Search Results (25)

TS-1 zeolite and a series of Zr-modified samples (TS-1/xZr) were synthesized and systematically characterized to investigate the influence of zirconium incorporation on structural, textural, and photocatalytic properties. The structural and textural properties of the samples were examined by XRD and nitrogen adsorption isotherms. Elemental analysis (EDXRF, SEM/EDS) and FTIR confirmed successful incorporation of Zr into the TS-1 framework. Photocatalytic tests under white light irradiation using crystal violet (CV), methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes revealed enhanced degradation efficiency for the Zr-containing samples, particularly TS-1/10Zr. Kinetic modeling using pseudo-first-order (PFO) and pseudo-second-order (PSO) approaches indicated that dye degradation followed mainly PSO kinetics. Reusability studies demonstrated sustained stability and recyclability of the catalysts. The improved photocatalytic performance is attributed to synergistic electronic effects between Ti and Zr species, which enhance charge separation and light absorption. Full article

The dyes used to produce two Palestinian garments from the British Museum’s collection attributed to the late 19th–early 20th century were investigated by high pressure liquid chromatography coupled with diode array detector and tandem mass spectrometry (HPLC-DAD-MS/MS). Palestinian embroidery is a symbol of national identity and the topic of scholarly research. However, little attention has been given to the dyes and how these changed with the introduction of new synthetic formulations in the second half of the 19th century. The results revealed the use of natural indigoid blue and red madder (Rubia tinctorum), in combination with tannins. Yellow from buckthorn (probably Rhamnus saxatilis) and red from cochineal (probably Dactylopius coccus) were found mixed with synthetic dyes in green and dark red embroidery threads, respectively. Early synthetic dyes were identified in all the other colours. These include Rhodamine B (C.I. 45170), Orange II (C.I. 15510), Orange IV (C.I. 13080), Metanil Yellow (C.I. 13065), Chrysoidine R (C.I. 11320), Methyl Violet (C.I. 42535), Malachite Green (C.I. 42000), Fuchsin (C.I. 42510), Auramine O (C.I. 41000) and Methyl Blue (C.I. 42780). As the date of the first synthesis of these dyes is known, the production date of the garments was refined, suggesting that these were likely to be produced towards the end of the 1880s/beginning of the 1890s. The continuous use of historical local sources of natural dyes, alongside new synthetic dyes, is of particular interest, adding rightful nuances to the development of textile-making practices in this region. Full article

This study is the first to convert two waste materials, waste rice noodles (WRN) and red mud (RM), into a low-cost, high-value magnetic photocatalytic composite. WRN was processed via a hydrothermal method to produce a solution containing carbon quantum dots (CQDs). Simultaneously, RM was dissolved in acid to form a Fe³⁺ ion-rich solution, which was subsequently mixed with the CQDs solution and underwent hydrothermal treatment. During this process, the Fe³⁺ ions in RM were transformed into the maghemite (γ-Fe₂O₃) phase, while CQDs were incorporated onto the γ-Fe₂O₃ surface, resulting in the CQDs/γ-Fe₂O₃ magnetic photocatalytic composite. Experimental results demonstrated that the WRN-derived CQDs not only facilitated the formation of the magnetic γ-Fe₂O₃ phase but also promoted a synergistic interaction between CQDs and γ-Fe₂O₃, enhancing electron-hole pair separation and boosting the production of reactive radicals such as O₂^·− and ·OH. Under optimized conditions (pH = 8, carbon loading: 10 wt%), the CQDs/γ-Fe₂O₃ composite exhibited good photocatalytic performance against methylene blue, achieving a 97.6% degradation rate within 480 min and a degradation rate constant of 5.99 × 10⁻³ min⁻¹, significantly outperforming RM and commercial γ-Fe₂O₃ powder. Beyond methylene blue, this composite also effectively degraded common organic dyes, including malachite green, methyl violet, basic fuchsin, and rhodamine B, with particularly high efficiency against malachite green, reaching a degradation rate constant of 5.465 × 10⁻² min⁻¹. Additionally, due to its soft magnetic properties (saturation magnetization intensity: 16.7 emu/g, residual magnetization intensity: 2.2 emu/g), the material could be conveniently recovered and reused after photocatalytic cycles. Even after 10 cycles, it retained over 98% recovery and 96% photocatalytic degradation efficiency, underscoring its potential for cost-effective, large-scale photocatalytic water purification. Full article

Piezocatalytic materials have attracted widespread attention in the fields of clean energy and water treatment because of their ability to convert mechanical energy directly into chemical energy. In this study, γ-AlON particles synthesised using carbothermal reduction and nitridation (CRN) were used for the first time as a novel piezocatalytic material to degrade dye solutions under ultrasonic vibration. The γ-AlON particles exhibited good performance as a piezocatalytic material for the degradation of organic pollutants. After 120 min under ultrasonic vibration, 40 mg portions of γ-AlON particles in 50 mL dye solutions (10 mg/L) achieved 78.06%, 67.74%, 74.29% and 64.62% decomposition rates for rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and crystal violet (CV) solutions, respectively; the fitted k values were 13.35 × 10⁻³, 10.79 × 10⁻³, 12.09 × 10⁻³ and 8.00 × 10⁻³ min⁻¹, respectively. The piezocatalytic mechanism of γ-AlON particles in the selective degradation of MO was further analysed in free-radical scavenging activity experiments. Hydroxyl radicals (•OH), superoxide radicals (•O₂⁻), holes (h⁺) and electrons (e⁻) were found to be the main active substances in the degradation process. Therefore, γ-AlON particles are an efficient and promising piezocatalytic material for the treatment of dye pollutants. Full article

Photocatalytic membranes are crucial in addressing membrane fouling issues. However, the grafting amount of the catalyst on the membrane often becomes a key factor in restricting the membrane’s self-cleaning capability. To address the challenge, this manuscript proposes a method for solving membrane fouling, featuring high grafting rates of bismuth oxide (Bi₂O₃) and acrylic acid (AA), significant contaminant degradation capability, and reusability. A highly photocatalytic self-cleaning microfiltration membrane made of polyvinylidene fluoride bismuth oxide and acrylic acid (PVDF-g-BA) was prepared by attaching nano Bi₂O₃ and acrylic acid onto the polyvinylidene fluoride membrane through adsorption/deposition and UV grafting polymerization. Compared with pure membranes and pure acrylic grafted membranes (PVDF-g-AA), the modified membrane grafted with 0.5% bismuth oxide not only improves the grafting rate and filtration performance, but also has higher self-cleaning ability. Furthermore, the degradation effect of this membrane on the organic dye methyl violet 2B under visible light irradiation is very significant, with a degradation rate reaching 90% and almost complete degradation after 12 h. Finally, after repeated filtration and photocatalysis, the membrane can still significantly degrade contaminants and can be reused. Full article

Coordination polymers (CPs) are a diverse class of multi-dimensional compounds that show promise as photocatalysts for degrading dyes in polluted water. Herein, a new 1D Cd(II)-based coordination polymer with the formula [Cd(bpyp)(nba)₂] (1) (bpyp = 2,5-bis(pyrid-4-yl)pyridine and Hnba = 4-nitrobenzoic acid) is synthesized and characterized. In 1, the two carboxyl groups of two different nba⁻ ligands show μ₂-η¹:η¹ and μ₁-η¹:η¹ coordination modes to connect the Cd^II centers and sit on either side of the chain along the b direction. The produced CP 1 was utilized as the photocatalyst in the process of the photodegradation of methyl blue (MB), methyl orange (MO), rhodamine B (RhB), and methyl violet (MV) dyes when exposed to UV light. The photocatalytic degradation activities of CP 1 were analyzed, and the results suggest that it exhibits an extraordinary efficiency in the degradation of MB, MV, MO, and RhB. RhB has a 95.52% efficiency of degradation, whereas MV has a 58.92% efficiency, MO has 35.44%, and MB has 29.24%. The photodecomposition of dyes is catalyzed mostly by •O₂⁻ and •OH⁻, as shown by research involving the trapping of radicals. Full article

The exploration of low-cost, high-performance adsorbents is a popular research issue. In this work, a straightforward method that combined hydrothermal with tube firing was used to produce Osmanthus fragrans biomass charcoal (OBC) from low-cost osmanthus for dye adsorption in water. The study examined the parameters of starting concentration, pH, and duration, which impacted the process of adsorption of different dyes by OBC. The analysis showed that the adsorption capacities of OBC for six dyes: malachite green (MG, C₀ = 800 mg/L, pH = 7), Congo red (CR, C₀ = 1000 mg/L, pH = 8), rhodamine B (RhB, C₀ = 500 mg/L, pH = 6), methyl orange (MO, C₀ = 1000 mg/L, pH = 7), methylene blue (MB, C₀ = 700 mg/L, pH = 8), and crystalline violet (CV, C₀ = 500 mg/L, pH = 7) were 6501.09, 2870.30, 554.93, 6277.72, 626.50, and 3539.34 mg/g, respectively. The pseudo-second-order model and the Langmuir isotherm model were compatible with the experimental findings, which suggested the dominance of ion exchange and chemisorption. The materials were characterized by using XRD, SEM, FTIR, BET, and XPS, and the results showed that OBC had an outstanding specific surface area (2063 m²·g^–1), with potential adsorption mechanisms that included electrostatic mechanisms, hydrogen bonding, and π-π adsorption. The fact that the adsorption capacity did not drastically decrease after five cycles of adsorption and desorption suggests that OBC has the potential to be a dye adsorbent. Full article

Blended biopolymer-based photocatalytic hydrogel beads were synthesized by dissolving the biopolymers in 1-ethyl-3-methylimidazolium acetate ([Emim][Ac]), adding TiO₂, and reconstituting the beads with ethanol. The incorporation of modifying biopolymer significantly enhanced the adsorption capacity of the cellulose/TiO₂ beads. Cellulose/carrageenan/TiO₂ beads exhibited a 7.0-fold increase in adsorption capacity for methylene blue (MB). In contrast, cellulose/chitosan/TiO₂ beads showed a 4.8-fold increase in adsorption capacity for methyl orange (MO) compared with cellulose/TiO₂ beads. In addition, cellulose/TiO₂ microbeads were prepared through the sol–gel transition of the [Emim][Ac]-in-oil emulsion to enhance photodegradation activity. These microbeads displayed a 4.6-fold higher adsorption capacity and 2.8-fold higher photodegradation activity for MB than the millimeter-sized beads. Furthermore, they exhibited superior dye removal efficiencies for various dyes such as Congo red, MO, MB, crystal violet, and rhodamine B, surpassing the performance of larger beads. To expand the industrial applicability of the microbeads, biopolymer/TiO₂ magnetic microbeads were developed by incorporating Fe₂O₃. These magnetic microbeads outperformed millimeter-sized beads regarding the efficiency and time required for MB removal from aqueous solutions. Furthermore, the physicochemical properties of magnetic microbeads can be easily controlled by adjusting the type of biopolymer modifier, the TiO₂ and magnetic particle content, and the ratio of each component based on the target molecule. Therefore, biopolymer-based photocatalytic magnetic microbeads have great potential not only in environmental fields but also in biomedical fields. Full article

Tea is the third most consumed beverage in Saudi Arabia (a country in the Middle East) after water and Arabian coffee. Hence, a large amount of consumed tea leaves is discarded as solid waste. Waste tea leaves (WTLs) have no commercial value and could be considered as an environmentally sustainable costless material. This work aimed to manufacture an adsorbent material from the discarded WTLs and charge-transfer (CT) interaction and use this adsorbent material effectively for the removal of different kinds of pollutants from water. The adsorbent material was manufactured in three steps. First, a CrFeO₃ metal composite was synthesized from the CT interaction between FeCl₃ and CrCl₃ with urea. Second, activated carbons were prepared from consumed WTLs using facile and clean treatments of pre-carbonization, and a simple potassium hydroxide (KOH) activation treatment. Finally, the adsorbent material was fabricated by grounding CrFeO₃ composite with the activated carbons in a 1:10 molar ratio (metal composite to activated carbons). The prepared materials were characterized spectroscopically and morphologically using FT-IR, XRD, SEM/EDX, and TEM analysis. The synthesized absorbent material was used to adsorb two organic dyes (Azocarmine G2; M1, and Methyl violet 2B; M2), and two commercial pesticides (Tiller 480SL; M3, and Acochem 25% WP; M4) from aqueous solution, and it showed promising adsorption efficacy. The minimum adsorbent material’s dosage to obtain a maximum removal efficiency (R%) for M1, M2, M3, and M4 removal from 100 mL solution (100 mg/L) was 0.11, 0.14, 0.13, and 0.12 g, respectively. The max R% for M1 (96.8%) was achieved in the first 45 min, the max R% for M2, 95.5%, was achieved during the first 55 min, and the max R% for M3 (96.4%) was achieved in the first 35 min, while the max R% for M4, 98.6%, was achieved during the first 35 min. Full article

In this work, activated carbon (referred to as MCAC) was produced by microwave radiation assisted ZnCl₂ activation using Malaysian coal (MC) as a precursor. The Brunauer–Emmett–Teller findings indicate that the MCAC has a relatively large surface area (798.18 m²/g) and a mesoporous structure (average pore diameter of 3.67 nm). The removal of Methylene Violet (MV 2B) a cationic dye model, was employed to investigate the adsorption properties of MCAC. A numerical desirability function in the Box–Behnken design (BBD) was employed to optimize the independent crucial adsorption variables as follows: A: MCAC dose (0.02–0.1 g); B: pH (4–10); and C: time (5–25 min). The results of equilibrium and dynamic adsorption showed that the adsorption of MV 2B followed Freundlich and pseudo-second order models, respectively. The maximum amount of MV 2B dye that the MCAC could adsorb (q_max) was 134.1 mg/g. Electrostatic interactions, π-π stacking, H-bonding, and pore diffusion contribute to the adsorption of MV 2B dye onto the MCAC surface. This study demonstrates the potential to utilize MC as a low-cost precursor for the efficient synthesis of MAC and its utility for the removal of pollutants. Full article

The widely used dyes in the pharmaceutical, chemical, and medical industries have brought about an intensive concern for the sustainable development of the environment. Membrane separation offers a versatile method for classified recycling and the reuse of residual components. In this work, polyimide membranes were synthesized via the polymerization of 4,4′-(hexafluor-isopropylidene) diphthalic anhydride and 1,4-bis (4-aminophenoxy) benzene diamine. The organic solvent nanofiltration membrane was prepared by casting onto a glass plate and precipitating in the non-solvent phase. The properties of the membranes were recorded by FTIR, ¹HNMR, TGA, and GPC. The molecular simulations were carried out to analyze the affinity between the membrane and different solvents. The membrane was used in the removal of Rose Bengal, methyl blue, Victoria blue B, and crystal violet from methanol. The effects of the feed liquid concentration, operating pressure, swelling degree, organic solvent resistance, and long-term running on the membrane performance were studied. Results showed that membranes prepared in this work demonstrated high solvent permeation and dye rejection due to the sieving effect and solvent affinity. For methyl blue, the solvent performance achieved a permeability of 2.18 L∙m⁻²∙h⁻¹∙bar⁻¹ corresponding to a rejection ratio of 94.2%. Furthermore, the membrane exhibited good stability over 60 h of continued testing. These results recommend a potential strategy in the development of a suitable monomer to prepare a polyimide membrane for dye separation. Full article

The traditional shirt (“ie”) is the most well-known element of Romanian anonymous textile art. Apart from aesthetic and utilitarian roles, it has strong symbolic significance, mainly through the colours used for decoration. Very recently, the traditional shirt with decoration over the shoulder (“ia cu altiță”) was introduced as a Romanian identity element as part of UNESCO heritage. Depending on the ethnographic area, the traditional shirt with decoration over the shoulder has acquired special expressive particularities over time. Particularly relevant is that from Valea Hârtibaciului, an area of Transylvania in the very centre of Romania. Although sober in appearance with large fields of white plain weave, it is discreetly decorated with elaborated embroidery on the sleeve bracelets, over the shoulders and neck. Even the colour range and decoration motifs remain unchanged in time, evolution in the materials used and a subtle transition from natural hues to more strident alternatives were observed in the late 19th and early 20th centuries. For the present study, samples were taken from representative objects in the collections of the ASTRA Museum, Sibiu and Ethnographical Museum, Brasov, documented as belonging to the area of Valea Hârtibaciului and dated in the museum archives as from the late 19th and early 20th century. The textile materials and the dyes used in the shirts’ embroidery were monitored. Fibre identification was made by optical microscopy and infrared spectroscopy (FTIR-ATR). Dye analysis was performed by liquid chromatography coupled with UV-Vis (diode array) detection, while some of the samples were also analysed by liquid chromatography coupled with mass spectrometric detection (LC-DAD-MS). Dyes were extracted from the fibres by acid hydrolysis. Identification was based on data collected on standards, dyes and dyed fibres. For the early synthetic dyes, a dedicated library of references was built, which includes information relative to the most relevant representatives used between 1850 and 1900, the ‘Helmut Schweppe list’. According to the study, in the last decades of the 19th century, natural dye sources such as dyer’s broom, madder, Mexican cochineal and indigoid dyes were gradually replaced by early synthetic dyes: fuchsine (1856), methyl violet (1861), synthetic alizarin (1871), brilliant green (1879), azo flavine 3R (1880), rhodamine B (1887) and others. Full article

A simple method for organically modifying a natural acid clay (Japanese acid clay) rapidly with alkylamine has been developed. Japanese acid clay mainly consists of acidic montmorillonite and was successfully modified with decylamine in water at room temperature for a short time period (10 min) using an ultrasonic bath without any pretreatments. The structure of the modified clay changed from exterior surface modification to intercalation with an increase in the decylamine content. The equilibrium adsorption capacity for the anionic dye methyl orange (MO) increased with increasing decylamine content. The adsorption kinetics and isotherm were well described by the pseudo-second-order and Langmuir models, respectively. Better MO adsorption was obtained under the conditions of high dosage, low pH value, and low temperature. The adsorbent was also found to have good adsorption for not only MO but also other anionic dyes (Congo red and eosin Y) and cationic dyes (methylene blue, crystal violet, and rhodamine B). In particular, the decylamine-intercalated clay adsorbent exhibited a high level of adsorption capacity for Congo red and crystal violet. The results demonstrate that the synthesis process can provide a simple and cost-effective organoclay as an adsorbent with high performance for the removal of anionic and cationic dyes. Full article

In the framework of the ‘Amorepacific Project for the conservation of Korean pictorial art’ (2018–2023) at the British Museum, three traditional Korean paintings have been investigated with the aim of supporting their conservation and obtaining information about the dyes used in the mounting textiles and other mounting elements. The paintings include a rare example of late 18th-century traditional Korean portraiture (accession number 1996,0329,0.1); a late 19th-century two-panel screen silk painting of Pyeongsaeng-do-Scenes of life (accession number 2016,3028.1); and a late 19th-century twelve-panel screen silk painting representing the Five Confucian virtues (accession number 1957,1214,0.1). The mounting textiles were investigated non-invasively by using digital microscopy and fibre optic reflectance spectroscopy (FORS), and the results guided a minimally invasive sampling campaign. Fourteen samples were analysed by using high-pressure liquid chromatography coupled with diode array and tandem mass spectrometry detectors (HPLC-DAD-MS/MS), leading to the identification of the natural dyes indigo, sappanwood (Biancaea sappan, formerly Caesalpinia sappan), amur cork tree (Phellodendron amurense) and safflower (Carthamus tinctorius) in the mounting elements of the 18th-century portrait. These results confirmed some of the non-invasive observations and were in agreement with the production date of the painting. Both natural and synthetic dyes were identified in the mounting textiles of the panel screens. Among the synthetic dyes, fuchsin (C.I. 42510), methyl violet 3B (C.I. 42536), methyl blue (C.I. 42780) and benzopurpurin 4B (C.I. 23500) were identified. These are early synthetic dyes first synthesised between the 1860s and the 1880s, suggesting that the silk textiles are likely to have been dyed in the last part of the 19th century. Full article

In the current study, CoFe₂O₄ and TiO₂ nanoparticles were primarily made using the sol-gel method, and subsequently, the hybrid magnetic composites of TiO₂ loaded with CoFe₂O₄ (5–15 percent w/w) were made using a hydrothermal procedure. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) were all used to thoroughly characterize the materials. Additionally, the zero-charge point (ZCP) determination, the examination of the pore structure by nitrogen adsorption, and an evaluation of magnetic properties were performed. Six organic dye pollutants were selected to evaluate the performance of the synthesized nanocomposites toward photocatalytic degradation, including methylene blue (MB), methyl orange (MO), crystal violet (CV), acridine orange (AO), rhodamine B (RhB), and rhodamine 6G (R-6G). Photodegradation of tetracycline (TL), a model pharmaceutical pollutant, was also studied under UV and visible light. The composites exhibited a high degradation performance in all cases without using any oxidants. The photocatalytic degradation of tetracycline revealed that the CoFe₂O₄/TiO₂ (5% w/w) composite exhibited a higher photocatalytic activity than either pure TiO₂ or CoFe₂O₄, and thus attained 75.31% and 50.4% degradation efficiency under UV and visible light, respectively. Trapping experiments were conducted to investigate the photodegradation mechanism, which revealed that holes and super oxide radicals were the most active species in the photodegradation process. Finally, due to the inherent magnetic attributes of the composites, their easy removal from the treated solution via a simple magnet became possible. Full article