Search Results (594)

Industrial synthetic dyes are among the most common and hazardous pollutants in manufacturing wastewater. In this study, effective dye-decolorizing fungi were isolated from industrial discharge and evaluated for their decolorization efficiency for various dyes, including a triphenylmethane (malachite green, MG), an anthraquinone (reactive blue 19, RB19), and an azo dye (reactive black 5, RB5). The fungus with the highest potential for MG decolorization was identified as Penicillium rubens, whereas Aspergillus fumigatus proved to be the most effective for RB19 and RB5 decolorization. Maximum decolorization for all dyes occurred at pH 9 and 30 °C after 6–7 days of shaking in the dark. Enzyme activity assays revealed that both P. rubens and A. fumigatus produced multiple oxidative and reductive enzymes, including laccase, azoreductase, anthraquinone reductase, triphenylmethane reductase, lignin peroxidase, manganese peroxidase, and tyrosinase. The decolorized filtrates of MG, RB19, and RB5 exhibited very low phytotoxicity for RB5 and no phytotoxicity for MG and RB19. Furthermore, these filtrates demonstrated significant reductions in chemical oxygen demand (46%, 63%, and 50%) and biological oxygen demand (37%, 60%, and 40%) for MG, RB19, and RB5, respectively, compared to untreated dyes. Given their efficient biological removal of dyes under alkaline conditions, these fungal isolates are promising candidates for sustainable wastewater treatment. Full article

The present study involves the synthesis of polyvinylpyrrolidone (PVP)-stabilized iron-based trimetallic nanoparticles with different metal addition sequences (Fe/Ag/Zn, Fe/Zn/Ag and Fe/(Zn/Ag)) using the sodium borohydride reduction method. In order to investigate the catalytic reactivity of the nanoparticles, a series of batch experiments were performed using methyl orange dye as a model pollutant. It was found that the Fe/Ag/Zn system showed the maximum catalytic activity compared to the other studied trimetallic systems. About 100% of the methyl orange dye was removed within 1 min and the second-order rate constant obtained was 0.0744 (mg/L)⁻¹ min⁻¹; the rate of reaction was higher than that of the other trimetallic systems. Furthermore, the effects of pH, initial dye concentration and nanoparticle dosage on the degradation of methyl orange were investigated. The results showed that the reactivity of the Fe/Ag/Zn trimetallic nanoparticles was highly dependent on the aforementioned parameters. Higher reactivity was obtained at lower pH, lower initial methyl orange dye concentration and higher nanoparticle dosage. Lastly, liquid chromatography–mass spectroscopy (LC-MS) was used to elucidate the reaction pathway and identify by-products from methyl orange degradation. The developed catalyst demonstrated exceptionally rapid and apparent degradation of methyl orange within one minute, outperforming previously reported bimetallic and trimetallic systems. This work reports a cost-effective nZVI-based trimetallic system containing minimal silver, which shows promising reactivity toward azo dye degradation and may be suitable for future application in textile wastewater treatment. Full article

The main emphasis of the current study is to develop an eco-friendly method for producing silver nanoparticles (AgNPs) using an aqueous flower extract from Talipariti tiliaceum L., and to evaluate the photocatalytic degradation of azo dyes. The synthesized AgNPs were characterized using various spectroscopical and microscopical methods. The photocatalytic capacity of AgNPs was assessed through the degradation of methylene blue (MB) and methyl orange (MO) dye under solar irradiation. The results revealed that the AgNPs were spherical in morphology and 4–15 nm in size. The phytochemical analysis showed that the bioactive compounds from the flower extract aided in the reduction of silver ions to nanoparticles. Both visual observations and spectroscopic methods confirmed the photocatalytic degradation of MB and MO dyes. The degradation processes adhered to a pseudo-first-order kinetic model, demonstrating that photocatalytic activity is time-dependent. In addition, the AgNPs demonstrated stability and reusability through four consecutive cycles with little decline in efficiency. This research contributes significantly to sustainable nanotechnology, offering a practical solution for mitigating water pollution caused by industrial dye discharges. Full article

Water pollution from textile effluents poses serious environmental risks, particularly due to persistent anionic dyes such as Reactive Black 5 (RB5). This study demonstrates that simple deposition of Y₂O₃ onto commercially available, biobased TiO₂ (bTiO₂) significantly enhances photocatalytic degradation efficiency under simulated sunlight, suppressing rapid recombination of electron–hole pairs. Addressing a key research gap, the proposed method replaces expensive nanoscale precursors and complex synthesis routes typically used for Y₂O₃/TiO₂ systems with a low-cost, straightforward approach involving weak complexation and co-precipitation. The resulting Y₂O₃-bTiO₂ composite was characterized using FTIR, XRD, SEM, EDX, TEM, XPS, and UV-DRS techniques, confirming efficient incorporation of Y₂O₃ on the TiO₂ surface. Photocatalytic experiments revealed that nanoparticles calcined at 700 °C achieved complete RB5 degradation within 60 min—reducing the reaction time by half compared to undoped bTiO₂. Systematic studies of initial dye concentration, catalyst loading, and irradiation time confirmed that the degradation followed pseudo-first-order kinetics with a rate constant of 0.064 min⁻¹ (R² = 0.98). Calculated quantum yields corroborated the reduced electron–hole recombination induced by Y₂O₃ deposition. These findings highlight the novelty and practicality of the developed Y₂O₃-bTiO₂ photocatalyst as an efficient, affordable, and environmentally sustainable material for the degradation of industrial dyes. Full article

The contamination of water bodies by industrial dyes is a critical environmental challenge due to the toxicity and persistence of these compounds in aquatic ecosystems. This study evaluated the efficiency of Trichoderma koningiopsis immobilized on Luffa cylindrica matrices for the decolorization of the azo dye Direct Black 22 (DB22), proposing a biotechnological approach for wastewater treatment. The fungus was cultivated and immobilized on matrices characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Experiments under different temperature, pH, and initial dye concentration conditions demonstrated that the immobilized system achieved up to 96% decolorization within 24 h under optimized conditions of 50 °C and pH 4, significantly outperforming the free fungus. The Luffa cylindrica matrix provided mechanical stability and a larger contact area for DB22 decolorization. Thus, the immobilized Trichoderma koningiopsis system on Luffa cylindrica stands out as a sustainable, cost-effective, and efficient alternative for dye removal from textile effluents, contributing to safer and more effective environmental practices. Full article

This study systematically investigates the catalytic degradation performance and reaction mechanism of Fe₈₀P₁₃C₇ Metal Glass (MG) in a Fenton-like system for the removal of Methylene Blue (MB). Kinetic experiments on degradation reveal that under acidic conditions (pH = 3), Fe₈₀P₁₃C₇ MG exhibits exceptional catalytic activity, achieving complete degradation of a 50 mg/L MB solution within 12 min. Its degradation rate significantly surpasses that of Fe₇₈Si₉B₁₃ MG and commercially available ZVI powder. Key parameters such as catalyst dosage, H₂O₂ concentration, solution pH, and initial dye concentration were systematically examined to determine the optimal reaction conditions. The characterization results indicate that Fe₈₀P₁₃C₇ MG maintains high activity even after multiple cycles of use, attributed to surface selective corrosion and crack formation during the reaction process. This “self-renewal” mechanism continuously exposes fresh active sites. Mechanistic studies confirm that the degradation process is driven by an efficient redox cycle between Fe²⁺/Fe³⁺ within the material, ensuring sustained and stable generation of •OH, which ultimately leads to the complete mineralization of MB molecules. This research provides solid experimental and theoretical foundations for the application of Fe₈₀P₁₃C₇ MG in dye wastewater treatment. Full article

The textile industry releases effluents containing toxic contaminants such as azo dyes, which severely affect water quality and aquatic ecosystems. This study optimized the Fe⁰/H₂O₂/UV photo-Fenton process through Response Surface Methodology (RSM) using a Box–Behnken design applied to real textile wastewater. The process relies on in situ hydroxyl radicals (•OH) generation, which degrades refractory organic compounds. Under optimal conditions (pH 3.5, 0.5 g Fe⁰, and 0.55 mL H₂O₂), the system achieved complete color removal, 91% aromatic structures degradation, and an 80% COD reduction within 3 h. Statistical validation indicated an excellent model fit (R² = 1.0; Q² = 1.0), with strong correlation between experimental and predicted results. Spectroscopic analyses (UV–Vis and FTIR) further confirmed the cleavage of chromophoric and aromatic structures, indicating efficient pollutant degradation. Overall, the findings indicate that the Fe⁰/H₂O₂/UV system is an effective and sustainable technology for treating textile wastewater, offering strong potential for industrial-scale application. Full article

This study presents a custom-built, portable multispectral imaging (MSI) system integrated with computer vision for sodium nitrite detection via the Griess reaction on paper-based substrates. The MSI system was used to investigate the absorption characteristics of sodium nitrite at concentrations from 0 to 10 ppm across nine spectral bands spanning 360–940 nm on para-aminobenzoic acid (PABA) and sulfanilamide (SA) substrates. Upon forming azo dyes with N-(1-naphthyl) ethylenediamine (NED), the PABA and SA substrates exhibited strong absorption near 545 nm and 540 nm, respectively, as measured by a spectrometer. This agrees with the 550 nm MSI images, in which higher sodium nitrite concentration regions appeared darker due to increased absorption. A concentration-correlation analysis was conducted for each spectral band. The normalized difference index (NDI), constructed from the most and least correlated bands at 550 nm and 940 nm, showed a stronger correlation with sodium nitrite concentration than the single best-performing band for both substrates. The NDI increased the coefficient of determination (R²) by approximately 19.32% for PABA–NED and 19.89% for SA–NED. This improvement was further confirmed under varying illumination conditions and through comparison with a conventional smartphone RGB imaging approach, in which the MSI-based NDI showed substantially superior performance. The enhancement is attributed to improved contrast, illumination normalization by the NDI, and the narrower spectral bands of the MSI compared with RGB imaging. In addition, the NDI framework enabled effective image segmentation, classification, and visualization, improving both interpretability and usability and providing a practical guideline for developing more robust models with larger training datasets. The proposed MSI system offers strong advantages in portability, sub-minute acquisition time, and operational simplicity, enabling rapid, on-site, and non-destructive chemical analysis. Full article

The pervasive discharge of synthetic dyes into aquatic ecosystems poses a significant threat due to their chemical stability, low biodegradability, and carcinogenicity. Conventional dye remediation methods—such as biological treatments, coagulation, and adsorption—have demonstrated limited efficiency and poor reusability, particularly against resilient azo dyes. Cerium oxide (CeO₂) nanoparticles have gained traction as photocatalysts owing to their redox-active surfaces and oxygen storage capabilities; however, issues like particle agglomeration and rapid charge recombination restrict their catalytic performance. To address these challenges, this study presents the novel synthesis of a graphene oxide–cerium oxide (GO-CeO₂) nanocomposite via a facile in situ hydrothermal approach, using graphite from lead pencils as a sustainable precursor. The composite was structurally characterized using UV–visible spectroscopy, XRD, FTIR, and TEM. The GO matrix not only facilitates uniform dispersion of CeO₂ nanoparticles but also enhances interfacial electron mobility and active site availability. The nanocomposite demonstrated exceptional photocatalytic degradation efficiencies for methyl orange (94%), methyl red (98%), congo red (96%), and 4-nitrophenol (85.6%) under sunlight irradiation, with first-order rate constants significantly exceeding those of pure CeO₂. Notably, GO–CeO₂ retained strong catalytic activity over four degradation cycles, confirming its recyclability and structural stability. Total organic carbon (TOC) analysis revealed 79% mineralization of methyl orange, outperforming CeO₂ (45%), indicating near-complete conversion into benign byproducts. This work contributes a scalable, low-cost, and highly active heterogeneous photocatalyst for wastewater treatment, combining green synthesis principles with improved photodegradation kinetics. Its modular architecture and reusability make it a promising candidate for future environmental remediation technologies and integrated photocatalytic systems. Full article

Ensuring food safety and quality has become increasingly critical due to the complexities introduced by globalization, industrialization, and extended supply chains. Traditional analytical methods for food quality control, such as chromatography and mass spectrometry, while accurate, face limitations including high costs, lengthy analysis times, and limited suitability for on-site rapid monitoring. Electrochemical sensors integrated with molecularly imprinted polymers (MIPs) have emerged as promising alternatives, combining high selectivity and sensitivity with portability and affordability. MIPs, often termed ‘plastic antibodies,’ are synthetic receptors capable of selective molecular recognition, tailored specifically for target analytes. This review comprehensively discusses recent advancements in MIP-based electrochemical sensing platforms, highlighting their applications in detecting various food quality markers. It particularly emphasizes the detection of antioxidants—both natural (e.g., vitamins, phenolics) and synthetic (e.g., BHA, TBHQ), artificial sweeteners (e.g., aspartame, acesulfame-K), colorants (e.g., azo dyes, anthocyanins), traditional contaminants (e.g., pesticides, heavy metals), and toxicants such as mycotoxins (e.g., aflatoxins, ochratoxins). The synthesis methods, including bulk, precipitation, surface imprinting, sol–gel polymerization, and electropolymerization (EP), are critically evaluated for their effectiveness in creating highly selective binding sites. Furthermore, the integration of advanced nanomaterials, such as graphene, carbon nanotubes, and metallic nanoparticles, into these platforms to enhance sensitivity, selectivity, and stability is examined. Practical challenges, including sensor reusability, regeneration strategies, and adaptability to complex food matrices, are addressed. Finally, the review provides an outlook on future developments and practical considerations necessary to transition these innovative MIP electrochemical sensors from laboratory research to widespread adoption in industry and regulatory settings, ultimately ensuring comprehensive food safety and consumer protection. Full article

Eugenol, a natural product abundant in clove oil, represents a promising precursor for the synthesis of azo dyes, proving potential for textile coloration. The eugenol azo dyes were synthesized and characterized, showing stable absorption profiles across a wide pH range. Their application to cotton and wool knitted fabrics by exhaustion dyeing demonstrated good affinity, particularly for wool, while chitosan pretreatment improved washing fastness in cotton. These eugenol-derived azo dyes emerge as promising candidates for sustainable textile coloration. Full article

Textile dyeing wastewater, rich in recalcitrant organic compounds such as azo and anthraquinone dyes, poses significant environmental concerns. This study investigates the degradation of methyl orange (MO) using two ozone (O₃) oxidation systems—O₃/H₂O₂ and O₃/K₂S₂O₈—and analyzes the degradation products and toxicity via ESR characterization. The O₃/K₂S₂O₈ system shows a higher removal rate in the initial stage (<4 min) due to rapid ·SO₄^- radical generation. However, O₃/H₂O₂ produces more ·OH radicals, leading to better overall degradation performance. The O₃/K₂S₂O₈ system is more effective for pollutants with electron-rich groups, such as Congo red and sulfamethoxazole, while O₃/H₂O₂ performs better in natural lake water. Mechanistic studies reveal that ·O₂^- is the dominant oxidizing species in O₃/H₂O₂, while ·SO₄^- and ·O₂^- dominate in O₃/K₂S₂O₈. The toxicity of degradation products is assessed, showing lower bioaccumulation and developmental toxicity in most intermediate products compared to MO. This research provides valuable insights into the use of combined ozonation-peroxidation coupling technology for effective wastewater treatment. Full article

The ability of ultrasound/peracetic acid (US/PAA) to degrade the azo dye Sunset Yellow FCF (SSY) was evaluated considering the impacts of power, pH, inorganic carbon, common salts, radical scavengers, and real water matrices. Pseudo-first-order rate constants revealed synergy indices of 2.90, 3.28, 2.22, and 2.03 at electrical powers of 40, 60, 80, and 100 W, respectively. Selective scavenger assays revealed a mixed radical regime. ^•OH radical involvement was confirmed by inhibition with alcohols (tert-butanol, 2-propanol), benzoic acid, nitrobenzene, sodium azide, and phenol, while suppression by TEMPO highlighted the key role of PAA-derived acyl and peroxyl radicals. Nitrobenzene caused pronounced inhibition at elevated doses, while nitrite acted as a decisive quencher by converting ^•OH and other oxidants into less reactive species. Carbonate alkalinity exerted dual effects: at acidic pH (3.7–4.4) it diverted ^•OH radicals to carbonate radicals and reduced cavitation through dissolved CO₂, whereas at near-neutral pH it buffered conditions toward the optimum (pH 9) and enhanced degradation. Common anions (chloride, sulfate, nitrate) at ≤10 mM produced minor effects. Tests in environmental waters revealed the following reactivity order: seawater > ultrapure water > tap water ≈ Zamzam water > tertiary effluent. Enhanced performance in seawater was attributed to halide-mediated formation of reactive chlorine and bromine species, while inhibition in effluent was linked to organic matter scavenging. Overall, US/PAA emerges as a robust and adaptable advanced oxidation process for azo dye abatement across diverse water matrices. Full article

The photoinitiation properties of two porphyrins were evaluated for the free-radical photopolymerization (FRP) of a bio-based acrylated monomer, i.e., soybean oil acrylate (SOA). Their combination with various co-initiators, such as a tertiary amine as electron donor (MDEA), an iodonium salt as electron acceptor (Iod), as well as two biosourced co-initiators used as H-donors (cysteamine and N-acetylcysteine), makes them highly efficient photoinitiating systems for FRP under visible light irradiation. Electron paramagnetic resonance spin trapping (EPR ST) demonstrated the formation of highly reactive radical species, and fluorescence and laser flash photolysis highlighted the chemical pathways followed by the porphyrin-based systems under light irradiation. High acrylate conversions up to 96% were obtained with these different systems at different irradiation wavelengths (LEDs@385 nm, 405 nm, 455 nm, and 530 nm), in laminate or under air. The final crosslinked and bio-based porphyrin-based materials were used for the full photo-oxidation in water of an azo-dye (acid red 14) and under UV irradiation. These materials have been involved in three successive depollution cycles without any reduction in their efficiency. Full article

Azo dyes are widely used in the textile industry due to their vibrant colors and chemical stability; however, wastewater containing these dyes poses significant environmental and health risks due to their toxic, persistent, and potentially carcinogenic properties. In this study, the treatment of wastewater containing trypan blue dye was investigated using the electrooxidation process with boron-doped diamond electrodes, and the efficiency of the process was modeled through the Extreme Gradient Boosting (XGBoost) algorithm. In the experimental phase, the effects of key operational parameters, including current density, pH, electrolysis time, and supporting electrolyte concentration, on TB dye removal efficiency were systematically evaluated. Based on the experimental data obtained, a machine learning-based XGBoost prediction model was developed, and hyperparameter optimization was performed to enhance its predictive performance. The model achieved high accuracy (R² = 0.996 for training and 0.954 for testing) and yielded low error metrics (RMSE and MAE), confirming its reliability in predicting removal efficiency. This study presents an integrated and data-driven approach for improving the efficiency and sustainability of electrooxidation processes and offers an environmentally friendly and effective method for the treatment of azo dye-contaminated wastewater. Full article