In the present study, highly dispersed Co-MCM-41 catalysts have been prepared by a novel two-step method consisting of the co-condensation and the template ion exchange. The samples are characterized by ICP–AES, UV-vis, N2-adsorption and XRD, respectively, and evaluated by the epoxidation of styrene using molecular oxygen as oxidant. The typical samples have the pore structure and phase characteristics of MCM-41 mesoporous molecular sieve. Introducing methyl or ethyl into MCM-41 can really increase the Co dispersity of the final Co-MCM-41 and accordingly improve its catalytic performance. Higher Co dosages will give rise to higher Co/Si in final catalysts and better catalytic performance to an appropriate extent. Among the catalysts, the sample with a dosage of 0.05 methyl/Si and a dosage of Co/Si of 0.02 performs best in catalytic epoxidation of styrene. The sample results in a highest Yield of styrene oxide of 29.0
To enhance the tribological property of Ti-6Al-4V alloy, a chemically bonded phosphate ceramic coating (CBPC) reinforced by oriented ferroferric oxide-hexagonal boron nitride (Fe3O4/h-BN) was fabricated via a weak magnetic field. FTIR, TEM, SEM, and EDS were employed to systematically investigate the structural evolution of Fe3O4/h-BN hybrids. Furthermore, the wear resistance of CBPC was assessed through tribological tests, supported by microstructure and phase characterization. The results demonstrate that increasing the Fe3O4/h-BN hybrid content significantly reduces both the friction coefficient and wear rate of CBPC. Additionally, CBPC with aligned h-BN exhibits superior wear resistance compared to coatings containing randomly dispersed h-BN. This enhancement arises from three key mechanisms: Firstly, the magnetic-field-induced alignment of h-BN platelets facilitates efficient stress distribution, reducing localized wear damage. Secondly, the hybrid structure promotes the generation of a protective lubricating film during friction, which reduces shear forces and abrasive wear. Thirdly, within an optimal range, higher h-BN loading promotes coating densification, leading to superior wear resistance. These findings highlight the potential of coating with magnetically aligned structures for developing high-performance, wear-resistant materials in industrial applications.
The sono-electrolytic system is complex in terms of heterogeneous fluid flows, particularly due to simultaneous formation and collapse of acoustic cavitation bubbles within an aqueous electrolyte, the evolution of H2 and O2 gases on the electrodes, and the overall bubbling phenomenon. The present study presents a numerical design to investigate the effect of sonication on PV-supplied alkaline electrolysis through a parametric modelling and simulation of the variation of the electrolyte resistance and the kinetics of hydrogen production as functions of bubble degassing, the diffusion coefficient and the Faraday efficiency. The model has been validated through a comparative analysis with experiments. Based on the effect of ultrasound on the diffusion coefficient, the analysis demonstrated that the influence of ultrasound cannot be attributed to an enhancement of mass diffusion. If such an effect exists, its extent remains negligible. Furthermore, the effect of ultrasounds cannot be explained by a change in Faraday efficiency. The comparison of experimental and simulation results shows that the Faraday efficiency remains consistently equal to unity regardless of the presence or absence of ultrasounds. In conclusion, sonication role in sono-electrolysis process is rather due to the degassing effect and hence the reduction of electrode bubble coverage, the bubble resistance, and consequently, the overall ohmic resistance.
Comparative analysis of membrane materials was provided for the recovery of volatile organic compounds (VOCs) from vapor-gas mixtures generated during petroleum product loading operations. Mathematical modeling of membrane separation in a countercurrent mode was used to evaluate the effectiveness of two different membranes: polydecylmethylsiloxane (C10) and polydimethylsiloxane (PDMS), for recovery n-octane vapors, a model component limiting mass transfer during gasoline fraction recovery. Calculations were performed for a rail tank car loading and unloading process with a capacity of 830 m3/h and a target VOC recovery rate of 90
A thermodynamic analysis of the conditions for Fe2O3 reduction during downdraft gasification of coal and low-grade ore mixture was performed under conditions characteristic of the high-temperature zone of downdraft-type gasifier reactors, using the commercial TERRA code for calculating thermochemical equilibria in the range of 800–1600 K. A complete reduction of iron is impossible with the stoichiometric ratio of reducing gas excess χ < 2. The quantitative reduction of Fe2O3 to metallic iron is achieved at χ ≥ 3 and temperature over 1000 K.
This study investigates castor oil biodiesel as a sustainable, second-generation alternative to conventional diesel, focusing on its production, characterization, and engine performance. Biodiesel was synthesized via transesterification, achieving a 64
The problem of indoor air purification is becoming increasingly relevant every year. Among devices, filters based on dielectric fibers stand out, which capture precharged aerosol particles in the filtered air flow. In this study, we demonstrate the influence of the configuration of the grounding electrode located in the filter for removing excess charge to ensure safe filter operation on the filter efficiency in capturing NiO aerosol particles. This study proposes a method for measuring the total charge and local potential of dielectric polypropylene fiber filters. It has been shown that placing the grounding electrode closer to the outer surface results in significant potential non-uniformity, with the potentials between the electrode turns being approximately three times higher than those above the turns. This disparity directs charged particles toward low-potential zones, reducing overall efficiency. Conversely, shortening the electrode and embedding it deeper promotes uniform surface potential and maximizes total charge, which provide the lowest penetration rates for NiO particles (0.23 and 0.14
Polyvinyl acetate (PVAc) water-resistant adhesives are one of the most utilized in the wood industry and classified as D3 durability, exhibiting superior resistance to water and heat when compared to typical Polyvinyl acetate (PVAc) thermoplastic items. The synthesized adhesives by conventional methods were dependent on using inorganic salts, such as aluminum chloride and/or other specific metal via emulsion polymerization seeking to enhance the durability against water and heat. The present investigation aims to improve the durability of polyvinyl acetate (PVAc) to class D3 in accordance with European Standards related to wood adhesives “EN204-205”, through emulsion polymerization using core/shell technique. In this method, vinyl acetate was used as specific shell monomer with a mixture of Veova 10 and methyl acrylic acid in very limited ratio as core and ethylene glycol dimethacrylate (EGDMA) as cross-linker. The morphology was investigated by TEM microscopy and FTIR, thermogravimetric analysis was carried out to investigate the heat resistance characteristics. The results showed high water and heat resistance compliments the EN204-205 specifications.
This study aims to optimize the synthesis parameters of iron-exchanged bentonite catalysts prepared by solid phase and liquid phase ion exchange methods for photo-Fenton degradation of methylene blue. A central composite design was employed to investigate the effects of temperature, time, and iron-to-bentonite ratio on the photo-Fenton activity of the synthesized catalysts. The results showed that the optimized catalysts exhibited high decolorization efficiency, with removal percentages of up to 85
A series of Ag-containing catalysts for CO oxidation based on CeO2–Fe2O3@SBA-15 composites synthesized by salt encapsulation in the hybrid material Pluronic-P123@SBA-15 was obtained. The effect of a block copolymer of polyethylene glycol and polypropylene glycol Pluronic-P123 inside the SBA-15 structure (ordered mesoporous silicon dioxide) on the distribution and dispersion of the deposited CeO2 and Fe2O3 components is shown. The deposition of cerium and iron oxides on Pluronic@SBA-15 makes it possible to stabilize CeO2 and Fe2O3 in the form of highly dispersed particles evenly distributed on the surface of the carrier. It was shown that the use of CeO2 and Fe2O3 stabilized in the SBA-15 structure makes it possible to increase the activity of Ag-containing catalysts in the CO oxidation reaction compared with the Ag/SBA-15 catalyst.
With the help of physicochemical methods (viscometry, UV spectroscopy, dynamic light scattering and scanning electron microscopy), the viscosity and structural characteristics of solutions and hydrogels based on L-cysteine and silver nitrate (cysteine–silver solution, CSS) and polysaccharide carrageenan (CAR) are studied. It is found that transparent, stable over time CSS–CAR solutions are formed, if CAR concentration in the samples is varied in the range of 0.0010–0.0030 mg/mL. We assume that association of opposite charged chain structures of cysteine–silver solution with CAR macromolecules due to electrostatic interactions takes place in CSS–CAR samples. Addition of an electrolyte (CuSO4) into CSS–CAR solution initiates gelation, electrolyte ions join as a linker CSS cluster chains, the same as in CSS–CuSO4 gels. A scheme of self-assembly and gelation in CSS–CAR and CSS–CAR–CuSO4 hydrogels is suggested.
Rhodamine B (RhB) is a widely used organic dye, but its high toxicity and recalcitrance pose a significant threat to water environments and ecosystems. Photocatalysis, as a green and efficient water treatment technology, has demonstrated great potential in the degradation of RhB. This review systematically summarizes the research progress on photocatalytic degradation of RhB globally, with a focus on the development of photocatalytic materials, reaction mechanisms, and strategies for performance optimization. It also discusses the existing problems and challenges in current research and provides an outlook on future development directions.
Active and eco-friendly bionanocomposite films were developed using plasticized cellulose acetate butyrate (CAB) as the matrix. Silver nanoparticles doped-zeolite (AgZ) and thymol (Th) were incorporated at varying concentrations to serve as antibacterial and antioxidant bioactive components, respectively. The results revealed the formation of silver nanoparticles (AgNPs) within a zeolite framework with a face-centered cubic crystalline structure. While the films containing AgNPs showed a slight decrease in transparency, they exhibited significantly improved UV-blocking properties, and reduced water solubility and water vapor permeability mostly in M/AgZ5
Click chemistry, exemplified by the copper-catalyzed azide-alkyne cycloaddition (CuAAC), is a pivotal technique in modern synthetic chemistry for its efficiency, selectivity, and mild reaction conditions. This method is forming 1,2,3-triazole rings from azides and alkynes, thus aiding in the synthesis of complex molecules. In this study, we exploit CuAAC to synthesize and characterize 2-oxo-1-((1-phenyl-1H-1,2,3-triazol-4-yl)methyl)-1,2-dihydroquinoline-3-carbaldehyde derivatives (7a–7t). These compounds were synthesized by reacting quinoline-based precursors with azidobenzene derivatives in the presence of a copper catalyst. We meticulously optimized reaction conditions, leading to a maximum yield of 96
In this work, the corrosion behavior of AA 5052 aluminum alloy, a candidate material for nuclear fuel cladding, was studied using potentiometry, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) in three electrolytes (NaCl, H3BO3, and Na2SO4) at two temperatures (25 and 38°C). The corrosion products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the corrosion potentials (Ecorr) of AA 5052 in Na2SO4 and H3BO3 electrolytes are similar and higher than that of AA 5052 in NaCl electrolyte. Depending on the potential and chemical composition of the electrolyte (presence or absence of H2BO3–, Cl–, and SO42– anions), passivation and different types of corrosion (pitting, uniform, and partial corrosion) occurred for AA 5052. In Na2SO4 and H3BO3 electrolytes, AA 5052 exhibits acceptable passivation behavior: the passivation current density (ipass) is low, and the passivation potential range (ΔEpass) is extended. However, in NaCl electrolyte, the passive layer is not very stable: ipass is high, and ΔEpass is limited. Additionally, the stability of the passive layer decreases with increasing NaCl concentration. In all three electrolytes, the passivation current density (ipass) and corrosion current density (icorr) increase, and the passivation potential range (ΔEpass) is limited when the temperature increases from 25 to 38°C.
This study presents a dynamic numerical model of a hybrid membrane desalination system that combines evaporation module and condensation in hollow fibre membranes contactor. Developed in MATLAB/Simulink, the model accounts for unsteady heating and a closed gas circulation loop. A quasi-steady condenser module was first validated against experimental literature data, demonstrating less than 8
The pollution control of polyethylene terephthalate (PET) and the resource utilization of waste biomass are important issues for sustainable development. This study uses discarded oyster shell biomass after consumption as a precursor to prepare highly active calcium oxide-based catalysts through high-temperature calcination, achieving synergistic governance of “treating waste with waste.” The thermal stability, microscopic morphology and crystalline structure of the oyster shell matrix were systematically characterized through TGA, SEM, and XRD, and the correlation mechanism between the catalytic activity and physical and chemical properties was clarified. Based on single-factor experimental results, the response surface methodology (RSM) was used to optimize the PET glycolysis process in a multivariate way, and a mathematical model was established by combining with the Design–Expert software to quantify the interactions of the parameters of reaction temperature (199℃), time (3.8 h), ethylene glycol dosage (16 mL), and catalyst dosage (0.39
This work presents a detailed study of an industrial CuCr catalyst used to produce furfuryl alcohol from furfural. The catalyst was tested in a flow-type reactor under two modes: gas-phase and liquid-phase. We determined the optimal process parameters: T = 100°C, PH2(excess) = 0.4 atm for gas-phase and PH2 = 50 atm for liquid-phase, Vcat = 4.00 cm³, dgrain = 1.00–0.80 mm, mixture with quartz 1: 1 (vol.), GHSV = 265 h–1 (LHSV = 1 h–1), furfural: H2 ratio = 1 : 20 (vol.), and conducted long-term tests (50–100 h). The catalyst demonstrated high stability in the liquid-phase process and exhibited excellent reaction parameters 100
A study was conducted of ultrafiltration separation of a water-in-oil emulsion based on I-20A oil using polyethersulfone membranes with a cut-off particle mass of 10–300 kDa. The water-in-oil emulsion composition was as follows,
A promising direction for modifying the properties of electrodeposited coatings is the use of non-stationary electrolysis and the introduction of an additional alloying component. The effect of the reverse potential polarization mode parameters on the composition and corrosion resistance of Zn–Ni, Zn–Ni–Co alloys was studied. The coatings were deposited on a steel support (St45) in a sulfate-glycinate solution. The alloys were studied by X-ray diffraction, X-ray fluorescence and gravimetric analysis, scanning electron microscopy. It is established that the use of the reverse electrolysis mode contributes to the production of finer crystalline coatings with a high Ni content in the alloy. The inclusion of Co in the Zn–Ni alloy, the use of the reverse polarization mode contributes to an increase in its corrosion resistance by 2 times at a thickness of 5‒10 μm.
