Search Results (2,313)

The massive discharge of methylene blue causes severe water pollution, and the development of efficient and stable heterogeneous Fenton catalysts is crucial for wastewater treatment. To address the shortcomings of traditional iron-based amorphous catalysts, such as low activity and poor stability, this study employed Fe₈₀Si₆B₁₀Cu₁Nb₃ five-component amorphous alloy as the catalyst to investigate its catalytic degradation performance, cyclic stability, and catalytic mechanism for MB. Batch experiments, SEM, XRD characterization, and kinetic fitting were combined to carry out the research. The results showed that under the optimal conditions (25 °C, pH = 3, H₂O₂ concentration of 5 mM, catalyst dosage of 0.5 g/L), the catalyst could completely degrade methylene blue within 9 min with a reaction rate constant k_obs of 0.44 min⁻¹, and the degradation efficiency showed no obvious attenuation after 20 consecutive cyclic degradation runs. After degradation, slight selective corrosion occurred on the catalyst surface, while the amorphous structure of the matrix remained stable. This study confirms that the Cu/Nb dual synergy improves the catalytic performance and stability, clarifies the relevant catalytic mechanism, and provides theoretical and technical support for the design of high-performance iron-based amorphous catalysts and the treatment of dye-containing wastewater. Full article

Ternary heterojunction photocatalysts enhance the separation and transport of photogenerated charge carriers, thereby boosting their redox activity for use in environmental and sustainable energy applications. This study focuses on the synthesis of a TiO₂/Bi₂O₃/g-C₃N₄ heterojunction composite via a ceramic method with TiO₂ loadings of 80%, 85%, and 90% (denoted 80T-BC, 85T-BC, and 90T-BC, respectively) to investigate structure–property–performance relationships in photocatalytic dye degradation. The structural, optical, and morphological properties of the synthesised materials were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance UV–Vis spectroscopy (DRS). The photocatalytic performance was evaluated by measuring the degradation of Rhodamine B under visible light irradiation. Under optimised conditions (pH 6, initial RhB concentration of 5 mg/L, and a reaction time of 120 min), a degradation rate of 99% was achieved. Furthermore, the semiconductor demonstrated significant antibacterial activity against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. This study presents a promising strategy for modifying TiO₂-based semiconductors by incorporating different metal oxides. The formation of the resulting heterojunction significantly enhances photocatalytic efficiency, demonstrating strong potential for practical environmental remediation. Full article

In this research work, Ag-doped and undoped TiO₂ nanocomposites were prepared through a sol–gel method, using diethanolamine as a solvent. From the evolution of various characterized techniques (XRD, FT-IR, SEM and TGA analysis), it was found that Ag-TiO₂ nanocomposites have a mixture of rutile and anatase phases of titania. The catalytic performance of the Ag-TiO₂ nanocomposites was evaluated for Eriochrome Black T (EBT) photodegradation. To determine the photocatalytic efficiency of the nanocomposites, different factors including pH (2–12), catalytic dose (2–12 mg), reaction time (0–180 min) and concentration (2–10 mg/L) were investigated. The calcined Ag-TiO₂ showed high degradation (94%) for EBT at a low pH for 0.01 g of catalyst using 10 mg/L of dye solution. The kinetic study revealed that the photocatalytic degradation process obeys pseudo second-order kinetics. To investigate antibacterial effects, different bacteria such as Enterococcous, Staph Avrius, serritia and Escherichia E. coli were utilized. A total of 200 mg of calcined Ag-TiO₂ nanocomposite showed optimum activities against bacterial strains. Full article

This study presents the rational design of a visible-light-responsive TiO₂/polyaniline (PANI) nanofiber heterostructure via in situ oxidative polymerization to overcome the limited visible-light absorption and rapid charge recombination of TiO₂. Comprehensive characterization using XRD, FT-IR, XPS, SEM, UV–Vis DRS, and EIS confirmed the successful integration of TiO₂ nanoparticles within a conductive polyaniline nanofiber network, enabling efficient interfacial charge transfer. The optimized TiO₂/PANI-30 composite exhibited outstanding photocatalytic performance, achieving ~99% degradation of Basic Fuchsin dye within 40 min under visible light, significantly outperforming pristine TiO₂. The enhanced activity is attributed to improved visible-light absorption, reduced bandgap energy, and suppressed electron–hole recombination, supported by optical and electrochemical analyses. Kinetic studies indicated pseudo-first-order behavior, with TiO₂/PANI-30 showing the highest rate constant. Radical trapping experiments identified superoxide and hydroxyl radicals as the main active species, with •OH playing a dominant role. A direct Z-scheme charge transfer mechanism was suggested, preserving strong redox potentials and promoting reactive oxygen species generation. Additionally, the photocatalyst demonstrated excellent stability and reusability. These findings highlight the suggested potential of TiO₂/PANI systems as efficient and sustainable photocatalysts for wastewater treatment. Full article

The discharge of metal-complex dyes from textile industries poses significant environmental challenges due to their chemical stability and resistance to conventional biological treatment. This study examined the degradation of Acid Black 194 (AB–194), a 1:2 chromium-complex azo dye, using Co²⁺-activated peroxymonosulfate (PMS). A central composite design based on response surface methodology was used to evaluate the effects of Co²⁺ (5.93–20.07 µM), PMS (1.67–7.33 mM), and dye (13.79–56.21 mg L⁻¹) concentrations on decolorization and mineralization. The polynomial models demonstrated strong predictive accuracy (R² > 0.9896), identifying Co²⁺ and dye concentrations as the most influential factors. Under optimal conditions (18.0 µM Co²⁺, 6.5 mM PMS, 20.0 mg L⁻¹ dye), 99.19% decolorization was achieved at 30 min and 41.43% TOC removal at 240 min. Degradation kinetics were described by a mechanistic model incorporating 15 elementary reactions that comprise the Co²⁺/Co³⁺ redox cycle, radical generation, and dye oxidation, yielding a global R² of 0.9617. Estimated rate constants for dye oxidation (k₁₄ = 3.52 × 10⁹ M^–1 s^–1 for and k₁₅ = 2.00 × 10¹⁰ M^–1 s^–1 ) were consistent with values reported for aromatic compounds in sulfate radical systems. Radical contribution analysis confirmed sulfate radicals as the principal oxidizing species, accounting for 96.75% of the overall process. Full article

The adsorption and desorption behavior of the azo dye Orange II (OII) was investigated using composite beads prepared from shrimp shell–derived chitosan (50 wt%) and montmorillonite-rich clay. The structural and morphological properties of the synthesized beads were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and FT-IR (Fourier Transform Infrared Spectroscopy). Batch adsorption experiments were performed to evaluate the removal efficiency of OII from aqueous solutions under various conditions, revealing that a low adsorbent dosage (0.5 g L⁻¹) and an acidic medium (pH 4) provided optimal adsorption performance. Adsorption kinetics and equilibrium isotherms were analyzed to elucidate the adsorption mechanism. Thermodynamic parameters indicated that the adsorption process was spontaneous (ΔG° < 0) and endothermic (ΔH° > 0). Equilibrium data were fitted to both Langmuir and Freundlich isotherm models, with the Freundlich model providing the best correlation (R² = 0.99), suggesting multilayer adsorption on a heterogeneous surface. The adsorption capacity increased significantly with temperature, rising from 98.35 mg g⁻¹ at 298 K to 182.57 mg g⁻¹ at 318 K, further confirming the endothermic nature of the process. Kinetic analysis revealed relatively rapid adsorption, with maximum adsorption capacities increasing from approximately 100 mg g⁻¹ at 25 °C to 123 mg g⁻¹ at 45 °C. Regeneration and reusability tests demonstrated that the composite beads could be reused through adsorption–desorption cycles; however, a gradual decline in removal efficiency was observed, decreasing from 97% in the first cycle to 25% after the fifth cycle. This decrease is likely associated with partial structural degradation or the detachment of bead components during repeated regeneration. Overall, the results highlight the potential of chitosan–clay composite beads as promising and sustainable adsorbents for the removal of azo dyes from aqueous media. Full article

Actual printing and dyeing wastewater (APDW), as one of the most difficult types of wastewater to treat, has become a significant environmental risk due to its toxicity and the challenges associated with its degradation. Microalgae-based treatment of APDW is a promising, eco-friendly, and cost-effective strategy. In this study, a cyanobacterium, Synechocystis aquatilis, was isolated from APDW. The strain demonstrated good environmental tolerance and the capacity to remove pollutants and valorize biomass simultaneously. Under optimized conditions, it removed COD (120.27 mg·L⁻¹·d⁻¹), NH₄-N (0.89 mg·L⁻¹·d⁻¹), and total phosphorus (9.52 mg·L⁻¹·d⁻¹), while achieving substantial decolorization. The strain concurrently accumulated lipids (373.08 mg/g), polysaccharides (167.85 mg/g), and proteins (72.05 mg/g). Mechanistic analyses revealed that S. aquatilis microalgae adsorb dyes and impurities via bioadsorption and then biodegrade dyes and nitrogen and phosphorus compounds via NADPH generation, glutamate and butyrate metabolism, and oxidoreductase activity. This study presents a promising application of S. aquatilis as a novel and environmentally friendly treatment method for APDW, enabling simultaneous wastewater treatment and resource recovery. Full article

As anodized aluminum components are increasingly deployed in high-power optical and precision industrial systems operating in non-vacuum environments, their outgassing behavior has emerged as a critical material reliability concern. In contamination-sensitive optical assemblies, released volatiles can accumulate on nearby surfaces, leading to haze formation, scattering, and progressive optical degradation. The porous anodic oxide layer retains water, hydrogen, dyes, and processing residues that are released under thermal, photonic, and environmental stresses typical of industrial operation. While most qualification data remain vacuum-centric, equivalent evaluation frameworks for ambient environments are limited. This review analyzes surface-driven desorption mechanisms relevant to non-vacuum systems and provides practical guidance for material and process engineers by evaluating mitigation strategies across the anodizing process chain, including fine-grain substrate selection, controlled anodizing with nickel acetate sealing, post-bake stabilization, and alternative dense coatings such as electroless nickel, sol–gel films, and Acktar. The analysis underscores the need for non-vacuum-specific qualification standards to support reliable material selection and long-term system performance. Full article

Hexagonal boron nitride (h-BN) is a chemically stable two-dimensional material whose wide band gap and low surface reactivity limit its performance in adsorption and photocatalysis, motivating strategies to tailor its structure. In this work, a mechanochemical approach combining high-energy ball milling with NaOH-assisted treatment was used to induce simultaneous exfoliation and hydroxylation of h-BN, promoting defect generation, reduced crystallinity, interlayer expansion, and incorporation of oxygen-containing groups (B-OH and B-O). These modifications led to band gap narrowing, increased surface polarity, and improved dispersion, enabling the formation of heterogeneous active sites. The hydroxylated material (BN-OH) exhibited high adsorption capacities of 248 mg/g for methylene blue (MB) and 215 mg/g for rhodamine 6G (R6G), following Freundlich behavior, indicative of heterogeneous adsorption governed by electrostatic interactions, π–π stacking, hydrogen bonding, and defect-mediated sites. Under solar irradiation, BN-OH achieved up to 99% degradation of both dyes, following predominantly pseudo-first-order kinetics and outperforming pristine BN; additionally, the kinetic behavior under solar conditions was successfully described using the Behnajady–Modirshahla–Ghanbary (BMG) model, which accurately predicts the two-stage degradation process. Scavenger experiments revealed that ⦁OH radicals dominate MB degradation, while ⦁OH, O₂⦁⁻, and h⁺ contribute to R6G removal. Overall, defect engineering and hydroxyl functionalization synergistically enhance photocatalytic performance, providing a scalable strategy for wastewater treatment. Full article

The textile industry has contributed significantly to global microplastic pollution, generating both primary and secondary microplastics. Primary microplastics, released during the manufacturing process of textiles, are the main concern due to their long-chain structure and persistence, while secondary microplastics are generated from the degradation of synthetic or blended textile products, which have already been in service or use. This review provides a comprehensive overview of methods for investigating fibrous primary microplastics generated throughout the major stages of the textile value chain, including yarn production, fabric manufacturing, garment processing, finishing, and packaging. In fact, there is an urgent need to deal with fibrous primary microplastics, as they are particularly hazardous due to their form (thin, long and often needle-like) and long-lasting life (can sustain in the environment over hundreds of years). Each manufacturing stage produces measurable microfiber losses. For example, pre-consumer production emits approximately 0.12 million metric tons of microplastics per year. High-speed yarn spinning releases additional MP (microplastics); rotor-spun polyester yarns shed 2000–8000 MFPs/g (microplastic fibers/g). The mechanical stresses such as friction, abrasion, and yarn breakage during weaving and knitting operations contribute significantly up to 10⁴–10⁶ microfibers per m² of fabric during production. Wet processing (dyeing, printing, and finishing) is another major hotspot for primary microplastic generation, with dye house effluents reporting up to 54,100 microfibers per liter. Moreover, during mechanical and chemical finishing operations, the generated nanoplastics (NPs) rose significantly, exceeding 10¹¹ particles per gram of material. Subsequently, the garments manufacturing units are estimated to produce 10,000 garments per day (5 tons of fabric), which equates to 5–25 kg/day of microplastic fiber waste. Targeted schemes for the study of primary microplastics at the earliest stages of textile production could significantly reduce environmental release and strengthen progress toward a more circular and sustainable textile economy. Full article

This work presents a novel one-step plasma–solution synthesis of Prussian Blue (PB) and copper hexacyanoferrate (Cu-PBA) nanoparticles via underwater pulsed DC discharge. For the first time, the direct plasma-assisted formation of these coordination polymers is reported. The obtained materials were examined by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy (SEM). These analyses confirmed that the desired phases had formed, along with small amounts of oxide byproducts (α-Fe₂O₃, CuO) arising from the erosion of the electrodes. Photocatalytic activity was evaluated through the degradation of organic dyes (Reactive Red 6C, Rhodamine B, and Methylene Blue) under UV-light irradiation. Both catalysts achieved complete dye degradation within 90 min of UV irradiation (after an initial 30 min dark adsorption step, total experiment time 120 min). Notably, selective performance was observed: PB exhibited higher activity toward the cationic dye Methylene Blue, while Cu-PBA was more effective for the anionic dye Reactive Red 6C. This selectivity is attributed to the specific oxide impurities forming heterojunctions that facilitate charge separation and generate distinct reactive oxygen species. The plasma–liquid method offers a rapid and environmentally benign route to functional PBA-based composites, with potentially scalable characteristics pending further engineering optimization. These findings highlight the potential of utilizing synthesis-induced impurities to tailor photocatalytic selectivity for water purification applications. Full article

This study addresses the need for sustainable approaches in textile wastewater treatment by investigating laccase production with the white-rot fungus Schizophyllum commune TMF3 using agro-industrial waste as a substrate. Laccase was produced via solid-state fermentation on brewery spent grain under optimized conditions (1.75 g malt extract, 75% moisture, 7 days, 25 °C), reaching a maximum activity of 21.06 IU/g dry substrate. The crude enzyme was applied for the decolorization of azo and triphenylmethane dyes (50 mg/L). Decolorization efficiencies above 80% were achieved within 60 min without redox mediators, while chemical oxygen demand (COD) was reduced by more than 50% for all tested dyes. HPLC analysis showed parent dye peaks decreasing and the transformation products’ appearance. Antimicrobial activity testing showed no increase in inhibitory effects against Escherichia coli, Lactobacillus rhamnosus, Candida albicans, and Saccharomyces cerevisiae, while slight growth stimulation was observed in selected cases. Phytotoxicity assays using Triticum aestivum showed no inhibitory effects, with germination index values of 77–124%. Cytotoxicity assessment showed no effects for azo dyes, while cytotoxicity of the triphenylmethane dye decreased by 30% after treatment. These findings support the potential of agro-industrial laccase production as an effective approach for dye removal in sustainable wastewater strategies. Full article

Cyclic pollutants such as dyes, antibiotics, phenols and VOCs in water and atmosphere feature stable structures and are difficult to mineralize, which constitutes the core problem in current environmental governance. Semiconductor photocatalysis provides a green strategy for the advanced treatment of such pollutants. Electrospun black TiO₂/Ag-loaded SiO₂ nanofiber membranes have become a research hotspot owing to their multi-component synergistic advantages. This paper systematically reviews the preparation processes and structure regulation methods of electrospun SiO₂ nanofiber membranes; expounds the loading strategies of black TiO₂ and Ag nanoparticles, the interface regulation mechanisms and the synergistic photocatalytic mechanism of the ternary composite system; summarizes the application progress in the degradation of cyclic pollutants in water and atmospheric VOCs; and emphatically analyzes the performance characteristics and key issues in the ring-opening degradation of cyclic pollutants. Studies show that the high specific surface area and porous structure of SiO₂ nanofiber membranes offer excellent support for catalytic reactions. In addition, black TiO₂ achieves a full-spectrum response through defect engineering; the SPR effect and Schottky barrier of Ag significantly improve carrier separation efficiency; and the synergistic effect of the three components enhances the adsorption–catalytic degradation capacity. Current challenges remain in ring-opening efficiency and stability, requiring multi-method breakthroughs to overcome bottlenecks, clarify mechanisms and promote engineering applications. This paper provides theoretical references for the development of high-performance fiber-based photocatalytic materials and lays a foundation for the practical application of electrospun inorganic nanofiber membranes in the field of environmental catalysis. Full article

Acid Black 1 (AB1), a recalcitrant disazo dye from the textile industry, poses a severe threat to aquatic ecosystems owing to its resistance to biological treatment. Although ferrate(VI) (${\mathrm{K}}_2\mathrm{Fe}{\mathrm{O}}_4)$ and plasma-based advanced oxidation processes have shown promise for dye remediation, the effect of treatment sequence on synergistic mineralization remains largely unaddressed. Nano-ferrate(VI) (nano-Fe(VI), ${\mathrm{K}}_2\mathrm{Fe}{\mathrm{O}}_4$) synthesized via the Solution Plasma Process (SPP) was integrated with Gliding Arc Plasma (GAP) in a sequential hybrid system, with nanoscale morphology and ${\mathrm{K}}_2\mathrm{F}\mathrm{e}{\mathrm{O}}_4$ composition confirmed by FE-SEM and EDS. pH, molar ratio, and temperature were systematically optimized for the standalone nano-Fe(VI) process, and synergistic performance was evaluated via Synergy Effect Factor (SEF) analysis. Optimization identified pH 7.0, [AB1]:[Fe(VI)] = 1:0.9, and 45 °C as optimal, achieving 90.24% decolorization within 12 min. The sequential nano-Fe(VI)–GAP configuration achieved the highest mineralization efficiency of 58.7%, outperforming standalone nano-Fe(VI) (36.0%), standalone GAP (16.0%), and simultaneous application (37.8%), with SEF values of 1.3 and 1.2 for mineralization and decolorization. This is the first study to quantify treatment sequence effects in a nano-Fe(VI)–GAP system via SEF analysis. The proposed system eliminates intermediate pH adjustment while achieving superior mineralization, offering a practical AOP framework for refractory textile wastewater treatment. Full article

The SnO₂-TiO₂ binary nanocomposites’ metal oxide was synthesized by a co-precipitation method and potentially utilized for wastewater treatment applications. The average crystallite size, dislocation density, and micro strain of the synthesized nanocomposites were calculated by the Debye–Scherrer, modified Debye–Scherrer, and W–H methods. The nanocomposites exhibit a tetragonal crystal structure with 62% crystallinity. The presence of Ti–O–Ti and Sn–O–Sn bonds was identified using the FTIR technique. The surface morphology was examined during SEM and EDAX analyses. The optical properties were interpreted with the help of UV–Vis and PL spectroscopy, and the bandgap energy was ascertained. From the CV and EIS studies, the behavior of the diffusive and capacitive natures was determined. Photocatalytic studies were carried out under sunlight and UV light by degrading (cationic) malachite dye at concentrations of 10, 20, and 40 mg/L. When analyzed with seven kinetic models, it was inferred that a pseudo-second and first-order were followed under visible and UV light. The maximum degradation efficiency of 94% was achieved for the 20 mg/L dye concentration within 50 min under UV and 150 min under solar irradiation. Complete decolorization was observed for both 10 mg/L and 20 mg/L dye concentrations under both irradiations. Full article