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Cyanide degradation in aqueous solution by heterogeneous photocatalysis using boron-doped zinc oxide
摘要： The photocatalytic activity of boron-doped ZnO with varying concentration (1, 1.5 and 2% wt of B) synthesized by sol-gel method was evaluated on cyanide (CN-) degradation in aqueous solution under simulated solar radiation. The obtained catalysts were characterized by XRD, UV-Vis/DRS, ICP-OES, FT-IR, and XPS. The photocatalytic experiments were carried out in a quartz batch reactor using 300 mL of cyanide solution adjusted at pH 11, evaluating different parameters such as the amount of B dopant, catalyst loading and initial concentration of cyanide solution. A 23 central composite faced design was used to maximize CN- photocatalytic degradation. The cyanide concentration was measured by ISE potentiometric method and the content of intermediate ions (OCN?, NO3?, and NH4+) was determined by UV-visible spectrophotometry. The boron incorporation into ZnO lattice (ZnO-B) reduced wurtzite crystallite size (25 nm) and narrowed band gap (3.0 eV) compared to bare ZnO (43 nm and 3.2 eV, respectively). The ZnO-B 1.5 wt% showed better photocatalytic performance by degrading 89% of a 10 mg L-1 CN- solution compared to 75% that was reached by undoped ZnO; using in both cases 1.4 g L-1 of catalyst loading at accumulated energy of 400 kJ m-2.
关键词： central composite faced design,ZnO-B,sol-gel,cyanate,cyanide
更新于2025-09-23 15:21:21
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Composition analysis of Ta <sub/>3</sub> N <sub/>5</sub> /W <sub/>18</sub> O <sub/>49</sub> nanocomposite through XPS
摘要： A characterization of a nanocomposite material consisting of Ta3N5 nanoparticles and W18O49 nanowires is presented. The material is of interest for photocatalytic applications, with a focus on pollution reduction through the photodegradation of dye waste; under white light illumination, the combination of Ta3N5 and W18O49 yielded an enhanced rate of dye degradation relative to Ta3N5 particles alone. The facile method of synthesis is thought to be a promising route for both upscale and commercial utilization of the material. X-ray photoelectron spectroscopy revealed a core–shell composite structure with W18O49 present as an overlayer on Ta3N5; the analyzed spectra for the C 1s, O 1s, Ta 4f, N 1s, W 4f, and Na 1s regions are reported. It should be noted that due to differential charging of the underlying Ta3N5 component relative to the W18O49 shell, an additional uncompensated voltage shift may exist in the Ta 4f and N 1s spectra.
关键词： x-ray photoelectron spectroscopy,XPS,dye degradation,W18O49,nanowires,composite,Ta3N5,photocatalysis
更新于2025-09-23 15:21:21
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Engineering of ZnO/rGO nanocomposite photocatalyst towards rapid degradation of toxic dyes
摘要： ZnO quantum dot (QD) is prepared in a soft chemical route by ageing process and successfully embedded on reduced graphene oxide (rGO) surface using solvothermal method as confirmed by XRD, TEM and Raman studies. Due to charge transfer from the lowest unoccupied molecular orbital of the rGO layer to the conduction band of ZnO, the luminescence of rGO is also found to be quenched in ZnO/rGO composites. A brief systematic study of photocatalytic behavior towards degradation of various toxic medical and textile dyes, like Safranin O, Methylene blue and Rhodamine 6G by ZnO QD and ZnO/rGO composites are showcased in this work. As a result of high surface to volume ratio, ZnO QD showed good photocatalytic activity towards degradation of different dyes under ultraviolet (UV) irradiation. A composite with ZnO and rGO in 3:1 wt ratio degraded almost 100% of dyes under UV irradiation within 15, 25 and 30 min, showing good efficacy in dye degradation. Photoluminescence lifetime measurement revealed the charge transfer process from rGO to ZnO resulting a Prompt recombination of the UV light induced electron-hole pair in ZnO/rGO composite.
关键词： Reduced graphene oxide,ZnO QD,Composite,Toxic dyes,Photocatalyst
更新于2025-09-23 15:21:21
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Effect of the photoactivation method on composite resin cure.
摘要： For composite resins to obtain good properties, they must present a high degree of conversion and minimal polymerization contraction. To minimize this contraction, alternative photoactivation techniques have been suggested. The objective of this study was to compare the hardness of a photoactivated composite resin using the pulse-delay, soft start and conventional techniques, in thicknesses of 1, 2 and 3 mm in the irradiated surface and in the opposite surface. Photoactivation was performed with halogen light for 20 seconds in the conventional and soft start techniques. In the pulse-delay technique, each increment of 1 mm was photoactivated for 3 seconds with a final photoactivation of 40 seconds. The samples were stored in an oven at 37°C for one week and submitted to the Vickers microhardness test. The results were submitted to ANOVA and the Tukey’s test with a level of significance of 5%. It was concluded that the hardness was higher with photoactivation of 40 seconds, and for the techniques that had the photoactivation time of 20 seconds (conventional and soft start), there was no difference in terms of hardness. Therefore, the hardness is not influenced by the technique, but rather, by the polymerization time.
关键词： Polymerization,Hardness,Composite Resin
更新于2025-09-23 15:21:21
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Effects of TiC on the microstructure and properties of TiC/TiAl composite coating prepared by laser cladding
摘要： In order to study the effect of TiC on the microstructure and properties of cladding coatings, TiC/TiAl composite coatings have been prepared by using a laser cladding technique on TiAl alloy, and the microstructure and properties of the resulting composite coatings have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-hardness testing, X-ray stress measurements, friction and wear testing, and an electrochemical workstation. The results showed that when the particle size of TiC is up to micron, the growth of TiC is more developed, the dendrite growth direction is disordered, and the cladding quality is poor. When the particle size of TiC is nanoscale, the morphology of the reinforcement phase TiC is mainly granular and thin rods, which is uniform in the coating and the direction of growth is regular. When the concentration of TiC reaches 20%, the microstructure of the cladding layer grows well and is dense. The microhardness and wear resistance of the coatings prepared by adding nano TiC are better than those of the coatings prepared by micron TiC. When the content of nano TiC in the coatings increases from 10% to 20%, the microhardness and wear resistance of the coatings are obviously improved. The residual stress of the coating is positively related to the crack rate. The residual stress in the coating is tensile stress, and the crack type is the crystal crack in the hot crack. When the particle size of TiC is small and the concentration is high, the coating shows better corrosion resistance.
关键词： TiAl alloy,TiC/TiAl composite coating,Laser cladding,Properties,Microstructure
更新于2025-09-23 15:21:21
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Zinc oxide array/polyurethane nanocomposite coating: Fabrication, characterization and corrosion resistance
摘要： Novel zinc oxide (ZnO) array/polyurethane (PU) nanocomposite coatings on the stainless steel substrates was fabricated via a simple process. ZnO arrays were prepared using zinc nitrate and hexamethylenetetramine by a seed growth method, followed by the spinning of PU. The morphologies, structure, wettability, mechanical performance and infrared radiation properties were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, surface contact angle, nano indentation and infrared radiation tests. The corrosion properties of the ZnO array/PU nanocomposite coating were evaluated by the electrochemical tests. The results showed that the ZnO arrays were hexagonal wurtzite and well dispersed in the composite coatings, resulting in slight increase in hydrophilicity. The mechanical properties of the coatings were improved with increased content of the ZnO arrays. The as-prepared ZnO array/PU nanocomposite coatings exhibited excellent corrosion resistance. The infrared radiation performance was observed to be slightly improved as well. It is believed that the unique organic/inorganic nanocomposite coating offers the effective strategy and potential applications for designing the functional coatings of good corrosion resistance and mechanical properties in various polymer systems.
关键词： PU,Composite,Corrosion,ZnO array
更新于2025-09-23 15:21:21
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Role of ion energy flux on the structural and morphological properties of silicon oxy-nitride composite films deposited by plasma focus device
摘要： Crystalline silicon oxy-nitride (SiON) composite films are deposited on Si substrate for multiple (5, 15, 25 and 50) focus shots (FS) by plasma focus device. The X-rays diffraction patterns reveal the development of various diffraction peaks related to Si, Si3N4, and SiO2 phases which confirms the formation of SiON composite film. The intensity of Si3N4 (1 0 2) plane is linearly increased with the increase of FS. The Si3N4 (1 0 2) phase does not nucleate for 5 FS. Raman analysis confirms the formation of β–Si–N phase. Raman and Fourier transform infrared spectroscopy analysis reveals that the strength of chemical bonds like Si–N, Si–O formed during the deposition process of SiON composite films is associated with the bonds intensity which in turn depends on the number of FS. The field emission scanning electron microscopic analysis reveals that the surface morphology like size, shape and distribution of micro/nano-dimensional particles, film compactness and the formation of micro-rods, micro-teethes and micro-tubes of SiON composite films is entirely associated with the rise in substrate surface transient temperature which in turn depends on the increasing number of FS. The EDX spectrum confirms the presence of Si (22.5 ± 4.7 at. %), N (13.4 ± 4.5 at. %) and O (54.7 ± 11.3 at. %) in the SiON composite film. The thickness of SiON composite film deposited for 50 FS is found to ～ 15.47 μm.
关键词： composite,crystallite size,micro-tubes,Plasma focus,thickness,XRD
更新于2025-09-23 15:21:21
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Ionic Liquid Stabilized Gelatin-Lignin Films: A potential UV Shielding Material with Excellent Mechanical and Antimicrobial Properties
摘要： Significant research is going on to develop environmental friendly UV shielding materials. Herein, we have constructed choline citrate (a bio-based ionic liquid, IL) stabilized homogeneous gelatin-lignin UV shielding films with excellent antimicrobial and mechanical properties. Synthesis procedure of films is less energy demanding, one pot and sustainable in nature. Prepared films are characterized for its mechanical and thermal analysis using UTM and TGA respectively. ATR-IR and PXRD is employed to explore the possible formation of H-bonding between biopolymers and IL and change in crystallinity in films after addition of IL to gelatin-lignin matrix. Surface morphology of prepared films has been studied using optical microscope, AFM and FE-SEM. Optical properties of prepared films are measured using UV-Visible spectroscopy. Antimicrobial activity of prepared films has been tested against Bacillus subtilis.Prepared bio-films have shown sun protection factor (SPF) up to ~ 45.0, large elongation ~200% and tensile strength ~70 MPa, which are as good as exhibited by organic polymeric films, indicating a promising renewable resources-based material for UV-light-blocking.
关键词： UV blocking material,Composite,biomass,lignin gelatin composite,ionic liquids
更新于2025-09-23 15:21:01
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Tunable luminescence and transmittance nature of CdS:PMMA nanocomposites for optoelectronic applications
摘要： Optical and energy storage materials based on semiconductors are of great interest today. The present report explains the semiconductor nanocomposite centered on highly transparent Poly(methyl methacrylate) (PMMA) matrix and Cadmium Sulphide (CdS) nano particles. The solid ?lms of CdS:PMMA composite was prepared using simple and cost e?ective solution casting technique. The surface morphology and the presence of CdS particles in PMMA matrix was analysed using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectra (EDX). The size of the particles was analysed using Atomic Force Microscopy (AFM) and Transmission Electron Microscope (TEM) and they revealed the presence of nano sized particles. The narrow size distribution of particles was identi?ed from TEM and AFM analysis. The transmittance of the CdS:PMMA nanocomposite solid ?lms was found to be above 90%. The blue and green emission of CdS:PMMA nanocomposite solid ?lms were observed from Photoluminescence (PL) spectra.
关键词： Composite materials,Polymeric composite,Luminescence,Green emission,Particle distribution,Transmittance
更新于2025-09-23 15:21:01
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Densification behavior, microstructure evolution, and tensile properties of selective laser melting additive manufactured TiB <sub/>2</sub> /AlSi10Mg composite
摘要： The fabrication of TiB2/AlSi10Mg composites by selective laser melting (SLM) additive manufacturing has been conducted. The influence of laser processing parameters on the densification behavior, microstructure evolution, and tensile properties of the SLM-processed composites is addressed. With the increase in laser volume energy density, the densification rate increased and reached 99% at a laser speed of 1000 mm/s. Meanwhile, the TiB2 particles underwent a partial melting behavior with the formation of an irregular pattern in the solidified part and complete melting with the smooth surface of the reinforcing particles as the laser volume energy increased. The cellular-dendritic microstructure and the width of the eutectic phase of the as-fabricated composites were significantly refined due to the high cooling rate and complete melting of the reinforcing particles as the nucleation sites using the laser energy density of 117 J/mm3. Therefore, the micro-hardness, ultimate tensile strength, yielding strength, and elongation of the as-fabricated TiB2/AlSi10Mg composites obtained in this process condition were 131.3 HV0.2, 375 MPa, 260 MPa, and 3.1%, respectively, which were significantly higher than those of the unreinforced AlSi10Mg alloy.
关键词： tensile properties,aluminum-based composite,selective laser melting,microstructure evolution
更新于2025-09-23 15:21:01