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This study addresses the pressing issue of environmental pollution caused by antibiotics and synthetic dyes in aquatic ecosystems, presenting a novel approach for their efficient photocatalytic degradation. Zinc oxide (ZnO)-based nanoscale photocatalysts, including ZnO nanoparticles (NPs) and ZnO/Ag nanocomposite heterostructure (NCH), were synthesized through an innovative and eco-friendly method utilizing an extract derived from discarded lemon peels as a biogenic reducing agent. The synthesized materials were extensively characterized through UV spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results confirmed the different morphologies of ZnO NPs and ZnO/Ag NCH, with average sizes of 20 nm and 42 nm, respectively. Notably, the ZnO NPs and ZnO/Ag NCH exhibited optical bandgap energies of 3.2 eV and 2.85 eV, respectively, signifying their potential as efficient photocatalysts. Under natural sunlight irradiation, these materials demonstrated exceptional photocatalytic activity, achieving a remarkable 98.8 % degradation rate for metronidazole and 90 % for ciprofloxacin in just 12 min. Furthermore, the ZnO NPs effectively removed 84 % of Toluidine Blue and 77 % of Congo red after 120 min, while ZnO/Ag NCH enhanced degradation rates to approximately 90.5 % for Toluidine Blue and 86 % for Congo Red. This research highlights the significant physicochemical properties and novel synthesis methods employed, positioning these sustainable nanomaterials as promising solutions for mitigating environmental pollution effectively. [ABSTRACT FROM AUTHOR]

The textile industry significantly contributes to environmental pollution through its use of synthetic dyes, especially sulfur black, known for its toxicity and resistance to degradation. This research focuses on a fungal strain, Aspergillus sp. strain DS-28, isolated from activated sludge, which exhibits an exceptional ability to biodegrade sulfur black dye. This study systematically assessed the biodegradation capacity of this strain through a series of experiments conducted over a 7-day period. Analytical techniques including high-performance liquid chromatography time-of-flight mass spectrometry (HPLC-TOF/MS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) were employed to monitor the degradation process. SEM showed a significant reduction in particle size, with surfaces becoming smoother and flatter post treatment. XRD indicated a decrease in the intensity of several chemical bonds, and FTIR analysis demonstrated the enhanced vibrational absorption peaks of benzene ring bonds, with the disappearance of -C-S- and -C-S-S-C- groups. The results demonstrate that Aspergillus sp. DS-28 degrades sulfur black by initiating the oxidative breakdown of its complex structures into simpler forms. This study not only elucidates the biodegradation pathway facilitated by Aspergillus sp. DS-28, but also highlights its potential application in developing eco-friendly waste management strategies for treating dye-contaminated wastewater. [ABSTRACT FROM AUTHOR]

Synthetic dyes pose a significant environmental threat due to their complex structures and resistance to microbial degradation. S. commune 15R-5-F01 exhibited over 96% degradation efficiency of Methyl Red in a medium with 100 mg L−1 Methyl Red within 3 h. The fungus demonstrated adaptability to various environmental conditions, including different pH levels, temperatures, oxygen concentrations, salinity, and heavy metals. S. commune 15R-5-F01 is capable of achieving repeated cycles of Methyl Red reduction with sustained degradation duration minimum of 6 cycles. It showed a maximum Methyl Red biodegradation capacity of at least 558 mg g−1 dry mycelia and a bioadsorption capacity of 57 mg g−1. Gas chromatography–mass spectrometry analysis confirmed the azo reduction of Methyl Red into N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Enzymatic activity assays indicated the involvement of lignin peroxidases, laccases, and manganese peroxidase in the biodegradation process. Phytotoxicity tests on Triticum eastivum, Oryza sativa, and Vigna umbellata seeds revealed reduced toxicity of the degradation products compared to Methyl Red. This study identifies S. commune 15R-5-F01 as a viable candidate for the sustainable degradation of synthetic dyes in industrial wastewater. [ABSTRACT FROM AUTHOR]

Synthetic textile dyes in the Tanjung Bumi batik coloring process in Madura, Indonesia, have been used extensively for decades, raising environmental concerns due to hazardous wastewater. This research aims to evaluate the quality characteristics of synthetic textile dye wastewater, assess batik artisans' awareness of batik waste hazards, and analyze the interaction between these factors. Wastewater samples were collected from four locations with two repetitions each. Thirty-seven batik artisans participated in a survey. The wastewater analysis included measurements of BOD5, COD, pH, TSS, phenol, Cr, NH3-N, sulfide, and oil and grease. The survey assessed the artisans' use of synthetic dyes and their awareness of environmental hazards. The results showed that the toxic substance levels in Tanjung Bumi batik waste exceed the quality standard thresholds for textile waste. Survey findings indicate that 100% of respondents use synthetic textile dyes, 83.78% dispose of waste without processing, and 91.89% are unaware of the hazards posed by synthetic textile dyes. There is a direct correlation between the artisans' low awareness of the negative impacts of waste and their lack of environmental preservation practices. The novelty of this research lies in its dual evaluation of chemical wastewater characteristics and socioenvironmental awareness among artisans. This approach highlights the urgent need for educational interventions and improved waste management practices. The implications are significant for developing sustainable batik production methods and enhancing environmental awareness, contributing to broader societal benefits. [ABSTRACT FROM AUTHOR]

Abstract Banana fibers being highly strong and biodegradable, have always been an interesting aspect of polymer science. The research examines the pretreatment process to enhance the dyeability of banana fibers with synthetic dyes, followed by the preparation of polypropylene (PP) composites with dyed fibers to explore their mechanical properties. Raw banana fibers were extracted from the pseudo stems of banana plants for pretreating with sodium hydroxide and hydrogen peroxide and further dyed in the exhaust method using direct, basic, reactive, and vat dyes. Despite a decrease in fiber strength, the scoured‐bleached fibers appeared whiter and lustrous compared to untreated fibers. Direct dye exhibited a higher color strength (K/S) value of 20.7 and better wash fastness on average of 4‐3 rating compared to basic dye. Later polypropylene sheets were prepared using a Hot Plate Molding Machine, and composite specimens were fabricated by sandwiching the fibers between PP sheets and hot pressing. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed minor bond formations between the dyed fibers and polypropylene matrix in composites showing significant bonding at NH, CH, and OH regions. The composites containing dyed fibers showed slight improvements in tensile strength and modulus which is at best 2% than that of untreated fiber. Highlights Direct and basic dyes were determined as the most suitable synthetic dyes. FTIR analysis revealed minimal bond formation between the fiber and PP matrix. Composites having dyed banana fiber showed little better mechanical features.

Industries extensively use synthetic dyes, and it is crucial to eliminate them from effluents to prevent their accumulation in nature. The elimination of synthetic dyes is effectively achieved through the well-established method of adsorption; previous researchers have developed a range of materials dedicated to the adsorption of such dyes. In this regard, natural materials have received much attention as environmentally friendly. This study examined the ability of SiO2-based stone samples, including silica, zeolite, pumice, and scoria, to adsorb carmoisine and malachite green dyes from water. The ball-milling method was utilized to prepare the nanosized adsorbents. Physicochemical properties were evaluated by analytical methods, including dynamic light scattering (DLS), X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer-Emmett-Teller (BET), and Fourier transform infrared spectroscopy (FTIR). The removal of dyes was experimentally undertaken utilizing both granular and nanosized adsorbents with conditions of 30°C temperature, pH 7, and initial dye concentrations set at 45 mg/l. Adsorption isotherm models and kinetic models were evaluated for dye adsorption. The highest levels of adsorption capacities for carmoisine and malachite green were 54.42 and 19.01 mg/g, respectively. The findings of this research demonstrated that nanosized scoria and silica have the potential to be used as efficient adsorbents in cationic and anionic dye removal, respectively.

The aim of this research was to assess the hazardousness and ecotoxicity of paiche leather (Arapaima gigas) dyed with natural colourants (turmeric and purple corn) versus synthetic colourants (anilines). To determine hazardousness, the methodology included the assessment of flammability, corrosivity, reactivity to H2S and HCN, toxicity from metals, and organic compounds of dyed leather. Additionally, its ecotoxicity was determined using the California red worm (Eisenia fetida) as a bioindicator through a bioassay, with treatments at 0.02, 0.04, 0.08, 0.16, and 0.20 g of leather/g of substrate, including undyed leather and a negative control in the investigation. The hazardousness analysis results indicated that leather samples dyed with both natural and synthetic colourants are not hazardous. However, the concentrations of chromium, nickel, cadmium, and lead exceed the permitted values for their use in footwear according to the European Union. Regarding ecotoxicity, the results demonstrate that acute toxicity to E. fetida is lower for natural colourants compared to synthetic colourants, where 100% mortality occurs at concentrations between 0.04 and 0.08 g of leather/g of the substrate. Concerning chronic toxicity, after 12 weeks of exposure, the tolerance concentration for undyed paiche leather is 0.035 g of leather/g of the substrate, and for leather dyed with purple corn and turmeric, it is 0.2 g of leather/g of the substrate. It is shown that the active compounds of natural colourants have a positive effect on worm survival, and it is concluded that paiche leather dyed with these colourants presents environmental advantages over leather dyed with synthetic colourants.

Our study explores the potential of ZnO nanostructured coatings synthesized through ultrasonic spray pyrolysis and focuses on the dual functionality of these coatings: efficiently removing amoxicillin and methyl orange, while also assessing their antibacterial activity. The characterization techniques used in this work include Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Photoluminescence spectroscopy (PL), X-ray Photoelectron Spectroscopy (XPS) and UV–visible spectroscopy. The degradation rates of amoxicillin and methyl orange were studied through the decrease in absorption bands at 228 nm and 436 nm, respectively, under UV irradiation. By closely analyzing the responses of Pseudomonas Aeruginosa , Bacillus Cereus and Bacillus Subtilis bacteria, zinc oxide thin films demonstrate antibacterial efficacy due to the attraction of opposite charges to the bacterial surface, which influences the oxidation process of the membrane, ultimately resulting in cellular death. [Display omitted] [ABSTRACT FROM AUTHOR]

More as a decade before aniline and phenol were isolated from coal tar by Runge in 1834 and used for the fabrication of a number of important dyes, such as Aniline Black, Mauveine, and Fuchsine, the German naturalist von Reichenberg observed the formation of a red dye from beech tar, which he called pittakal. In this report, both the history of discovery and the laborious structure elucidation of this first tar dye were discussed and the subsequent efforts to obtain further usable dyes from phenol outlined. A decisive contribution for that came from Kolbe and Schmitt, who better known as the inventors of the first technical synthesis of salicylic acid. [ABSTRACT FROM AUTHOR]

Banana fibers being highly strong and biodegradable, have always been an interesting aspect of polymer science. The research examines the pretreatment process to enhance the dyeability of banana fibers with synthetic dyes, followed by the preparation of polypropylene (PP) composites with dyed fibers to explore their mechanical properties. Raw banana fibers were extracted from the pseudo stems of banana plants for pretreating with sodium hydroxide and hydrogen peroxide and further dyed in the exhaust method using direct, basic, reactive, and vat dyes. Despite a decrease in fiber strength, the scoured‐bleached fibers appeared whiter and lustrous compared to untreated fibers. Direct dye exhibited a higher color strength (K/S) value of 20.7 and better wash fastness on average of 4‐3 rating compared to basic dye. Later polypropylene sheets were prepared using a Hot Plate Molding Machine, and composite specimens were fabricated by sandwiching the fibers between PP sheets and hot pressing. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed minor bond formations between the dyed fibers and polypropylene matrix in composites showing significant bonding at NH, CH, and OH regions. The composites containing dyed fibers showed slight improvements in tensile strength and modulus which is at best 2% than that of untreated fiber. Highlights: Direct and basic dyes were determined as the most suitable synthetic dyes.FTIR analysis revealed minimal bond formation between the fiber and PP matrix.Composites having dyed banana fiber showed little better mechanical features. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the removal of harmful cationic dyes, namely brilliant green and safranin-O, from wastewater produced by industries like textile, pigment, and pharmaceutical, which pose a direct threat to human health and the environment. An emulsion liquid membrane (ELM) was employed to eliminate these dyes, and the efficiency of the membrane was measured by calculating the percentage of dye removal and the breaking rate. The study successfully optimized the ELM process to remove the dyes within an hour and demonstrated the membrane's stability for more than 60 minutes. The results showed that the prepared ELM could remove 100% of the brilliant green dye and 99.6% of the safranin-O dye. A maximum breaking rate of 0.029% was obtained for brilliant green and 0.008% for safranin-O. Furthermore, the study resulted in the maximum removal of 99.36% and 99.15% for brilliant green and safranin-O dyes, respectively, in the binary system. When both dyes were present simultaneously, the maximum breakage observed was only 0.16%. The experimental results were analyzed using a UV–visible spectrophotometer and an optical microscope, and the optimization and analysis of the variance of means and signal-to-noise (S/N) ratio were carried out using the Taguchi L16 orthogonal array. [ABSTRACT FROM AUTHOR]

Synthetic dyes, exceeding 100,000 types on the market and produced at a global scale of over 700,000 tons annually, are extensively used in the textile industry. This industry, a leading contributor to water contamination, relies on dyes like reactive, azo, anthraquinone, and triphenylmethane, resulting in substantial water usage and significant effluent generation. A significant modern challenge is the pollution caused by dye-mixed wastewater, releasing hazardous chemicals into water bodies and posing threats to ecosystems, plants, and human health. Traditionally, physicochemical techniques have addressed textile dye-containing wastewater, but their drawbacks, including cost, inefficiency, and potential secondary pollution, have steered attention towards biological alternatives. Utilizing microorganisms and enzymes, these biological methods, such as microbial cell enzyme immobilization, the biofilm technique, bioreactors, biofuel/bioelectricity production, and genetic engineering, have emerged as promising, cost-effective, and environmentally friendly solutions for efficient dye removal from wastewater. This review paper specifically highlights advanced biological techniques and emphasizes their efficacy in addressing the challenges posed by synthetic textile dyes. Through a systematic review of recent research papers, published results, and observations, this review paper provides insights into emerging biological treatment strategies for effectively removing synthetic textile dyes and contaminants from wastewater. [ABSTRACT FROM AUTHOR]

As a crucial ingredient for human and animal survival, clean water also contributes significantly to a nation's ever‐expanding economy. However, the availability of clean water has deteriorated as contaminants, such as dyes, have a significant detrimental effect on the pure and clean main waters. Coffee residue with micro‐ and macropores is a potential biosorbent for the removal of synthetic dyes from aqueous solutions. This study aims to determine the efficacy of adsorption of synthetic colors by coffee dregs. Using the Central Composite Design (CCD), the impacts of four adsorption factors (contact time, pH, starting concentration, and adsorbent dosage) were investigated (CCD). For the percent elimination of Remazol brilliant blue R (RBBR) and Remazol brilliant violet 5R, quadratic models were created (RBV‐5R). The ideal adsorption conditions consisted of a pH of 3, a dosage of 5 g of adsorbent, an initial concentration of 10 mg/L, and a contact period of 30 min for RBBR and 60 min for RBV‐5R, resulting in a removal of 49.98% and 93.8%, respectively. The experimental and projected values for RBBR were 96.57% and 95.2% for RBV‐5R, respectively, demonstrating high agreement with minimal errors. The Langmuir isotherm model fit the equilibrium adsorption data of the two selected dyes the best. In addition, the pseudo‐second‐order kinetic model was able to better characterize the experimental data with good respective regression coefficients. [ABSTRACT FROM AUTHOR]

Dye analysis is an important subject in historical textile research because it helps researchers understand the structural and chemical features of colorants and provides a solid base to determine the date, provenance, and trade of textile artifacts. This study is the first investigation of dyes used in historical silk of Indonesia using high-performance liquid chromatography coupled with a diode array detector and mass spectrometry (HPLC-DAD-MS). Three Indonesian silk textiles dating from the nineteenth (19th) and twentieth (20th) centuries are selected from the Southeast Asian textile collection of the China National Silk Museum. Dyes are extracted from the representative silk threads of these artifacts and subjected to chromatographic analysis. The characterization results indicated the use of a variety of natural dyes in the studied threads. In particular, madder dye (Rubia spp.), lac dye (Laccifer lacca Kerr.), and Morindone dye (Morinda citrifolia L.) were used for producing red shades, while green yarns were dyed by a combination of indigo and safflower (Carthamus tinctorius L.) yellow dyes. Furthermore, this study provides the first proposal of the use of saffron (Crocus sativus L.) dye in Indonesian textile dyeing during this period. In addition, Congo Red (C.I. 22,120), Orange I (C.I. 14,600), and Diamond Green B (C.I. 42,000) were identified, signifying the adoption of early synthetic dyes by Indonesian dyers. The current work takes advantage of the sensitivity and reliability of the HPLC-DAD-MS technique in dye analysis in order to give a report on the chemical aspects of coloring materials used in Southeast Asian textiles in the 19th and 20th centuries. [ABSTRACT FROM AUTHOR]

Synthetic dyes play a crucial role in our daily lives, especially in clothing, leather accessories, and furniture manufacturing. Unfortunately, these potentially carcinogenic substances are significantly impacting our water systems due to their widespread use. Dyes from various sources pose a serious environmental threat owing to their persistence and toxicity. Regulations underscore the urgency in addressing this problem. In response to this challenge, metal oxide nanoparticles such as titanium dioxide (TiO2), zinc oxide (ZnO), and iron oxide (Fe3O4) have emerged as intriguing options for dye degradation due to their unique characteristics and production methods. This paper aims to explore the types of nanoparticles suitable for dye degradation, various synthesis methods, and the properties of nanoparticles. The study elaborates on the photocatalytic and adsorption-desorption activities of metal oxide nanoparticles, elucidating their role in dye degradation and their application potential. Factors influencing degradation, including nanoparticle properties and environmental conditions, are discussed. Furthermore, the paper provides relevant case studies, practical applications in water treatment, and effluent treatment specifically in the textile sector. Challenges such as agglomeration, toxicity concerns, and cost-effectiveness are acknowledged. Future advancements in nanomaterial synthesis, their integration with other materials, and their impact on environmental regulations are potential areas for development. In conclusion, metal oxide nanoparticles possess immense potential in reducing dye pollution, and further research and development are essential to define their role in long-term environmental management. [ABSTRACT FROM AUTHOR]

Synthesis of cadmium sulfide (CdS) nanoparticles using watermelon rind aqueous extract was explored for its effectiveness in eliminating Methylene Blue (MB) and Crystal Violet (CV) dyes from water. The synthesised CdS nanoparticles were characterised with XRD, TEM and EDX and found to be around 10 nm in size with spherical shape. A central composite design was developed to optimise independent variables such as pH, contact time and initial concentrations. The developed quadratic model was found to be significant with p-value <0.0001 and lack of fit >0.005 suggesting the reliability of the model. Isotherm modelling analysis revealed that Langmuir and Freundlich's isotherms provided better explanation for the equilibrium data. The loading capacities of the CdS nanoparticles were found be 227.3 and 185.1 mg g-1, respectively for MB and CV. The experimental data showed a good fit with the pseudo-second-order kinetic model, indicating that chemical reactions were the determining factor in controlling the rate-limiting step. Thermodynamic analyses indicated that the process was spontaneous and exothermic. Desorption and regeneration investigations demonstrated that CdS nanoparticles could be successfully regenerated up to 5 times and reused in the adsorption process. The results conclude that the CdS nanoparticles are capable of remediating water containing cationic dyes. [ABSTRACT FROM AUTHOR]

Industries extensively use synthetic dyes, and it is crucial to eliminate them from effluents to prevent their accumulation in nature. The elimination of synthetic dyes is effectively achieved through the well-established method of adsorption; previous researchers have developed a range of materials dedicated to the adsorption of such dyes. In this regard, natural materials have received much attention as environmentally friendly. This study examined the ability of SiO2-based stone samples, including silica, zeolite, pumice, and scoria, to adsorb carmoisine and malachite green dyes from water. The ballmilling method was utilized to prepare the nanosized adsorbents. Physicochemical properties were evaluated by analytical methods, including dynamic light scattering (DLS), X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer-Emmett-Teller (BET), and Fourier transform infrared spectroscopy (FTIR). The removal of dyes was experimentally undertaken utilizing both granular and nanosized adsorbents with conditions of 30°C temperature, pH 7, and initial dye concentrations set at 45 mg/l. Adsorption isotherm models and kinetic models were evaluated for dye adsorption. The highest levels of adsorption capacities for carmoisine and malachite green were 54.42 and 19.01 mg/g, respectively. The findings of this research demonstrated that nanosized scoria and silica have the potential to be used as efficient adsorbents in cationic and anionic dye removal, respectively. [ABSTRACT FROM AUTHOR]

Synthetic dyes, particularly azo dyes, pose environmental and health risks because of their toxicity and persistence. To reduce these negative effects, it is necessary to degrade and detoxify these dyes into simple, non-toxic substances. Enzymes from various organisms play crucial roles in dye degradation and detoxification, making biological treatments cost-effective and environmentally friendly. Reductases are key players in breaking the azo bonds in azo dyes under limited oxygen conditions. This review emphasizes the importance of reductases in azo dye degradation and the exploration of various organisms that produce these enzymes. Azorereductases and NADH-DCIP reductases have been extensively investigated and have been shown to degrade azo dyes efficiently. These enzymes play key roles in azo dye degradation and detoxification by catalyzing the cleavage of azo linkages in the presence of redox coenzymes, such as NADH, NADPH, and FADH2. However, despite their effectiveness, different conditions, such as pH, temperature, dye concentration, and incubation time, affect enzyme activity during degradation; thus, optimization is required for efficient decolorization. Further studies are necessary to identify new species and strains, isolate and characterize enzymes, and determine the possible pathways for degrading azo dyes.

Abstract The present study aimed to investigate the decolorization of various commercial dyes by azoreductases (AzrBmH21, AzrBmH22/3, and AzrBmH24/5) through bioinformatics means, comprising molecular docking, molecular dynamics simulation, and molecular mechanics Poisson–Boltzmann surface area (MM-PBSA). Therefore, four commercial dyes, namely acid orange 7, cresol red, methylene blue, and malachite green, were selected as potential targets for degradation by the above said azoreductases derived from Bacillus megaterium H2. The prediction of ligand binding or catalytic sites for AzrBmH21, AzrBmH22/3, and AzrBmH24/5 were performed using a machine learning algorithm based on the Prank Web and DeepSite chemoinformatic tool. This analysis revealed that several amino acids of AzrBmH2 interacted with the tested dyes, indicating the presence of distinct ligand-binding sites for AzrBmH2-dye complexes. Likewise, the binding affinity for AzrBmH21, AzrBmH22/3, and AzrBmH24/5 ranged from − 9.4 to − 5.5 kcal/mol, − 9.2 to − 5.4 kcal/mol, and − 9.0 to − 5.4 kcal/mol, respectively, with each complex stabilized at a minimum of 0–5 hydrogen bonds. MD simulations revealed stable AzrBmH2-dye complexes with RMSD and RMSF values ranging from 0.15 to 0.42 nm and 0.05 to 0.48 nm, respectively, with Rg values between 1.75 and 1.88 nm. MM-PBSA calculations indicated that the AzrBmH2–dye complexes, except for AzrBmH2–malachite green, exhibited the lowest binding energy (− 191.05 ± 7.08 to 314.19 ± 6.88 kcal/mol), with prevalent hydrophobic interactions (− 268.25 ± 12.25 to − 418.92 ± 29.45 kcal/mol) through van der Waals forces. Therefore, this study was able to highlight the potential role of enzymes, specifically azoreductases from Bacillus megaterium H2, in predicting the decolorization of commercial dyes. These findings could contribute to our understanding of the azoreductases’ mechanisms in bioremediation and for biotechnological applications.

The development of simple, effective, economical, and environmentally friendly methods for removing hazardous substances of anthropogenic origin from aquatic systems is currently one of the greatest challenges, among others, due to the variety of pollutants and the transformations they may undergo in the environment. In recent years, there has been an increased interest in adsorption methods based on the use of natural polymers, including non-toxic chitosan (CS), which is characterized by good coating properties, biocompatibility, and biodegradability. This review concerns the latest developments (since 2019) in the application of novel chitosan-based materials for the removal of hazardous substances (e.g., metal and metalloid ions, synthetic dyes, pharmaceuticals) from aqueous solutions, with particular emphasis on their most important advantages and limitations, as well as their potential impact on sustainability. [ABSTRACT FROM AUTHOR]

Characterising synthetic dyes on heritage textiles represents a relatively recent research frontier, which aims to obtain new information about the evolution of textile manufacturing and industrial chemistry. Whilst spectral enhancement or amplification methods are often considered a requirement for the Raman analysis of textile dyes, this work highlights the potential of standard Raman spectroscopy for the non-invasive analysis of synthetically dyed fibres. In this research, Raman spectroscopy was used for the chemical characterisation of early 20th century synthetic dyes, in both powder form and on dyed fibres. The dyes were produced by the Italian company Azienda Coloranti Nazionali e Affini (ACNA) and housed in the Sapienza University Museum of Chemistry. The investigation first employed literature research into the ACNA's commercial nomenclature. This information was used to hypothesise likely molecular structures of the dyes, pointing towards the azo dye class. The application of Raman spectroscopy confirmed these hypotheses and the high-quality spectra collected provided structural information about the dye molecules. Spectral features of azo-groups, aromatic moieties, and substituents were observable in spectra. Comparison with a Raman spectrum of wool allowed confident dye signal attribution, and some spectra displayed features linked to changes in the fibre during the dyeing process. Combining literature research and Raman vibrational information proved a powerful non-invasive approach for the characterisation of synthetic dyes, allowing molecular identification of some colorants and structural information for most. Standard Raman spectroscopy may provide a widely applicable, non-invasive method for acquiring information about synthetically dyed historical and artistic textiles in future research. [ABSTRACT FROM AUTHOR]

• Natural and synthetic dyes in Central Asian ikats were identified by HPLC-DAD-MS/MS. • Cotton weft threads were often dyed with red synthetic dyes. • Yellow from larkspur kept being used well after synthetic dyes were available. • A local species of scale insect (cochineal) might have been used to obtain red. • The introduction of synthetic dyes in ikat dyeing was a gradual and experimental process. Central Asian ikat textiles are characterised by their bold and large abstract patterns, made up of vibrant colours with a characteristic "blurred edge" effect, which makes them some of the most recognisable fabrics worldwide. Eleven ikats from the collection of the National Museum of Asian Art, Smithsonian Institution (Washington, DC, USA) and six ikats from the collection of the British Museum (London, UK) were investigated by high pressure liquid chromatography coupled to diode array detector and high-resolution tandem mass spectrometry (HPLC-DAD-HRMS/MS) to identify the dyes and expand on recent research focused on the integration of synthetic dyes in ikat dyeing during the second half of the 19th century. The results confirmed that the palette of natural dyes includes cochineal (probably mostly from a local species native to central Asia) for red, larkspur (Delphinium semibarbatum) for yellow, and indigo for blue as the main dye sources. In some of the textiles, madder (Rubia tinctorum) for red and pagoda tree (Sophora japonica) for yellow were also detected as minor components mixed with cochineal and larkspur, respectively. Synthetic dyes, such as scarlet reds (C.I. 16150 and 16155), rose bengale (C.I. 45435), eosin (C.I. 45380), erythrosine (C.I. 45430), fuchsin (C.I. 42510/42520), methyl violet (C.I. 42535/42555), malachite green (C.I. 42000) and brilliant green (C.I. 42040) were detected in eight textiles. In three textiles, natural dyes were identified in the ikat-dyed silk warp threads and synthetic dyes in the red cotton weft threads, highlighting interesting mixtures of materials and textile-making practices. Natural yellow dyes were used in all textiles, even those for which all the other colours are synthetic. These results provide significant new information about the changes in ikat production that occurred during the 19th century in Central Asia. [ABSTRACT FROM AUTHOR]

Synthetic dyes are found in a wide variety of applications today, including but not limited to textiles, foods, and medicine. The analysis of these molecules is pertinent to several fields such as forensics, environmental monitoring, and quality control, all of which require the sensitivity and selectivity of analysis provided by mass spectrometry (MS). Recently, there has been an increase in the implementation of MS evaluation of synthetic dyes by various methods, with the majority of research thus far falling under electrospray ionization and moving toward direct ionization methods. This review covers an overview of the chemistry of synthetic dyes needed for the understanding of MS sample preparation and spectral results, current fields of application, ionization methods, and fragmentation trends and works that have been reported in recent years. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the decolorization of various commercial dyes by azoreductases (AzrBmH21, AzrBmH22/3, and AzrBmH24/5) through bioinformatics means, comprising molecular docking, molecular dynamics simulation, and molecular mechanics Poisson–Boltzmann surface area (MM-PBSA). Therefore, four commercial dyes, namely acid orange 7, cresol red, methylene blue, and malachite green, were selected as potential targets for degradation by the above said azoreductases derived from Bacillus megaterium H2. The prediction of ligand binding or catalytic sites for AzrBmH21, AzrBmH22/3, and AzrBmH24/5 were performed using a machine learning algorithm based on the Prank Web and DeepSite chemoinformatic tool. This analysis revealed that several amino acids of AzrBmH2 interacted with the tested dyes, indicating the presence of distinct ligand-binding sites for AzrBmH2-dye complexes. Likewise, the binding affinity for AzrBmH21, AzrBmH22/3, and AzrBmH24/5 ranged from − 9.4 to − 5.5 kcal/mol, − 9.2 to − 5.4 kcal/mol, and − 9.0 to − 5.4 kcal/mol, respectively, with each complex stabilized at a minimum of 0–5 hydrogen bonds. MD simulations revealed stable AzrBmH2-dye complexes with RMSD and RMSF values ranging from 0.15 to 0.42 nm and 0.05 to 0.48 nm, respectively, with Rg values between 1.75 and 1.88 nm. MM-PBSA calculations indicated that the AzrBmH2–dye complexes, except for AzrBmH2–malachite green, exhibited the lowest binding energy (− 191.05 ± 7.08 to 314.19 ± 6.88 kcal/mol), with prevalent hydrophobic interactions (− 268.25 ± 12.25 to − 418.92 ± 29.45 kcal/mol) through van der Waals forces. Therefore, this study was able to highlight the potential role of enzymes, specifically azoreductases from Bacillus megaterium H2, in predicting the decolorization of commercial dyes. These findings could contribute to our understanding of the azoreductases' mechanisms in bioremediation and for biotechnological applications. [ABSTRACT FROM AUTHOR]

Natural dyes have been used for centuries for coloring textiles, food, and other materials. Synthetic dyes are particularly popular due to their ease of use, wide range of available colors, and fastness. However, their usage comes with significant environmental and health challenges. In recent years, there has been a renewed interest in natural dyes due to their eco-friendliness, ready availability, affordability, non-toxicity, and sustainability. Hence, natural dyes are fast gaining popularity as better alternatives to synthetic dyes. Nature is blessed with a rich diversity of plant species with varying colors and properties which can be harnessed in textile, printing, cosmetics, and food industries. This paper presents a comprehensive review on natural and synthetic dyes with particular focus on their history, properties, classification, extraction methods, applications, and health challenges. Although many plants have been suggested as potential sources of natural dyes, there is insufficient information on their exploration and application. Additionally, chemical analyses of these dyes have not been extensively done. Overall, the results of studies conducted so far identified a number of promising taxa for further investigation as plant-based dyes with many indigenous plants as potential sources of natural dyes.

Abstract Enzymatic degradation of synthetic dyes holds an immense promise for addressing the environmental concerns associated with the textile and dye industries. This study aimed to isolate bacteria capable of producing laccase enzymes from an anthropogenic environment. Subsequently, viability of utilizing cost-effective agricultural residues as substrates for laccase production was assessed. Response Surface Methodology (RSM) and the One Variable at a Time (OVAT) approach was pursued for the optimization of laccase production, followed by pH and temperature stability, dye degradation and decolorization experiments, toxicological studies on the degraded dye metabolites. In results, laccase-producing bacterial strain was identified as Stenotrophomonas maltophilia strain E1 (S. maltophilia). Among variety of substrates, coconut husk exhibited optimal efficacy. In a statistical optimization study, it was found that S. maltophilia was capable of producing laccase 51.38 IU/mL, i.e., three times higher than the amount of laccase produced by unoptimized medium (16.7 IU/mL), and the enzyme activity was found to be steady at an acidic pH, and a mesophilic temperature range. The laccase obtained from S. maltophilia E1 demonstrated proficient dye decolorization capabilities, achieving a notable 92.1% reduction in Malachite green dye coloration at a concentration of 500 ppm. Gas chromatography–mass spectrometry (GC–MS) analysis of the decolorized derivatives of Malachite green revealed a conversion into a distinct compounds. Moreover, after undergoing laccase treatment, Malachite green exhibited decreased phytotoxic effects on Oryza sativa, pointing to enzymatic detoxification. Collectively, insights gained from the present study will contribute to the development of efficient enzymatic approaches for addressing the environmental pollution caused by synthetic dyes. Graphical Abstract

Dating silk mounting textiles is important for understanding their condition and susceptibility to degradation. Amino acid racemization is a technique currently used for this purpose. The research presented here aimed to clarify when this technique is reliable and when it is not. Silk fibers taken from a cocoon and from Japanese mounting textiles were studied using optical microscopy to document surface roughness. Chiral capillary electrophoresis mass spectrometry for amino acid racemization dating (AAR), liquid chromatography mass spectrometry for dye analysis, and FTIR for analysis of sericin and other materials adhering to the silk were also used. A change from rough fiber surfaces (greater than a hundred years old) to smooth fiber surfaces (less than a hundred years) was found. This correlated with the time of the introduction of Western degumming methods in Japan. Synthetic dyes were not found on the earlier silk fibers with rough surfaces. AAR dating measurements on rough surfaced fibers with remaining sericin correlated better with the estimated age of the silk fabrics than fibers with smooth surfaces, suggesting the technique should only be used for silk fibers with rough surfaces. A screening method for fibers for AAR analysis was outlined. [ABSTRACT FROM AUTHOR]

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Enzymatic degradation of synthetic dyes holds an immense promise for addressing the environmental concerns associated with the textile and dye industries. This study aimed to isolate bacteria capable of producing laccase enzymes from an anthropogenic environment. Subsequently, viability of utilizing cost-effective agricultural residues as substrates for laccase production was assessed. Response Surface Methodology (RSM) and the One Variable at a Time (OVAT) approach was pursued for the optimization of laccase production, followed by pH and temperature stability, dye degradation and decolorization experiments, toxicological studies on the degraded dye metabolites. In results, laccase-producing bacterial strain was identified as Stenotrophomonas maltophilia strain E1 (S. maltophilia). Among variety of substrates, coconut husk exhibited optimal efficacy. In a statistical optimization study, it was found that S. maltophilia was capable of producing laccase 51.38 IU/mL, i.e., three times higher than the amount of laccase produced by unoptimized medium (16.7 IU/mL), and the enzyme activity was found to be steady at an acidic pH, and a mesophilic temperature range. The laccase obtained from S. maltophilia E1 demonstrated proficient dye decolorization capabilities, achieving a notable 92.1% reduction in Malachite green dye coloration at a concentration of 500 ppm. Gas chromatography–mass spectrometry (GC–MS) analysis of the decolorized derivatives of Malachite green revealed a conversion into a distinct compounds. Moreover, after undergoing laccase treatment, Malachite green exhibited decreased phytotoxic effects on Oryza sativa, pointing to enzymatic detoxification. Collectively, insights gained from the present study will contribute to the development of efficient enzymatic approaches for addressing the environmental pollution caused by synthetic dyes. [ABSTRACT FROM AUTHOR]

For consumers, the colour presents an indicator that characterizes the quality of the food. As a result of the processes of caramelization of carbohydrates and products of the Maillard reaction, brown compounds are formed with a negative impact on the external appearance of food, which has led to the massive use of synthetic dyes, stable from a technological point of view. The objectives of the European Union foresee the transition to the exclusive use of natural dyes, because synthetic dyes significantly affect the health of the population. Compounds with "azo" type chromophore groups (amaranth, tartrazine) present carcinogenic dangers, being banned in several European countries. The aim of the present study was to evaluate the problem of synthetic dyes and their substitution in food, obtaining, stabilizing and using natural dyes for the food industry. The study highlighted that safflower (Carthamus tinctorius L.) presents a promising source of yellow and red dyes, necessary for use in the food industry, but insufficient information was found regarding the technological properties of safflower petals, the methods of simultaneous extraction of yellow and red dyes and the peculiarities of the use of dyes in the finished product.

Both natural and synthetic dyes have gained increasing attention in the leather dyeing process due to environmental and health considerations. This research was designed to determine and compare the antimicrobial efficacy of four natural dyes (Acacia catechu, Trema orientalis, Camellia sinensis, Swietenia macrophylla) with four synthetic dyes (brown BFR, brown NG, brown EDK, red G) to develop safer leather dyeing process. The above eight dyes were evaluated against eight prevalent pathogenic and opportunistic pathogenic bacteria Bacillus megaterium, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Salmonella sp., Escherichia coli, Shigella sp., Pseudomonas aeruginosa, and four fungi. Dyestuff from Acacia catechu, Trema orientalis, and Swietenia macrophylla was effective against the three Bacillus strains, and Staphylococcus aureus with an inhibition zone extending from 6.3 mm to 11 mm. Synthetic dye brown BFR was effective against the three Bacillus strains, and Staphylococcus aureus with zone diameter of 14.8 mm to 19.7 mm. Brown EDK and Red G showed activity against Bacillus megaterium and Bacillus cereus. Camellia sinensis and brown NG showed no antimicrobial efficacy. Also, all eight dyes showed no antifungal activity. For both types of dyes, the zone of inhibition increased approximately linearly as dye concentrations increased. Of the natural dyes, Acacia catechu showed the highest activity. Brown BFR showed the maximum zone diameter of the eight dyes tested. The results indicated that both natural and synthetic dyes were quite effective. Synthetic dyes had remarkable antibacterial properties compared to natural dyes. These dyes having antimicrobial activity can be used in a safer leather dyeing process.

Emerging research highlights the potential neurobehavioral impacts of synthetic food dyes on children, prompting a reevaluation of their safety and regulatory standards. This letter discusses recent findings that associate synthetic food dyes with adverse behavioral outcomes, such as hyperactivity, particularly in children with or without identified behavioral disorders. It calls for updated regulatory guidelines that reflect current research, advocating for protecting children's behavioral health.

The synergetic enhancement effect of the polyaniline (PANI) integration process on the adsorption properties of the PANI/zeolite-A composite (PANI/ZA) as an adsorbent for malachite green and Congo red synthetic dyes was evaluated based on classic equilibrium modelling in addition to the steric and energetic parameters of advanced isotherm studies. The PANI/ZA composite displays enhanced adsorption capacities for both methylene blue (270.9 mg/g) and Congo red (235.5 mg/g) as compared to ZA particles (methylene blue (179.6 mg/g) and Congo red (140.3 mg/g)). The reported enhancement was illustrated based on the steric parameters of active site density (Nm) and the number of adsorbed dyes per active site (n). The integration of PANI strongly induced the quantities of the existing active sites that have enhanced affinities towards both methylene blue (109.2 mg/g) and Congo red (92.9 mg/g) as compared to the present sites on the surface of ZA. Every site on the surface of PANI/ZA can adsorb about four methylene blue molecules and five Congo red molecules, signifying the vertical orientation of their adsorbed ions and their uptake by multi-molecular mechanisms. The energetic investigation of the methylene blue (−10.26 to −16.8 kJ/mol) and Congo red (−9.38 to −16.49 kJ/mol) adsorption reactions by PANI/ZA suggested the operation of physical mechanisms during their uptake by PANI/ZA. These mechanisms might involve van der Waals forces, dipole bonding forces, and hydrogen bonding (<30 kJ/mol). The evaluated thermodynamic functions, including enthalpy, internal energy, and entropy, validate the exothermic and spontaneous behaviours of the methylene blue and Congo red uptake processes by PANI/ZA. [ABSTRACT FROM AUTHOR]

Major part of the aesthetics and beauty of idols, textiles, paper, paintings industries, etc. finds its roots in the use of colours (azo compound). These synthetic dyes can not degrade easily by physical and chemical means and are toxic for the environment and animals including humans. Even if they get degraded, it becomes difficult to get rid of the secondary toxic products. Microbes especially bacteria can be used which results cheap, eco friendly and complete degradation of azo dye products without production of any secondary toxic products (or secondary products with way lesser toxicity). Also, it requires no new chemical to be added (in an attempt to degrade azo dye) in an already polluted environment, as the bacterial enzymes would do the job without requiring any other added chemicals. This review article discusses the use of bacteria for azo dye degradation, the bacterial enzymes such as laccase etc. that degrade azo dye and how they work to decolourise the dyes, the common genetic elements found in the different bacteria that can degrade azo dye. This article also includes information on future prospects and some genetically modified organism (GMO) that are being/ (can be) brought to use for dye degradation and pollution reduction. [ABSTRACT FROM AUTHOR]

The brightly colored synthetic dyes used in the textile industry are discharged at high concentrations—for example, various azo dyes including Methylene Blue (MB) and Methyl Orange (MO)—which is a matter of global concern, as such dyes are harmful to humans and the environment. Microbial degradation is considered an efficient alternative for overcoming the disadvantages of conventional physical and chemical dye removal methods. In this study, we investigated the potential of multiple types of the enzyme-producing extremophilic bacteria Bacillus FW2, isolated from food waste leachate, for the decolorization and bioremediation of artificial synthetic dyes. The screening of enzyme production and assaying of bacterial strain enzymes are essential for enhancing the breakdown of azo bonds in textile azo dyes. The degradation efficiencies of the water-soluble dyes MB and MO were determined at different concentrations using rice husk, which is an efficient substrate. Using the rice husks, the MO was removed completely within 20 h, and an estimated 99.8% of MB was degraded after 24 h by employing shaking at 120 rpm at 40 °C—whereas a removal efficiency of 98.9% was achieved for the combination of MB + MO. These results indicate the possibility of applying an extremophilic bacterial strain, Bacillus sp., for large-scale dye degradation in the future. [ABSTRACT FROM AUTHOR]

Chromotope, the 19th Century Chromatic Turn, is a multidisciplinary ERC research programme that focuses on the “chromatic turn” of the 1860s in France and England, following the invention of the first synthetic dyes. This project, based on a partnership between Sorbonne University (PI: Charlotte Ribeyrol), Oxford University, and the Conservatoire national des arts et métiers (Cnam), investigates how this turn led to new ways of thinking about colour in art, literature, history, and science throughout the second half of the 19th century. One of the key aims of this research is to reappraise the role played by the Cnam in the dissemination of knowledge about synthetic dyes, from the creation in 1852 of the first chair in dyeing and printing until the Interwar period, when a collection of dyes including more than 2500 references, obtained from major European firms, was formed. A full inventory based on the description of each container has just been made together with a bibliographical research. Nevertheless, 2% of the containers are unlabeled and the reattribution of their composition is the main goal of our study. In order to set an appropriate analysis protocol to identify these orphan containers, a preliminary work was conducted on a random selection of identified dyes. For this purpose, electrospray ionization mass spectrometry and Fourier-transform infrared spectroscopy were used on 13 samples from different dye classes. The relevance of this protocol will be discussed for the identification of unknown compounds.

Ecobrick and ecoprint are one of several solutions that can be used to reduce plastic waste through making crafts resembling stone blocks and synthetic dyes. The aims of the training on handicrafts of natural materials and plastic waste are participant can understand the content and purpose of this webinar, able to provide an evaluation for the entire webinar activity as part of the role of humans who are the crown of God's creation in carrying out cultural mandates, able to increase commitment participants in contributing to share this webinar activity with the public, and also to participate in supporting the SDGs program especially on minimizing the disposal of chemicals and hazardous materials and increasing recycling such as recycling single-use plastics into Ecobricks. Activities are carried out in five stages, observation and problem identification, preparation, work, webinar, and evaluation. The analysis method used is descriptive quantitative. The evaluation results were given to participants after the event and calculated using Ms. Excel. The evaluation is carried out by providing nine questions that will be answered by training participants. The results of the evaluation show that participants become more educated about the use of natural materials and used plastics to be used as handicrafts. The results were 5% neutral answers, 25% answered affirmatively, and 70% answered strongly agreed about the success of the activity.

The introduction of synthetic dyes completely changed the industrial production and use of colorants for art materials. From the synthesis of the first synthetic dye, mauveine, in 1856 until today, artists have enjoyed a wider range of colors and selection of chemical properties than was ever available before. However, the introduction of synthetic dyes introduced a wider variety and increased the complexity of the chemical structures of marketed dyes. This work looks towards the analysis of synthetically dyed objects in heritage collections, applying an extraction protocol based on the use of ammonia, which is considered favorable for natural anthraquinone dyes but has never before been applied to acid synthetic dyes. This work also presents an innovative cleanup step based on the use of an ion pair dispersive liquid–liquid microextraction for the purification and preconcentration of historical synthetic dyes before analysis. This approach was adapted from food science analysis and is applied to synthetic dyes in heritage science for the first time in this paper. The results showed adequate recovery of analytes and allowed for the ammonia-based extraction method to be applied successfully to 15 samples of suspected azo dyes from the Azienda Coloranti Nazionali e Affini (ACNA) synthetic dye collection, identified through untargeted HPLC-HRMS analyses. [ABSTRACT FROM AUTHOR]

The use of waste from various agricultural sectors has recently drawn increased interest from the scientific, technological, ecological, economic, and social fields. As such, in this study, a novel production of an affordable and environmentally friendly photocatalyst of silicotitanate (S1, S2, and S3) made from silica solution (extracted from rice husk ash) and various molar ratios of titanium (IV) 2-ethylhexyl-oxide is reported. Following that, chitosan/silicotitanate (CHMix) nanocomposite material was created through a crosslinking reaction between chitosan and fabricated silicotitanate (S2). Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), as well as N2 adsorption-desorption isotherm and zeta potential measurements were used to characterize each of the fabricated samples. Additionally, in comparison to neat chitosan, the newly fabricated material's (CHMix) photocatalytic reactivity was investigated using two synthetic anionic dyes, reactive blue and Congo red, with decolorization rates of up to 95.76% and 99.9%, respectively. The decolorization results showed that CHMix is the most efficient photocatalyst for the degradation of reactive blue and Congo red. Reactive blue and Congo red's molecular structures were almost completely broken when equilibrium was reached using sunlight, and the decolorization rate for both dyes was close to 100%. As a result, the combination of chitosan and silicotitanate, or CHMix, has an effective photocatalytic capability for dye degradation in both natural and concentrated sunlight. [ABSTRACT FROM AUTHOR]

This study focuses on the modification of natural hydroxyapatite (HAp) derived from clamshell by impregnation with palladium (Pd) at different pH in wet precipitation method to produce photoactive green materials for the degradation of synthetic dyes. It was found that, at pH 10, Pd has been successfully impregnated into HAp lattice with Ca/P ratio of 1.77 and particle distribution size range of 40-470 nm. The impregnation has resulted in the band gap of Pd/HAp at 3.19 eV, as calculated using Tauc's plot from the UV-Vis spectroscopy data of the Pd/HAp. Next, the photocatalytic activities of Pd/HAp were carried out with methyl oranges (MO) as models of water pollutants under UV irradiation. The photodegradation efficiency of the catalyst reached the optimum value of 41.63%, 48.17%, and 43.64% after 120 min of continuous UV irradiation for pH values 8, 10, and 11.5 of Pd/HAp samples, respectively. This study opens a new paradigm in using naturally derived materials as photocatalysts in the reduction of persistent water pollutants at a low cost and green sustainable approach. [ABSTRACT FROM AUTHOR]

Sir William Henry Perkin was a famous organic chemist and pioneer in industrial organic synthesis. The story of his life, personal qualities, and achievements have bequeathed a legacy to future generations. Although there are English biographies about Perkin, the information in Chinese literature is relatively limited. This paper describes the background, scientific contributions, and influence of Perkin based on the relevant literature to inspire teachers in chemistry education and encourage personal development. [ABSTRACT FROM AUTHOR]