Silver nanoparticles have good sterilization performance due to their small size and large specific surface area, while the small size also brings about reunification and reduces the sterilization activity. To resolve the problem, magnesium hydroxide [Mg(OH)2] microsphere was designed as a supported material to load silver particles on its surface. Mg(OH)2 microspheres were successfully synthesized under the control of a biotemplate of eggshell membrane. X-ray diffraction, thermal gravimetric analysis/differential scanning calorimetry, and transmission electron microscopy were performed to characterize the Mg(OH)2 microspheres. The results indicate that the Mg(OH)2 microspheres of average size ~ 2 μm were formed from nanoflakes. The silver nanoparticles were loaded on the surface of Mg(OH)2 microspheres to form Mg(OH)2/Ag nanocomposite, which exhibited enhanced antibacterial effect compared to that of silver nanoparticles. The enhanced antibacterial mechanism was investigated in detail. 相似文献
In this study, polystyrene (PS)-encapsulated magnesium hydroxide (Mg(OH)2) was successfully prepared by in situ polymerization of styrene on the surface of Mg(OH)2 in a high-speed mixer. A large amount of PS chemically bonded on Mg(OH)2 surface was confirmed by means of FT-IR, TGA and SEM. A series of composites of high impact polystyrene (HIPS) were prepared by melt blending in a co-rotating twin-screw extruder. The effects of PS-encapsulated filler on the properties of HIPS composites were studied by SEM, rheology and combustion tests (horizontal burning tests and cone calorimetry). The dispersion and adhesion patterns of PS-encapsulated Mg(OH)2 in HIPS matrix were investigated through FT-IR and SEM. The experimental results demonstrated that comparing to the composites containing untreated filler, the rheological and flame retardant properties of those containing PS-encapsulated filler were found to be significantly improved. This improvement is mostly attributed to a better dispersion of the encapsulated filler and a strong adhesion between the filler and matrix. 相似文献
Applying of the most toxic halogenated and aromatic flame retardants is limited with respect to the environmental requirements. Nontoxic Al(OH)3 nanoparticles were synthesized via a simple surfactant-free precipitation reaction at room temperature. The effect of various precipitation-agents on the morphology of the products was investigated. Al(OH)3 nanoparticles were added to the polysulfone and poly styrene (PS) matrices. Electron microscope images show excellent dispersion of aluminium hydroxide in PS matrix. Nanoparticles appropriately enhanced both thermal stability and flame retardant property of the polymeric matrices. The enhancement of flame retardancy is due to endothermic decomposition of Al(OH)3 that absorbs heat and simultaneously releases of water (makes combustible gases diluted and cold). Dispersed nanoparticles play the role of a barrier layer against flame, oxygen and polymer volatilization. Al(OH)3 was converted to Al2O3 and its photo-catalyst property in degradation three different organic dyes as pollutants was investigated. 相似文献
Magnesium hydroxide and magnesium oxide nanostructures have been prepared by microwave/hydrothermal technique using magnesium metal in hydrogen peroxide (H2O2). The applied power of the microwave was 700?W for 10?min at 145?°C. The method produced Mg(OH)2 powder as a base material for MgO by calcinations at 550?°C for 2?h. X-ray diffraction data confirms the microwave production of Mg(OH)2 and (MgO) through the agreement with the standard JCDPS cards. Scanning electron microscopy shows nanoplates morphology for Mg(OH)2 and large-scale nanoplates with a hexagonal shape for MgO. The fundamental direct optical band gap of Mg(OH)2 equals 5.8?eV while for MgO equals 5.2?eV from the analysis of diffused reflectance data. MgO has higher dielectric constant than Mg(OH)2 at the higher frequencies. AC electrical conductivity increases with increasing the applied frequency for both materials. The microwave-hydrothermal technique shows a promising method for production of magnesium compounds from magnesium metal which can be used in different aspects such as catalysis, wastewater treatment, pharmaceutical and coated materials.
Low-grade magnesium hydroxide (LG-MH) is a solid by-product that undergoes an endothermic decomposition in the temperature range of 300-750 °C. Due to its thermal behaviour and its lower cost relative to pure Mg(OH)2, it was studied as a non-halogenated flame retardant filler in a 28% vinyl acetate (VA) content poly(ethylene-co-vinyl acetate) matrix. The solid was characterized by XRF and the crystalline phases determined by XRD, composed predominantly of Mg(OH)2 and calcium and magnesium carbonates. Particle size reduction was performed by both mechanical as well as air jet milling in order to optimize the particle size distribution.Composites with different filler concentrations were prepared to evaluate the mechanical properties and flame retardancy by means of limiting oxygen index tests. LOI was also determined in specimens filled with commercial flame-retardants to analyse the effectiveness of this solid. 相似文献
It has demonstrated that there are major advantages and synergistic effects on flame retardancy in using a combination of borates with magnesium hydroxide. In this paper, a novel 2MgO·B2O3·1.5H2O–Mg(OH)2 nanocomposite has been controllably prepared by in situ hydrothermal reaction, and the formation mechanism of the nanocomposite was proposed. As a comparison, 2MgO·B2O3·1.5H2O nanobelt and Mg(OH)2 nanosheet were also prepared. All samples were characterized by XRD, FT-IR, TG, SEM, TEM and HRTEM. Furthermore, their flame-retardant properties were investigated by thermal analysis method and oxygen index method, demonstrating that the flame retardancy of nanocomposite is significantly higher than that of single 2MgO·B2O3·1.5H2O or Mg(OH)2. The possible flame retarding mechanism has been proposed. It can be predicted that this nanocomposite could serve as a potential flame retardant. 相似文献
The apparent melt shear viscosity of polypropylene (PP) composites filled with aluminium hydroxide (Al(OH)3) and magnesium hydroxide (Mg(OH)2) was measured by means of a melt flow rate instrument under experimental conditions of temperature ranging from 170 to 195 °C and load varying from 2.16 to 12.5 kg, to identify the effects of particle size and content. The results showed that the melt shear flow of the composites obeyed the power law under the experimental conditions, the dependence of the melt apparent shear viscosity (ηa) on temperature was consistent with the Arrhenius equation, and the sensitivity of the ηa for the composite melts to temperature increased with addition of flame retardant. The ηa of the composites decreased with increasing apparent shear rate. The ηa increased with an increase of the content of flame retardant, but this rate of increase decreased with a rise of temperature or load. When the particle size of flame retardant was smaller than 5 μm, the ηa of the composites increased with increase of particle size of flame retardant, and then reduced with a further increase of particle size of flame retardant. 相似文献
new material of Cu(OH)2 nanostructures was prepared using cupric nitrate and sodium hydroxide as raw materials by the chemical precipitation method. The Cu(OH)2 nanostructures were characterized by scanning electron microscope, transmission electron microscopy, infrared spectrometer, and X-ray diffractometer. The results showed that the Cu(OH)2 nanostructures exhibited excellent uniform and dispersion at 40°C. A series of factors was investigated to effect the photocatalytic efficiency of methyl orange (MO), such as the concentration of Cu(OH)2 nanostructures, the reaction time of the Cu(OH)2 nanostructures, the initial concentration of MO, and so on. As a result, the Cu(OH)2 nanostructures exhibited excellent photocatalytic efficiency with the concentration of 20 mg L–1 Cu(OH)2 nanostructures, the initial concentration of MO was 15 mg L–1 and the stirring time was 70 min. 相似文献
The hydrothermal method was used to synthesize multi-walled carbon nanotube/nickel hydroxide composites (MWCNT/Ni(OH)2). The structure and morphology of the prepared materials were characterized by X-ray diffraction and transmission electron microscopy. The electrochemical performance of cathodes prepared with multi-walled carbon nanotubes (MWCNT) loaded into the β-nickel hydroxide materials was investigated employing cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopic measurements. It is shown that the cathode active material utilization increases for MWCNT/Ni(OH)2 obtained after 24 h of hydrothermal synthesis. These composites exhibit a fairly good electrochemical performance as cathode materials. Based on the results, this fact could be associated with the formation of a continuous conductive network structure in the hydroxide matrix. The analyses of impedance data, according to a physicochemical model, allow the improvement of a better understanding of the main structural and physicochemical parameters that control the electrochemical performance of these systems. 相似文献
Li2ZnTi3O8/C nanocomposite has been synthesized using phenolic resin as carbon source in this work. The structure, morphology, and electrochemical properties of the as-prepared Li2ZnTi3O8 samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy (RS), galvanostatic charge–discharge, and AC impedance spectroscopy. SEM images show that Li2ZnTi3O8/C was agglomerated with a primary particle size of ca. 40 nm. TEM images reveal that a homogeneous carbon layer (ca. 5 nm) formed on the surface of Li2ZnTi3O8 particles which is favorable to improve the electronic conductivity and inhibit the growth of Li2ZnTi3O8 during annealing process. The as-prepared Li2ZnTi3O8/C composite with 6.0 wt.% carbon exhibited a high initial discharge capacity of 425 and 159 mAh g?1 at 0.05 and 5 A g?1, respectively. At a high current density of 1 A g?1, 95.5 % of its initial value is obtained after 100 cycles. 相似文献
This paper reports a successful preparation of a pure forsterite Mg2SiO4 using the sol–gel approach and its application for the removal of impurities from a Tunisian frying oil. Magnesium nitrate hexahydrate and tetraethylortho-silicate were used as magnesium and silicon precursors, respectively. The synthesis was held at different calcination temperatures for 30?min. The annealed samples were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, and laser diffraction. The results revealed that the sample calcined at 500?°C was forsterite with unimodal particle size distribution (PSD) centered at 122.8?±?0.3?μm. The dispersion index I (indicator of particle size uniformity) was 1.84. With the temperature increase, well crystallized compounds were obtained. Their PSDs remain unimodal and shift towards smaller particles. A decrease of the dispersion index was also noted, indicating the formation of Mg2SiO4 with more uniform particle size. This study showed that 900?°C could be selected as energy saving temperature suitable for the preparation of a pure and well crystallized Mg2SiO4 within just 30?min of annealing time. The obtained silicate exhibited promoting results for the purification of waste frying oils.
Pure and fine Mg2SiO4 powder with unimodal particle size distribution was prepared by sol gel route under energy saving conditions. The obtained magnesium orthosilicate showed excellent results for waste frying oil purification
In view of the close relationship between the morphology of LiNi0.8Co0.15Al0.05O2 (NCA) and its electrochemical performance, polyvinyl alcohol (PVA) was added to control the NCA morphology. And thus a new NCA cathode material modified by PVA (NCA-PVA) was prepared. The morphology and structure of the obtained samples were characterized by X-ray diffraction, scanning electron microscopy, and laser diffraction. The electrochemical performance was characterized with electrochemical workstation and cell tester by assembling into CR2032 coin-type half-cell. The results show that the obtained NCA-PVA has a better layer structure and smaller cation mixing degree, smaller particle size, and more uniform particle size distribution than the pristine NCA without adding PVA. The electrochemical performance is also improved: the initial discharge capacity increases from 143.36 to 184.84 mAh g?1. And the charge-discharge efficiency increases from 78.25 to 86.42%. The specific discharge capacities of NCA-PVA are all higher than that of the NCA (about 50 mAh g?1) at all testing rates (0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 C). 相似文献
Nanotubular (Mg,Fe2+,Fe3+)3Si2O5(OH)4 hydrosilicates with a chrysotile structure were synthesized under hydrothermal conditions. The phases prepared were studied
thermochemically on a high-temperature Tian-Calvet microcalorimeter by solution calorimetry. The standard enthalpies of formation
of magnesium-iron nanotubular hydrosilicates were determined. The formation of iron-containing nanotubes was shown to be lass
favorable energetically than the formation of magnesium nanotubes. 相似文献
Herein, we introduce a facile, inexpensive and fast, and additive-/template-free method to fabricate highly stable nickel hydroxide nanofibers for supercapacitor applications. Ni(OH)2 nanofibers were electrodeposited on electro-etched carbon fiber paper by a potential step method (Ni(OH)2-ECFs) and characterized using scanning electron microscopy and X-ray diffraction analysis. Electrochemical performance of Ni(OH)2-ECF was studied in symmetric two-electrode assembly by cyclic voltammetry, galvanostatic charge–discharge method, and electrochemical impedance spectroscopy. A specific capacitance of 277.5 F g?1 was achieved for the symmetric supercapacitor based on two identical Ni(OH)2-ECFs. Our findings demonstrate high-rate capability with excellent stability (approximately 100 % capacitance retention) for Ni(OH)2-ECF supercapacitor, originated from the intimate contact between Ni(OH)2 and ECF. Our studies suggest the Ni(OH)2-ECF electrode as an excellent material for supercapacitor applications. 相似文献
The stability and solubility of UO2(OH)2 has been studied as a function of the humic acid concentration in 0.1M NaClO4, in the pH range from 4 to 7 under normal atmospheric conditions. The solid phase under investigation has been prepared by
alkaline precipitation and characterized by TGA, ATR-FTIR, XRD, SEM and solubility measurements. According to the experimental
data UO2(OH)2 is stable and remains the solubility limiting solid phase even in the presence of increased humic acid concentration in the
solution. However, humic acid affects texture and particle size of the solid phase. Increasing humic acid concentration results
in decreasing crystallite size of the UO2(OH)2 solid phase. Based on the solubility data, the logKsp(UO2(OH)2) has been evaluated to be −22.0±0.3 and the stability constant for the UO2(OH)HA(I) species has been estimated to be logβ1101 = 15.3±0.5. 相似文献
In this study, an ionic complex of V(V) was synthesized by using ultrasonic method, and it was used as a precursor for production of a new catalyst for selective preparation of methylal or dimethoxymethane (DMM). By reaction between an ionic ligand [pyda.H2]2+[pydc]2? (LH2), (pyda.H2 = 2,6-pyridine diammonium and pydc = 2,6-pyridinedicarboxylate) and ammonium vanadate, the five coordinated V(V) complex, [pyda.H][V(pydc)O2], {2,6- diaminopyridinum 2,6-pyridinedicarboxylatodioxovanadate(V)}, VLH2 was synthesized. The prepared complex VLH2 was characterized by SEM, thermal analysis TGA/DTA, FT-IR spectroscopy and X-ray diffraction studies. The results showed that the yield of the reaction was increased up to 64%. The average particle sizes of the obtained complex VLH2 were about 50–60 nm. Also, the nano-catalyst of V2O5/Al2O3 was synthesized by impregnation method and was prepared as a nano-catalyst with average particles sizes of 50–60 nm, and its characterization was performed by XRD, EDX and SEM methods. Finally, the prepared catalyst was used to converting of methanol to methylal at different process conditions. 相似文献
Herein, we introduce the application of nickel hydroxide nanosheets on the electro-etched carbon fiber (ECF) formed via a direct electrodeposition, for fabrication of asymmetric supercapacitor. To confirm the practical applicability of prepared Ni(OH)2–ECF, an asymmetric device was assembled using Ni(OH)2–ECF in combination with an activated carbon (AC) electrode. Our results showed a substantial cycling stability (96% capacitance retention after 10000 cycles) and considerable rate capability at large discharge currents (60% capacitance retention at 8 A g??1) for this asymmetric supercapacitor that may have originated from the good contact between Ni(OH)2 and ECF. A maximum specific capacitance of 88.1 F g??1 was achieved for Ni(OH)2–ECF//AC/CF device and showed considerable rate capability at large discharge currents (60% capacitance retention at 8 A g??1). The results of this study suggest the Ni(OH)2–ECF electrode is an excellent material for fabrication of supercapacitor electrodes. 相似文献
Three-dimensional Ni(OH)2 nanoflakes were prepared via a facile and cost-effective electrodeposition method using commercial activated carbon (AC) as substrate. Nitric acid treatment (NT) and partial crystallization (PC) by metal nickel catalysis were applied for AC. The effects of the oxygen-containing functional groups and the degree of crystallization on the electrochemical performance of the electrode were investigated. The resulting Ni(OH)2/PC–NT–AC/nickel foam electrode exhibits distinct performance with a specific capacitance of 2971 F/g (scaled to the mass of active Ni(OH)2) at a current density of 6 A/g. A high capacitance of 1919 F/g was still achieved even at 40 A/g, which is much higher than Ni(OH)2/AC/nickel foam electrode and Ni(OH)2/NT–AC/nickel foam electrode. The excellent performance of Ni(OH)2/PC–NT–AC/nickel foam electrode can be attributed to the presence of large surface area and highly conductive PC–NT–AC network on nickel foam. This study presents an effective method to improve the dispersion and rate capability of Ni(OH)2 nanostructure electrodes. 相似文献
