Search Results (10,640)

The improper discharge of industrial effluents containing dyes, such as methylene blue, represents a serious environmental problem. The present study, therefore, aimed to evaluate the potential of biochar derived from carnauba stalks as an adsorbent for removing dyes from aqueous media. The raw stalks were subjected to carbonization under an inert atmosphere to yield biochar, and both materials were characterized by proximate and elemental analyses, SEM/EDS, PSD, XRD, FTIR, and thermal analyses. Batch adsorption experiments were monitored by UV-Vis spectrophotometry. Pyrolysis resulted in an increase in aromatic fixed carbon (+26.5%) and ash content (+23.8%), while simultaneously reducing volatile matter (−39.3%), moisture, and the atomic H/C (0.39) and O/C (0.07) ratios. Furthermore, thermal stability was enhanced without causing a significant alteration to the average particle size (~30 μm). Adsorption tests showed a maximum uptake of 32.5 mg∙g⁻¹ at low dosage (2 mg), corresponding to 8.66% removal, while 27.83% removal was achieved at higher dosage (25 mg). Equilibrium data were best described by the Langmuir model (q_m = 210.7 mg∙g⁻¹; R² = 0.971), with q_m representing a theoretical fitting parameter. These findings of this study demonstrate the adsorption potential of carnauba stalk biochar and support its evaluation as a lignocellulosic material for dye removal applications. Full article

Polymeric microspheres synthesized via Pickering emulsion polymerization offer structural tunability, making them attractive platforms for dye adsorption. This study investigates the adsorption behavior of methylene blue onto two classes of polymeric microspheres—poly(methacrylic acid) crosslinked with ethylene glycol dimethacrylate (PM), containing both micro- and nanopores, and poly(methacrylic acid) crosslinked with divinylbenzene (PD), containing only nanopores. The adsorption kinetics were modeled using a dual-process approach that distinguishes between diffusion-controlled transport and surface-controlled kinetic adsorption. We quantified the relative contributions of these mechanisms and correlated them with particle architecture. In the PM particles, diffusion plays a significant role in smaller particles with larger macropores, enabling methylene blue to penetrate the interior. As the particle size increased and macroporosity decreased, adsorption becomes increasingly dominated by surface kinetics. In contrast, PD particles —which lack macropores—showed the opposite trend: smaller particles were primarily governed by fast surface adsorption, while in larger particles, diffusion through nanopores became increasingly relevant. Correlation analysis between adsorption rate constants and structural parameters such as particle diameter and pore sizes revealed strong, opposing trends. In PD particles, a near-perfect inverse correlation was observed between the diffusion and kinetic components, indicating competitive suppression, where the dominance of one mechanism limited the contribution of the other. These results demonstrated that internal pore architecture played a central role in controlling the adsorption mechanism. Tuning particle size and porosity allowed deliberate control over the balance between diffusion and surface kinetics, enabling the rational design of microparticle adsorbents with tailored uptake behavior for water purification and dye removal applications. Full article

The world’s water resources are being deteriorated by the continuous discharge of various contaminants, highlighting the problem of dyes. Many industrial activities (dyeing, food, and medicines) depend on the use of synthetic dyes. Due to their strong color, toxicity, and carcinogenic properties, dye effluents are detrimental to human health and the environment and their treatment is mandatory before discharge. The manuscript intends to present a comprehensive summary of the advantages and drawbacks of using different treatments on the removal of dyes, mainly those based on adsorption. Emphasis is placed on the use of adsorbents from biomass or biomass waste, which are used in their original form or after conversion into biochar or activated carbon (AC). In this review, the use of biomass-based feedstocks to produce biochar and ACs and their application on the removal of various types of dyes from liquid effluents are compiled and critically discussed. This approach positions waste and sub products not as a problem, but as a valuable raw material for producing high value-added materials. The performance of different adsorbents, for the removal of cationic and anionic dyes, is discussed and related to the textural, physical and chemical characteristics of adsorbents and adsorption. It differs from the other revision manuscripts in that it elucidates to the readers the points to ponder before choosing an adsorbent for the removal of a specific dye, mainly for large-scale uses. Full article

Antimony oxide nanoparticles (Sb₂O₃ NPs) were synthesized via a chemical vapor deposition (CVD) method and systematically characterized to evaluate their multifunctional performance. Powder X-ray diffraction (PXRD) confirmed the formation of an orthorhombic Sb₂O₃ phase with an average crystallite size of 53.50 nm, while SEM analysis revealed elongated nanostructures with diameters in the range of 20–100 nm. The stoichiometric composition of Sb₂O₃ (Sb:O ≈ 2:3) was verified by EDAX, and optical studies indicated a direct band gap of 3.10 eV. The electrochemical sensing capability of Sb₂O₃ NPs was investigated using a modified nickel mesh electrode for the detection of Metronidazole (MTZ) in 0.1 N KOH. The presence of Sb₂O₃ NPs resulted in an additional irreversible reduction peak at −0.14 V, confirming enhanced electrocatalytic activity toward MTZ, along with excellent cycling stability (94.36% retention after 10 cycles). In addition, the photocatalytic performance of Sb₂O₃ NPs was evaluated through the degradation of Acid Orange (AO) dye under UV-Vis irradiation, achieving a degradation efficiency of 73.31%. These results demonstrate that Sb₂O₃ nanoparticles are promising multifunctional materials for environmental remediation and electrochemical sensing applications, highlighting their potential for industrial implementation. Full article

Adsorption is an effective method frequently used for removing contaminants, including dyes, from liquid effluents. This study uses silk fibroin nanoparticles produced by the Bombyx mori moth as an adsorbent material to remove methylene blue dye from aqueous solutions. Batch tests were carried out to examine the effect of pH and temperature on methylene blue adsorption and to obtain kinetic and equilibrium data. The experimental data were fitted to different kinetic models (pseudo-first-order, pseudo-second-order, Elovich, intraparticular diffusion and Bangham) and isotherm models (Langmuir, Freundlich, Sips and Redlich–Peterson). The experimental data can be best explained by the pseudo-second-order and Bangham kinetic models. The adsorption capacity increases with temperature so adsorption is an endothermic process. The maximum adsorption capacities achieved in the experiments were 122 mg·g⁻¹, 132 mg·g⁻¹, and 155 mg·g⁻¹ at temperatures of 10 °C, 25 °C, and 40 °C, respectively. Among the models studied, the ones that best describe the equilibrium data are Freundlich and Redlich–Peterson models. Full article

Azo dyes in textile industry effluents cause major environmental problems, highlighting the need to remove these compounds before discharge. The Nyex Rosalox™ (NR) process, a water treatment process that combines adsorption, electrochemical oxidation, and in situ regeneration using a patented novel graphite-based adsorbent (Nyex™ 2000 media), could potentially be used to remove azo dyes before being discharged. In this study the efficiency of the NR process for removing these compounds is assessed. Analyses indicate that (i) the Nyex™ media was able to adsorb all azo dyes quickly, with 50% of the total dye absorbed being absorbed in the first 30 min and >10% in the first minute alone and (ii) all azo dyes used were completely oxidised during the NR process without the formation of any detectable harmful byproducts that were previously observed during the electrochemical oxidation of azo dyes, with only a relatively small amount of energy needed to enable optimal electrochemical oxidation. The Nyex™ media can be consistently regenerated, maintaining its adsorptive capacity after extensive reuse, albeit the use of fresh adsorbent will always have a slightly greater adsorptive capacity. Combined, these findings suggest that the NR process can effectively destroy azo dyes with relatively low energy, proving an effective method of water treatment without producing harmful secondary pollutants. Full article

The maxillary sinus is frequently implicated in facial pain syndromes arising from infection, neoplasia, dental procedures, and, importantly, migraine, which can mimic “sinus headache” and contribute to misdiagnosis and inappropriate antibiotic use. Despite the clinical burden of chronic maxillary sinus pain, the sensory neuron subtypes that convey nociceptive and mechanosensory signals from the sinus mucosa remain incompletely defined. In this study, trigeminal ganglion (TG) neurons innervating the maxillary sinus (maxillary sinus TG neurons) were retrogradely labeled with the fluorescent dye DiD in mice and characterized using ex vivo patch-clamp electrophysiology and single-cell RT-PCR. Maxillary sinus TG neurons were found to be predominantly small-diameter, C-afferent nociceptors with electrophysiologic features including high thresholds, repetitive firing, and broad action potentials. Notably, maxillary sinus TG neurons formed a distinct molecular and functional subgroup: they expressed Nav1.9, while showing minimal Nav1.8 expression and limited overlap with Nav1.8-positive nociceptor populations. A majority of maxillary sinus TG neurons were mechanically responsive, generating mechanically activated currents with heterogeneous adaptation profiles, and a subset expressed the mechanoreceptor Piezo2. Collectively, these findings identify maxillary sinus TG neurons as a specialized population of Nav1.9-enriched C-afferent nociceptors with mechanosensitive properties, providing a mechanistic framework for pressure-evoked sinus pain. This work advances the neurobiological basis of sinus-related pain and suggests that Nav1.9 and mechanoreceptor pathways may be potential therapeutic targets for conditions in which sinus symptoms overlap with migraine and other craniofacial pain disorders. Full article

Growing concerns about environmental pollution and the sustainability of conventional nanomaterial synthesis have accelerated interest in plant-based routes for nanoparticle production. This review provides an in-depth analysis of more than 290 peer-reviewed research and review articles published between 2010 and 2025, extracted from the Web of Science and Scopus databases, on the green synthesis of metallic and metal oxide nanoparticles using plant extracts, with particular emphasis on their characterization and application in water treatment. Plant-derived phytochemicals serve as natural reducing and stabilizing agents, enabling nanoparticle formation without hazardous reagents. Key physicochemical characterization techniques, including UV–Visible spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, scanning and transmission electron microscopy, and energy-dispersive X-ray analysis, are evaluated for their roles in confirming nanoparticle structure, morphology, surface chemistry, and optical behavior. The review focuses on water purification applications, highlighting adsorption and photocatalytic degradation as the most extensively investigated removal pathways. Particular attention is given to widely studied material classes such as silver, zinc oxide, titanium dioxide, and iron-based nanoparticles, which demonstrate effective removal of heavy metals, synthetic dyes, pesticides, and pharmaceutical residues. Current limitations related to synthesis reproducibility, mechanistic understanding, stability, and scalability are critically discussed. The review concludes by identifying priority research directions, including standardized synthesis protocols, deeper chemical analysis of plant extracts, and the integration of green nanoparticles into immobilized and membrane-based systems to advance their practical implementation in sustainable water treatment technologies. Full article

Magnetic nanomaterials (MNMs) have been adopted as effective platforms for water remediation owing to their excellent surface-area-to-volume ratios, tunable surface chemistry, and magnetic separability. This review highlights the recent progress made in the synthesis, properties, and environmental applications in the removal of organic and inorganic contaminants using magnetic nanoparticles (MNPs) and one-dimensional magnetic nanofibers. Demonstrated removal rates of organic contaminants such as dyes, pharmaceuticals, and pesticides are often up to 85–100% under laboratory conditions, with adsorption capacities of 580 mg·g⁻¹ for melanoidin, 397.43 mg·g⁻¹ for Congo Red, and 392.64 mg·g⁻¹ for tetracycline. For heavy metals such as As(V), Cd(II), Cr(VI) and Pb(II), efficiencies are generally between 90–99% with maximum adsorption capacities of 909.1 mg·g⁻¹ for Pb(II). In particular, the review compares major synthesis routes such as coprecipitation, hydrothermal, solvothermal, thermal decomposition, sol–gel, microwave, and green methods by evaluating their effect on particle size (6–50 nm), magnetic properties (saturation magnetization up to ~101 emu·g⁻¹), and removal performance. The four principal mechanisms are described in this paper—adsorption, filtration, transformation, and photocatalysis—giving special emphasis to the advantages of magnetic recovery and advanced oxidation processes. Although most studies remain at the laboratory scale, MNMs demonstrate strong potential for scalable wastewater treatment, provided that toxicity, life-cycle impacts, and matrix effects are carefully evaluated. Full article

Textile wastewater contains recalcitrant azo dyes and auxiliary chemicals that are resistant to conventional biological treatment, resulting in persistent organic pollution in aquatic ecosystems. While supercritical water oxidation (SCWO) achieves superior chromophore mineralization, its high energy requirements limit industrial scalability. Conversely, biomass-derived activated carbon (BAC) offers a low-cost adsorption solution, but it rapidly becomes saturated with toxic oxidation intermediates. Notably, the literature lacks systematic analyses of hybrid SCWO-BAC systems with integrated thermal energy, which represents a crucial gap in assessing their economic feasibility. This review employed a systematic methodology, selecting studies relevant to the topic from peer-reviewed publications and databases, including Scopus, SciELO, ScienceDirect, and Google Scholar, for critical synthesis. Using SCWO as a pretreatment (which significantly reduces COD load), followed by BAC polishing, results in superior detoxification compared to individual processes. However, three barriers hinder scale-up: (i) chloride ion corrosion in real effluents; (ii) irreversible collapse of BAC pores after multiple regeneration cycles; and (iii) absence of standardized ecotoxicity data for hybrid-treated streams. This work outlines a technological roadmap for integrated supercritical water oxidation and biological activated carbon (SCWO-BAC) systems, targeting economically viable operational parameters for industrial-scale implementation. Full article

Background: In cancer surgery, resection of the primary tumor and regional lymph nodes (LNs) is critical. Adequate LN examination is essential to detect metastasis, which determines the cancer stage. Fluorescence emission allows for visual differentiation and rapid monitoring of LNs. Methods: Cancer tissue is stained with a fluorescent dye (indocyanine green, ICG) to identify LNs. Fluorescence is induced from the stained LNs using LED light, and a photosensor coupled with a speaker detects the fluorescence signal and triggers an audible alarm. Filters are applied to prevent false alarms. Results: Upon LN detection, an alarm is emitted from the speaker, and the results are recorded using the LED and a digital multimeter (DMM). In clinical trials, ICG is injected to induce LN fluorescence staining, followed by LED irradiation to induce the fluorescent wavelength and verify LN imaging. Discussion: In clinical trials, ICG stains both LNs and blood vessels, which may lead to false positives. To address this limitation, artificial intelligence algorithms can be trained to specifically identify LNs. Conclusions: Detection of fluorescence wavelengths via photosensors allows for rapid identification of LNs, confirmed through an audible alarm, thereby reducing surgical time. This method shows potential for broad application in cancer surgery. Full article

The management of invasive alien species (IAS) generates large amounts of plant waste biomass that is commonly disposed of by burning or destruction, leading to environmental and economic drawbacks. At the same time, the production of synthetic dyes and pigments used in printing and graphic applications remains a significant source of pollution. In this context, the valorization of IAS biomass as a source of natural colorants represents a sustainable alternative aligned with circular economy principles. Here, biocompounds and natural dyes were extracted from four invasive or non-native plant species—Arundo donax, Phytolacca americana, Tradescantia fluminensis, and Eucalyptus globulus—using five solid–liquid extraction methods: infusion, infusion with heat, thermal agitation, Soxhlet extraction, and ultrasonic-assisted extraction. Extraction efficiency and color preservation were comparatively evaluated. Although Soxhlet extraction provided the highest extraction yield (up to 30.5%), infusion with heat proved to be the most suitable method for preserving color integrity and minimizing oxidation. Liquid dyes obtained by the selected extraction method were converted into solid pigments through a lake pigment precipitation process using aluminum potassium sulfate and sodium bicarbonate. The resulting pigments were characterized in terms of chemical composition, particle size, and chromatic properties, and subsequently formulated into oil-based inks using linseed oil as binder. Scanning electron microscopy revealed pigment particle sizes ranging from approximately 2.1 to 8.3 µm, depending on the plant source, and confirmed adequate ink penetration and distribution on commercial printmaking paper. The obtained pigments exhibited color tones ranging from yellow to brown and grey, mainly associated with the phenolic and tannin content of the original biomass. Printing tests demonstrated the suitability of the developed inks for manual printmaking techniques, highlighting the potential of IAS-derived pigments as sustainable alternatives for artistic and printing applications. Full article

Background: Successful root canal treatment depends on the synergy between mechanical instrumentation and chemical disinfection. The internal canal geometry, particularly taper configuration, critically influences irrigant flow and penetration. Conventional taper designs tend to displace irrigants coronally, creating stagnation zones and limiting cleaning efficacy. The MEA Inverse Taper^® technique introduces a reversed taper geometry designed to retain irrigant within the canal during shaping, forming a fluid reservoir termed the Radicular Tank (RT). This proof-of-concept study aimed to experimentally demonstrate the formation of the RT generated by the MEA Inverse Taper^® design and to compare its qualitative hydrodynamic and shaping behavior with a conventional rotary system (MTWO). Methods: Standardized transparent canal models were instrumented using either the MEA Inverse Taper^® or MTWO sequence. A 1% methylene blue dye served as a visual tracer to assess potential intracanal retention at successive shaping stages. Standardized photographic documentation and digital image superimposition were used to evaluate residual dye retention, canal morphology, and taper variation. Results: The MEA Inverse Taper^® sequence maintained residual dye in the coronal and middle thirds, confirming the formation of the RT. Compared with MTWO, it produced a more conservative taper, minimized coronal and apical displacement of dye, and preserved canal curvature, removing less coronal dentin. Conclusion: The MEA Inverse Taper^® technique creates a qualitative dye-retention phenomenon (Radicular Tank) that allows continuous instrumentation within a visually persistent dye environment. This novel concept may support disinfection efficiency, alongside preserving dentin structure and reducing mechanical stress on rotary instruments, representing a potential advancement in endodontic shaping and irrigation protocols. Full article

Poly(vinyl alcohol) (PVA)/montmorillonite (MMT)/Ti₃C₂T_x (MXene) nanocomposite membranes (PVA/MMT/MXene) were developed and evaluated in terms of their mechanical properties, mesoporosity, and adsorption performance toward Pb²⁺ ions and methylene blue (MB). The incorporation of MMT and MXene resulted in a strong synergistic reinforcement, increasing the ultimate tensile strength from 10 to 20 MPa, the Young’s modulus from 14.7 to 29.5 MPa, and reducing the swelling ratio from 2.0 to 1.1 g·g⁻¹. BJH porosimetry revealed a refined and interconnected mesoporous structure, with the cumulative pore volume increasing from 0.134 to 0.448 cm³·g⁻¹. In adsorption experiments (mono-solute systems, 25 °C), the ternary membrane achieved high uptake capacities of 55 mg·g⁻¹ for Pb²⁺ and 80 mg·g⁻¹ for MB, outperforming binary PVA/MMT and neat PVA. Statistical–physics modeling provided microscopic descriptors consistent with the experimental isotherms: Pb²⁺ adsorption follows a monolayer regime (n ≈ 1), whereas MB exhibits multilayer behavior (n > 1) with a higher site density (Nm ≈ 1.6 mmol·g⁻¹). These results demonstrate that the hybrid 2D–2D architecture of MMT and MXene significantly enhances the structural robustness, pore accessibility, and adsorption efficiency of PVA-based membranes, highlighting their potential for efficient removal of metal ions and dyes from aqueous media. Full article

Dye-sensitized solar cells (DSSCs) represent a promising low-cost photovoltaic technology with relatively high conversion efficiency and a simple fabrication process. Natural dyes have drawn growing interest compared to ruthenium-based dyes since they are greener. However, the power conversion efficiency (PCE) of natural dyes is generally low. In this study, we investigated novel approaches to improve the PCE of DSSCs using Delonix regia extracts by polarity-based separation using preparative thin-layer chromatography (PTLC). Our study indicated that polarity-based separation can significantly enhance the PCE, with one fraction achieving a PCE of 1.13%, which is high compared to most natural dye-based DSSCs, and is also 1.85 times that of the crude methanol extract. The major compounds in the highest-efficiency layer were flavanol-based dyes. Our study demonstrates the potential antagonistic effects within Delonix regia extracts in DSSC applications, which play a critical role in improving PCE. The study is expected to support future efforts to enhance the PCE of natural compound-based DSSCs, especially those using flavanol-based natural dyes. Full article