purpose were the flow rate (4.0 mL/min; 6.1 mL/min), initial pollutant concentration (51.2 mg/L; 77.84 mg/L), and biosorbent mass (16 g; 20 g). The experimental data of the fluidized bed study were evaluated by mathematical modeling. The Yoon–Nelson, Bohart–Adams, Clark, and Yan models were investigated for an appropriate correlation with the experimental data. An acceptable fit was obtained for a flow rate of 4 mL/min, an initial pollutant concentration of 51.2 mg/L, and a biosorbent amount of 20 g. The obtained results indicate that the biosorbent can be used efficiently in a dynamic system both for the removal of the studied dye and in extended operations with a continuous flow of wastewater. As a conclusion, the investigated biocomposite material can be considered a viable biosorbent for testing in the removal of reactive dyes from aqueous environments and creates the necessary conditions for the extension of studies toward the application of these types of biosorbents in the treatment of industrial effluents loaded with organic dyes.

We report an analytical approach to study dye desorption and transfer processes in aqueous environment. The study was conducted simulating standard laundry washes using two different donor textiles, a polyester textile dyed with Disperse Blue 79 and a cotton textile dyed with Reactive Red 239, and two acceptor textiles, undyed cotton and polyester, respectively. Dye bleeding/solubilization from a donor textile to the solution was investigated through UV–visible absorbance analysis, while the dye absorption onto acceptor textile was quantified by UV–visible reflectance analysis. Dye desorption and transfer processes were investigated in water and surfactant solutions at different concentrations. A desorption and transfer model for the two classes of dyes was hypothesized by performing kinetic experiments. The results show that both processes depend on the presence of surfactants for the disperse dye. Conversely, the presence of surfactants has little effect on the reactive dye. Finally, the presence of an acceptor polyester significantly increases the bleeding of the disperse dye, while the presence of an acceptor textiles less influences the total release of the reactive dye. [ABSTRACT FROM AUTHOR]

As is known, color stripping can be done with oxidizing or reducing agents. Today, reactive dye stripping is conventionally carried out via reductive method using hydrosulfite. However, from an environmental point of view, the use of more ecological chemicals has gained importance. In this study, it is aimed to determine the performances of reducing and oxidizing chemical alternatives to hydrosulfite, depending on the reactive dye chromophore. On the other hand, it was also aimed to provide a color fading effect on reactive dyed cotton fabrics with a treatment applied after dyeing. For this purpose, color stripping and/or fading effect was investigated on cotton knitted fabrics dyed with four different reactive dyes having anthraquinone (Reactive Blue 19), phthalocyanine (Reactive Blue 21), monoazo (Reactive Red 239) and metal azo (Reactive Red 23) chromophores. Studies were carried out with hydrosulfite, sodium hydroxymethane sulfinate and potassium persulfate at five different concentrations. It can be said that sodium hydroxymethane sulfinate and potassium persulfate can be used as an alternative to hydrosulfite in red dyes and blue dyes, respectively. COD and BOD values of wastewater of potassium persulfate treatment was found to be lower than hydrosulfite, which indicates that it is an ecological alternative over hydrosulphite. [ABSTRACT FROM AUTHOR]

Today, innovative productions have gained great importance to meet customer expectations. In this study, color stripping in reactive dyed knitted cotton fabrics with ozone technology was investigated. Furthermore, it was also aimed to obtain vintage effect by fading the color with the ozonation process. For this purpose, fabrics were dyed into three primer colors, namely yellow, red and blue, and also black color, then they were subjected to ozonation at different durations and the resulting stripping efficiency was evaluated in comparison with conventional caustic-hydrosulfite stripping method. From the color fading values (%), it is possible to say that yellow is the hardest and blue is the easiest to fade among the three primer colors. It was observed that as the ozonation time increased, the color lightened, but the actual fading occurred within the first 15 minutes, after which the change in color was smaller. Besides, it has been shown that if the ozonation is done for a very short time such as 5 minutes on reactive dyed fabrics, the vintage effect can be obtained. On the other hand, color stripping can be achieved as an alternative to caustic-hydrosulfite treatment, if the ozonation is performed for 15 minutes or longer. [ABSTRACT FROM AUTHOR]

In this work, we study a unique phenomenon, which is the formation of surface plasmons on the surface of woven cotton fabrics dyed with reactive red dye and the effect of dye concentration on the surface plasmonicactivity. The results show that a peak was observed in the optical reflectivity spectra, which is an extension of the plasma edge. We called it the plasma peak. It represents the growth and decay phases of the plasmonic activity. Furthermore, the effect of dye concentration on both the plasma edge and the main characteristics of the plasma peak (position, spectral width, and intensity) is investigated. On the other hand, the dye concentration that results in the highest optical activity of surface plasmons was recorded (c = 2%). [ABSTRACT FROM AUTHOR]

Viscose fibre has been dyed with various dye concentrations and the needle-punched nonwoven fabrics are prepared using the dyed fibre, keeping machine parameters the same. The physical properties, such as tenacity & bursting strength, and functional performance properties, such as mean flow pore size, filtration efficiency & pressure drop, are measured. It is found that the dyeing plays a big role in altering the overall performance of the needle-punched nonwoven. The tenacity of the needle-punched nonwoven fabric is reduced as dye concentration is increased. Filtration efficiency is measured for three different sizes of particles, namely 3µm, 5µm, and 10µm. For all three cases, the filtration efficiency is increased initially till 3% dye concentration and beyond that it is reduced. [ABSTRACT FROM AUTHOR]

Adsorption of dyes on solid surfaces has been given considerable interest as one of the most efficient water treatment procedures owing to their low cost, simplicity, recyclability and adsorption efficiency. In this contribution, we report a simplified synthetic route of a novel bipyridinium-based viologen polymer from the polymerization of a viologen-based dialdehyde with aryl-based dihydrazide in an acidic aqueous solution. The developed polyviologen was exposed to the simple freeze-drying process to introduce the corresponding fibrous-like aerogel with high surface area. The chemical structure of the acylhydrazone-based viologen polymer (AHVP) was fully characterized using different spectroscopic techniques. AHVP displayed excellent affinity to form assembled hydrogel. Interestingly, the produced polymers introduced AHVP-linked covalent organic hydrogel framework that is organized in the form of nanofibers. Due to large surface area and surface functionalization, the ability of the active freeze-dried AHVP to adsorb Reactive Blue 19 (RB19) from an aqueous solution worth to be examined. Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), and UV–Vis absorption spectra were utilized to examine the aerogel surface morphology of the three-dimensional metal–organic viologen framework before and after adsorption of Reactive Blue 19.