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AbstractThe present study evaluated and characterized the performance in the biosorption of the dye azo Reactive Red 2 (RR2) on thermally sterilized biomass of the fungus Trichoderma reesei. An FTIR analysis of unloaded and loaded biomass with RR2 confirmed the interactions between dye molecules and functional groups on the fungal biomass surface. The decrease in the initial pH of 9 to 3 with an increase in the temperature of 20 to 40 °C improved the biosorption, reaching for RR2 a higher removal efficiency of 76.88% at pH 3 and 40 °C. A pseudo-second-order model explained the biosorption kinetics of RR2 (R2≥0.9869), and the intraparticle diffusion model showed that the biosorption process was initially controlled by diffusion rate and later by biomass surface saturation with the dye molecules. The Langmuir isotherm explained the biosorption equilibrium well (R2 ≥ 0.9241), achieving the maximum biomass biosorption capacity (qmax) value at 61.72 mg g−1. The dimensionless separation factor values (0.0632 ≤ RL ≤ 0.0973) and the thermodynamic evaluation of the process (ΔG° ≤ −24.09 kJ mol−1, ΔH° ≥ 12.39 kJ mol−1, ΔS° ≥ 0.1265 kJ mol−1 K−1) demonstrate that the biosorption was favorable, reversible, spontaneous, and endothermic. The findings in the present study allow it to consider the biomass of Trichoderma reesei thermally sterilized as a biosorbent biomaterial that can be used for bioprocess design in removing the azo reactive dyes from textile wastewater. [ABSTRACT FROM AUTHOR]

The anionic nature of both cellulose fibres and reactive dyes prevents substantial exhaustion of dye from the dyebath, which is at neutral pH before alkali is added to initiate dye fixation. Conventionally, salt is added to minimize the electrostatic repulsions that interfere with dye sorption, but that increases salt loads in effluents. An alternative is to affix cationic agents on the cellulose to overcome the inherent anionic charge, but that has generally been observed to result in uneven dye sorption. The focus of investigations in this work is to examine the influence of the ratio of charges on cellulose (of affixed cationic charges to inherent anionic charges) on the extents and evenness of dye sorption. The cationisation agent 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride (CHPTAC) was grafted on loose viscose fibres to yield 12 to 185 mmol kg−1 cationic group content on the fibre that exhibited an inherent carboxyl group content of 68 mmol kg−1. Three different dyes (of varying molecular sizes and anionic group content) were employed for examination of sorption profiles. The results from both zeta potential measurements and dye sorption profiles showed evidence of limited dye uptake until the cationic group content in fibres exceeded that of the inherent carboxyl groups. Thereafter, an uptick in dye sorption was observed, with dye sorption levels increasing with rise in degree of cationisation. There were differences between the dyes in their degrees of sorption, which appear correlated with their molecular sizes. [ABSTRACT FROM AUTHOR]

Cobalt-based catalysts were synthesized using the molten metal salt method and applied for the degradation of reactive dyeing wastewater. The results demonstrated a degradation of 97.1% for the C.I. Reactive Red 195 solution under the following conditions: 1.0 g/L of Co@MXene, 3 g/L of peroxymonosulfate (PMS), treated at 25 oC for 36 min with initial pH of 7. After adding 20 g/L of NaCl, the dye degradation rate increased to 5.57 times compared to the original rate 0.0894 min−1, but the difference in final degradation was not significant. The enhanced degradation was attributed to the combined action of hydroxyl radicals (•OH), sulfate radicals (SO4•−), and singlet oxygen (1O2). Notably, the Co@MXene catalyst maintained a high dye degradation percentage of 93.5% even after being recycled ten times. The treated dye residue can be recycled for dyeing cotton fabrics with reactive dyes. This study achieves rapid treatment of dye wastewater with wide applicability and provides valuable insights into dye wastewater treatment and environmental remediation. [ABSTRACT FROM AUTHOR]

A series of novel reactive dyes D1–D3 based on vinamidinium salt were designed and synthesized. Bis(monochlorotriazine) was introduced as the reactive group and sodium sulfonate was the water‐soluble group. Their photophysical properties were studied systematacially. The strong and sharp ground‐state absorption peak in the 250–320 nm range in the UV‐vis absorption spectrum of the aqueous solution could be attributed to the 1π–π* transition by the parent structure of the dyes, and the relatively broad absorption peak in the range of 300–650 nm could be attributed to the 1π–π* mixed intramolecular charge transfer. By applying this series of reactive dyes to the dyeing of four fabrics (silk, cotton, polyester/cotton blends, and polyester), the dyeing depths were in the range of 5.2–28.6 under salt‐free conditions. The results show that D3 with higher planarity can increase the dyeing depth. At length, fastening tests on dyed cotton fabrics and silk showed that this series of reactive dyes had a color fastness between grades 3 and 5 for abrasion and soap‐washing. In summary, these reactive dyes could be potential dyes for salt‐free dyeing 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]

The textile industry generates large volumes of waste throughout its production process. Most of this waste is colored, therefore, discoloration is an important step toward recycling and reusing this waste. This study focused on the chemical reductive discoloration of textile waste composed of cotton dyed with reactive dye. The experimental design demonstrated the significant influence of the concentration of reducing agent and time of reaction on the degree of whiteness of the cotton fibers. The concentration of the alkaline agent was not significant in the process. The optimization of the reaction conditions lead to Berger degree of 50.5 ± 3.5. The discolored cotton was chemically recycled through dissolution in ionic liquid 1-ethyl-3-methylimidazolium chloride and regeneration in film form in water. The microstructure of the regenerated cellulose films was evaluated by Scanning Electron Microscopy (SEM) indicating complete dissolution and uniform regeneration. The discoloration process reduced the polymerization degree and crystallinity index of the cotton fibers but retained the cellulose I structure. The dissolution and cellulose regeneration process results in transparent films with an amorphous structure. The thermal behavior, evaluated by thermogravimetric analysis, indicated that residues and regenerated film presented a main decomposition step. The maximum decomposition rate temperature of the regenerated films was approximately 40°C lower than the cotton fibers, which correlates well with the reduction in polymerization degree and amorphous structure. In general, the study demonstrated that textile cotton waste dyed with reactive dyes can be chemically discolored to form transparent and amorphous films, contributing to the development of sustainable strategies for the textile industry. [ABSTRACT FROM AUTHOR]

Textile industry uses large quantities of different dyes to fulfill the rapidly growing demand for the dyed textile products, resulting in more dye consumption, greater dye discharge as textile dyeing effluent, and higher cost. To decrease the dyes consumption, this research evaluates the performance of novel ozone-based dyeing processes for cotton fabric. So far, reported ozone-based processes for textile involve the usage of high ozone intensity for removing impurities, discoloration of solution, color fading in denim and other fabrics. This research is a first effort, which concentrates on the performance enhancement of the exhaust dyeing process for cotton fabrics through the application of controlled and lower amount of ozone. In this research, ozone dosage is controlled through ozone generator knob to only 0.5 g/h (10%), 1 g/h (20%), 1.5 g/h (30%), 2 g/h (40%), and 2.5 g/h (50%). In contrast, ozone dosage reaches up to 60 g/h in cotton bleaching. This research evaluates the four ozone-based dyeing processes for cotton fabrics using two primary reactive dyes and two primary direct dyes under different concentrations of ozone. Effect of ozonation was evaluated for both direct and reactive dyes at four stages, namely during dyeing, dry ozonation before dyeing, pre-wet ozonation before dyeing, and ozonation after dyeing. Results showed that K/S value of the optimized ozone-based processes was better than the conventional exhaust process. For instance, K/S value for benchmarked conventional dyed sample was 2.147 for reactive yellow, and it was 3.271 (33.5% higher) for the "ozonation after dyeing" process. Similar trends were observed for many other trials, resulting in higher K/S value. In addition, the fastness properties of the optimized processes were comparable with the conventional exhaust process. FTIR and SEM analysis were also performed on selective ozone dyed fabrics. [ABSTRACT FROM AUTHOR]

Dyes employed in many production cycles are characterized by high toxicity and persistence in the environment, and conventional wastewater treatments often fail to reach high removal efficiencies. Consequently, there is an increasing research demand aimed at the development of more efficient and sustainable technologies. A two-step strategy consisting of dye sorption followed by sorbent bio-regeneration is proposed here, with a special focus on the regeneration step. The objective of this study was to establish the best operating conditions to achieve regeneration of dye-loaded polymers and concurrently the ultimate removal of the dyes. To this aim, the bio-regeneration of the Hytrel 8206 polymer, used as a sorbent material to remove Remazol Red dye from textile wastewater, was investigated in a two-phase partitioning bioreactor (TPPB) under alternated anaerobic–aerobic conditions. Comprehensive analysis of operational parameters, including sorbent load and initial contamination levels, was conducted to optimize bio-regeneration efficiency. Experimental data demonstrated high regeneration efficiencies (91–98%) with biodegradation efficiencies up to 89%. This study also examines the biodegradation process to investigate the fate of biodegradation intermediates; results confirmed the successful degradation of the dye without significant by-product accumulation. This research underscores the potential of TPPB-based bio-regeneration of polymeric sorbent material for sustainable wastewater treatment, offering a promising solution to the global challenge of dye pollution in water resources. [ABSTRACT FROM AUTHOR]

It is shown that one‐electron oxidation of aniline with methylene blue is possible only at low temperatures under UV radiation. The kinetics of aniline polymerization under the action of ammonium persulfate in the presence of catalytic amounts of methylene blue is studied. Kinetic curves are obtained by electron paramagnetic resonance (EPR) spectroscopy at various temperatures and concentrations of methylene blue. The catalytic action of the unassociated form of methylene blue and the deactivation of reactive complexes by the dye dimers are shown to compete. In the context of the obtained results the autocatalysis mechanism of oxidative polymerization is considered, which suggests the formation of complexes of aniline and polyaniline that are subject to subsequent rapid oxidation by the persulfate anion. [ABSTRACT FROM AUTHOR]

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]

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]

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]

This investigation explores “batch adsorption of turquoise blue dye” from aqueous solutions using phosphoric acid-activated “Delonix regia Pod carbon prepared using a tubular furnace” (DRTFC). Various factors were examined and equilibrium data were gathered at different temperatures (205 K, 315 K, and 325 K) and for varying initial dye concentrations. Optimal pH for dye removal was found to be 2. Kinetic modeling was done using “Lagergren's first-order kinetics”, Ho's “second-order kinetics”, and Weber Morris equations, with the “pseudo-second-order kinetic model” showing the best fit based on Sum of Squared Errors (SSE) analysis. Thermodynamic parameters were determined through “Van’t Hoff plots”, suggesting that the adsorption process was endothermic, spontaneous, and with increased randomness. [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]

Uneven dyeing results from the different ways the fibers in a blended fabric made of viscose and cotton (50/50) absorb reactive dyes. Measuring the color levelness continues to be an obstacle for dyers. In the present study, several color levelness measurements are analyzed in particular. In addition, the functional group on the outer structure of the viscose-cotton blended fabric has been developed using air plasma to enhance the color intensity. The blended fabric was exposed to an air-based plasma treatment at an atmospheric pressure of 0.15 Tor for varying durations (2, 4, 6, 8, and 10 min). Furthermore, the existence of the functional groups in the blended fabrics treated with plasma (-OH, -COOH) was examined by FT-IR analysis. SEM and an optical microscope confirmed that the blended fabric had undergone surface deformation due to plasma treatment. The hydrophilicity of the Viscose-Cotton blended fabric was enhanced by plasma treatment and consequently, the maximum dye exhaustion of 85% (C.I. Reactive Red 195) and 65% (C.I. Reactive Blue 21) was reached. The degree of color levelness was determined through extensive experimental tests using an instrumental method and color difference (ΔE) data. Additionally, utilizing the image J software enabling the analysis of images, the levelness of colored blended fabric was further measured. The levelness values for the untreated viscose-cotton blended fabric dyed with C.I. Reactive Red 195 and C.I. Reactive Blue 21 were 4.11 and 4.26, respectively. After 6 min of plasma treatment, the viscose-cotton (50/50) blended fabric exhibited excellent levelness with values between 4.94 and 4.91. [ABSTRACT FROM AUTHOR]

Water contamination is one of the biggest environmental issues the world is currently experiencing, and it is a result of growing industry and urbanization. The main causes of contaminated water are the textile industry and the colours included in waste effluent. The production of polymeric ferrite composites is the focus of this investigation. To the best of our knowledge these combinations of polymer and ferrites have not been synthesized before. The purpose of using these polymeric ferrite composites was to eliminate the artificially reactive Orange-122 dye from aqueous solutions. Various factors were optimized to get the best clearance, including pH (2–12), composite dose (0.01–0.3 g), contact time (10–120 min), temperature, and beginning dye concentration (20–200 mg/L). The acidic range (2–5) was shown to have the maximum dye removal of reactive dye, and the ideal composite dose was found to be 0.03 g/50 mL. Within the first sixty to ninety minutes, balance was reached. At 120–150 mg L–1, the maximum level of reactive dye clearance was attained. As the temperature was raised, the chosen dye was more effectively removed, indicating that the process was endothermic. Various models, including thermodynamic, kinetic, and equilibrium models, were used to verify. [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.

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]