Search Results (383)

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

To address the challenge of treating refractory organic dyes in textile wastewater, this study synthesized a novel copper-based composite material (designated MEL-Cu-6HNA) via a supramolecular self-assembly–pyrolysis pathway. Its core component consists of CuO/Cu₂O(SO₄), which was applied to efficiently degrade the Reactive Red 3BS dye within a sodium bicarbonate-activated hydrogen peroxide (BAP) system. This material was applied to degrade the Reactive Red 3BS dye using a sodium bicarbonate-activated hydrogen peroxide system. The morphology, crystal structure, and surface chemistry of the material were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Electron paramagnetic resonance (EPR) was employed to identify reactive species generated during the reaction. The effects of dye concentration, H₂O₂ concentration, MEL-Cu-6HNA dosage, and coexisting substances in water on degradation efficiency were systematically investigated, with active species identified via EPR. This study marks the first application of the supramolecular self-assembled CuO/Cu₂O(SO₄)₂ composite material MEL-Cu-6HNA, prepared via pyrolysis, in a sodium bicarbonate-activated hydrogen peroxide system. It achieved rapid and efficient decolorization of the recalcitrant Reactive Red 3BS dye. The three-dimensional sulfate framework and dual Cu²⁺ sites of the material significantly enhanced the degradation efficiency. MEL-Cu-6HNA achieved rapid and efficient decolorization of the recalcitrant Reactive Red 3BS in a sodium bicarbonate-activated hydrogen peroxide system. The material’s three-dimensional sulfate framework and dual Cu²⁺ sites significantly enhanced interfacial electron transfer and Cu²⁺/Cu⁺ cycling activation capacity. ·OH served as the primary reactive oxygen species (ROS), with SO₄²⁻, ¹O₂, and ·O₂⁻ contributing to sustained radical generation. This system achieved 95% decolorization within 30 min, demonstrating outstanding green treatment potential and providing a reliable theoretical basis and practical pathway for efficient, low-energy treatment of dyeing wastewater. Full article

The Electro-Fenton (EF) process is a promising technology for the sustainable remediation of organic contaminants in complex wastewater. In this study, a weak magnetic field (~150 G) was applied to enhance the performance of an EF system using magnetite (Fe₃O₄) synthesized by a controlled co-precipitation route as a recyclable solid iron source. The magnetite was characterized by FTIR, SEM/EDS, and XPS, confirming the coexistence of Fe²⁺/Fe³⁺ species essential for in situ Fenton-like reactions. Under the selected operating conditions (90 min reaction time), magnetic-field assistance improved methylene blue decolorization from 14.2% to 46.0% at pH 3. FeSO₄ was used only as a homogeneous benchmark, whereas the magnetite-based system operated without soluble iron addition, minimizing sludge formation and secondary contamination. These results demonstrate the potential of magnetite-assisted and magnetically enhanced EF systems as a low-cost, sustainable alternative for the treatment of dye-containing industrial wastewater and other complex effluents. Full article

The textile industry widely uses reactive anthraquinone dyes, which exhibit strong resistance to color removal and generate substantial volumes of wastewater containing significant quantities of residual dye requiring treatment prior to discharge. As part of a study aimed at reusing rather than discharging spent reactive anthraquinone dyebaths, Reactive Blue 4 (RB4) dye was used in dyeing cotton, and the generated spent dyebaths were biologically decolorized using a fluidized bed reactor (FBR) operated under hypersaline conditions at a salt concentration of 100 g NaCl/L, which is typically found in commercial spent reactive dyebaths. Across five consecutive runs, the FBR achieved a mean decolorization efficiency of 91.2 ± 2.8% within a 6 h incubation period. The quality of cotton dyed with the treated and reused spent dyebaths was evaluated through shade reproducibility and color consistency assessments. Five repetitive dyeings using the biologically decolorized dyebaths showed that the ΔE_cmc fabric color difference values were 0.58~0.80, which were lower than the industry-accepted value of 1.0. This study demonstrates that biologically decolorized spent dyebaths can be effectively reused, offering substantial reductions in water and salt consumption and improving the economic and environmental sustainability of the reactive dyeing process. 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 investigates the performance of an electrooxidation (EO) process employing Sb₂O₅-doped RuO₂–ZrO₂|Ti anodes integrated into a concave-cover solar still for the degradation of Allura Red dye in aqueous solution and real river water. The anode was synthesized and characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD) to confirm its porous morphology and crystalline structure. Operational parameters—including supporting electrolyte concentration, initial solution pH, and current density—were systematically optimized. Under optimal conditions (pH 2–3 and 5 mA cm⁻²), the EO process was evaluated under natural solar irradiation. Sunlight exposure increased the solution temperature from approximately 20 °C to 50 °C, enhancing molecular diffusion and mass transport, thereby accelerating decolorization kinetics. Compared to EO performed under laboratory conditions, the solar-assisted system achieved an additional 20% increase in chemical oxygen demand (COD) removal and a fast reduction in color. When applied to real Lerma River water samples under these optimal conditions, the treatment achieved approximately 50% reduction in both COD and true color, demonstrating its applicability to complex environmental matrices. These results confirm that coupling electrooxidation with solar thermal input significantly improves pollutant degradation efficiency and energy performance, establishing this integrated approach as a promising and sustainable technology for advanced wastewater treatment. Full article

In this study, three benign oxidants, potassium ferrate (Fe(VI)), sodium persulfate (PS), and sodium percarbonate (SPC), were combined with nonthermal plasma (NTP) to enhance the degradation of Malachite Green (MG) and Metanil Yellow (MY). Experimental factors, including dye concentration, oxidant dose, and treatment time, were optimized using Response Surface Methodology (RSM). The hybrid systems achieved markedly improved decolorization rates, with maximum efficiencies exceeding 99% within 30 min, compared to 96% for NTP alone. Kinetic analysis confirmed significantly higher rate constants for NTP-assisted oxidants, particularly NTP + Fe (VI) (k_obs = 0.127 min⁻¹), followed by NTP + PS (0.114 min⁻¹) and NTP + SPC (0.098 min⁻¹). Enhanced mineralization, together with stable pH and controlled conductivity variations, further substantiated the efficient breakdown of the dye molecules. Phytotoxicity assays demonstrated that untreated dyes severely inhibited germination. In contrast, effluents treated with NTP + PS and NTP + Fe (VI) restored germination and root growth to levels comparable to the deionized water (DIW) control, indicating substantial toxicity reduction. These results confirm that NTP-oxidants significantly improve oxidation performance, accelerate reaction kinetics, and yield environmentally safe effluents suitable for practical wastewater remediation. Full article

This study presents a bibliometric review of scientific progress concerning the synergy between microbial fuel cells (MFCs) and textile dye remediation. Drawing from the Scopus database, the analysis spans the years 2005–2025 and applies systematic filters to derive a final corpus of 239 articles compatible with Bibliometrix software (4.2.1). Quantitative and structural analyses were conducted using RStudio with the Bibliometrix package, thematic network visualizations via VOSviewer (1.6.19), and frequency matrices, citation rates, and international collaboration indicators organized in Excel. Results reveal exponential growth in scholarly output, particularly within Environmental Sciences, Chemical Engineering, and Microbiology. China and India lead in publication volume, while countries such as the United Kingdom, United States, and Australia show high impact and international collaboration. Co-authorship networks reflect consolidated clusters, though connectivity gaps remain among emerging authors. Bioresource Technology is identified as a central journal, with terms like “wastewater treatment” and “microbial fuel cell” indicating thematic consolidation. Opportunities still exist in areas such as explainable artificial intelligence, integration with microalgae, and heavy metal remediation. Highly cited articles contribute key technical insights, highlighting hybrid configurations and advancements in electrode materials. Strategic mapping suggests that MFCs have evolved from experimental concepts to viable alternatives in industrial sustainability, though scalability, operational costs, and geographic representation remain significant challenges. This bibliometric review not only maps accumulated knowledge but also serves as a strategic compass for guiding future research toward integrated, accessible, and replicable bioelectrochemical technologies for textile dye treatment. Full article

Non-thermal plasma (NTP) is a fast, reagent-free technology for dye removal, yet its performance is highly dependent on the operating conditions and on plasma–catalyst interactions. In this work, a coaxial falling-film dielectric barrier discharge (DBD) reactor was optimized for the degradation and decolorization of organic dyes, with ceria (CeO₂) employed as a catalyst. For the first time, CeO₂ prepared via a supercritical antisolvent (SAS) micronization route was tested in plasma-assisted dye decolorization and directly compared with its non-micronized counterpart. Optimization of plasma parameters revealed that oxygen feeding, an input voltage of 12 kV, a gas flow of 0.2 NL·min⁻¹, and an initial dye concentration of 20 mg·L⁻¹ resulted in the fastest decolorization kinetics. While the anionic dye Acid Yellow 36 exhibited electrostatic repulsion and negligible plasma–ceria synergy, the cationic dyes Crystal Violet and Methylene Blue showed strong adsorption on the negatively charged CeO₂ surface and pronounced plasma–catalyst synergy, with SAS-derived CeO₂ consistently outperforming the non-micronized powder. The SAS catalyst, characterized by a narrow particle size distribution (DLS) and spherical morphology (SEM), ensured improved dispersion and interaction with plasma-generated species, leading to significantly shorter decolorization radiation times compared to the literature benchmarks. Importantly, this enhancement translated into higher energy efficiency, with complete dye removal achieved at a lower specific energy input than both plasma-only operation and non-micronized CeO₂. Scavenger tests confirmed •OH radicals as the dominant oxidants, while O₃, O₂•⁻, and e⁻_a played secondary roles. Tests on binary dye mixtures (CV + MB) revealed synergistic decolorization under plasma-only conditions, and the CeO₂-SAS catalyst maintained high overall efficiency despite competitive adsorption effects. These findings demonstrate that SAS micronization of CeO₂ is an effective material-engineering strategy to unlock plasma–catalyst synergy and achieve rapid, energy-efficient dye abatement for practical wastewater treatment. Full article

A major obstacle to textile recycling is the presence of dyes, which limits the reuse of fibers in high-value applications. Despite previous studies on, cotton decolorization, the systematic development of an optimal formulation that preserves fabric integrity remains lacking. This study addresses this gap by investigating a decolorization method for mixed-dyed cotton textiles that enables successful redyeing while preserving fabric quality. Reactive and vat-dyed cotton fabrics were treated with sequential reductive and oxidative processes, in a full factorial design. The impact of input parameters on tensile strength was evaluated through statistical analysis using analysis of variance at a significance level of α = 0.05. The developed recipe was subsequently validated on post-consumer cotton textiles. Stripping efficiency was assessed using K/S values, and fabric quality was evaluated through tensile strength, pilling, and fuzzing appearance. Temperature showed the strongest influence on dye removal. Fabric strength was significantly affected by temperature and oxidizing agent, and by interactions of temperature with reducing agent and oxidation time. The optimized process achieved 98–99.5% color removal and retained 95% of the fabric’s tenacity. A stripping efficiency of >90% for post-consumer cotton validates the method’s applicability in real-world circular systems. Full article

The discharge of dye-laden effluents remains an environmental challenge since conventional treatments remove color but not the organic load. This study systematically compared anodic oxidation (AO), electro-Fenton (EF), and photoelectro-Fenton (PEF) processes for three representative industrial dyes, such as Coriasol Red CB, Brown RBH, and Blue VT, and their ternary mixture, using boron-doped diamond (BDD) and Ti/IrO₂–SnO₂–Sb₂O₅ (MMO) anodes. Experiments were conducted in a batch reactor with 50 mM Na₂SO₄ at pH = 3.0 and current densities of 20–60 mA cm⁻². Kinetic analysis showed that AO-BDD was most effective at low pollutant loads, EF-BDD became superior at medium loads due to efficient H₂O₂ electrogeneration, and PEF-MMO dominated at higher loads by fast UVA photolysis of surface Fe(OH)²⁺ complexes. In a ternary mixture of 120 mg L⁻¹ of dyes, EF-BDD and PEF-MMO achieved >98% decolorization in 22–23 min with pseudo-first-order rate constants of 0.111–0.136 min⁻¹, whereas AO processes remained slower. COD assays revealed partial mineralization of 60–80%, with EF-BDD providing the most consistent reduction and PEF-MMO minimizing treatment time. These findings confirm that decolorization overestimates efficiency, and electrode selection must be tailored to dye structure and effluent composition. Process selection rules allow us to conclude that EF-BDD is the best robust dark option, and PEF-MMO, when UVA is available, offers practical guidelines for cost-effective electrochemical treatment of textile wastewater. Full article

Metallic glass, as an emerging catalytic material, possesses an atomic structure characterized by long-range disorder and short-range order, which creates abundant and accessible active sites that enhance the adsorption and reactivity toward pollutant molecules, particularly dye compounds. In treating highly colored and recalcitrant Reactive Black 5 (RB5) dye wastewater, Mo₅₁Fe₃₄B₁₅ metallic glass wire demonstrate outstanding catalytic degradation performance within a conventional Fenton-like system. Under acidic conditions (pH = 2), the material exhibits a degradation rate constant of 0.698 min⁻¹ for a 20 ppm RB5 dye solution, achieving a degradation efficiency of 98.8% within 10 min. After 10 consecutive cycles, the efficiency remains at 95%, and throughout 15 cycles, it consistently maintains a performance level above 90%. As the reaction proceeds, the degradation rate gradually decreases, primarily due to the accumulation of corrosion products on the catalyst surface, which are predominantly composed of MoO₃ and Fe₂O₃. During the degradation process, metallic Mo⁰ and Fe⁰ serve as electron donors that facilitate the decomposition of H₂O₂, generating highly reactive hydroxyl radicals (•OH). These radicals attack the chromophoric structure of the dye, leading to its structural disruption and enabling rapid decolorization. Full article

Effluents from the textile industry, particularly those containing synthetic azo dyes, poses a significant environmental threat, necessitating the development of more effective and sustainable pollutant removal methods. Traditional dye removal techniques often fall short in efficiency and environmental impact, prompting the exploration of enzymatic degradation as a promising alternative. This study focuses on chloroperoxidase, a natural biocatalyst recognized for its ability to oxidize synthetic dyes into less harmful products. By exploring the mechanistic distinction between chlorination and oxidative processes, we investigate the enzyme’s specific degradation pathways for azo dyes and the resulting by-products. Utilizing analytical techniques, including liquid chromatography/mass spectrometry (LC/MS), and density functional theory (DFT), we gain insights into the decolorization mechanism, revealing that the enzyme preferentially generates oxidative products through C–N bond cleavage as its initial degradation step. These findings underscore not only the unique mechanistic properties of chloroperoxidase but also its potential as a biocatalyst for industrial applications. This study advocates further research into the optimization of enzyme-based systems, highlighting their relevance in advancing greener chemical practices in the textile industry, thus contributing to more sustainable manufacturing processes. Full article

Fungal laccases are promising oxidative enzymes for bioremediation applications, particularly in the degradation of synthetic dyes present in industrial effluents. Here, we evaluated the inhibitory effects of sodium chloride (NaCl) and sodium sulfate (Na₂SO₄) on the activity of Trametes versicolor laccase and its ability to decolorize Congo Red (CR), Malachite Green (MG), and Remazol Brilliant Blue R (RBBR). Enzyme assays revealed concentration-dependent inhibition, with IC₅₀ values of 0.22 ± 0.04 M for NaCl and 1.00 ± 0.09 M for Na₂SO₄, indicating stronger inhibition by chloride. Kinetic modeling showed mixed-type inhibition for both salts. Despite this effect, the enzyme maintained significant activity: after 12 h, decolorization efficiencies reached 95 ± 4.0% for MG, 88 ± 3.0% for RBBR, and 75 ± 3.0% for CR, even in the presence of 0.5 M salts. When applied to a mixture of the three dyes, decolorization decreased only slightly in saline medium (94.04 ± 4.0% to 83.43 ± 5.1%). FTIR spectra revealed minor structural changes, but toxicity assays confirmed marked detoxification, with radicle length in lettuce seeds increasing from 20–38 mm (untreated dyes) to 41–48 mm after enzymatic treatment. Fungal growth assays corroborated reduced toxicity of treated dyes. These findings demonstrate that T. versicolor laccase retains functional robustness under ionic stress, supporting its potential application in saline textile wastewater remediation. Full article

The relationship between the structure and function of bacterial laccases has garnered significant research attention thanks to their straightforward molecular structure. Nevertheless, studies examining the impact of an altered molecular structure on the heterologous expression of bacterial laccases in Escherichia coli remain scarce. Our research focuses on elucidating the impact of incorporating copper ions into the molecular structure of modified CotA on its exogenous expression in E. coli as well as its impact on the significance of the amino acid residues surrounding the internal electron channels and water molecule channels of the enzyme molecule. The results show that single-site mutation may affect the expression of CotA by affecting its soluble expression with different binding capacities for copper ions. In addition, the mutants exhibited different laccase activity levels. The catalytic efficiency of T466A was found to be significantly enhanced, reaching 2.29 times that of the wild type. We used structural models to illustrate the correlation between molecular structure and function after the replacement of three mutation sites with alanine. The reduction of hydrogen bonds may be an important factor influencing Cu²⁺’s binding ability and the water molecule production rate. The T466A mutant exhibited strong decolorization ability for Reactive Blue 19 and Eriochrome Black T with 42.2% and 58.2% decolorization rates after one hour of reaction, respectively. This study demonstrates that the molecular mutation studied influences the CotA expression level, enzyme activity, and dye decolorization. Full article