Peng Tian

Synthesis of porous hierarchical MgO and its superb adsorption properties.

The porous hierarchical MgO with superb adsorption properties has been synthesized by a facile and scaled-up method. The X-ray powder diffraction, electron microscopy, Fourier transformed infrared, and N2 adsorption-desorption were carried out to study the microstructure of the as-synthesized precursor and product. It has been demonstrated that the as-prepared MgO has a porous hierarchical structure and a high specific surface area (148 m(2) g(-1)). And the MgO sample exhibited super adsorption properties, with maximum adsorption capacity of 2409 mg g(-1) for Congo red, which is the highest reported value. Moreover, the adsorption process of Congo red on porous hierarchical MgO was systematically investigated, which was found to obey the pseudo-second-order rate equation and Langmuir adsorption model.

Facile synthesis of magnetic hierarchical MgO–MgFe2O4 composites and their adsorption performance towards Congo red

MgO–MgFe2O4 composites with magnetism and adsorption capacity for Congo red were synthesized by an ion exchange route using magnesium carbonate as templates. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and magnetic hysteresis loop were carried out to characterize the crystalline phase, microstructure, and magnetic property of as-obtained MgO–MgFe2O4 composites. Congo red adsorption experiments were conducted to evaluate the adsorption property of the as-synthesized samples. The results showed that the as-synthesized MgO–MgFe2O4 composites have a hierarchical structure, magnetic properties and good adsorption performance. The optimized sample exhibited an excellent adsorption capacity (498 mg g−1) for Congo red, which is much higher than many other hierarchical magnetic materials.

Ag/TiO2 and Ag/SiO2 composite spheres: synthesis, characterization and antibacterial properties

Ag/TiO2 and Ag/SiO2 composite spheres with core–shell structures were synthesized via an ion-exchange method. Thin layers of TiO2 or SiO2 are deposited onto CaMg(CO3)2 templates using tetrabutyl titanate or tetraethoxysilane, respectively, and the CaMg(CO3)2 cores are subsequently replaced by Ag2CO3 based on the solubility product constant gap, followed by calcination of the intermediates, resulting in Ag/TiO2 and Ag/SiO2 composite particles. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX). The amount of Ag nanoparticles in the composites can be adjusted using the relative concentration of the AgNO3 solution. Both the Ag/TiO2 and Ag/SiO2 composites exhibit excellent antibacterial activities using E. coli and S. aureus as test bacterial spawn.

NiO hierarchical structure: template-engaged synthesis and adsorption property

NiO hierarchical structure was synthesized via a facile template-engaged solvothermal reaction of Mg5(CO3)4(OH)2·4H2O and Ni(NO3)2·6H2O, followed by annealing Ni-base precursor at high temperature in air. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and N2 adsorption-desorption. It has been demonstrated that the NiO hierarchical structure retains the morphology of the template, and possesses a high surface area (over 58 m2 g−1). Moreover, the growth mechanism of Ni-base precursor has been proposed. The porous hierarchical NiO exhibited good adsorption for the removal of organic dye pollutants from water. Thus, the porous hierarchical NiO is expected to find promising applications in catalysis, energy storage and sensors.

Synthesis of porous MgAl2O4 spinel and its superior performance for organic dye adsorption

A porous MgAl2O4 spinel (MAS) has been synthesized via a facile hard template process with further calcination, in which a hierarchical Mg5(OH)2(CO3)4·4H2O template with a high surface area was used as a hard template and magnesium source, and AlCl3·6H2O was used as an alumina source. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetry analysis (TGA) and N2 adsorption–desorption. The MAS samples showed superior adsorption performance, including rapid adsorption rate, excellent adsorption capacity and good reusability for removal of Congo red (CR) from aqueous solution. The superior performance could be ascribed to the strong interaction between the MAS samples and CR, as well as the hierarchical porous structure and the high specific surface area of the samples. The maximum adsorption capacity of the MAS samples for CR was nearly 845 mg g−1, which is higher than most of the previously reported adsorbents. The CR removal process was found to follow the pseudo-second-order rate equation and the Sips adsorption model.

A magnesium carbonate recyclable template to synthesize micro hollow structures at a large scale

A facile strategy by using magnesium carbonate as the recyclable template has been developed to synthesize a variety of uniform inorganic hollow structures whose composition, size and shape can be readily modulated to generate interesting structures such as TiO(2), Al(2)O(3), SiO(2), Gd(2)O(3) and NiO microtubes and TiO(2), SiO(2) hollow microboxes.

Template-induced synthesis and superior antibacterial activity of hierarchical Ag/TiO2 composites

Hierarchical Ag/TiO2 composites were successfully synthesized via a hydrated magnesium carbonate hydroxide template-induced route. The prepared composites possess hierarchical flower-like structure and high Brunauer–Emmett–Teller (BET) surface area of 131.9 m2 g−1. The amount of silver nanoparticles (Ag NPs) with diameter of 20–40 nm in the composite can be adjusted by the concentration of AgNO3 solution. The antibacterial potency of Ag/TiO2 composites was investigated against Gram-negative bacteria, Escherichia coli (E. coli) and Gram-positive bacteria, Staphylococcus aureus (S. aureus) by determining the minimal inhibitory concentration (MIC), the growth curve of bacteria and using the zone of inhibition technique. The synergistic effect of Ag NPs and TiO2 lead to superior and long-term antimicrobial activities of the composites with a bacteriostatic rate as high as 99.99%. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the fluorescence microscopy showed the integrity of membrane of the bacteria was destroyed by adding a given amount of composites resulting in cell death as well. The mechanism of antibacterial activity of composites was also taken into account by using TEM, inductively coupled plasma atomic emission spectrometry (ICP-AES), ultraviolet visible diffuse reflectance spectroscopy and fluorescent microscopy.