J. Nanosci. Nanotechnol.

alpha-Fe(2)O(3) hollow micospheres have been successfully synthesized by solvothermal method at 200 degrees C. The synthesized products are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and the nitrogen adsorption-desorption isotherm technique. The alpha-Fe(2)O(3) hollow microspheres have an average diameter of 2-3 mu m, the shell consists of numerous aligned nanorods with length of about 200-400 nm. The effects of solvent and reaction time have been studied. The Ostwald ripening mechanism is proposed to account for the formation of alpha-Fe(2)O(3) hollow microspheres. Because of the porous hollow microstructure and large specific surface area, the microspheres were found to be effective sorbents for the removal of Cr(VI) ions from wastewater.alpha-Fe(2)O(3) hollow micospheres have been successfully synthesized by solvothermal method at 200 degrees C. The synthesized products are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and the nitrogen adsorption-desorption isotherm technique. The alpha-Fe(2)O(3) hollow microspheres have an average diameter of 2-3 mu m, the shell consists of numerous aligned nanorods with length of about 200-400 nm. The effects of solvent and reaction time have been studied. The Ostwald ripening mechanism is proposed to account for the formation of alpha-Fe(2)O(3) hollow microspheres. Because of the porous hollow microstructure and large specific surface area, the microspheres were found to be effective sorbents for the removal of Cr(VI) ions from wastewater

Template-free Synthesis of a Novel 3D Cage-like Nanostructured α-Fe2O3

Synthesis of inorganic nanostructures with specific size and well defined morphologies has attracted considerable attention due to their superior electrical, optical, magnetic, and chemical properties. Up to now, various kinds of metal oxide, sulfide, and hydrate with controlled hierarchical and complex morphologies have been successfully synthesized

templatefreesynthesisofanovel3dcagelikenanostructuredfe2o3

Synthesis of inorganic nanostructures with specific size and well defined morphologies has attracted considerable attention due to their superior electrical, optical, magnetic, and chemical properties. Up to now, various kinds of metal oxide, sulfide, and hydrate with controlled hierarchical and complex morphologies have been successfully synthesized

Template-free Synthesis of a Novel 3D Cage-like Nanostructured α-Fe2O3

Synthesis of inorganic nanostructures with specific size and well defined morphologies has attracted considerable attention due to their superior electrical, optical, magnetic, and chemical properties. Up to now, various kinds of metal oxide, sulfide, and hydrate with controlled hierarchical and complex morphologies have been successfully synthesized

Morphology manipulation of alpha-Fe2O3 in the mixed solvent system

By using simple mixed solvents, the morphologies of hematite (alpha-Fe2O3) particles could be manipulated, and the spherical, mulberry-like, nanospherical and top-like products could be controllably obtained. The as-obtained products were characterized by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer. The results indicated that the morphology manipulation could be achieved by systematically adjusting the polarity of the mixed solvent via the ratio control. And the magnetic properties of the products were critically affected by their grain size and assembly morphologies. (C) 2009 Elsevier Masson SAS. All rights reserved

Catal. Today

A study on the removal of cadmium ions from aqueous solutions by synthetic hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2), HAP) with different morphologies was conducted in batch conditions. The influence of different sorption parameters, such as equilibration time, initial concentration of metal ion, the amount of HAP, pH value of solution and the specific surface area on the sorption amount of Cd(2+) were studied and discussed. Our experimental results are in agreement with pseudo-second-order kinetic equation. The Freundlich and Langmuir adsorption isotherms, often used to describe the sorption of solutes from a liquid phase, can be applied to our experimental results. The Langmuir adsorption isotherm constant corresponding to adsorption capacity, X(m), was found to be 260.42 mg/g. The sorption amount of Cd(2+) increased as the pH value enhanced from 5 to 8. The ion-exchange mechanism and surface complex mechanism may both exist in the adsorption process. Nearly linear dependence between Cd(2+) sorption amount and specific surface area within a certain range has been confirmed. Cd(2+) desorption amount decreased with the increasing pH value of the extracting solution. (C) 2008 Elsevier B.V. All rights reserved.A study on the removal of cadmium ions from aqueous solutions by synthetic hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2), HAP) with different morphologies was conducted in batch conditions. The influence of different sorption parameters, such as equilibration time, initial concentration of metal ion, the amount of HAP, pH value of solution and the specific surface area on the sorption amount of Cd(2+) were studied and discussed. Our experimental results are in agreement with pseudo-second-order kinetic equation. The Freundlich and Langmuir adsorption isotherms, often used to describe the sorption of solutes from a liquid phase, can be applied to our experimental results. The Langmuir adsorption isotherm constant corresponding to adsorption capacity, X(m), was found to be 260.42 mg/g. The sorption amount of Cd(2+) increased as the pH value enhanced from 5 to 8. The ion-exchange mechanism and surface complex mechanism may both exist in the adsorption process. Nearly linear dependence between Cd(2+) sorption amount and specific surface area within a certain range has been confirmed. Cd(2+) desorption amount decreased with the increasing pH value of the extracting solution. (C) 2008 Elsevier B.V. All rights reserved

preparationandphotocatalyticpropertyofporoustio2filmwithnetlikeframework

By the UV-curing method, a porous TiO2 film with net-like framework has been prepared. The characterization results of the porous TiO2 film by means of SEM, TEM, XRD, and N-2 adsorption-desorption analysis show that the net-like framework of the porous TiO2 film is composed of TiO2 nanoparticles, forming three dimensional porous structure. The porous TiO2 film exhibits higher photocatalytic activity for the degradation of methylene blue(MB) dye compared with the conventional dense TiO2 film

Preparation of SiO2 Aerogels Heat Insulation Composites Reinforced by Aramid Fiber

A high malleable silica aerogel composite was prepared by acid/base two step sol-gel process in alcohol-water mixed solvents with tetraethoxysilane (TEOS) as precursor, aramid fiber as reinforcement, followed by ambient-dried method. The microstructure and properties were characterized by FESEM, BET and so on. The results indicated that the composites with different density, contour and thermal conductivity can be prepared by changing the reaction parameters. The average pore size of aerogel is 10 similar to 20 nm, specific surface area is more than 1000 m(2)/g, which is hopeful to be applied in heat insulation field

Direct hydrothermal synthesis of single-crystalline hematite nanorods assisted by 1,2-propanediamine

Uniform alpha-Fe2O3 nanorods with high aspect ratios were synthesized in large scale by a simple and direct 1,2-propanediamine-assisted hydrothermal method. The resultant products were characterized by x-ray diffraction scanning electron microscopy, and transmission electron microscopy. The as-synthesized alpha-Fe2O3 nanorods were single crystalline and uniform, with an average aspect ratio greater than 10. The effects of various experimental parameters on the morphology of products, such as 1,2-propanediamine content, pH value, concentration of FeCl3 and reaction temperature, were studied. In the formation process of alpha-Fe2O3 nanorods, the 1,2- propanediamine not only provides OH- but also plays a role for retaining the rod-like morphology of hematite. The magnetic properties including Morin transition and coercivity of the samples with different synthesis conditions and aspect ratios were also investigated in detail

General Synthesis of Homogeneous Hollow Core-Shell Ferrite Microspheres

A general method has been developed for the synthesis of homogeneous hollow core-shell microspheres of spinel ferrites (MFe(2)O(4), M = Zn, Co, Ni, Cd) by using carbonaceous saccharide microspheres as template. The products were characterized by X-ray powder diffraction, inductively coupled plasma-atomic emission spectroscopy, scanning electronic microscopy, transmission electron microscopy, and nitrogen sorption measurement. The effects of the concentration of metal salts have been studied using ZnFe(2)O(4) as an example. Increasing the concentration of metal salts could avoid the generation of impurity phase. The core size and shell thickness of hollow spheres obtained can be manipulated by changing the concentration of metal salts. Gas-sensor investigations revealed the ZnFe(2)O(4) hollow spheres used as gas-sensor materials possess high sensitivity and quick responses to organic gases such as ethanol