Search Results (85)

Silk fabrics and caftans preserved in the Topkapı Palace Museum collection constitute a distinguished group of cultural heritage objects reflecting the advanced weaving technologies, refined metal-thread use, and sophisticated natural dyeing practices of Ottoman court textile production. In this study, selected ceremonial caftans attributed to five Ottoman sultans were examined through a multidisciplinary and multi-analytical approach to characterize their structural, chromatic, and chemical properties. Color characteristics were evaluated in the CIE L*a*b* color space, while yarn properties, weave structures, and production techniques were investigated by optical microscopy. The morphology and elemental composition of the metal threads were analyzed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX), and dyestuffs were identified by high-performance liquid chromatography with diode-array detection (HPLC–DAD). The results show that compound silk weaving structures were widely used in Ottoman court textiles, metal threads were predominantly silver-based and often gold-gilded, and dyestuffs with high fastness properties were preferentially selected. The revised manuscript situates these findings within a broader international literature on historical textile analysis and natural dye characterization, while using only a limited number of directly relevant studies from the authors’ previous work. The present study therefore provides new, object-specific and comparable data for the scientific documentation, material characterization, and conservation-oriented understanding of Ottoman textile heritage. Full article

In this study, the dyeing kinetics of polyamide fabrics with acid dyes, such as Telon Blue M2R, under both conventional and microwave-assisted heating conditions were comprehensively investigated. While the conventional dyeing reaction was completed in 30 min, microwave-assisted dyeing was performed in the microwave device for 10 min. Dyeing kinetics were investigated as a function of reaction time, reaction concentration and dyeing temperatures. The K/S values (color depth) of the dyed fabrics were correlated with the concentration. A significant reduction in the dyeing process time for polyamide fabric was observed with microwave heating compared to the conventional method. Kinetic analysis revealed that the Pseudo-Second-Order (PSO) kinetic model provides a better fit to the experimental data on the diffusion process of acid dye in polyamide fabrics, as evidenced by higher correlation coefficients (R²) compared to the Pseudo-First-Order (PFO) model. The activation energy of the reaction in dyeing was found to be 63.27 kJ/mol, and the Arrhenius constant was determined as 7.20 × 10¹⁰ L/g·min in conventional media and 18.70 × 10¹⁰ L/g·min in microwave media. The Arrhenius factor in the microwave medium was more than two times higher than in the conventional media. Full article

This review summarizes recent applications of carbon-based materials as catalysts in the ozonation of wastewater contaminated with persistent organic pollutants. Methods available for production of commonly used inexpensive carbonaceous materials such as biochar and hydrochar are presented. Differences between production methods of active carbon and biochar or hydrochar are discussed. Interestingly, biochar, in a role of rather simple and cheap charcoal, is catalytically active and increases the rate of oxidative degradation of nonbiodegradable aqueous contaminants such as drugs or textile dyestuffs. This review documents that even the addition of biochar to the ozonized wastewater increases the rate of removal of persistent organic pollutants. Cheap bio-based carbonaceous materials such as biochar work as adsorbent of dissolved pollutants and catalysts for ozone-based degradation of organic compounds via the formation of reactive oxygen species (ROS). Low-molecular-weight degradation products produced by ozonation of pharmaceuticals and textile dyes are presented. The combination of air-based ozone generation, together with application of biochar, represents a sustainable AOP-based wastewater treatment method. Full article

Dyed wool samples and lake pigments prepared from the same dyestuffs were exposed to light over the course of 14 months. Brazilwood or sappanwood, cochineal, madder, and weld were used for both wools and pigments, with the addition of dyer’s broom, indigo, and tannin-containing black dyes for the wools and eosin for the pigments. The wools were dyed within the MODHT European project on historic tapestries (2002–2005), using recipes derived from fifteenth- to seventeenth-century sources. The pigments were prepared according to European recipes of the same period, or using late nineteenth-century French or English recipes. Colour measurements made throughout the experiment allowed for overall colour difference (ΔE₀₀) to be tracked and half-lives to be calculated for some of the colour changes. Alterations in the samples’ hue and chroma were also monitored, and spectral information was collected. The results showed that, for both textiles and pigments, madder is the most stable red dye, followed by cochineal, and then brazilwood. Eosin was the most fugitive sample examined. Comparisons of textile and lake samples derived from the same dyestuff, whether red or yellow, indicate that the colourants are more stable when used as textile dyes than in analogous lake pigments. Full article

In 1906, Charles T. Currelly participated in excavations at Deir el-Bahri, Egypt, recovering votive offerings from the Temple of Hathor (Dynasty XVIII, reign of Hatshepsut, 1479–1458 BCE). These objects became part of the founding collection of the Royal Ontario Museum, where Currelly served as the first director. Among the offerings are several paintings on linen cloth. During examination of one painted textile, a border fringe with cream (suspected undyed), yellow and blue looped threads was sampled and analysed for dyes using gas chromatography–mass spectrometry. The yellow threads were found to contain a tannin-rich dyestuff, likely derived from Rhus spp., a common dye in ancient Egypt. Unexpectedly, the blue threads yielded brominated-indigoid marker compounds, indicating the use of a Murex-derived dye. While purple shellfish dye is rare due to the high cost of its complex production, blue shellfish dye is even more exceptional and has only been identified a handful of times on archaeological textiles. Calculated values of di-brominated to mono-brominated indigoid compounds suggests the dye originated from an indigotin-rich type of Hexaplex trunculus snail, a Mediterranean species. This finding represents a rare example of blue shellfish dye use in ancient Egypt and provides new insights into the dyeing technologies of Dynasty XVIII and the importance of this sky-blue colour in the worship of the goddess Hathor. Full article

In 1842, carpet manufacturer W.H. Worth of Kidderminster, England, began assembling a sample book of wool yarns dyed with natural dyestuffs. This paper reports on a study of the “Greens” section, which contains sixteen yarn samples—six still green and ten now ranging from tan to dark brown. The accompanying recipes list similar ingredients: old fustic and either “mixture” or extracet of indigo. To verify whether Worth’s recipes were followed, the yarns were analyzed using HPLC-DAD and FORS. Additionally, mock-ups were prepared according to Worth’s green dye recipes and subjected to thermal ageing to explore potential causes of discoloration. Preliminary analysis of the historic samples revealed that the discoloured yarns contain both indigo and indigo carmine, while the still-green samples contain only indigo carmine. This suggests that one or more components of the indigo vat may have contributed to discoloration. To test this hypothesis, contemporary wool yarns were dyed using a Worth green recipe, with and without indigo, at varying pH levels. These were thermally aged, and their colour changes monitored. HPLC-DAD and FORS analyses of the mock-ups were compared to the historic samples to identify dyeing conditions that may have led to the observed browning. Full article

Aldehyde green, a dye first obtained by reacting fuchsine with acetaldehyde in 1862, consists of, according to analytical investigations carried out on a sample of this dye deposited in the Historical Dyestuff Collection of the Technical University Dresden and performed with liquid chromatography and high-resolution mass spectrometry, a mixture of various compounds in which the aniline groups of fuchsine are converted into quinaldine and dihydroquinaldine moieties. The dye owns its green color by two absorption bands in the visible range at 435 and 616 nm. Full article

The objective of this study is to investigate the performance of the ultrafiltration process as a purification method on the dyeing properties of a newly synthesized homobifunctional reactive dye. This is a green–blue reactive dye with two vinylsulfone groups. Namely, several properties, such as exhaustion, substantivity, fixation, time to half dyeing, migration index, light fastness, and the effect of metal salts, were studied thoroughly. It was proven that the processed bifunctional reactive dye shows higher exhaustion, substantivity, and dye-uptake values than the untreated one. It was found that the dye fixation is higher for the ultrafiltrated (92%) compared to the non-ultrafiltrated (85%) dye, while the migration index is slightly lower. It is indicated that, due to the possible chemical affinity between the dye and the substrate, a stronger retention is noticed for the treated dye. All in all, high fixation and substantivity lead to higher dye valorization and result in less hydrolyzed waste dyestuff, leading to less water and organic liquid waste at an industrial scale. The effect of metal salts addition (Fe³⁺, Co²⁺ and Cu²⁺) was studied as well, for comparison reasons, but it was found to be unnecessary. It is proven by the property values calculated that the overall process is valuable, since lower dyebath concentrations are required for satisfactory results. Thus, in large-scale dyeings, the ultrafiltration process can be proven to be valuable for environmental protection reasons. Full article

Herein, a WO₃@TCN photocatalyst was successfully synthesized using a self-assembly method, which demonstrated effectiveness in degrading organic dyestuffs and photocatalytic evolution of H₂. The synergistic effect between WO₃ and TCN, along with the porous structure of TCN, facilitated the formation of a heterojunction that promoted the absorption of visible light, accelerated the interfacial charge transfer, and inhibited the recombination of photogenerated electron–hole pairs. This led to excellent photocatalytic performance of 3%WO₃@TCN in degrading TC and catalyzing H₂ evolution from water splitting under visible-light irradiation. After modulation, the optimal 3%WO₃@TCN exhibited a maximal degradation rate constant that was twofold higher than that of TCN alone and showed continuous H₂ generation in the photocatalytic hydrogen evolution. Mechanistic studies revealed that •O₂⁻ constituted the major active species for the photocatalytic degradation of tetracycline. Experimental and DFT results verified the electronic transmission direction of WO₃@TCN heterojunction. Overall, this study facilitates the structural design of green TCN-based heterojunction photocatalysts and expands the application of TCN in the diverse photocatalytic processes. Additionally, this study offers valuable insights into strategically employing acid regulation modulation to enhance the performance of carbon nitride-based photocatalysts by altering the topography of WO₃@TCN composite material dramatically. Full article

This review analyzes the use of magnetite-based catalysts in various oxidation reactions. It is shown that magnetite-based catalysts are the most promising candidates from the standpoint of easy separation from the reaction zone and reusability. Diverse examples of the use of magnetite-based composites are discussed, including the following reactions: partial oxidation of methane to formaldehyde; the oxidation of cycloalkanes into alcohols and ketones; the oxidation of alkenes and alcohols with the major focus made on benzylic alcohol oxidation; oxidative cracking of alkenes; Fenton-type reactions with H₂O₂ as a benign oxidant; the removal of dyestuff in water (including wastewater by oxidation); reactions of sulfides and thiols; the oxidation of 5-hydroxymethylfurfural as a platform chemical to 2,5-diformylfuran; the oxidation of D-glucose to D-gluconic acid; and the electrocatalytic oxidation of methanol and ethanol. The most important and best-studied applications of magnetic nanoparticles in the oxidation reactions are believed to be the oxidation of diverse benzylic alcohols and D-glucose, and Fenton-like reactions aiming at the removal of S- and N-compounds from ware and fuels. Magnetic nanocomposites are determined as the materials meeting a range of criteria: (1) they should be magnetic, (2) they contain nanoparticles, and (3) they consist of two (or more) nanocomponents. The core–shell materials with magnetic nanoparticles used as a core or as decorating nanoparticles are discussed in the review. Three main types of magnetic nanocomposites can be distinguished: (1) the systems where the magnetic phase is active in the considered reaction, for instance, Fenton-like oxidation; (2) the systems containing active metal nanoparticles supported onto the magnetic nanoparticles; and (3) materials with magnetic nanoparticles as a core coated with one or two shells (porous or non-porous), with the magnetic nanoparticles being active or not in the title reaction. Magnetic nanoparticles exhibit a number of advantages compared with supported non-magnetic catalysts of oxidation reactions. The advantages include the possibility of separation from the reaction medium (5–10 times) without a significant loss of the activity, their non-toxicity, low cost, and availability, and the easy preparation of these materials. The drawbacks may include the leaching of active components; a decrease in saturation magnetization in comparison with the bulk magnetite; a limited accessibility of active sites due to diffusion through the shells; the complicated composition and structure of the nanomaterials; a decrease in the activity and specific surface area; and a limited number of magnetic compounds with acceptable characteristics. Nevertheless, the advantages of magnetic nanocatalysts stimulate their wide use in liquid-phase oxidation reactions, which will be discussed in the review. Future perspectives on the use of magnetic composites are considered. Full article

This study developed a MgBi₂O₆-based photocatalyst via low-temperature hydrothermal synthesis. AgBr was co-precipitated onto MgBi₂O₆, and silver nanoparticles (AgNPs) were photo-reduced onto the surface. The photocatalytic performance, assessed by methylene blue (MB) degradation under white-light LED irradiation (2.5 W, power density = 0.38 W/cm²), showed that Ag/AgBr/MgBi₂O₆ achieved 98.6% degradation in 40 min, outperforming MgBi₂O₆ (37.5%) and AgBr/MgBi₂O₆ (85.5%). AgNPs boosted electron-hole separation via surface plasmon resonance, reducing recombination. A Z-scheme photocatalytic mechanism was suggested, where photogenerated carriers transferred across the p–n heterojunction between AgBr and MgBi₂O₆, producing reactive oxygen species like superoxide and hydroxyl radicals critical for dye degradation. Thus, the Ag/AgBr/MgBi₂O₆ composites possessed excellent photocatalytic performance regarding dyestuff degradation (85.8–99.9% degradation within 40 min) under white-light LED irradiation. Full article

In this study, the effectiveness of Fe₃O₄-based clay as a cost-effective material for removing methylene blue (MB) dye from aqueous solutions was evaluated. The structural properties of the clay and Fe₃O₄-based clay were analyzed using SEM, XRF, BET, XRD, FTIR, and TGA techniques. In this research, the effects of various aspects, such as adsorbent amount, contact time, solution pH, adsorption temperature, and initial dye concentration, on the adsorption of Fe₃O₄-based clay are investigated. The experiments aimed at understanding the adsorption mechanism of Fe₃O₄-based clay have shown that the adsorption kinetics are accurately described by the pseudo-second order kinetic model, while the equilibrium data are well represented by the Langmuir isotherm model. The maximum adsorption capacity (qm) was calculated as 52.63 mg/g at 25 °C, 53.48 mg/g at 30 °C, and 54.64 mg/g at 35 °C. All variables affecting the MB adsorption process were systematically optimized in a controlled experimental framework. The effectiveness of the artificial neural network (ANN) model was refined by modifying variables such as the quantity of neurons in the latent layer, the number of inputs, and the learning rate. The model’s accuracy was assessed using the mean absolute percentage error (MAPE) for the removal and adsorption percentage output parameters. The coefficient of determination (R²) values for the dyestuff training, validation, and test sets were found to be 99.40%, 92.25%, and 96.30%, respectively. The ANN model demonstrated a mean squared error (MSE) of 0.614565 for the training data. For the validation dataset, the model recorded MSE values of 0.99406 for the training data, 0.92255 for the validation set, and 0.96302 for the test data. In conclusion, the examined Fe₃O₄-based clays offer potential as effective and cost-efficient adsorbents for purifying water containing MB dye in various industrial settings. Full article

Herein, this study has examined the influence of Zn²⁺ sources during a biogenic-mediated pathway to synthesize ZnO nanoparticles with highly desirable solar-responsive catalytic properties. Salts of nitrate, acetate and chloride have been utilized. The ZnO powders underwent characterization using diverse analytical tools, including XRD, FTIR, Raman, BET, SEM, TEM with EDS/elemental mapping and UV-vis absorption/emission spectroscopic analyses. Accordingly, precursors have proved to affect crystallinity, morphology, surface characteristics, optical properties and the photocatalytic degradation of methylene blue (MB) model pollutant. It was observed that ZnO derived from zinc acetate precursor (Z-AC NPs) exhibits very fast photocatalytic degradation of MB at pH 11 with superior kinetic estimates of 0.314 min⁻¹ and t_1/2 = 2.2 min over many of recent reports. In contrast, the chloride precursor is not recommended along with the employed biogenic route. The intriguing findings could be directly correlated to the decreased crystal size, augmented surface area, the hexagonal morphology of the crystals, high potency in absorbing visible photons, high efficacy in separating photogenerated charge carriers and producing high amounts of ^•OH radicals. Further testing of Z-AC NPs in photocatalytic remediation of water samples from Dumat Aljandal Lake in Aljouf, Saudi Arabia, contaminated with MB and pyronine Y (PY) dyestuffs, showed high dye photodegradation. Therefore, this work could lead to an extremely fast avenue for decontaminating wastewater from hazmat dyestuff. Full article

The issue of water pollution is one of the hot topics of global concern, which requires us to efficiently treat pollutants in water, especially printing and dyeing sewage. There are varieties of dyestuffs and intermediates, which are complex and difficult to degrade, and they even contain heavy metals. In this study, a bacterial strain named Q3-6 with potential for sewage treatment was isolated and its physiological, biochemical, and genomic characteristics, and potential application value, were further investigated. The genome sequence confirmed that it belongs to Bacillus thuringiensis. Strain Q3-6 has a significant decolorization effect on the dyes. The decolorization rate for Brilliant blue G-250 (0.1 g/L) and Congo Red (0.1 g/L) can reach 93.9% and 91.9%, respectively. In addition, strain Q3-6 is resistant to many kinds of antibiotics and heavy metals. Further, it has strong heat resistance, and heating at 80 °C can promote the biomass of the strain. Genomic analysis revealed the presence of genes related to heat shock proteins (GroES, GrpE, DnaJ, GroEL, DnaK, ClpB, and ClpA) in strain Q3-6. These results suggest the strain’s exceptional resilience and adaptability to intricate environments with heavy metals, antibiotics, or high-temperature environments, suggesting its pivotal role in the bioremediation of complex contaminated effluents. Full article

Early modern materials are not well represented in dye and mordant analyses despite extensive documentary evidence suggesting the enormous demand for coloured fabrics, even among those below the elite. Non-wovens likewise receive less attention than woven textiles despite their ubiquity in the early modern historical record. Knitted garments, in particular, have rarely been subjected to dye analysis. One garment is noteworthy for its colourfulness, despite not being visible in formal wear. Men throughout society wore knitted undergarments known as waistcoats from the late sixteenth century. The waistcoats under investigation here are from the collections at the London Museum and the Grimsthorpe and Drummond Castle Trust, Scotland. They are made of silk and are now a pale blue-green colour. Small samples were taken from each and subjected to a series of analytical techniques: micro-Raman spectroscopy, UV-Vis microspectrofluorimetry, and high-performance liquid chromatography (HPLC) coupled with a mass spectrometer. Using this protocol, it was possible to characterise the dyes in the waistcoats by ensuring that maximum information was gleaned from a sample before it was exhausted. Full article