Immobilization of TiO2 nanoparticles on activated carbon fiber and its photodegradation performance for organic pollutants

The immobilization of titanium dioxide(TiO2) on activated carbon fiber(ACF),(TiO2/ACF),was accomplished by sol-gel-adsorption method followed by calcination at temperatures varying from 300 to 600℃ in an argon atmosphere.The material properties were determined by scanning electron microscope(SEM),X-ray diffraction(XRD) and nitrogen adsorption.The photodegradation behavior of TiO2/ACF was investigated in aqueous solutions using phenol and methyl orange(MO) as target pollutants.The effects of calcination temperature,photocatalyst dosage,initial solution pH and radiation time on the degradation of organic pollutants were studied.It was found that organic pollutants could be removed rapidly from water by the TiO2/ACF photocatalyst and the sample calcined at 500℃ exhibited the highest removal efficiency.Kinetics analysis showed that the photocatalytic degradation reaction can be described by a first-order rate equation.In addition,the possibility of cyclic usage of the photocatalyst was also confirmed.Moreover,TiO2 is tightly bound to ACF and can be easily handled and recovered from water.It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.     

Progress in the synthesis and applications of hierarchical flower-like TiO2 nanostructures

Flower-like TiO₂ materials, with their advantages of high specific surface area, developed pore structure, and high photocatalytic activity, have been widely used in environmental management and air purification, sterilization, and surface self-cleaning, among other areas. This paper summarizes several methods used to fabricate the flower-like TiO₂ nanostructures, such as the hydrothermal, solvothermal, microemulsion, sol–gel, hydrolysis, and electrodeposition oxidation methods. In addition, the morphologies, properties, and performance of different flower-like TiO₂ structures are discussed. Meanwhile, the application progresses of different flower-like TiO₂ structures are also analyzed.     

In situ synthesis of CNTs/Fe-Ni/TiO2 nanocomposite by fluidized bed chemical vapor deposition and the synergistic effect in photocatalysis

Carbon nanotube(CNTs)/Fe-Ni/TiO_2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition(FBCVD) method.The composite photocatalysts were characterized by XRD,Raman spectroscopy,BET,FESEM,TEM,UV-vis spectroscopy,and XPS.The results showed that the CNTs were grown in situ on the surface of TiO_2.Fe(lll) in TiO_2 showed no chemical changes in the growth of CNTs.Ni(Ⅱ) was partly reduced to metal Ni in the FBCVD process,and the metal Ni acted as a catalyst for the growth of CNTs.The photocatalytic activities of CNTs/Fe-Ni/TiO_2 decreased with the rise of the FBCVD reaction temperature.For the sample synthesized at low FBCVD temperature(500℃),more than 90% and nearly 50% of methylene blue were removed under UV irradiation in 180 min and under visible light irradiation in 300 min,respectively.The probable mechanism of synergistic enhancement of photocatalysis on the CNTs/Fe-Ni/TiO_2 nanocomposite is proposed.     

Immobilization of Ti02 nanoparticles on activated carbon fiber and its photodegradation performance for organic pollutants

The immobilization of titanium dioxide （TiO2） on activated carbon fiber （ACF）, （TiO2/ACF）, was accomplished by sol-gel-adsorption method followed by calcination at temperatures varying from 300 to 600℃ in an argon atmosphere. The material properties were determined by scanning electron microscope （SEM）, X-ray diffraction （XRD） and nitrogen adsorption. The photodegradation behavior of TiO2 /ACF was investigated in aqueous solutions using phenol and methyl orange （MO） as target pollutants. The effects of calcination temperature, photocatalyst dosage, initial solution pH and radiation time on the degradation of organic pollutants were studied. It was found that organic pollutants could be removed rapidly from water by the TiO2/ACF photocatalyst and the sample calcined at 500℃ exhibited the highest removal efficiency. Kinetics analysis showed that the photocatalytic degradation reaction can be described by a first-order rate equation. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. Moreover, TiO2 is tightly bound to ACF and can be easily handled and recovered from water. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.     

TiO2-loaded activated carbon fiber: Hydrothermal synthesis,adsorption properties and photo catalytic activity under visible light irradiation

TiO₂-loaded activated carbon fibers (ACF) were prepared by a hydrothermal method. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry and UV–vis diffuse reflectance spectra (DRS). SEM images showed that the TiO₂ nanoparticles were deposited on the surface of ACF, and the particle size and loading amount of TiO₂ were varied by changing the initial concentration of tetrabutyl titanate (TBOT). The results of an ash experiment showed that the loading amounts of TiO₂ were 18.4%, 43.3%, 52.5%, 75.1%, and 91.1% for initial concentrations of TBOT of 0.07, 014, 0.21, 0.28, and 0.35 mol/L, respectively. Physical interactions played an important role in the formation of TiO₂/ACF composite fibers that absorb UV and visible light. Compared with those of ACF, improved adsorption and photocatalytic activity toward Rhodamine B (RhB) were observed for TiO₂/ACF composite fiber. The Rhodamine B could be removed efficiently by TiO₂/ACF composite fibers, and the TiO₂ loading amount had a significant effect on the photocatalytic activity of TiO₂/ACF composite fibers.     

TiO2-modified nano-egg-shell Pd catalyst for selective hydrogenation of acetylene

Pd-based egg-shell nano-catalysts were prepared using porous hollow silica nanoparticles(PHSNs)as support,and the as-prepared catalysts were modified with TiO2 to promote their selectivity for hydrogenation of acetylene.Pd nanoparticles were loaded evenly on PHSNs and TiO2 was loaded on the active Pd particles.The effects of reduction time and temperature and the amount of TiO2 added on catalytic performances were investigated by using a fixed-bed micro-reactor.It was found that the catalysts showed better performance when reduced at 300 C than at 500 C,and if reduced for 1h than 3h.When the amount of Ti added was 6 times that of Pd,the catalyst showed the highest ethylene selectivity.     

Synthesis of TiO2 nanoparticles by propane/air turbulent flame CVD process

Synthesis of TiO2 nanoparticles by the oxidation of titanium tetrachloride (TiCl4) in high-strength propane/air turbulent flame is investigated tentatively for mass production ofTiO2 nanoparticles. Effects of reactor heat flux varying from 247 to 627 kJ/m2 s, initial TiO2 number density from 2×1020> to 1 × 1021 m-3, and apparent residence time of TiO2 nanoparticles in reactor from 0.06 to 0.9 s, on particle morphology, phase composition, UV absorption and photoluminescence (PL) spectra are studied. The TiO2 nanoparti-cles synthesized, with mean size of 30-80 nm and rutile mass fraction from 0.155 up to 0.575, exhibited a strong PL signal at the wavelength of 370-450 nm, with a wide peak signal at 400-420 nm, reflecting significant oxygen vacancies on the surface of the TiO2 nanoparticles.     

Aeroelastic modeling of wind loading on a cable-net supported glass wall

Wind loading study on a cable-net supported glass wall is conducted by means of wind tunnel tests. An equiva- lent aeroelastic model is designed and constructed. Response of displacements of the wall is measured and analyzed. In order to design a glass wall under wind loading, the ＂wind- vibration factor＂ is estimated and discussed. In fact, the mech- anism of wind acting on the wall is commonly known not only as positive pressure, but also as negative pressure caused by the flow separation on the corners of the building. Due to the diffidence in the mechanism of wind acting, two typi- cal response cases are classified. The results show that the dynamic response of the structure caused by the negative pressure is stronger than that of the positive pressure case. To determine the aerodynamic wind loading on a flexible part of structure on a building, wind tunnel study may be useful and play an important role.     

Optimized synthesis and photovoltaic performance of TiO2 nanoparticles for dye-sensitized solar cell

This paper presents response surface methodology （RSM） as an efficient approach for modeling and optimizing TiO2 nanoparticles preparation via co-precipitation for dye-sensitized solar cell （DSSC） perfor- mance. Titanium （IV） bis-（acetylacetonate） di-isopropoxide （DIPBAT）, isopropanol and water were used as precursor, solvent and co-solvent, respectively. Molar ratio of water, aging temperature and calcina- tion temperature as preparation factors with main and interaction effects on particle characteristics and performances were investigated, Particle characteristics in terms of primary and secondary sizes, crys- tal orientation and morphology were determined by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Band gap energy and power conversion efficiency of DSSCs were used for perfor- mance studies. According to analysis of variance （ANOVA） in response surface methodology （RSM）, all three independent parameters were statistically significant and the final model was accurate. The model predicted maximum power conversion efficiency （0.14%） under the optimal condition of molar ratio of DIPBAT-to-isopropanol-to-water of 1 ： 10：500, aging temperature of 36 C and calcination temperature of 400 ℃. A second set of data was adopted to validate the model at optimal conditions and was found to be 0.14 ± 0.015%, which was very close to the predicted value. This study proves the reliability of the model in identi（ving the optimal condition for maximum performance.     

W骨架/Zr基非晶合金复合材料破片侵彻能力与后效研究

将W骨架/Zr基非晶合金复合材料破片装入弹体制备成预制破片弹丸,并进行实爆试验,研究W骨架/Zr基非晶合金复合材料预制破片侵彻靶板的能力,以及预制破片贯穿靶板后对棉被、油箱的引燃能力。结果表明:制备的W骨架/Zr基非晶合金复合材料密度大、强度高,爆炸完整性和侵彻能力能够满足作为榴弹预制破片的要求;W骨架/Zr基非晶合金复合材料破片侵彻过程中自身变形是影响侵彻能力的主要原因之一;W骨架/Zr基非晶合金复合材料预制破片侵彻和贯穿靶板的过程中伴随着强烈的爆轰,当穿透率足够高时,预制破片的爆轰作用能够引燃靶后的棉被和油箱。     

Facile aqueous synthesis and thermal insulating properties of low-density glass/TiO2 core/shell composite hollow spheres

Anatase TiO2 shells assembled on hollow glass microspheres(HGM)with tunable morphologies were successfully prepared through a controllable chemical precipitation method with urea as the precipitator. Thus,glass/TiO2 core/shell composite hollow spheres with low particle density(0.40 g/cm3)were fabricated.The phase structures,morphologies,particle sizes,shell thicknesses,and chemical compositions of the composite microspheres were characterized by X-ray diffraction(XRD),scanning electron microscopy (SEM),and energy dispersive X-ray spectroscopy(EDS).The morphology of the TiO2 shell can be tailored by properly monitoring the reaction system component and parameters.The probable growth mechanism and fabrication process of the core/shell products involving the nucleation and oriented growth of TiO2 nanocrystals on hollow glass microspheres was proposed.A low infrared radiation study revealed that the radiation properties of the products are greatly influenced by the unique product shell structures. A thermal conductivity study showed that the TiO2/HGM possess low thermal conductivity that is similar to that of the pristine HGMs.This work provides an additional strategy to prepare low-density thermal insulating particles with tailored morphologies and properties.     

Facile aqueous synthesis and thermal insulating properties of low-density glass/TiO2 core/shell composite hollow spheres

Anatase TiO₂ shells assembled on hollow glass microspheres (HGM) with tunable morphologies were successfully prepared through a controllable chemical precipitation method with urea as the precipitator. Thus, glass/TiO₂ core/shell composite hollow spheres with low particle density (0.40 g/cm³) were fabricated. The phase structures, morphologies, particle sizes, shell thicknesses, and chemical compositions of the composite microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The morphology of the TiO₂ shell can be tailored by properly monitoring the reaction system component and parameters. The probable growth mechanism and fabrication process of the core/shell products involving the nucleation and oriented growth of TiO₂ nanocrystals on hollow glass microspheres was proposed. A low infrared radiation study revealed that the radiation properties of the products are greatly influenced by the unique product shell structures. A thermal conductivity study showed that the TiO₂/HGM possess low thermal conductivity that is similar to that of the pristine HGMs. This work provides an additional strategy to prepare low-density thermal insulating particles with tailored morphologies and properties.     

Influence of mixture sensitivity and pore size on detonation velocities in porous media

Experiments have been carried out to determine the dependence of the detonation velocity in porous media, on mixture sensitivity and pore size. A detonation is established at the top end of a vertical tube and allowed to propagate to the bottom section housing the porous bed, comprised of alumina spheres of equal diameter (1–32 mm). Several of the common detonable fuels were tested at atmospheric initial pressure. Results indicate the existence of a continuous range of velocities with change in Φ, spanning the lean and the rich propagation limits. For all fuels in a given porous bed, the velocity decreases from a maximum value at the most sensitive mixture near Φ≈1 (minimum induction length), toV/V _CJ≈0.3 at the limits. A decrease in pore size brings about a reduction inV/V _CJ and a narrowing of the detonability range for each fuel. For porous media comprised of spherical particles, it was possible to correlate the velocity data corresponding to a variety of different mixtures and for a broad range of particle sizes, using the following empirical expression:V/V _CJ=[1–0.35 log(d _c /d _p)]±0.1. The critical tube diameterd _c is used as a measure of mixture sensitivity andd _p denotes the pore diameter. An examination of the phenomenon at the composition limits, suggests that wave failure is controlled by a turbulent quenching mechanism.     

Conductive hydrogels incorporating carbon nanoparticles: A review of synthesis,performance and applications

As one of the most rapidly expanding materials, hydrogels have gained increasing attention in a variety of fields due to their biocompatibility, degradability and hydrophilic properties, as well as their remarkable adhesion and stretchability to adapt to different surfaces. Hydrogels combined with carbon-based materials possess enhanced properties and new functionalities, in particular, conductive hydrogels have become a new area of research in the field of materials science. This review aims to provide a comprehensive overview and up-to-date examination of recent developments in the synthesis, properties and applications of conductive hydrogels incorporating several typical carbon nanoparticles such as carbon nanotubes, graphene, carbon dots and carbon nanofibers. We summarize key techniques and mechanisms for synthesizing various composite hydrogels with exceptional properties, and represented applications such as wearable sensors, temperature sensors, supercapacitors and human-computer interaction reported recently. The mechanical, electrical and sensing properties of carbon nanoparticles conductive hydrogels are thoroughly analyzed to disclose the role of carbon nanoparticles in these hydrogels and key factors in the microstructure. Finally, future development of conductive hydrogels based on carbon nanoparticles is discussed including the challenges and possible solutions in terms of microstructure optimization, mechanical and other properties, and promising applications in wearable electronics and multifunctional materials.     

纳米TiO2改性玻璃纤维织物复合材料的摩擦磨损性能研究

采用玄武三号栓-盘式摩擦磨损试验机研究了纳米TiO2和硅烷偶联剂改性玻璃纤维织物的摩擦磨损性能;用配备X射线能量色散谱仪的扫描电子显微镜观察和分析了复合材料磨损表面形貌以及纳米TiO2在粘结剂中的分散情况.结果表明,纳米TiO2和硅烷偶联剂改性玻璃纤维织物可明显改善玻璃纤维织物的摩擦磨损性能,当纳米TiO2的质量分数为5%时,改性玻璃纤维织物的摩擦磨损性能最佳,其磨损率比纯玻璃纤维织物低60%,且其最大承载能力提高.温度对纳米TiO2改性玻璃纤维织物的摩擦磨损性能影响很大,当温度高于200 ℃时,其摩擦系数开始增大、磨损加剧;当温度达到240 ℃时,纳米TiO2改性玻璃纤维织物因发生严重磨损而失效.     

SiO2-coated pure anatase TiO2 catalysts for enhanced photo-oxidation of naphthalene and anthracene

Our current efforts reveal the preparation of SiO₂@TiO₂ nanocomposites having different thicknesses of silica shell and the relationship to photocatalytic activity (PCA) for the photo-oxidation of naphthalene and anthracene. The presence of SiO₂ coating over TiO₂ surface was demonstrated by FT-IR analysis, with peaks corresponding to SiOSi (1081 cm⁻¹) and SiOTi (950 cm⁻¹) bonds observed. High-resolution transmission electron microscopy analysis confirmed the presence of SiO₂ in the as-prepared nanocomposites and the amount of Si, Ti, and O was determined by energy dispersive X-ray spectroscopy analysis. Increasing the SiO₂ shell thickness increases the surface area of the nanocomposites (69–235 m²/g), which enhances naphthalene/anthracene adsorption. However, the observed PCA trend presents an inverse correlation to the adsorption studies, where the as-prepared samples possessing the highest surface areas exhibited the least PCA, while catalysts having lower surface areas (among silica coated samples) displayed the highest PCA in the degradation of naphthalene and anthracene to CO₂. Despite complete degradation of naphthalene and anthracene, incomplete mineralization occurred, ascribed to the formation of various intermediates, identified by GC–MS analysis.     

Green synthesis,characterization and physiological stability of gold nanoparticles from Stachys lavandulifolia Vahl extract

The synthesis of nontoxic stable gold nanoparticles is important for medical applications. An aqueous extract of the plant Stachys lavandulifolia Vahl was used to synthesize gold nanoparticles. This green method involved the S. lavandulifolia Vahl extract acting as a reducing and stabilizing agent. The nanoparticles were characterized by transmission electron microscopy, dynamic light scattering analysis and UV–vis absorption and Fourier transform-infrared spectroscopies. Stability under physiological conditions is important for medical applications. The stability of the nanoparticles was compared with that of conventional citrate-capped nanoparticles, under both synthetic and physiological conditions. The nanoparticles synthesized from the S. lavandulifolia Vahl extract were stable under physiological conditions, in contrast with conventional citrate-capped nanoparticles.     

Capuli cherry-mediated green synthesis of silver nanoparticles under white solar and blue LED light

In this article, the Capuli (Prunus serotina Ehrh. var. Capuli) cherry extract was used for the synthesis of silver nanoparticles (AgNPs) in the presence of white/visible solar and blue light-emitting diode (LED) light. For the characterization of the extract and the AgNPs, Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy were employed, along with hydrodynamic particle size analysis, transmission electron microscopy and X-ray diffraction. The Ag nanospheres obtained using white light were 40–100 nm in diameter and exhibited an absorption peak at λ_max = 445 nm, whereas those obtained using blue LED light were 20–80 nm in diameter with an absorption peak at λ_max = 425 nm. Thermal analysis revealed that the content of biomolecules surrounding the AgNPs was about 55–65%, and it was also found that blue LED light AgNPs (56.28%, 0.05 mM) had a higher antioxidant efficacy than the white solar light AgNPs (33.42%, 0.05 mM) against 1,1-diphenyl-2-picrylhydrazyl. The results indicate that obtaining AgNPs using a blue LED light may prove to be a simple, cost-effective and easily reproducible method for creating future nanopharmaceuticals.     

Combined effect of thermal modulation and rotation on the onset of stationary convection in a porous layer

The stability of a fluid-saturated horizontal rotating porous layer subjected to time-periodic temperature modulation is investigated when the condition for the principle of exchange of stabilities is valid. The linear stability analysis is used to study the effect of infinitesimal disturbances. A regular perturbation method based on small amplitude of applied temperature field is used to compute the critical values of Darcy–Rayleigh number and wavenumber. The shift in critical Darcy–Rayleigh number is calculated as a function of frequency of modulation, Taylor number, and Darcy–Prandtl number. It is established that the convection can be advanced by the low frequency in-phase and lower-wall temperature modulation, where as delayed by the out-of-phase modulation. The effect of Taylor number and Darcy–Prandtl number on the stability of the system is also discussed. We found that by proper tuning of modulation frequency, Taylor number, and Darcy–Prandtl number it is possible to advance or delay the onset of convection.     

Biogenic synthesis of silver nanoparticles using Persicaria odorata leaf extract: Antibacterial,cytocompatibility, and in vitro wound healing evaluation

Biogenic synthesis of silver nanoparticles (b-AgNPs) utilising plant extract has gained the interest of researchers due to the environmentally friendly and cost-effective technique. However, the extent of its application in the biomedical field remains scarce. This study evaluates the antibacterial, cytocompatibility, and wound healing activities of synthesised AgNPs using Persicaria odorata leaves extract (PO-AgNPs). The formation of PO-AgNPs was observed by visual colour changes and verified by ultraviolet-visible (UV–vis) spectrophotometer, which revealed a surface plasmon resonance (SPR) at around 440 nm, and further confirmed by X-ray diffraction (XRD). Characterisation using Fourier transform infrared (FTIR) spectroscopy showed biomolecules from the leaves extract presented together on PO-AgNPs. Field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscopy (HR-TEM) images revealed PO-AgNPs nanospheres with diameters of 11 ± 3 nm. Disc diffusion test (DDT) and minimum inhibitory concentration (MIC) analysis resulted in a dose-dependent inhibition of PO-AgNPs against tested Staphylococcus epidermidis and Methicillin-resistant Staphylococcus aureus (MRSA). These results were further corroborated by time-kill kinetic assay which revealed that PO-AgNPs were bactericidal against both strains 24 h post-treatment. Cytocompatibility and in vitro wound healing evaluation against normal human fibroblast cells, HSF 1184 inferred that PO-AgNPs are non-toxic to normal cells and able to enhance cell migration as compared to the non-treated cells. Therefore, PO-AgNPs are biocompatible and possess antibacterial and wound healing capabilities that are useful in biomedical applications.