Search Results (595)

The green synthesis of zinc oxide (ZnO) nanoparticles using plant biomass offers a sustainable approach for developing photocatalytic materials for water treatment. In this study, ZnO nanoparticles were biosynthesized using aqueous extracts of Eichhornia crassipes from the Medio Atrato region, Chocó, Colombia, at 1%, 2%, and 4% (w/v). The materials were characterized by FTIR, UV-Vis, XRD, and SEM–EDX. All samples exhibited the hexagonal wurtzite structure of ZnO without detectable secondary crystalline phases. Average crystallite sizes were 38.66, 38.16, and 31.52 nm for EC-1%, EC-2%, and EC-4%, respectively, decreasing with increasing extract concentration. Photocatalytic activity was evaluated under UV irradiation using six organic dyes: amido black 10B, eosin yellow, methylene blue, methyl orange, methyl red, and rhodamine B. Performance depended on both pollutant type and extract concentration. EC-2% showed the most consistent overall performance, achieving 87% degradation of amido black 10B, 92% of methyl orange, 81% of methyl red, and 93% of rhodamine B. Eosin yellow reached approximately 97% removal at 90 min, while EC-4% achieved 95% methylene blue degradation after 180 min. EC-2% also removed approximately 56.78% of chlorpyrifos ethyl after 180 min. Overall, E. crassipes-mediated ZnO nanoparticles demonstrate promising photocatalytic activity toward diverse organic pollutants and provide a potential route for valorizing invasive aquatic biomass. Full article

Background and Objectives: The aim of this study was to evaluate the penetration of laser-activated irrigation solutions into dentinal tubules in root canals with different degrees of curvature and different coronal flaring. Materials and Methods: Seventy-six maxillary first molar teeth previously extracted for various reasons were included in the present study. The specimens were divided into two main groups according to distal root canal curvature, determined using the Schneider method: straight (<10°) and curved (20–40°). These groups were further classified into two subgroups according to whether a coronal flaring procedure was performed (n = 19). Following root canal preparation of all specimens, final irrigation was performed using a laser activation method and an irrigation solution prepared with the fluorescent dye Rhodamine B. Horizontal apical, middle, and coronal sections of 1 ± 0.1 mm thickness were obtained from the specimens at 2 mm, 5 mm, and 8 mm from the apical foramen, respectively. The effect of the irrigation solution on dentinal tubule penetration in the root canals was evaluated in the obtained sections using confocal laser scanning microscopy. Following evaluation, the mean and maximum penetration distances into the dentinal tubules were measured. The obtained data were statistically analyzed using Generalized Estimating Equations and Bonferroni correction for multiple comparisons, with the significance level set at p < 0.05. Results: The analysis revealed that only the region factor had a statistically significant effect on mean penetration values (p < 0.001), whereas canal curvature (p = 0.010), coronal flaring (p = 0.002), and region (p < 0.001) had statistically significant effects on maximum penetration values. However, none of the two-way or three-way interactions were significant (p > 0.05). Conclusions: Coronal flaring did not affect mean dentinal tubule penetration but increased maximum penetration depth. Maximum penetration was higher in straight canals than in curved canals, while both mean and maximum penetration were significantly affected by the root canal region. Full article

The present study reports the green synthesis of iron oxide nanoparticles (α-Fe₂O₃ NPs) using Azadirachta indica leaf extract as a sustainable stabilizing agent and evaluates their antimicrobial and photocatalytic potential. The synthesized nanoparticles were characterized by UV–Visible, FT-IR, XRD, FESEM-EDS and TEM techniques. UV–Visible analysis confirmed nanoparticle formation, while XRD revealed the rhombohedral crystalline phase of α-Fe₂O₃ with high crystallinity. FT-IR analysis indicated the involvement of phytochemicals from A. indica in nanoparticle synthesis and stabilization. FESEM and TEM images showed predominantly irregular agglomerated rod-shaped nanoparticles. EDS analysis confirmed the elemental composition of iron and oxygen. Photocatalytic performance was evaluated through the degradation of Rhodamine B dye under xenon arc lamp irradiation simulating sunlight. The synthesized α-Fe₂O₃ NPs achieved a maximum degradation efficiency of 95.38% at 180 min and followed pseudo-first-order kinetics. The effects of pH, catalyst reusability, and stability confirmed the excellent photocatalytic performance and durability of the nanoparticles. The antimicrobial activity of α-Fe₂O₃ NPs was assessed against selected bacterial pathogens (E. coli, P. aeruginosa, B. subtilis, and S. aureus) and fungal strains (C. albicans, A. flavus, and A. niger) using the disk diffusion method. The nanoparticles exhibited broad-spectrum antimicrobial activity, with the highest inhibition observed against E. coli. These findings demonstrate that A. indica-mediated α-Fe₂O₃ NPs are effective multifunctional nanomaterials with significant potential for wastewater treatment, environmental remediation, and antimicrobial applications. Full article

In this paper, we have investigated the photocatalytic performances of some yttrium-doped ZrO₂ films for decomposing Rhodamine B and Methylene Blue. The as-deposited thin films (obtained by RF magnetron sputtering) were heat-treated to stabilize their structure. To assess the films’ characteristics, a group of analytical methods (XRD, XPS, AFM and DRS) allowed for the determination of their structural, surface, and optical properties. These characteristics were correlated with the observed photocatalytic activity and wetting behaviour. The Y-doped ZrO₂ film with medium nanoparticle size and a high contribution of the oxygen vacancy is found to be more efficient in Rhodamine B and Methylene Blue photodegradation; the 100% degradation efficiency was reached in 70 min and 40 min, respectively, for the 3 mg/L solution dye. The photodegradation mechanism is driven by photogenerated holes, and a possible reaction mechanism was proposed. By investigating the charge carrier separation at the film–ITO interfaces, made through a comparative analysis of their determined band edge potentials, we conclude that the transfer is not possible in either of the semiconductor pairs, so ITO does not “help” the photocatalytic process. Full article

Activated carbon is a highly porous adsorbent material that is often used to treat wastewater using physical and chemical adsorption. Agricultural and urban biomass waste valorization to activated carbon is a low-cost, renewable solution to commercial adsorbents, and can help prevent waste from tree pruning from being dumped in landfills or openly burned. In this study, the ability of the ground and unground Ficus nitida leaves to efficiently adsorb Rhodamine B dye and total chromium from model aqueous solutions was investigated. Chemical activation was performed using phosphoric acid (H₃PO₄) at different impregnation ratios (1:1, 2:1, and 4:1). Samples obtained as a result of the above activation were labeled G1–G3 (ground) and UG1–UG3 (unground). The adsorption test showed that the samples with the highest activation ratio (G3 and UG3) gave the best results, removing 92% and 94% RhB, respectively, in 20 minutes. After 24 h, sample G3 showed the best efficiency of 73.31% (13.35 ppm remaining) in chromium removal, where the adsorption kinetics were well described by the pseudo-second-order model (R² > 0.98), indicating that there may be some chemical interactions occurring during the adsorption process along with physisorption, and the RhB adsorption isotherms for sample UG3 were well described by the Langmuir isotherm (R² > 0.95). The higher activation ratio and grinding increased the carbon content (up to 90% C for G3), surface functional groups, and textural properties (BET surface area of 699 m²/g and total pore volume of 3.06 cm³/g). Furthermore, reusability tests over five consecutive cycles demonstrated the excellent recyclability of sample G3, retaining removal efficiencies of 80.5% for RhB and 50.2% for total chromium. The results revealed that Ficus nitida leaf-based AC can be used as an efficient, economical, and reusable adsorbent material for sustainable environmental cleanup and water purification systems and will create a circular economy for waste management. Full article

The synthetic industry has shortened human lifespans because of environmental contamination. Numerous physicochemical methods can be used to decompose the released organic contaminants, but heterogeneous photocatalysis stands out among them. The creation of a novel sunlight-active heterogeneous photocatalyst, ZVI@MnFe₂O₄/PTh, for possible degradation of RhB dye is discussed in this study. The nanocomposite was fabricated using the hydrothermal method and in situ polymerization of thiophene. The ternary composite photocatalyst (ZVI@MnFe₂O₄/PTh) and photocatalysts (ZVI@MnFe₂O₄ and MnFe₂O₄/PTh) were well characterized in terms of structure (Fourier transform infrared spectroscopy), morphology (scanning electron microscopy), composition (energy-dispersive X-ray), and crystallinity (X-ray diffraction). UV–visible spectroscopic analysis (Tauc plot) was used to determine the energy bandgaps of catalysts. The characterization study supports the successful assembly of ZVI@MnFe₂O₄ nanoparticles and polythiophene. To evaluate the photocatalytic performance, the photocatalytically helped degradation of Rhodamine B dye from wastewater was also investigated over the new catalysts. The designed heterojunction enhances photogenerated charge separation and stimulates the photocatalytic process. The proposed study’s findings demonstrated that the novel composite’s sunlight-active photocatalytic effectiveness (99% in 90 min at pH 4) was enhanced against the degradation of Rhodamine B dye. Different models were utilized to predict the reaction’s kinetics, and RSM was utilized as a statistical technique to examine the individual and then interaction effects of the influencing parameters. The RSM results were supported by the numerical values of the optimized parameters, which were pH = 4, H₂O₂ = 10 mM, and composite dose = 20 mg/50 mL, utilizing a 100 ppm RhB solution. Full article

Photocatalysis is a promising route for the environmentally friendly destruction of organic pollutants and recycling the polluted water in industrial contexts for future environmental challenges. In this novel research work, the coupling of definite proportions of silver phosphate and g-C₃N₄ is carried out sonochemically for engineering S-scheme Ag₃PO₄/g-C₃N₄ heterojunctions. With the data obtained from a N₂-adsorption–desorption isotherm, a diffuse reflectance spectrum, X-ray diffraction, a high-resolution transmission electron microscope and zeta potential measurement, as-synthesized nanocomposites are fully characterized and defined. Successful coupling of Ag₃PO₄/g-C₃N₄ heterojunctions was verified given the existence of diffraction peaks of g-C₃N₄ and Ag₃PO₄; the shift in the peak position of the DRS spectrum of g-C₃N₄ from 440 to 463 nm; and the decrease of 68% in the photoluminescence emission peak. The crystalline size of the nanocomposite decreased from 76 to 25 nm, which was ascribed to coupling of Ag₃PO₄ on g-C₃N₄ under sonochemical conditions. The as-synthesized nanocomposites exhibited different trends in the destruction of rhodamine B dye. The experimental results indicated that the sample containing 15 weight % of Ag₃PO₄ degraded 89% of the RhB dye. Precise analysis of reactive radicals species experiments indicated that superoxide radicals and positive roles directed the charge transportation between g-C₃N₄ and Ag₃PO₄ semiconductors toward the S-scheme mechanism that produces charge radicals of auspicious redox efficiency. Full article

Photocatalytic degradation technology has been widely acknowledged for its low cost and high degradation efficiency. However, the loss, migration and difficult recovery of powdered catalysts are still critical bottlenecks for practical applications. In this study, silver nanoparticles (Ag NPs)/polyvinylidene fluoride (PVDF) photocatalytic composite membranes were in situ fabricated by incorporating AgNO₃ into a PVDF casting solution, followed by electrospinning and UV post-treatment. The resulting membranes exhibited sustained photocatalytic capability towards dyes and antibiotics. The optimal membrane achieved 89.6% and 83.0% degradation efficiency for chloramphenicol (CAP) and rhodamine B within 16 h under UV irradiation, respectively. Free radical trapping experiments revealed that the superoxide radical (·O₂⁻) dominated the photocatalytic degradation of CAP, and the mechanism of photocatalytic degradation was explored. Additionally, the Ag NPs/PVDF photocatalytic membrane demonstrated a distinct antibacterial efficacy against Staphylococcus aureus (S. aureus) with a distinct inhibition zone of 20 mm, effectively inhibiting bacterial proliferation. Full article

Biomass-derived porous carbons are promising sustainable adsorbents for wastewater treatment. However, most reported materials require chemical activation, while the relationships between biomass precursor, pore structure, adsorption mechanism, and regeneration remain insufficiently understood. In this work, non-activated carbon materials were prepared from Juglans regia (JR) and Allium sativum (AS) biomass by pyrolysis at 400 and 900 °C and evaluated for the removal of methylene blue (MB), rhodamine B (RB), crystal violet (CV), and malachite green (MG). Carbonization at 900 °C markedly enhanced porosity, yielding a surface area of 790 m² g⁻¹ for JR900 and 177 m² g⁻¹ for AS900, together with predominantly microporous structures and negatively charged surfaces at neutral pH. The pseudo-second-order model best described adsorption kinetics, while intraparticle diffusion analysis indicated a multistep adsorption process. Equilibrium data were well fitted by both Langmuir and Freundlich isotherm models. JR900 exhibited the highest adsorption capacities for MB (321 mg g⁻¹) and RB (304 mg g⁻¹), whereas AS900 showed superior performance toward MG (278 mg g⁻¹). Stable dynamic filtration, efficient regeneration, and nearly complete dye recovery demonstrate the potential of these non-activated biomass-derived carbons for sustainable dye removal and recovery from water. Full article

Silica aerogel films are highly promising matrices for advanced optical applications, yet balancing ultra-high transmittance with structural stability during functionalization remains a critical challenge. Directly incorporating organic dyes often leads to aggregation and severe photodegradation, necessitating a robust host–guest encapsulation strategy. Herein, we report the fabrication of ultra-transparent, fluorescent silica aerogel films via precisely tailored acid/base two-step sol–gel kinetics and dip-coating. The optimized pure silica matrix achieves a peak visible transmittance of 97.4% and sub-nanometer surface smoothness (RMS = 276.7 pm). By utilizing this pristine network, Rhodamine 6G (Rh6G) and Rhodamine B (RhB) dyes were effectively confined within the amorphous mesoporous pores. Notably, RhB exhibited superior matrix integration, indicated by an H4 hysteresis loop transition and a significantly reduced pore volume (0.019 cm³/g). This mesoporous confinement successfully suppressed dye quenching, prolonging the fluorescence lifetimes to 5.22 ns and 5.36 ns for Rh6G and RhB, respectively. Crucially, we elucidate that the electrostatic and hydrogen-bonding interactions between the silica pore walls and the dye’s xanthene rings elevate the excited-state energy, inducing a distinct matrix-driven emission blue shift. This work provides a scalable pathway for high-performance optical coatings and offers deep insights into host–guest interfacial coupling in gel networks. Full article

A nickel oxide/attapulgite (A-ATP/NiO) nanocomposite was synthesized and evaluated for the adsorption and Fenton-like degradation of Rhodamine B (Rh-B) in an aqueous solution. The composite was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET), confirming the successful immobilization of NiO nanoparticles into the attapulgite framework. The attapulgite modification results in enhanced surface properties, including increased surface area (from 68.9 to 111.3 m² g⁻¹), pore volume, and the availability of active sites. Batch experiments demonstrated a high affinity of A-ATP/NiO toward Rh-B, achieving 52% adsorption within 60 min. Upon addition of Fenton reagent (H₂O₂), the composite exhibited excellent catalytic performance, achieving 97% Rh-B degradation in 10 min and almost complete removal (99.39%) within 60 min under optimized conditions (pH 3, 303 K, H₂O₂ 5 mmol L⁻¹, catalyst dose 0.03 g L⁻¹, dye concentration 50 ppm). The synergistic combination of adsorption and catalytic oxidation significantly enhanced dye removal, with reactive hydroxyl radicals (•OH) driving the degradation process. Kinetic analysis indicated that the removal followed a pseudo-first-order model, suggesting that physisorption and surface diffusion are the primary mechanisms for Rh-B degradation. These findings highlight A-ATP/NiO as a low-cost, environmentally friendly, and highly efficient material for the rapid and sustainable remediation of Rh-B-contaminated wastewater. Full article

Chili products are vulnerable to the addition of unauthorized substances, including Sudan dyes, Rhodamine B, Basic Orange 2, poppy-derived materials and improperly used processing chemicals. Their analysis is complicated by the high contents of lipids, carotenoids, capsaicinoids and other co-extracted matrix components in chili powder, chili oil, chili sauce and composite seasonings. This review critically evaluates conventional and emerging sample-preparation strategies, including solid-phase extraction; the quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure; deep eutectic solvent (DES)-assisted extraction; enhanced matrix removal for lipids (EMR-Lipid); and molecularly imprinted sorbents. Laboratory methods based on high-performance liquid chromatography (HPLC), liquid chromatography–tandem mass spectrometry (LC–MS/MS) and gas chromatography–mass spectrometry (GC–MS) are compared with enzyme-linked immunosorbent assay (ELISA), surface-enhanced Raman spectroscopy (SERS), electrochemical sensors, miniature mass spectrometry and artificial intelligence-assisted hyperspectral imaging (AI–HSI). The comparison considers representative limits of detection and quantification, recovery, precision, sample-preparation burden, cost, portability, validation status and regulatory role. LC–MS/MS remains the preferred confirmatory platform for targeted multi-residue analysis, whereas rapid and portable methods are more appropriate for screening and sample triage. A three-tier workflow linking rapid screening, laboratory confirmation, and emerging-risk identification and traceability is proposed. Future priorities include standardized chili reference materials, open AI training and validation datasets, greener DES-based extraction and interlaboratory validation of field-deployable methods. Full article

Agricultural waste-derived biochars have recently attracted increasing attention as sustainable adsorbents for wastewater treatment. In this study, biochars (BHBs) produced from buckwheat husks at 500, 600, and 700 °C were investigated as novel adsorbents for the removal of the cationic dyes Crystal Violet (CV) and Rhodamine B (RhB) from aqueous solutions. The obtained materials were characterized using thermogravimetric analysis and surface functional group analysis to evaluate the influence of pyrolysis temperature on their physicochemical properties. The effects of initial adsorbent dose, solution pH, and ionic strength were assessed, while adsorption kinetics and equilibrium isotherms were analyzed to elucidate the adsorption mechanisms. It was found that the adsorption of both dyes depended on pH. CV adsorption was lowest in an acidic environment and increased with increasing pH from 3 to 9. RhB was most effectively adsorbed in an acidic environment. Its adsorption decreased as the pH increased from 3 to around 5, after which it stabilized. The adsorption of CV decreased with increasing ionic strength of the solution, whereas the adsorption efficiency of RhB remained unaffected. The adsorption kinetics of CV and RhB on BHBs were found to follow a pseudo-second-order mechanism controlled by film diffusion. The Langmuir, Freundlich, and Temkin models all provided good fits to the equilibrium experiments. The adsorption capacities of BHBs for CV and RhB decreased with increasing pyrolysis temperature and surface alkalinity of the biochars (BHB700 < BHB600 < BHB500). The adsorption capacities of biochars ranged from 41.00 mg/g (BHB700) to 56.10 mg/g (BHB500) for CV and from 9.74 mg/g (BHB700) to 13.24 mg/g (BHB500) for RhB. The study highlights the potential of buckwheat husk-derived biochars as sustainable adsorbents for the treatment of dye-contaminated wastewater and provides insight into the relationship between pyrolysis conditions and adsorption performance. Full article

This work reports the development of innovative enzyme–titanium nanobiohybrids synthesized via a protein-assisted approach to obtain efficient and sustainable photocatalysts for environmental remediation. By addressing the limitations of conventional TiO₂ nanoparticle synthesis, this strategy enables controlled material properties under milder, potentially scalable conditions for enhanced ROS-driven degradation of persistent dye pollutants. This work employs a bio-assisted synthesis approach using β-glucosidase as a protein scaffold, TiCl₄ as the titanium precursor, and H₂O₂ in bicarbonate buffer at room temperature, eliminating the need for harsh conditions and high temperatures. The biological moiety guides the nanoparticle formation, controlling size and morphology while preventing aggregation, all performed under mild conditions. X-ray diffraction determined that the Ti hybrid was composed of TiO₂ brookite species. TEM analyses demonstrated the formation of well-dispersed nanostructures of around 700 nm. The resulting nanobiohybrids showed excellent photocatalytic activity, achieving >99% Rhodamine B degradation under UV light in only 1 h compared to visible light. The catalyst was capable of degrading Rhodamine B at a concentration approximately 36 times above the recommended threshold for water. Furthermore, a preactivation of the catalyst by direct exposition of it to UV-395 nm light greatly enhanced the efficiency in the photocatalytic process, being inactive in visible light. The Ti–enzyme hybrid showed excellent recyclability over five consecutive cycles and retained good activity after storage, demonstrating its stability. This study introduces a sustainable and efficient route for synthesizing Ti-based nanobiohybrids, providing a promising strategy for advanced photocatalytic applications in water treatment and environmental remediation. Full article

Wastewater contamination with synthetic organic dyes is a significant environmental challenge. Zinc oxide (ZnO) has attracted considerable attention as a non-toxic, multifunctional material for electronics, optics, piezoelectric devices, and photocatalysis, where its performance is strongly governed by morphology. In this work, we investigate the effect of hexamethylenetetramine (HMTA) on the formation and photocatalytic behavior of ZnO nanostructures synthesized from different zinc precursors, namely zinc acetate and zinc nitrate, via a one-step sol–gel process at low temperature without any post-treatment. All samples crystallize in the hexagonal wurtzite phase without detectable impurities, and the incorporation of HMTA leads to smaller, more uniform rod- and flake-like nanostructures. Although ZnO derived from zinc acetate without HMTA exhibits the highest specific surface area, ZnO synthesized in the presence of HMTA shows more favorable crystallinity, morphology, and pore connectivity, which together enhance charge separation and reactive oxygen species generation. As a result, ZnO samples synthesized with HMTA exhibit improved photocatalytic degradation of rhodamine B under UV irradiation. Full article