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This article presents studies on the sorption of the anionic dyes Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84) from solutions of single dyes and from dye mixtures onto three chitosan sorbents–chitin, chitosan DD75% and chitosan DD95%. In this work, the influence of pH on sorption efficiency, the sorption equilibrium time for the tested anionic dyes and the sorption capacity in relation to the individual dyes and their mixtures were determined. It has been found that the sorption process for both dyes was most effective at pH 3 for chitin and chitosan DD75 and at pH 4 for chitosan DD95%. The obtained results were described by the double Langmuir equation (Langmuir 2). The obtained constants made it possible to determine the affinity of the tested dyes for the three sorbents and the sorption capacity of the sorbents. For RB5, the highest sorption capacity for chitosan DD95% was achieved with sorption from a single solution–of 742 mg/g DM and with sorption from mixed dyes–of 528 mg/g DM. For RY84, the highest efficiency was also achieved for chitosan DD95% and was 760 mg/g DM for a single dye solution and 437 mg/g DM for a mixture of dyes. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the feasibility of substituting the conventional inorganic alkalis (Na2CO3) with different organic alkoxide5s to explore the potential of replacing aqueous dyeing medium with environmentally friendly solvents like ethanol (EtOH). The study aimed to assess the dyeing characteristics, such as exhaustion, fixation, fastness qualities, physical properties, and environmental implications when EtOH and water were present, while also examining the impact of alkoxides. Time-gated Raman spectra provide insights into the allomorphic forms of cellulose-II after the alkoxide pretreatment, which significantly influences the overall reactivity of cellulose fibers and their dye absorption capabilities. Notably, organic alkoxide pretreated dyeing demonstrated improved color strength, exhaustion, and fixation efficiency compared to Na2CO3 pretreatment, as one of the work's key findings. For instance, the conventional dyed fabric exhibits 3.4 times lower color strength than alkoxide-based (RR239 + C2H5ONa 3 g/L + EtOH) dyeing, showing substantial potential for upscaling at commercial level as it requires no chemical auxiliaries (such as NaCl and Na2CO3). Importantly, the alkoxide pretreatment does not significantly alter the physical, mechanical and fastness properties of the fabrics, which are comparable to both the pristine and aqueous dyed fabrics, as confirmed by scanning electron microscopy experiments. The effluent's color intensity resulting from dyeing with C2H5ONa + EtOH (3 g/L) is approximately 24 times lower (250 Pt/Co) in comparison to the aqueous dyeing using 40 g/L of NaCl and 20 g/L of Na2CO3 in an aqueous medium (6154 Pt/Co). Apart from the color intensity, alkoxide pretreatment and EtOH-based dyeing drastically reduce the COD, BOD, TDS, TSS and total hardness values, which could have cost-saving implications for wastewater treatment plants (WWTPs). [ABSTRACT FROM AUTHOR]

Synthetic wastewater was treated in lab-scale constructed wetlands (CWs) in sequencing batch mode to evaluate roles of aquatic plants for removing an azo dye: Reactive Yellow 86 (RY86). Under hydraulic retention time (HRT) of 5 days, removal by unplanted CWs was less than 20% for RY86 of 10–50 mg/L. The CWs planted with cattail and papyrus demonstrated RY86 removal of 50–68% and 73–84%, respectively. For wastewater containing 50 mg/L RY86, removal in the unplanted CW was <12%, even under a 15 day HRT, although it was 22–71% in CWs planted with cattail and 34–81% in CWs planted with cattail, with increasing values under HRTs of 1 day to 15 days. Both cattail and papyrus grew well, extending their roots in the CWs for 90 days. RY86-decolorizing microorganisms were detected in CW effluent. Overall, RY86 removal was positively correlated with evapotranspiration in the CWs, indicating the plant uptake as the main removal mechanism. Papyrus and cattail, especially the former, are suitable plants for CWs intended to treat RY86-containing wastewater. [ABSTRACT FROM AUTHOR]

The objective of this study was to establish a solvent-assisted salt-free dyeing method for cotton fabric utilizing commercially available reactive dyes. In this study, the feasibility of substituting water as the dyeing medium with environmentally friendly solvents, specifically ethanol (EtOH), isopropyl alcohol (IPA), and propanol (PrOH), was investigated. Eight commercial reactive dyes, each possessing distinct chemical structures, were examined with various dyeing characteristics including exhaustion, fixation, and fastness properties, in the presence of various alcohols. However, solvent-assisted dyeing exhibited comparable or enhanced color strength (K/S) values, exhaustion, and fixation rates compared to conventional aqueous dyeing. For instance, the RR35 dye demonstrated a substantial increase in K/S values with PrOH, EtOH, and IPA, ranging from 115 to 369% improvement. The substitution of alcohol for water did not affect the wash, rub, and light-color fastness properties, as these properties remained consistently excellent. Solvent-assisted salt-free dyeing of cotton fabrics offers a promising solution to address the environmental impacts of traditional water-based dyeing methods by eliminating the requirement for water and salt. Overall, this study presents a solvent-assisted salt-free dyeing technique and contributes to the field by offering detailed insights into its mechanisms and performance. Our research has the potential to reduce water consumption, eliminate salt usage, and mitigate environmental pollution. [ABSTRACT FROM AUTHOR]

Reactive dyes have been widely used in cotton fabrics' dyeing due to their excellent application performance such as color diversity and simple use. Traditional dyeing of reactive dyes/ cotton fabrics is carried out under water bath conditions which consumes a large amount of energy and dyeing auxiliaries and generates a large amount of dyeing wastewater. The non-aqueous medium decamethylcyclopentasiloxane dyeing system of reactive dyes has attracted attention due to its significant advantages of zero salt and low water content in the dyeing process high dye utilization rate and energy conservation and environmental protection. It can effectively solve the problems of low dye utilization high electrolyte consumption and large sewage discharge in traditional reactive dyes' water bath dyeing. The dye solution is completely insoluble in the non-aqueous phase but has a strong affinity for cotton fibers so that more of the dye is rapidly distributed to the fibers with a small amount of water in a non-aqueous medium. However in the dyeing system polar aqueous solutions are tightly encapsulated by organic non-polar non-aqueous media forming a high concentration of dye solution resulting in poor dispersion of dyes in non-aqueous media. This may also cause aggregation or precipitation of dye molecules and uneven dyeing. The research on the adsorption mechanism of a reactive dye solution in salt-free and low-water dyeing systems is limited. In particular the comprehensive information on the effects of media on the diffusion and adsorption models of reactive dyes has not been systematically studied. In order to study the dyeing properties and dyeing kinetics of reactive dyes in the traditional water bath system and siloxane system and to explore the key factors affecting the dyeing of reactive dyes in non-aqueous medium salt-free and low-water dyeing systems the reactive dye of cyanuric acid-vinyl sulfone reactive yellow 145 was selected. The dyeing of reactive yellow 145 in the non-aqueous medium dyeing system and the traditional water bath dyeing system was investigated and an adsorption kinetic model of reactive dyes was established to explore the key factors affecting the dyeing of reactive dyes in non-aqueous medium salt-free and low-water dyeing systems. The intrinsic relationship between the diffusion behavior of reactive yellow 145 in non-aqueous dyeing systems was successfully determined and the adsorption kinetics and mechanisms of reactive dyes in non-aqueous dyeing systems and water bath systems were revealed. The experimental results show that the absorption rate of active yellow 145 is higher > 95% and the fixation rate is also higher 72% - 84% for non-aqueous dyeing and 43% - 71% for traditional dyeing in the nonaqueous medium salt-free and low-water dyeing system. The K/ S value of cotton fabric after dyeing is higher 5. 97 - 26. 63 for non-aqueous dyeing and 4. 35 - 21. 92 for traditional dyeing . The dyeing kinetics of reactive yellow 145 in the two dyeing systems can be described by using a quasi-second-order kinetic model. As the dye concentration increases the difference between the final adsorption amount of reactive dyes in the non-aqueous medium salt-free and low-water dyeing system and the final adsorption amount in the water bath system gradually increases. When the dye dosage is 8% the final adsorption capacity of the traditional water bath system 68. 32 is more than twice compared to 29. 20. The half dyeing time distribution of the water bath dyeing system is between 16. 60 and 7. 48. The half dyeing time distribution of the water bath dyeing system is between 16. 60 and 7. 48. The distribution of semi staining time in non-aqueous media is between 2. 03 and 2. 58. These results indicate that the dyeing speed of reactive dyes in salt-free and low-water systems is much higher than that in traditional water bath systems and the dye utilization rate is high. The K/ S value of the dyed fabric is also high. Non-aqueous dyeing technology provides an innovative method to increase dye uptake at low energy consumption in addition to saving large amounts of water. This study provides theoretical guidance for the dyeing of cotton fabrics with different dyeing depth requirements in the salt-free and low-water dyeing system and it is of great significance to improve the practical application of reactive dyestuffs in non-aqueous medium salt-free and low-water dyeing system as well as industrial production. [ABSTRACT FROM AUTHOR]

This study investigated the degradation and removal efficiency of reactive and direct dyes using various treatment processes, including UV alone, peroxide alone, Fenton, photo-Fenton, and UV-peroxide. The decolorization results showed that UV and peroxide alone had limited performance, achieving only 8.8% to 14.4% decolorization for direct dyes DR28 and DB71. The Fenton and photo-Fenton processes exhibited rapid total organic carbon (TOC) degradation within the initial 30 minutes, reducing reactive dyes RBla5, RB19, and RO16 by 41.3% to 38.8%. However, the reaction stagnated due to the depletion of Fe2+ in the Fenton process. Interestingly, the UV-peroxide treatment demonstrated superior decolorization performance, achieving 72.9% to 99.2% decolorization for DR28 and DB71 at pH 3 and 7. In contrast, TOC removal efficiency fell below expectations for all processes. The iron-based processes, Fenton and photo-Fenton, resulted in low TOC removal values for both direct dyes, possibly caused by the mordanting phenomena between dyes and iron, shown by visible sediment formation Further research is needed to optimize TOC removal efficiency, especially for direct dyes, and to elucidate the mechanisms of protonation and mordant interactions in the dye degradation process. [ABSTRACT FROM AUTHOR]

The undoped TiO2 (T), 1% Ni-doped TiO2 (N1T), and 1% Co–1% Ni co-doped TiO2 (C1N1T) photocatalysts were prepared by the sol–gel technique. The characterization of prepared materials was carried out by X-ray diffraction, Diffused Reflectance Spectroscopy, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Brunauer–Emmett–Teller and Thermogravimetric Analysis to analyze composition, phase, morphology, and optical properties. These results revealed that C1N1T exhibited higher surface area, better pore volume and enhanced optical properties as compared to undoped and Ni-doped TiO2. Furthermore, the photoactivity of C1N1T nanoparticles was manifested toward Acetaminophen, Phenol and reactive dyes i.e., Remazol Black B and Yellow 2 G. Moreover, C1N1T nanoparticles showed remarkable degradation efficiency of 53%, 56%, 98% and 89% for Acetaminophen, Phenol and anionic dyes, i.e. Remazol Black B and Yellow 2 G under optimized conditions (pollutant concentration = 20 ppm; time = 120 min; C1N1T loading = 20 mg; irradiation source = solar light; pH = 4 for each dye, pH = 7 for phenol and pH = 9 for acetaminophen). The significant degradation values suggested that the C1N1T photocatalyst can be effectively employed to degrade the textile dyes and PPCPs from industrial wastewater. [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]

A systematic procedure for the removal of color and chemical oxygen demand (COD) of an aqueous solutions comprising initial mixed binary azo reactive dyes (Corafix Red ME4B and Corazol Black BX), present in any proportions of initial concentrations, has been developed. It utilizes a Fenton-like advanced oxidation process (AOP) involving the activation of mixed binary oxidants as a pretreatment and a hybrid process, consisting of US cavitation and O3 based AOPs, as a post-treatment method. For the red dye, the optimum values of activator concentration, initial oxidant-ratio, initial oxidant-dosage, initial pH of initial H2O2 solution have been determined to be 100 g L−1, 3 wt% mM−1, 18:6 wt% mM−1, and 5 respectively; while, the US cavitation or O3 has been determined to be an optimum post-treatment. Similarly, for the black dye these optimum values and process are identified to be 100 g L−1, 3 wt% mM−1, 30:10 wt% mM−1, 3, and hybrid process respectively. The common optimum values of various parameters of pretreatment and a common optimum post-treatment method have been derived and experimentally demonstrated for the treatment of mixed binary dye solutions. The mechanisms responsible for decolorization and COD removal have been identified via hydroxyl and superoxide radical-trapping experiments [ABSTRACT FROM AUTHOR]

As a good alternative to natural fibers and petroleum-derived fibers, Lyocell fibers draw increasing interests owing to its advantages of sustainable forest source, low carbon emission, high strength and comfort. However, Lyocell exhibits significant fibrillation behavior under friction, which seriously reduce product quality and limit its further development. Herein, dual crosslinking networks were innovatively constructed in Lyocell cellulose structure to enhance the interaction of cellulose macromolecular chains. Bifunctional reactive dyes were loaded in the inner part of Lyocell fiber to form a primary crosslinking network. Then, the cellulose interaction in Lyocell skin layer was further enhanced after the coating by cationic waterborne polyurethane. The mechanism was determined and results showed that durable dual crosslinking networks were formed in Lyocell cellulose structure. From scanning electron microscope (SEM) observation, fibrillation behavior of Lyocell fibers was effectively prevented by dual crosslinking networks. Meanwhile, the durability was evaluated, showing that the treated fabric maintained good anti-fibrillation performance after washing for 50 times. Furthermore, the interaction of dyes and fibers was also enhanced by the cationic polymer via electrostatic attraction force, realizing high dye utilization efficiency. Therefore, the method exhibits great potential in promoting the application of Lyocell fibers in greener textile. [ABSTRACT FROM AUTHOR]

Bamboo fiber is gaining the curious attention of researchers as well as the fashion and apparel industries as an alternative to the cotton fiber. Bamboo fabric besides having prodigious characteristics, possess several limitations i. e. high-cost, poor spin-ability, a significant reduction in strength under wet conditions etc. The present study is focused to address the problems associated with the bamboo fiber to make it user and environment-friendly. An isocyanate based compound, HDI (blocked hexamethylene diisocyanate) was chemically crosslinked with bamboo fabric to enhance its dyeability and fastness properties without compromising on its thermal stability and tensile strength. The dyeing properties, levelness, thermal stability, absorbency, and tensile and tear strength measurements of the HDI-based bamboo fabric were compared with the untreated fabrics. The HDI-based bamboo fabric dyed with commercial reactive dyes exhibited up to 10% and 9% increase in exhaustion and total percent fixation, respectively. Whereas the modified fabrics dyed with lab-synthesized reactive dyes displayed 12–14% and 10% increase in fixation and total percent fixation, respectively. Furthermore, the HDI-based bamboo fabrics possessed better dyeing levelness compared to the untreated fabrics. Light and rubbing fastness of some of the modified fabrics increased significantly. Absorbency of the treated bamboo fabrics decreased while no significant change in the thermal stability and tensile strength of the treated fabrics was noticed after HDI treatment. [ABSTRACT FROM AUTHOR]

This study focuses on the improvement of bioremediation of textile dye Reactive Red 195 using agro-industrial waste, groundnut oil cake (GNOC) obtained after oil-pressing. The treatment of GNOC with 1 N H2SO4 had resulted in physiochemical changes on the insoluble porous adsorbent, which improved their adsorption efficiency. The dye removal efficiency increased from 55% to 94% on acidification of GNOC. The raw groundnut oil cake (RGNOC) and acid-treated groundnut oil cake (AGNOC) were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction, and zeta potential. The rate and efficiency of dye adsorption were examined using adsorption kinetics and isotherm models. The results confirm that acid-treated GNOC eliminates impurities, alter the surface functional groups, and significantly increase porous surface areas of RGNOC. The investigation of key factors such as contact time, initial concentration of dye, static/agitation impact, particle size, and adsorbent dose had significantly influenced adsorption capacity of GNOC. Adsorption of dye fits best into the Langmuir model and equilibrium data of dye on AGNOC was explained by psuedo-second-order reaction with maximum adsorption capacity of 12.65 mg/g. This emphasis AGNOC has a very excellent potential to remove the textile dye Reactive Red dye from industrial effluent. This study reports the primary investigation exploring the application of groundnut oil cake (RGNOC) and its acid-modified (AGNOC) version for the bioremediation of industrially used textile dye Reactive Red 195 (RR195). The core objective of this study is to use a low-cost biosorbent to remove RR195 dye from effluent that pose risk to the health and environment. This study analyses the adsorption capacity of RGNOC and its acid-modified version AGNOC to treat contaminated water and the influencing parameters. AGNOC adsorption potential for RR195 dye sequestration was shown to be higher compared to RGNOC. Acidification of the adsorbent is simple, cost expensive, and more efficient alternate approaches to scale up for industrial application. As a result, an attempt has been made to add a new adsorbent to the database. [ABSTRACT FROM AUTHOR]

The breakdown of dyes, which are environmentally hazardous substances and notoriously difficult to degrade, presents the main treatment challenge for wastewater from textile industries. Most advanced oxidation processes (AOPs) for dye degradation usually use costly decolorizing agents, whose residue from Wastewater Treatment Plants may be hazardous to the environment. The present study aimed to apply ultrafine bubbles (UFBs) for water AOPs to degrade textile dyes. Our most recent innovation, ultrafine bubbles, enables the production of reactive oxygen species recently introduced as oxidants in AOPs. First, the disc diffuser was optimized by introducing various flow rates of 1–5 L Per Minute (LPM) to generate UFBs with unique characteristics observed from Zeta Potential, pH, Dissolved Oxygen (DO), and Oxidation–Reduction Potential (ORP). The air UFBs using a disc diffuser with 3 LPM were selected to degrade the Navacron Ruby S-3B dye solution (1000 Pt-Co). The treatment was optimized on the coagulant dosage (0.25, 0.5, 0.75, and 1 ppm) and bubbling times (0–120 min). As a result, the UFBs were successful in degrading the Navacron Ruby S-3B dye solution, resulting in a 45% reduction in Pt-Co color scale with a bubbling time of only 120 min and minimal coagulant dosage (0.5 ppm) compared to the Navacron Ruby S-3B dye solution treatment commonly using a coagulant dosage of 1.5 ppm without UFBs. Based on FTIR, XRF, and PL analysis, we propose the AOP mechanism of hydroxyl radicals for the Navacron Ruby S-3B dye solution. It is emphasized that UFB water AOPs (UFBs–WAOPs) represent a promising alternative technology for treating textile wastewater without chemicals or decolorizing agents. Thus, the UFBs-WAOPs are economical and environmentally benign textile wastewater treatment methods. [ABSTRACT FROM AUTHOR]

This study explores the efficient removal of the synthetic anionic dye-reactive red Me4BL (RRMe4BL) from an aqueous medium which is a significant contributor to environmental pollution. The present study investigates the synthesis of zinc oxide, nickel oxide, cobalt oxide and copper oxide nano adsorbents (ZnO (II), NiO (II), CoO (II), CuO (II)) through the co-precipitation method and their effectiveness in eliminating the reactive red dye Me4BL(RRMe4BL). Maximum adsorption capacities were achieved at pH 2 for ZnO (96.1 mg/g), NiO (86.9 mg/g), CoO (93.4 mg/g) and at pH 6 for CuO (76.3 mg/g) under a 0.05 g/50 mL nano-adsorbent dose, 50 mg/L dye initial concentration and 25°C T and 90 min of contact time. The fitness of the pseudo-2nd-order model explained the kinetics, while Langmuir and Temkin adsorption isotherm highlighted the efficiency of the dye adsorption. Thermodynamic studies revealed the spontaneous and exothermic nature of adsorption. The influence of electrolytes, surfactants and desorption was also analysed. Characterisation of the nanoparticles was done through SEM, XRD and FTIR which revealed the morphology and functional groups of nano-adsorbents. The adsorption method used for eliminating this anionic red dye shows several benefits, including affordability, simplicity of use and the presence of intelligent adsorbents for environment-friendly removal of industrial dyes from wastewater. [ABSTRACT FROM AUTHOR]

Industrial dyes are the main cause of environmental pollution. The present study consists of the removal of synthetic anionic dye using batch study with photocatalyst using adsorption technology. The adsorbents were prepared using the chemical synthesis method. At pH 5, ZnO2 shows maximum results in the Reactive Blue dye. At the same time, CuO2 shows maximum results at pH 2. In contrast, the CdO2 and PbO2 nanoparticles presented maximum results at pH 4. The optimum dose for all four kinds of nanoparticles, ZnO2, CuO2, PbO2, and CdO2, was found to be 0.5 g/50 mL for the elimination of anionic dye at pH 2, 4, and 5. For ZnO2, CuO2, PbO2, and CdO2 nano photocatalyst, the maximum percentage of dye removal was recorded at 0.05 catalyst dosage. The starting concentration of dye in the series of 25–200 mg/L was measured as optimum for the highest deletion of anionic stain by dissimilar kinds of chosen adsorbents. The maximum adsorption capacity of ZnO2 (85.69 mg/L), CuO2 (79.04 mg/L), PbO2 (64.12 mg/L), and CdO2 (51.58 mg/L) was obtained at 100, 150 and 75 mg/L dye concentration. The optimum temperature for the highest removal of anionic dyes was detected at 37 °C, and the reduction examined a decline in the adsorption capacity of whole compounds as temperature decreases. It represented the exothermic behavior of all sorption processes intricate in the exclusion of certain anionic dyes. Langmuir biosorption isotherms were given the best fitness on equilibrium biosorption data, whereas the pseudo 2nd order displayed the fitness on adsorption kinetic data. Additionally, data show that the elimination of Reactive Blue dye by adsorption with ZnO2, CuO2, PbO2, and CdO2 nanoparticles follows second-order kinetics (R2 = 0.9855) and Langmuir model (0.9997). Utmost desorption was attained by 0.5 N sodium hydroxide. Fourier Transform Infrared (FTIR) was used to characterize the nanoparticles, which gave information about the functional groups on dyes. So, by using the adsorption technology, maximum dye removal from wastewater was observed, and ZnO2 showed maximum percentage removal of anionic dye. Reactive Blue is effectively degraded in aqueous solution by photocatalysis with ZnO2 assistance while being exposed to ultraviolet (UV) radiation. [ABSTRACT FROM AUTHOR]

Multifunctional cellulosic fibers are in high demand for use in a variety of applications. Functional cellulosic fibers obtained through green and sustainable approaches are getting special attention because of the need to limit the environmental impact of hazardous chemicals. Herein, a novel facile, efficient, and eco-friendly approach for multifunctional viscose fibers@Ag NPs (VF-Ag) was designed by a rapid, facile, and one-pot biosynthesis green route using guava leaf extract as a reducing and stabilizing agent. UV–Vis, TEM, SEM, EDX, FTIR, and XPS were used to analyze the formation of silver nanoparticles and their subsequent deposition on the surface of viscose fibers. The silver nanoparticles immobilized on the surface of viscose fibers endowed a yellow/brownish color to the fibers as well as improving the dyeing with reactive dye. The VF-Ag samples have multifunctional properties like protective activities against UV radiation and microorganisms, antioxidant activity, and sensor ability toward Hg2+. The results demonstrated that the UPF values of VF-Ag samples ranged from 280 to 355 compared to 103 for VF. The antioxidant activities of VF-Ag ranged from 79 to 85% compared to 9% for VF. VF-Ag samples exhibited excellent antimicrobial activities against Gram-positive and Gram-negative bacteria, very good activities against yeast, and low activities against fungus. VF and VF-Ag were dyed using reactive dye (CI-reactive blue-19) at two color intensities (2.5, and 5%). The results show that the color of VF turned blue, while the color of VF-Ag turned greenish. The color strength of VF-Ag significantly increased with increasing silver content. Furthermore, VF-Ag showed high sensitivity to naked-eye colorimetric sensing for the detection of Hg2+. In straightforward, this innovative approach provides an easy, quick, and low-cost that will open the door for a range of versatile applications for modified viscose fibers in the fields of medical and analytical applications. [ABSTRACT FROM AUTHOR]

The project aims to remove reactive blue dye from the effluent of textile industries by utilizing coal-associated soil as an adsorbent, as it possesses effective physical properties and distinguishing characteristics. In comparison to other separation techniques, the adsorption method is the most effective, cost-effective, and straightforward. A batch adsorption investigation was carried out to examine the various adsorption-influencing factors, including solution pH, adsorbent dosage, contact time, temperature, and dye concentration. Contact time of 30 min, an adsorbent dosage of 10g.100 mL-1, a solution pH of 7, a temperature of 30°C, and an initial dye concentration of 100 mg.L-1 were found to be optimal for dye adsorption. Using two distinct kinetic models, the evaluation of kinetic studies revealed that the pseudo-second-order provided the greatest fit, with a higher R² value than the pseudo-first-order. The thermodynamic parameters Gibbs free energy (ΔG°), entropy (ΔS°), and enthalpy (ΔH°) indicated that the current adsorption system was exothermic and spontaneous. Further study of the adsorption isotherm revealed that the Langmuir isotherm model provided the best fit, with an R² value of 0.977%. [ABSTRACT FROM AUTHOR]

Abstract Recently, focus has been placed on renewable sources, as they can be provided in large quantities at the lowest possible cost, in order to create nanoparticles. One of these sources is Zygnema moss which used in the present investigation to create Copper oxide nanoparticles (CuONPs). Several phenols and flavonoids were identified the extract of Zygnema sp. via analysis of High performance liquid chromatography. These constituents served as reducing and stabilizing agents for CuONPs. Characterization of CuONPs was performed via UV-visible spectrum that demonstrated peak at 252 nm, Transmission electron microscopy that showed spherical CuONPs with mean diameter of 30.06 nm, Fourier transform infrared spectroscopy that confirm that presence of several functional groups aided to formation of CuONPs. The crystallographic pattern of CuONPs was recorded via X-ray diffraction analysis. Antimicrobial potential of CuONPs was compared to copper acetate and antibiotic/antifungal drug. CuONPs exhibited more inhibition zones against S. aureus (32 ± 0.1 mm), E. coli (36 ± 0.1 mm), S. typhi (27 ± 0.2 mm), E. faecalis (37 ± 0.1 mm), C. albicans (34 ± 0.3 mm) than copper acetate and antibiotic/antifungal drug. Promising MIC values of were recorded against S. aureus, E. coli, and S. typhi. CuONPs at 200 ppm inhibited the growth of C. lunata, F. oxysporium, A. flavus, and Mucor circinelloid with inhibtion of 76.92, 73.33, 63.63, and 53.84%, respectively regarded the control 100% growth. The photocatalytic role of CuONPs was recorded for degradation of reactive red (RR195) and reactive blue (RB) dyes with maximum degradation of 84.66% and 90.82%, respectively at 75 min. Moreover, the optimal dyes degradation was 84.66 and 90.82%, respectively at 40 °C.

Recently, focus has been placed on renewable sources, as they can be provided in large quantities at the lowest possible cost, in order to create nanoparticles. One of these sources is Zygnema moss which used in the present investigation to create Copper oxide nanoparticles (CuONPs). Several phenols and flavonoids were identified the extract of Zygnema sp. via analysis of High performance liquid chromatography. These constituents served as reducing and stabilizing agents for CuONPs. Characterization of CuONPs was performed via UV-visible spectrum that demonstrated peak at 252 nm, Transmission electron microscopy that showed spherical CuONPs with mean diameter of 30.06 nm, Fourier transform infrared spectroscopy that confirm that presence of several functional groups aided to formation of CuONPs. The crystallographic pattern of CuONPs was recorded via X-ray diffraction analysis. Antimicrobial potential of CuONPs was compared to copper acetate and antibiotic/antifungal drug. CuONPs exhibited more inhibition zones against S. aureus (32 ± 0.1 mm), E. coli (36 ± 0.1 mm), S. typhi (27 ± 0.2 mm), E. faecalis (37 ± 0.1 mm), C. albicans (34 ± 0.3 mm) than copper acetate and antibiotic/antifungal drug. Promising MIC values of were recorded against S. aureus, E. coli, and S. typhi. CuONPs at 200 ppm inhibited the growth of C. lunata, F. oxysporium, A. flavus, and Mucor circinelloid with inhibtion of 76.92, 73.33, 63.63, and 53.84%, respectively regarded the control 100% growth. The photocatalytic role of CuONPs was recorded for degradation of reactive red (RR195) and reactive blue (RB) dyes with maximum degradation of 84.66% and 90.82%, respectively at 75 min. Moreover, the optimal dyes degradation was 84.66 and 90.82%, respectively at 40 °C. [ABSTRACT FROM AUTHOR]

Rapid activation of sodium persulfate (SPS) for the degradation of C.I. Reactive Red 218 (RR218) was achieved using Ti3C2 MXene reduction of trace Fe3+. The degradation rate of RR218 reached 97.7% using a mixture containing 3 g L−1 of SPS, 3.35 mg L−1 of Fe3+ and 60 mg L−1 of MXene stirred at 25 °C for 30 min. The intense reduction of Ti3C2 MXene triggers the Fe3+/Fe2+ cycle thereby accelerating the activation of SPS. When reactive dyes were degraded by Fe3+/SPS/MXene process, ·OH played a major role. The dye degradation capacity of the Fe3+/SPS/MXene process decreased after 5 cycles of recycling. In addition, the wastewater treated under these conditions resulted in high dyeing efficiencies in reuse experiments. This study not only improves the understanding of the catalytic reaction of MXene but also provides a wastewater treatment and reuse process with low metal consumption and high efficiency. [ABSTRACT FROM AUTHOR]

Biosorptive treatment with microbial biomass is regarded as an environmentally friendly and effective way to reduce dye contamination in contaminated aquatic environments. Immobilizing microbial cells for use in this process can significantly improve their effectiveness as biosorbents in the water treatment process. The current investigation searches for a sustainable and environmentally friendly approach to decolorization by employing a green biocomposite material sorbent system (ZM@GFC) created by immobilizing fungal cells (Gibberella fujikuroi) on maize tassel tissues to efficiently remove Reactive Yellow 2 (RY2) from contaminated water sources. Batch and dynamic flow tests were performed to evaluate the biodecolorization properties of the newly created immobilized biomaterial as well as the effects of several essential operating conditions factors on the sorption behavior. Biosorption yields of 95.7% and 90.0% in batch and dynamic modes were achieved for experimental dye decolorization. The biosorption of RY2 by ZM@GFC occurred fast and achieved equilibrium within 60 min. The pseudo-second-order kinetic model elucidated the dye biosorption onto ZM@GFC. The Langmuir model provided a more accurate representation of the results than the Freundlich model. At the same time, Redlich-Peterson isotherm demonstrated the best level of agreement with the experimental data. These findings indicate that the biosorption mechanism predominantly involved the formation of a monolayer covering and that the energy properties of the ZM@GFC surface were uniform. The breakthrough capacity at the exhaustion time was 537.32 mg g−1. The predicted cost of generating ZM@GFC was anticipated to be 61.03 USD/kg. The investigations on safe disposal demonstrated that the biosorption process did not generate any secondary pollution. In conclusion, using maize tassel tissue as an immobilized decolorization agent offers a possible method for removing reactive azo dye pollutants from the aquatic medium that is both economical and environmentally benign. [ABSTRACT FROM AUTHOR]

Heterobifunctional reactive dyes are widely used to dye cotton and protein fabrics owing to their characteristic such as excellent dyeing fastness high lightfastness and wide range of colors. The primary cause of color fading and coloring during the washing of cotton fabrics is the hydrolysis of covalent bonds between dyes and cellulose. However at present people are only familiar with the mechanism of hydrolysis of covalent bonds formed between individual active groups and cellulose such as the common halogenated homotriazine group and vinyl sulfone group. Specifically the ether bond formed by halotriazine active group and cellulose and the ether bond formed by vinyl sulfone group and cellulose will be hydrolyzed under alkaline conditions. Halogenated triazine reactive group will be hydrolyzed into hydroxytriazine and vinyl sulfone reactive group will be hydrolyzed into β-hydroxyethyl sulfone while the reaction mechanism that results in the breaking of covalent bonds between different reactive groups and cellulose molecules remains unclear. Based on the principle of quantum mechanics quantum chemical calculations can accurately simulate the movement and interaction of electrons as well as the formation and fracture of chemical bonds. These make predicting the properties of molecules and reactions without relying on experimental data possible. Thus quantum chemical calculations are widely used to describe molecular structures reaction mechanisms and energy changes. The wave function theory and density-functional theory DFT are two important parts of quantum chemical calculations. The frontier molecular orbital FMO and conceptual density functional theory CDFT are two representative theories to predict and rationalize molecular reactivity qualitatively and quantitatively. Some chemical reaction descriptors obtained from CDFT like Fukui function chemical hardness or softness electrophilicity or nucleophilicity are a new type of structural index specially used to describe the chemical reactivity of substances. This article combined wave function theory and CDFT to investigate chemical characteristics of the hydrolysis pathway of the covalent bond between heterobifunctional reactive dye and cellulose under alkaline conditions with the heterobifunctional reactive dye named Reactive Yellow 210 RY210 being used as an example. In order to reduce the complexity of the model the chromophores in RY210 molecule that are not related to the reaction were replaced by hydrogen atoms. At the same time according to previous studies cellobiose was substituted for cellulose molecules. The research process was divided into three steps. Firstly the possible pathways and products of RY210 and cellulose polymer were conjectured based on the hydrolysis mechanism of the covalent bond between a single reactive group dye and cellulose. The ether bond formed by the active group of triazine group and cellulose will be hydrolyzed into hydroxytriazine and the ether bond formed by the active group of vinyl sulfone and cellulose will be β-eliminated to generate vinyl sulfone which will be further hydrolyzed into β-hydroxyethyl sulfone. Based on this known mechanism it is hypothesized that there are seven possible hydrolysis pathways which involve hydrolysis of one reactive group alone followed by the other reactive group as well as hydrolysis of both reactive groups at the same time. Secondly the study constructed a dye-cellulose polymer model. To do this the study investigated the sites on the cellobiose molecule where OH - is easy to react with using electrostatic potential ESP frontier molecular orbital theory FMO and two chemical reaction descriptors CFF and CDD based on DFT. The model was constructed by taking into account their three spatial arrangements of the cellobiose and dye molecules in orthogonal anticlinal parallel and perpendicular directions. Then these structures were optimized by MD simulations and the most stable polymer structure was identified. Further the study calculated the Gibbs free energies of different hydrolysis pathways based on the theory of M06-2X∕6-311G d . Additionally the local nucleophilic reactivity of dye-cellulose compounds at the bonding sites of triazine and vinyl sulfone groups with OH- was compared to further verify the previous conclusions. The findings demonstrate that the cellobiose-dye polymer was readily hydrolyzed at the bonding with vinyl sulfone but could be hydrolyzed at the bonding with triazine difficultly. The covalent bonding of vinyl sulfone with OH - displayed higher nucleophilic activity. Initially the ether bond was hydrolyzed to form vinyl sulfone with a reaction energy barrier of 17. 1 kcal∕mol. Following this vinyl sulfone was hydrolyzed to produce β-hydroxyethyl sulfone with a reaction energy barrier of 27. 8 kcal∕mol. The nucleophilic reactivity at the homotriazine group was the lowest and the homotriazine group was hydrolyzed into hydroxytriazine with a significant amount of energy at 48. 6 kcal∕mol. This study is helpful to further understand the mechanism of hydrolysis of heterobifunctional reactive dyes from cellulose under alkaline conditions. At the same time the study also provides some ideas for slowing down the fading of heterobifunctional dyes from fabrics and washing crossovers as well as designing efficient and environmentally friendly reactive dyes. [ABSTRACT FROM AUTHOR]

A novel approach to enhance the utilization of low-cost and sustainable chitosan for wastewater remediation is presented in this investigation. The study centers around the modification of chitosan beads using a deep eutectic solvent composed of choline chloride and urea at a molar ratio of 1:2, followed by treatment with sulfuric acid using an impregnation accessible methodology. The effectiveness of the modified chitosan beads as an adsorbent was evaluated by studying the removal of the azo dye Reactive Black 5 (RB5) from aqueous solutions. Remarkably, the modified chitosan beads demonstrated a substantial increase in adsorption efficiency, achieving excellent removal of RB5 within the concentration range of 25–250 mg/L, ultimately leading to complete elimination. Several key parameters influencing the adsorption process were investigated, including initial RB5 concentration, adsorbent dosage, contact time, temperature, and pH. Quantitative analysis revealed that the pseudo-second-order kinetic model provided the best fit for the experimental data at lower dye concentrations, while the intraparticle diffusion model showed superior performance at higher RB5 concentration ranges (150–250 mg/L). The experimental data were successfully explained by the Langmuir isotherm model, and the maximum adsorption capacities were found to be 116.78 mg/g at 298 K and 379.90 mg/g at 318 K. Desorption studies demonstrated that approximately 41.7% of the dye could be successfully desorbed in a single cycle. Moreover, the regenerated adsorbent exhibited highly efficient RB5 removal (80.0–87.6%) for at least five consecutive uses. The outstanding adsorption properties of the modified chitosan beads can be attributed to the increased porosity, surface area, and swelling behavior resulting from the acidic treatment in combination with the DES modification. These findings establish the modified chitosan beads as a stable, versatile, and reusable eco-friendly adsorbent with high potential for industrial implementation. [ABSTRACT FROM AUTHOR]

Textile industry creates serious amount of dye effluents. These hazardous molecules threat environment, animal, and plants. Therefore, there is an urgent need to diminish the negative effects of these substances. The current study describes reactive dye removal capacities of newly isolated halotolerant yeast. Because of textile wastewaters contain significant amount of salts, 14 yeasts isolates from cheese and pickle factory wastes were screened for their ability to remove different reactive dyes in molasses media contained NaCl. One isolate showed high Reactive Black 5 removal performance in the presence of 4% NaCl (w/v) and this isolate was identified as Kluyveromyces marxianus. Effects of some important parameters such as pH, NaCl concentration, incubation period, inoculum amount, and initial dye concentration on bioremoval efficiency were investigated. K. marxianus was able to remove 70% Reactive Black 5 at an initial dye concentration of 100 mg/L, pH 6 in the presence of 4% NaCl (w/v) and 10% (v/v) inoculum amount. The maximum specific dye uptake (qm) was obtained as 14.8 mg/g when initial dye concentration was 100 mg/L and this value increased to 33.8 mg/g in the presence of 390 mg/L initial dye which is equal to 27.5% removal of the dye. Based on these findings, the current study shows that halotolerant yeast strains can be evaluated for the removal of salt-contained textile wastewaters. [ABSTRACT FROM AUTHOR]

This article explores the process of dyeing cotton fabric with reactive dye using glutaraldehyde as a crosslinking agent. Reactive dyes are commonly used for dyeing cotton fabrics because they create permanent color by forming covalent bonds with the fibers. Glutaraldehyde is a powerful crosslinking agent that can enhance dye uptake and improve fixation on the fabric. The article provides detailed instructions for the dyeing process using glutaraldehyde and discusses the benefits and challenges associated with this method. It also examines the effects of crosslinking agents on the physical properties of the dyed fabric, finding that glutaraldehyde improves stiffness, crease recovery, rubbing fastness, and light fastness. Additionally, replacing alkali with glutaraldehyde reduces hydrolysis of reactive dyes and makes the process more eco-friendly. [Extracted from the article]

Leather dyeing is a critical step in leather manufacturing, as it is responsible for providing leather products with an eye-catching visual aspect and adequate quality properties to meet customers' expectations. This step is becoming more and more challenging as the leather industry advances hand in hand with new environmentally friendly policies and regulations to achieve a safer and healthier planet by replacing the highly polluting Cr-based leather tanning technology with greener alternatives. As a result, achieving high-performance dyeing of organic chrome-free leather is one of the bottlenecks for the sustainable development of the leather industry. Herein, we propose a novel strategy to fabricate an isocyanate-based oligomeric dye (IBD) with high coloring capabilities (component content higher than 62.8%) based on toluene 2,4-diisocyanate and reactive red dye 180. This material has been tested for the dyeing of biomass-derived aldehyde (BDA)-tanned leather with excellent outcomes. The experimental results showed that the crust leather dyed with our novel IBD dyeing agent had higher color fastness and better fullness than the leather dyed with conventional anionic (CAD) or reactive red 180 (RRD-180) dyes. These excellent and promising results open new avenues in manufacturing high-performance organic Cr-free leather products and help to ensure the sustainable transition of the leather industry from Cr-based leather tanning to more sustainable alternatives, maintaining the final quality of the leather products. [ABSTRACT FROM AUTHOR]

The article discusses the development of a camouflage uniform production system for civilian use with an emphasis on survival and hunting. Effective camouflage requires precise reproduction of the colors, textures, and patterns of specific landscapes, increasing hunting success and unnoticed movement. The technological process of fabric dyeing, necessary for the production of high-quality camouflage uniforms, includes fabric preparation, dyeing and strict quality control.. Fabric preparation includes cleaning, soaking, bleaching, and mercerization to ensure uniform dye absorption and durability. Dyeing methods vary by fabric type, with reactive dyes for natural fibers and disperse dyes for synthetics. Quality control includes visual inspections and tests for colorfastness under various conditions. Advanced dyeing techniques such as continuous dyeing, spray dyeing, stencil dyeing and digital printing have been analyzed to offer certain advantages. Machines like the Mimaki TX300P handle various fabric widths with high precision and reliability, enhancing efficiency. Automation using the Mimaki TX300P streamlines the dyeing process, optimizing ink consumption and integrating fabric loading, printing, and cutting systems. A customer relationship management system further automates garment creation, enhancing design, order management, and quality control. Tools like CLO3D enable detailed 3D modeling and accurate pattern reproduction. The customer relationship management system coordinates production stages and provides precise paint usage recommendations, ensuring efficient resource management and high-quality outcomes. In conclusion, developing and automating fabric dyeing processes for camouflage uniforms involve advanced technologies and meticulous quality control, ensuring durable, colorfast camouflage clothing that blends effectively into natural environments for civilian use. [ABSTRACT FROM AUTHOR]

Ultrafine polyamide/polyurethane synthetic leather (UP/PSL), with a highly natural leather‐like appearance and touch, is widely used in many leather commodities. Generally, acid dyes, which are mostly used for dyeing UP/PSL, exhibit poor colour fastness. While, reactive dyes are well‐known for their good colour fastness. However, reactive dyes are not used to dye UP/PSL because they are water‐soluble and cannot stain the polyurethane (PU) in UP/PSL. In this study, five low water‐soluble reactive dyes with good affinity for both polyamide (PA) and PU were synthesised and characterised using ultraviolet‐visible and infrared spectroscopy, and mass spectrometry. All low‐water‐soluble reactive dyes were monoazo dyes with only one sulfonic group and two different functional groups. The reactive dyes were used to dye UP/PSL at 98°C and fixed at 90°C with 7‐azatridecane‐1,13‐diamine as a crosslinking agent. For comparison, Eriofast Red‐2B (ER‐2B) was used to dye UP/PSL using a special dyeing procedure. ER‐2B showed severe issues related to low utilisation and uneven dyeing, whereas the five low water‐soluble reactive dyes exhibited better performance than ER‐2B. Both the exhaustion and fixation of dyes 1 and 4 exceeded 90.0% when the dosage was less than 3.0% owf (on weight of fabric). In addition, they exhibited good levelling. The washing fastness of the five reactive dyes was excellent and higher than grade 4. The dry rubbing fastness was higher than grade 3‐4. Therefore, UP/PSL can be satisfactorily dyed using the reactive dyes with a solubility of less than 1.0 g/L and meet the requirements of daily life applications. [ABSTRACT FROM AUTHOR]

In this research, a photocatalytic reactor made of quartz was designed and built. Then modified ZnO photocatalysts with different percentages of Ag and Zr were made by combustion method and using the microwave. Photocatalytic experiments showed that nano photocatalysts with a mass ratio of 0.093 Ag and 0.04 Zr are more efficient. The characteristics of this catalyst were evaluated by XRD, SEM, and FT-IR analyses. Then the photocatalytic activities of ZnO-Ag-Zr in the degradation of reactive red dye 198 were investigated and the effective factors such as pH of the solution, amount of catalyst, and initial concentration of the solution were investigated. Experiments showed that the optimal conditions for decolorization of the dye at a concentration of 20 mg/liter are: pH=10 and the amount of catalyst is 0.3 g/l, and in these conditions, the decolorization rate is above 92%. Also, the study of the kinetics of the mentioned reaction showed that the removal rates of Reactive Red 198 dyes are in good agreement with the pseudo-firstorder Longmire-Hinshelwood equation, and therefore, the kinetic parameters were determined using this model. [ABSTRACT FROM AUTHOR]

To explore methods for achieving clean application of reactive dyes from the source, three polyfunctional reactive dyes (YMR-1–YMR-3) using different diamine compounds as bridge groups were developed. The three dyes showed different solubility in water, which was 230, 100, and 160 g/L, respectively, at 25 ℃. The three reactive dyes were used to dye cotton fabrics through an energy-saving cold pad-batch dyeing technique. The factors influencing on the dyeing performance in the cold pad-batch dyeing technique were also comprehensively studied. The maximum fixation values of YMR-1, YMR-2, and YMR-3 were 94.19, 90.79, and 92.18%, respectively. Levelness of the cotton fabrics dyed with the three dyes was investigated and further discussed. The results showed that the dyed cotton fabrics exhibited good levelness with a low color difference value (ΔE < 0.40). The dry rubbing fastness of the cotton fabrics dyed with the three dyes was grade 4, and the corresponding wet rubbing fastness was grade 3 or 2–3. The staining fastness of the dyed cotton fabrics was grade 4–5 or 4. The light fastness of the cotton fabric dyed with YMR-1 was grade 4, and that of YMR-2 and YMR-3 was grade 3. [ABSTRACT FROM AUTHOR]

Chemical stripping adversely affects the quality of cotton fabric due to prolonged exposure to harsh chemicals. High temperatures also affect the surface and tearing characteristics of recycled cotton. Microwave-assisted stripping is a viable approach to addressing these problems, requiring less time, energy, and chemical consumption. Furthermore, utilizing a microwave-absorbing molecule that assisted the heat generation, multiple treatment methods were applied to remove the dye reactive turquoise CLB from cotton fabric. In the reductive process, pretreatment with sodium citrate as a microwave absorber showed 94.8% stripping efficiency, while in the meta-treatment, stripping efficiency was 96.2%. In the conventional stripping procedure, 75.7% stripping efficiency was observed, much lower than microwave absorber stripping with an absorber. Moreover, FTIR analysis of treated and untreated fabrics confirmed the removal of Reactive Turquoise CLB from the cellulosic structure. The quality assurance parameters, weight loss, and tearing strength assure the performance of developed methods by showing higher tearing strength and negligible weight loss compared to conventional methods. [ABSTRACT FROM AUTHOR]

This study focuses on the improvement of the dyeability of cellulosic fibre with reactive dyes using a sustainable approach. A previously reported organic compound containing two epoxide rings, N1, N1'-(ethane-1,2-diyl) bis(N2-(oxiran-2-ylmethyl)ethane-1,2-diamine) (AXL-2) was employed as a cross-linker to the cotton fabric. AXL-2 was synthesized by reaction of epichlorohydrin (ECH) with triethylenetetramine (TETA). Reactive dyeing generates the most problematic effluent containing 20–50% dye in hydrolyzed form (due to the use of alkali in the dyeing process) along with large amounts of inorganic salts. Cotton fabric makes covalent interactions with AXL-2 that subsequently binds with the dye molecule containing free NH2 or OH groups in acidic conditions rendering efficient dyeing in the absence of alkali and salts. ESI-mass spectrometry and ATR–FTIR spectroscopy were used to characterize the synthesized compound, while the treated cotton fabric was characterized by ATR–FTIR and SEM–EDX. Dyeing properties of AXL-2 treated cotton fabrics were studied by measuring their K/S values, % exhaustion, % fixation, and % total fixation. Color difference between treated and untreated fabrics (DE) was evaluated using CIE lab system that exhibited excellent color depth on the AXL-2 treated cotton fabric compared to pristine cotton fabric. Color fastness properties of the dyed fabrics were also studied. No significant change in the absorbency and thermal stability of the fabric was noticed after treatment. The tensile strength of the treated cotton fabric before dyeing (TC) was reduced by 7.6% in warp and 3.5% in weft directions as compared to untreated cotton fabric (CC). However, the treated cotton fabric had lesser reduction in the strength warp-wise compared to untreated cotton fabric after dyeing along with an increase in the strength weft-wise. The novel dyeing method of treated cellulosic fibre by reactive dyes renders a sustainable and eco-friendly approach. [ABSTRACT FROM AUTHOR]

Textile industries release major fraction of dyestuffs in effluents leading to a major environmental concern. These effluents often contain more than one dyestuff, which complicates dye degradation. In this study ten reactive dyes (Reactive Yellow 145, Reactive Yellow 160, Reactive Orange 16, Reactive Orange 107, Reactive Red 195, Reactive Blue 21, Reactive Blue 198, Reactive Blue 221, Reactive Blue 250, and Reactive Black 5) that are used in textile industries were subjected to biodegradation by a bacterial consortium VITPBC6, formulated in our previous study. Consortium VITPBC6 caused single dye degradation of all the mentioned dyes except for Reactive Yellow 160. Further, VITPBC6 efficiently degraded a five-dye mixture (Reactive Red 195, Reactive Orange 16, Reactive Black 5, Reactive Blue 221, and Reactive Blue 250). Kinetic studies revealed that the five-dye mixture was decolorized by VITPBC6 following zero order reaction kinetic; Vmax and Km values of the enzyme catalyzed five-dye decolorization were 128.88 mg L−1 day−1 and 1003.226 mg L−1 respectively. VITPBC6 degraded the dye mixture into delta-3,4,5,6-Tetrachlorocyclohexene, sulfuric acid, 1,2-dichloroethane, and hydroxyphenoxyethylaminohydroxypropanol. Phytotoxicity, cytogenotoxicity, microtoxicity, and biotoxicity assays conducted with the biodegraded metabolites revealed that VITPBC6 lowered the toxicity of five-dye mixture significantly after biodegradation. [ABSTRACT FROM AUTHOR]

The optimization of pretreatment parameters is one of the most important factors for the successful dyeing of textile materials. The aim of this study was to investigate the most effective way of pre-treating cellulose based lyocell knitted fabric in order to achieve an optimal result when dyeing it with reactive dyestuffs. This research investigates the effects of pretreatment by exhaust method on lyocell knitted fabric, which is analyzed using five different recipes. Pretreatment techniques that are being used are mild pretreatment, hot wash without detergent, hot wash with detergent, causticization, and hot wash with causticization. Pretreated and untreated lyocell fabric is dyed with bi-functional reactive dyestuffs in a shade of 1%, to produce color. Three key factors are considered in this research work: optimum pretreatment technique, causticization time selection, and causticization concentration selection. In order to optimize the pretreatment technique, 16 trials are performed by varying the time and concentration. Compared to other pretreatment techniques, causticization is the best for dyeing lyocell fabric with reactive dyes. Additionally, causticization treatment is observed to have the best performance on lyocell fabric when applied for 30 min. The optimum concentration of NaOH for causticizing lyocell fabric is 3 mol/l, as determined by the results. This assessment of results is done based on four factors such as K/S value (color strength), strength loss %, weight loss % as well as pilling test results. [ABSTRACT FROM AUTHOR]

The grafting of cotton fabrics with diallyldimethylammonium chloride was studied. The objective was to improve reactive dye adsorption and antibacterial properties. The cotton fabric was modified with the diallyldimethylammonium chloride at room temperature using the redox initiator system of potassium persulfate as an initiator and N,N,N′,N′-tetramethylethylenediamine as an accelerator. It was found that the nitrogen content of the cationized cotton fabrics increased with an increase in the diallyldimethylammonium chloride concentration and stayed constant at a concentration of 40% (v/v). The adsorption of the reactive dyes on the cotton fabrics was investigated. The contact time of the reactive dye adsorption on the modified cotton fabrics reached equilibrium at 30 min. The dye adsorption properties of the modified cottons depended on the concentration of the diallyldimethylammonium chloride, dyes concentration, chemical structure, and molecular weight of the reactive dyes. By grafting the fabrics with the diallyldimethylammonium chloride, the cotton fabric's antibacterial function was also enhanced. [ABSTRACT FROM AUTHOR]

Tussah silk is one of the most widely used wild silks. It is usually dyed with acid dyes, despite the shortcoming of poor wet fastness. Reactive dyeing is a good solution to this problem. In our work, sulfatoethylsulfone (SES), sulfatoethylsulfone/monochlorotriazine (SES/MCT), monochlorotriazine (MCT), and bis(monochlorotriazine) (Bis(MCT)) dyes were used to dye tussah silk. All of these dyes showed lower exhaustion and fixation on tussah silk than on mulberry silk under alkaline conditions. Among them, SES dyes were more applicable, with a fixation of 70–85% (at 4%owf dye) at 90 °C when using sodium bicarbonate as an alkali. SES dyes also showed a rapid fixation speed. The dyeing of tussah silk required lower sodium bicarbonate dosage, the use of more neutral electrolytes, and a higher dye quantity to achieve deep effects compared to mulberry silk. Dyed tussah silk displayed lower apparent color depth and brilliance than dyed mulberry silk. The neutral boiling dyeing of tussah silk with SES dyes exhibited higher exhaustion, higher fixation (82–92% at 4%owf dye), and a slower fixation speed compared with alkaline dyeing. Furthermore, in this dyeing method, SES dyes showed higher and more efficient fixation on tussah silk than on mulberry silk. All dyed tussah silk had excellent color fastness to soaping. [ABSTRACT FROM AUTHOR]

The textile industry is known for its excessive water consumption and environmental impact. One of the major challenges it faces is managing pollution generated by dyes, particularly bifunctional dyes, such as sumireact supra yellow s-hbu, with a red appearance and sumifix supra lemon-yellow e-xf, with a yellow appearance. This study aimed to investigate the decolorization kinetics of synthetic solutions of said bifunctional dyes, which comprise triazine and vinylsulfon. We conducted various tests, including modifications of pH, the addition of TiO2 P-50 nanoparticles, exposure to solar radiation, limited contact with oxygen, and eolic agitation. The initial solutions had a concentration of 1000 ppm of textile dye. The study showed that the reaction order for the "red" solutions in the R6 and R9 reactors and all the yellow solutions was ½. The concentration of nanoparticles and pH had a significant impact on the reaction rate. The yellow solutions with a concentration of 800 ppm and pH levels of 3.15, 4.13, and 2.25 demonstrated 100% color discoloration, followed by solutions with a concentration of 400 ppm and pH levels of 3.15, 2.25, and 4.13. The analysis of variance confirmed the reaction rate constants for the yellow solutions and emphasized the significance of pH in this process. [ABSTRACT FROM AUTHOR]

We investigated the removal of the reactive dye Remazol Red from segregated dye bath with an integrated physical-biological approach combining easy applicability and fast kinetics of the sorption process with intrinsic sustainability of biological treatments. The proposed process consists in a first step dye removal by sorption on a cheap commercial polymer (Hytrel 8206) followed by anaerobic polymer bioregeneration. Excellent dye removals were achieved (up to 100%) under acidic conditions with fast kinetics (in most cases, 4 h are sufficient to reach efficiencies ≥ 80%). Experimental sorption data were well correlated with the Freundlich isotherm and pseudo-first-order kinetic model. The sorption process was optimized with response surface methodology. Practically complete removal was achieved with pH of the solution, initial dye concentration and polymer-to-water ratio equal to 4, 50 mg/L and 8.03% v/v, respectively. High desorption performance under neutral conditions makes Hytrel suitable for bioregeneration in a two-phase partitioning bioreactor. Polymer bioregeration reached 82% efficiency with the added value of achieving effective biodegradation (> 50% in 4 days) of the dye desorbed from the polymer. The study demonstrated the two-step process feasibility, which is characterized by the advantage of employing a cheap commercial polymer and has the potential of achieving complete dye mineralization. [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]

Agricultural wastes are potential sustainable adsorbents since they are available in large quantities, are low-cost, and may require little or no treatment, in some cases. In this study, several fruit peels, such as banana, orange, and pomegranate, were collected from local markets and prepared by a simple and eco-friendly method and used as natural adsorbents for the removal of both anionic (Reactive Red 120 (RR120), Reactive Black 5 (RB5), Remazol Brilliant Blue R (RBBR)) and cationic Methylene Blue (MB) dyes found in wastewaters. Many industries, such as leather and textiles, can release huge amounts of synthetic dyes into the wastewater during dyeing processes. These are one of the most important pollutants of water pollution as they cause enormous damage to the water body and also affect the health of organisms due to their toxicity and carcinogenicity. The search for a sustainable and at the same time efficient material for the removal of a wide variety of dyes is the innovation of this work. These peels were prepared by washing, drying, grinding, and finally sieving, under natural sustainable conditions. Porosometry (BET analysis), FTIR, SEM/EDS, and XRD techniques were used to characterize the fruit peels before and after the adsorption process. Factors affecting the adsorption of dyes (adsorbent dosage, pH solution, initial concentration of dyes, contact time, and temperature) were investigated. According to the results, in terms of the effectiveness of fruit peels as (natural) adsorbent materials, for anionic dyes, 5.0–6.0 g/L of banana or orange dry peels was sufficient to remove near or even more than 90% anionic dyes at pH 2.0, and 4.0 g/L was sufficient to remove 98% of cationic MB dye at pH 9.0. Similar amount of pomegranate peels had lower efficiency for anionic dyes (50–70%), while cationic MB was still efficiently removed (98%) at pH 9.0. Moreover, the adsorption process in all cases was found to better fit to pseudo-second-order model, in comparison to pseudo-first-order model. According to isotherms, Freundlich model fitted better in some cases to the equilibrium data, while the Langmuir model in others. Finally, this study demonstrates the viability of reusing the banana, orange, and pomegranate peel adsorbents for eight, four, and five cycles, showing a gradual reduction of around 50% of their effectiveness. [ABSTRACT FROM AUTHOR]

A starch-based adsorbing-flocculating bifunctional material St-A/F is prepared via graft copolymerization with two cationic monomers DMC and DMDAAC, using a safe and clean Fenton initiating system. 13C NMR, XRD, SEM and BET are used in characterization of chemical construction and physicochemical property for the product. St-A/F has double functions of adsorbing and flocculating; it can remove hydro-soluble reactive and direct dyes, and insoluble disperse dyes simultaneously. In adsorption study, the removal ratio (RR) of direct dye 4BS and reactive dye KE-4B were 92.06 and 94.13%, respectively. The adsorption behaviors have higher fitting degree to pseudo-second-order kinetic and Langmuir isothermal model than pseudo-first-order and Freundlich isothermal model. In flocculation study, the RR of St-A/F was recorded above 93.91% to three disperse dyes. St-A/F has significantly increased Zeta potential and isoelectric point (pI 9.08). St-A/F can cause destabilization and aggregation to negatively charged disperse dye particles, via charge neutralization and bridging effects, using its positively charged graft branched chains. St-A/F can simultaneously remove soluble and insoluble pollutants, so it considered to have great advantage in treatment for practical textile printing and dying wastewater with complicated composition. [ABSTRACT FROM AUTHOR]

The study investigated the effect of modifying rapeseed husks with ammonia and epichlorohydrin on their sorption capacity against anionic reactive dyes: Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84). Its scope included sorbents characterization (FTIR, pHPZC), determination of pH influence on the sorption effectiveness of dyes, the adsorption kinetics of dyes, as well as the maximum sorption capacity. The study proved that the reaction of rapeseed husk biomass with ammonia can lead to its amination, namely to the introduction of amine functional groups into the material's structure. The sorption effectiveness of RB5 and RY84 on the tested sorbents was the highest in the pH range of 2–3. The dye sorption kinetics was well described by the pseudo-second-order model. The sorption equilibrium time ranged from 90 to 180 min, and depended on the initial concentration of dyes and the number of amino groups on the sorbent's surface. The most efficient of the sorbents tested were rapeseed husks pre-activated with epichlorohydrin and then aminated with ammonia. Their sorption capacity determined for RB5 and RY84 was 135.83 mg/g and 114.23 mg/g, respectively, which was 794% and 737% higher than that of the non-modified husks. [ABSTRACT FROM AUTHOR]