Search Results (855)

This study investigated the aerobic biodecolorization of azo dyes by Shewanella oneidensis MR-1. S. oneidensis MR-1 can rapidly degrade azo dyes under aerobic conditions, even at high concentrations of up to 270 mg/L, demonstrating remarkable dye decolorization capabilities. This decolorization efficiency persists even under high concentrations of oxygen. The introduction of different environmental metal ions led to either inhibitory or stimulatory effects on the decolorization of Methyl Orange and Amaranth. Furthermore, the addition of extracellular electron shuttles and electron scavengers confirmed that dyes were being reduced via electron transfer, and the decolorization capability of S. oneidensis MR-1 correlated with electron density. Our study unveils the rapid degradation ability of S. oneidensis MR-1 for dyes under aerobic conditions, which is closely linked to its electron transfer capacity. This research holds significant implications for a deeper understanding of the biodegradation mechanisms of azo dyes under aerobic conditions. Full article

Piezoelectric catalytic technology has attracted much attention in the field of dye wastewater treatment, in which inorganic piezoelectric materials have been widely studied. Its core mechanism involves utilizing the piezoelectric effect to generate positive and negative charges, which react with oxygen ions and hydroxyl radicals, respectively, to generate reactive oxygen species to degrade organic pollutants. Currently, while organic piezoelectric catalysts theoretically offer significant advantages such as low cost and high processability, there has been a notable lack of research in this area, which presents an innovative opportunity for the exploration of new organic piezoelectric catalytic materials. In this study, new research using natural nanocellulose (FC) suspension as an efficient organic piezoelectric catalyst is reported for the first time. The experimental results showed that the catalyst exhibited excellent degradation performance for Rhodamine B (RhB), Acid Orange 7 (AO7), and Methyl Orange (MO) under ultrasonic vibration (40 kHz, 200 W): the degradation rates reached 95.4%, 72.4%, and 31.2%, respectively, for 150 min, and the corresponding first-order reaction kinetic constants were 0.0205, 0.00858, and 0.00249 min⁻¹, respectively. It is noteworthy that the RhB solution can achieve the optimal degradation efficiency without adjustment under neutral initial pH conditions, which significantly enhances the practical application feasibility. The experimental results showed that the catalyst, with a measurable piezoelectric coefficient (d33 = 4.4 pm/V), exhibited excellent degradation performance for Rhodamine B (RhB), Acid Orange 7 (AO7), and Methyl Orange (MO) under ultrasonic vibration (40 kHz, 200 W). This organic piezoelectric catalyst, based on renewable biomass, innovatively converts mechanical vibration energy in the environment into the power to degrade pollutants. It not only expands the application boundaries of organic piezoelectric materials but also provides a new solution for sustainable water treatment technology, demonstrating extremely promising application prospects in the field of green and environmentally friendly water treatment. Full article

The blood orange arose from the insertion of a retrotransposon adjacent to the Ruby gene, an MYB-type transcriptional activator of anthocyanin production, as reported previously. However, the intricate process of anthocyanin regulation among different varieties of blood orange remains incompletely understood. In this study, mRNA levels of the transcription factors Ruby and TT8 were found to be upregulated in the juice vesicle tissues of a variety with higher concentrations of anthocyanins in the pulp compared with another variety with a lower anthocyanin content. In contrast, comparative analysis of the two varieties using two-dimensional electrophoresis and mass spectrometry did not identify differentially expressed proteins related to anthocyanin biosynthesis in the juice vesicle tissues. Furthermore, higher anthocyanin contents were observed in various tissues of transgenic Arabidopsis thaliana overexpressing the Ruby gene from blood orange compared with the wildtype plant. Moreover, the long terminal repeat (LTR) region of a retrotransposon inserted upstream of the Ruby locus exhibited the ability to drive reporter expression through histochemical assay in a transgenic seedling. Thus, a PCR-based molecular marker was developed, targeting the upstream sequence of the Ruby locus to identify Citrus hybrids with the unique trait of red-fleshed fruit. Intriguingly, bisulfite sequencing revealed differentially methylated regions within a Gag-Pol polyprotein-encoding sequence of a retrotransposon adjacent to Ruby locus when comparing two varieties with different anthocyanin contents. A higher average level of methylation status was observed in the fruit with a lower anthocyanin content. In conclusion, methylation modifications at specific upstream positions on the Ruby locus may influence anthocyanin production in blood oranges. Full article

Tribocatalysis is receiving more and more attention for its great potential in environmental remediation. In this study, a special tribocatalysis was explored as a powder-free catalytic technology for the degradation of organic dyes. Polytetrafluoroethylene (PTFE) and titanium (Ti) disks were first assembled as magnetic rotary disks and then driven to rotate through magnetic stirring in dye solutions in beakers with PTFE, Ti, and Al₂O₃ disks coated on bottoms separately. PTFE and Ti generated dynamic friction with the disks on the beaker bottoms in the course of magnetic stirring, from which some interesting dye degradations resulted. Among those dynamic frictions generated, 40 mg/L rhodamine b (RhB), 30 mg/L methyl orange (MO), and 20 mg/L methylene blue (MB) were effectively degraded by the one between PTFE and PTFE, the one between Ti and Ti, and the one between PTFE and Ti, respectively. Hydroxyl radicals and superoxide radicals were detected for two frictions, one between PTFE and PTFE and the other between Ti and Ti. It is proposed that Ti in friction increases the pressure in blocked areas through deformation and then catalyzes reactions under high pressure. Mechano-radicals are formed by PTFE through deformation, and are responsible for dye degradation. This work demonstrates a powder-free tribocatalysis for organic pollutant degradation and suggests an especially eco-friendly catalytic technology to wastewater treatment. Full article

Water pollution caused by increasing industrial and human activity remains a serious environmental challenge, especially due to the persistence of organic contaminants in aquatic systems. Photocatalysis offers a promising and eco-friendly solution, but in the case of bismuth oxide (Bi₂O₃) there is still a limited understanding of how structural and morphological features influence photocatalytic performance. In this work, a straightforward hydrothermal synthesis method followed by controlled calcination was developed to produce phase-pure α- and β-Bi₂O₃ with tunable morphologies. By varying the hydrothermal temperature and reaction time, distinct structures were successfully obtained, including flower-like, broccoli-like, and fused morphologies. XRD analyses showed that the final crystal phase depends solely on the calcination temperature, with β-Bi₂O₃ forming at 350 °C and α-Bi₂O₃ at 500 °C. SEM and BET analyses confirmed that morphology and surface area are strongly influenced by the hydrothermal conditions, with the flower-like β-Bi₂O₃ exhibiting the highest surface area. UV–Vis spectroscopy revealed that β-Bi₂O₃ also has a lower bandgap than its α counterpart, making it more responsive to visible light. Photocatalytic tests using Rhodamine B showed that the flower-like β-Bi₂O₃ achieved the highest degradation efficiency (81% in 4 h). Kinetic analysis followed pseudo-first-order behavior, and radical scavenging experiments identified hydroxyl radicals, superoxide radicals, and holes as key active species. The catalyst also demonstrated excellent stability and reusability. Additionally, Methyl Orange (MO), a more stable and persistent azo dye, was selected as a second model pollutant. The flower-like β-Bi₂O₃ catalyst achieved 73% degradation of MO at pH = 7 and complete removal under acidic conditions (pH = 2) in less than 3 h. These findings underscore the importance of both phase and morphology in designing high-performance Bi₂O₃ photocatalysts for environmental remediation. Full article

In this study, we report the development of a novel magnetized coal fly ash-supported nano-silver composite (AgNPs/MCFA) for dual-functional applications in wastewater treatment: the efficient degradation of methyl orange (MO) dye and broad-spectrum antibacterial activity. The composite was synthesized via a facile impregnation–reduction–sintering route, utilizing sodium citrate as both a reducing and stabilizing agent. The AgNPs/MCFA composite was systematically characterized through multiple analytical techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The results confirmed the uniform dispersion of AgNPs (average size: 13.97 nm) on the MCFA matrix, where the formation of chemical bonds (Ag-O-Si) contributed to the enhanced stability of the material. Under optimized conditions (0.5 g·L⁻¹ AgNO₃, 250 °C sintering temperature, and 2 h sintering time), AgNPs/MCFA exhibited an exceptional catalytic performance, achieving 99.89% MO degradation within 15 min (pseudo-first-order rate constant k_a = 0.3133 min⁻¹) in the presence of NaBH₄. The composite also demonstrated potent antibacterial efficacy against Escherichia coli (MIC = 0.5 mg·mL⁻¹) and Staphylococcus aureus (MIC = 2 mg·mL⁻¹), attributed to membrane disruption, intracellular content leakage, and reactive oxygen species generation. Remarkably, AgNPs/MCFA retained >90% catalytic and antibacterial efficiency after five reuse cycles, enabled by its magnetic recoverability. By repurposing industrial waste (coal fly ash) as a low-cost carrier, this work provides a sustainable strategy to mitigate nanoparticle aggregation and environmental risks while enhancing multifunctional performance in water remediation. Full article

Catalysts are ubiquitous in manufacturing industries and gas phase pollutant abatement but are not widely used in wastewater treatment, as high temperatures and concentrated waste streams are needed to achieve the reaction degradation rates required. Heating water is energy intensive, and alternative, low temperature solutions have been investigated, collectively known as advanced oxidation processes. However, many of these advanced oxidation processes use expensive oxidants such as perchlorate, hydroxy radicals or ozone to react with contaminants, and therefore have high running costs. This study has investigated microwave catalysis as a low-energy, low-cost technology for water treatment using NiO catalysts that can be heated in the microwave field to drive the decomposition of azo-dye contaminants. Using this methodology for the microwave-assisted degradation of two azo dyes (azorubine and methyl orange), conversions of >95% were achieved in only 10 s with 100 W microwave power. Full article

Aerogel sponges of bio-based polymers loaded with metal–organic frameworks (MOFs) are highly promising for environmental applications, but a central challenge is to improve their stability and efficiency for removal processes. Here, the effective incorporation of the MOFs MIL-100(Fe) and ZIF-8 in composite aerogels of chitosan–pectin–lactic acid is reported. The presence of pectin was critical to loading the MOFs efficiently and homogeneously, while the incorporation of lactic acid induced a large increase in the Young’s modulus and provided structural preservation in aqueous solutions. The presence of MOFs enhanced the removal of two dyes, methyl orange (MO) and methylene blue (MB), under batch and flow conditions, with removal efficiencies of methyl orange of about 85% and 90% when loaded with ZIF-8 and MIL-100(Fe), respectively. Bentonite, celite 545, and two ionenes were loaded for comparison. Factors beyond charge-to-charge electrostatic interactions influenced the removal, since no correlations were obtained between the electrical charges of dyes, fillers, and polymers. The kinetic data were analyzed by adapting the Langmuir kinetic model, incorporating absorption and desorption processes, which allowed the recovery of the respective rate constants. Full article

This study investigates the pyrolysis of construction, renovation, and demolition (CRD) wood waste to produce biochar, with a focus on its robustness, scalability, and characterization for energy and environmental applications. Pyrolysis conditions, including the temperature, biomass residence time (BRT), and feedstock mass, were varied to evaluate their effects on biochar properties. High-temperature biochars (B800) showed the highest fixed carbon (FC) (87%) and thermostable fraction (TSF) (96%) and the lowest volatile carbon (VC) (9%), with a high carbon content (92%), a large BET surface area (300 m²/g), and a high micropore volume (0.146 cm³/g). However, the hydrogen (0.9%) and oxygen (2.2%) content, Van-Krevelen parameters (H/C: 0.1; O/C: 0.02), and biochar yield (21%) decreased with increasing temperature. Moderate-temperature biochars (B600) have balanced physicochemical properties and yields, making them suitable for adsorption applications. Methyl orange dye removal exceeded 90% under the optimal conditions, with B600 fitting well with the Freundlich isotherm model (R² = 0.97; 1/n = 0.5) and pseudo-second-order kinetic model (R² = 1). The study highlights biochar’s suitability for varied applications, emphasizing the need for scalability in CRD wood pyrolysis. Full article

Membrane separation technology has shown significant potential in the treatment of mixed dye wastewater. In this study, a reduced graphene oxide (AH-rGO) membrane was prepared using an amino-hydrothermal method and applied for the first time in mixed dye separation. These membranes can selectively recover high-value dyes while addressing the technical challenges of balancing permeability and selectivity in traditional membrane materials, which are often at odds with each other in the treatment of mixed dye wastewater. We simulated actual dye wastewater using four dyes: methyl orange (MO), methyl blue (MB), rhodamine B (RB), and Victoria Blue B (VBB). The four combinations of mixed dyes were MO/VBB, RB/VBB, MO/MB, and RB/MB, all of which demonstrated high water permeability and separation efficiency. Notably, the MO/VBB combination achieved a maximum water permeability rate of 118.79 L m⁻² h⁻¹ bar⁻¹ and a separation factor of 24.2. The AH-rGO membrane is currently the highest-permeability membrane available, achieving excellent separation results with typical mixed dye wastewater. Additionally, it demonstrates good stability. The experimental results indicate that the overall performance of the AH-rGO membrane is superior to that ofother graphene oxide (GO) membranes, which reveals the significant application potential of this membrane in the field of mixed dye wastewater treatment. Full article

In sharp contrast to photocatalysis and other prevalent catalytic technologies, tribocatalysis has emerged as a promising technology to degrade high-concentration organic dyes in recent years. In this study, BaTiO₃ (BTO) nanoparticles were challenged to degrade methyl orange (MO) solutions with unprecedentedly high concentrations through magnetic stirring. With BTO nanoparticles and home-made PTFE magnetic rotary disks in 50 mg/L MO solutions, 10 h of magnetic stirring resulted in 91.4% and 98.1% degradations in an as-received glass beaker and in a beaker with a PTFE disk coated on its bottom, respectively. Even for 100 mg/L MO solutions, nearly complete degradation was achieved by magnetic-stirring-stimulated BTO nanoparticles in beakers with the following four kinds of bottom: 97.3% degradation in 30 h for a glass bottom, 97.4% degradation in 20 h for a PTFE coating, 97.9% degradation in 42 h for a Ti coating, and 97.4% degradation in 74 h for an Al₂O₃ coating. Electron paramagnetic resonance (EPR) analyses revealed that the generation of reactive oxygen species (ROS) by magnetic-stirring-stimulated BTO nanoparticles is dramatically affected by the bottom material of beakers. These findings suggest an appealing prospect for BTO nanoparticles to utilize mechanical energy for sustainable water remediation. Full article

A ceramic–metal composite was synthesized using sol–gel and electrospinning methods to serve as a SERS substrate. The precursors used were tetraethyl orthosilicate, aluminum nitrate, and zirconium, and polyvinylpyrrolidone was added to electrospun nonwoven fibrous membranes. The membranes were sintered, decorated with silver nanoparticles. The enhancement substrates were made of fibers of cylindric morphology with an average diameter of approximately 190 nm, a smooth surface, and 9 nm spherical particles decorating the surface of the fibers. The enhancement capacity of the substrates was tested using pyridine, methyl orange, methylene blue, crystal violet, and Eriochrome black T at different concentrations with Raman spectroscopy to determine whether the size and complexity of the analyte has an impact on the enhancement capacity. Enhancement factors of 2.53 × 10², 3.06 × 10¹, 2.97 × 10³, 4.66 × 10³, and 1.45 × 10³ times were obtained for the signal of pyridine, methyl orange, methylene blue, crystal violet, and Eriochrome black T at concentrations of 1 nM. Full article

In this study, the BPTCD/g-C₃N₄ heterojunction photocatalyst was successfully prepared by the hydrothermal method. BPTCD (3,3′,4,4′-benzophenone tetracarboxylic dianhydride) is immobilised on the surface of g-C₃N₄ by non-covalent π-π stacking. The BPTCD/g-C₃N₄ heterojunction photocatalyst is an all-organic photocatalyst with significantly improved photocatalytic performance compared with g-C₃N₄. BPTCD/g-C₃N₄-60% was able to effectively degrade MO solution (10 mg/L) to 99.9% and 82.8% in 60 min under full spectrum and visible light. The TOC measurement results indicate that MO can ultimately be decomposed into H₂O and CO₂ through photocatalytic action. The photodegradation of methyl orange by BPTCD/g-C₃N₄ composite materials under sunlight is mainly attributed to the successful construction of the heterojunction structure and its excellent π-π stacking effect. Superoxide radicals (^•O₂⁻) were found to be the main active species, while ^•OH and h⁺ played a secondary role. The synthesised BPTCD/g-C₃N₄ also showed excellent stability in the activity of photodegradation of MO in wastewater, with the performance remaining above 90% after three cycles. The mechanism of the photocatalytic removal of MO dyes was also investigated by the trap agent experiments. Additionally, BPTCD/g-C₃N₄-60% demonstrated exceptional photodegradation performance in the degradation of methylene blue (MB). BPTCD/g-C₃N₄ heterojunctions have great potential to degrade organic pollutants in wastewater under solar irradiation conditions. Full article

This study explores the enhanced photocatalytic performance of boron-doped zinc oxide (ZnO) nanoparticles synthesized via a scalable mechanochemical route. Utilizing X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), the structural and morphological properties of these nanoparticles were assessed. Specifically, nanoparticles with 1 wt%, 2.5 wt%, and 5 wt% boron doping were analyzed after calcination at temperatures of 500 °C, 600 °C, and 700 °C. The obtained results indicate that 1 wt% B-ZnO nanoparticles calcined at 700 °C show superior photocatalytic efficiency of 99.94% methyl orange degradation under UVA light—a significant improvement over undoped ZnO. Furthermore, the study introduces a predictive model using the artificial neural network (ANN) technique, developed in Python, which effectively forecasts photocatalytic performance based on experimental conditions with R² = 0.9810. This could further enhance wastewater treatment processes, such as heterogeneous photocatalysis, through ANN-guided optimization. Full article

The green-chemical preparation of silver nanoparticles (AgNPs) offers a sustainable and environmentally friendly alternative to conventional synthesis methods, thereby representing a paradigm shift in the field of nanotechnology. The biological synthesis process, which involves the synthesis, characterization, and management of materials, as well as their further development at the nanoscale, is the most economical, environmentally friendly, and rapid synthesis process compared to physical and chemical processes. Ligustrum ovalifolium flower extract was used for the preparation of AgNPs. The synthesized AgNPs were examined by using UV–visible spectroscopy, XRD, SEM, and TEM analysis. It indicates that AgNPs were formed in good size. AgNPs were applied as a catalyst for the degradation of pollutants, such as methyl orange, Congo red, and methylene blue, which were degraded within 8–16 min. Additionally, the reduction of para-nitrophenol (PNP) to para-aminophenol (PAP) was achieved within 2 min. This work demonstrates a practical, reproducible, and efficient method for synthesizing cost-effective and stable AgNPs, which serve as active catalysts for the rapid degradation of hazardous organic dyes in an aqueous environment. Full article