Potential applications of inorganic hollow/porous materials such as alumina in adsorption, catalysis, battery and energy materials:
(1) In view of the problem of narrow pore channels and small pore volume of conventional mesoporous materials, according to the principle of solubility modulation, the interface self-assembly method is adopted to explore the convenient construction of porous alumina and magnesium oxide with high specific surface area by changing the raw material or changing the solvent without adding template agent.
The formation mechanism of porous alumina and magnesium oxide was explored, and the dye adsorption performance of the constructed porous alumina and magnesium oxide was evaluated.
(2) In order to improve the purity and pore volume of alumina and reduce its particle size, this paper proposes a spray hydrolysis strategy, and attempts to construct large-pore capacity high-purity nano-nano-alumina using aluminum isopropoxide as raw material.
The effects of precursor preparation conditions and calcination temperature on the crystal phase, pore volume, specific surface area and pore channel of alumina products were investigated, and the adsorption performance of porous alumina in aqueous phase was characterized and evaluated.
(3) In order to construct alumina hollow spheres and solve the problem of universal construction of hollow metal oxide structures, a spray precipitation method is proposed based on the spray hydrolysis strategy.
Combined with the principle of solubility modulation and ultrasonic atomization technology, a hollow/porous structure containing alkaline substances was constructed with metal inorganic salt aerosol droplets in ethanol containing alkaline substances at room temperature, in order to obtain a series of metal oxides with high specific surface area and large porous volume.
This attempt is made to reveal the mechanism of this preparation process and realize the regulation of the hierarchical structure and components of the product.
(4) In order to realize the batch preparation of large-porous porous alumina, on the basis of the above research, a pneumatic atomization system is designed and built. Using aluminum sulfate as the aluminum source, the experiment of batch construction of porous alumina was carried out, and the influence of process parameters such as forging temperature, crystallization time and crystallization temperature on the product structure was investigated.
Congo red was used as a probe to evaluate and analyze the adsorption performance of the prepared porous alumina.
Constructed porous metal oxides such as alumina by interfacial self-assembly method:
Using non-covalent bond interactions between basic building blocks, the self-assembly process is widely used and plays an important role in constructing porous metal oxides with specific structures and functions.
Most of the traditional metal oxides with high specific surface area are prepared with template assistance under high temperature and pressure, but the subsequent processing of template is more complicated. The advantage of the self-assembly method is that porous metal oxides with regular morphology and large pore size can be prepared without adding template agents; And it has certain large-scale application potential and cost advantages.
For example, Huang et al. used diaspore trihydrate as the aluminum source, constructed hydrangea meadowfoam by self-assembly in ethanol solvent, and then obtained hydrangea mesoporous alumina with a specific surface area of 153m2/g and an average pore size of more than 18nm by heat treatment at 550°C.
However, in liquid phase systems, it is often difficult to obtain porous alumina with high specific surface area (>300m2/g) and large pore volume (>1.0cm3/g) without the use of organic raw materials, organic solvents or additional template agents. In view of this, based on the principle of solubility modulation, ammonium carbonate was used as the precipitant, porous alumina and magnesium oxide flower bulbs with high specific surface area were prepared by the self-assembly process of the gas-liquid interface, and the assembly mechanism and structure regulation of the precursor were analyzed.
Congo red (CR) was selected as a macromolecular model pollutant, and the adsorption performance of porous alumina and magnesium oxide on Congo red in water was evaluated, and the related adsorption mechanism was explored.
Sample characterization and testing:
(1) X-ray diffraction (XRD) testIn this paper, the D/Max2400 and Ultima IV X-ray diffractometers of Rigaku Co., Ltd. were used to obtain the phase pattern of the analyzed material, and the radiation sources were all Cu targets, and the scanning range 20 was controlled from 5° to 80°.
(2) Scanning electron microscopy (SEM) characterized the morphology and structure of powder samples observed by TESCANVEGA3LHM scanning electron microscopy of Tesken in the Czech Republic.
The powder is fixed after pasting on the conductive glue, and the gold spray treatment is about 120 seconds. The operating voltage of tungsten filament scanning electron microscopy is 20kV, and SEM data is obtained under vacuum.
(3) Transmission electron microscopy (TEM) characterizes the microstructure of samples observed by JEM-2100F transmission electron microscopy of Japan Electronics Co., Ltd. or Tecnai-F30 transmission electron microscopy of Thermo Fisher Scientific Corporation of the United States.
The sample was supported by a carbon film and the accelerating voltage tested was 200 kV.
(4) Thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) testIn this paper, the TGA-DSC3+ synchronous thermal analyzer of METTLER in Switzerland was used to study the thermal decomposition behavior of the sample.
Each test was performed in an air atmosphere with a flow rate of 50 mL/min and the test temperature started at room temperature.
(5) Inductively coupled plasma spectrometer (ICP-AES) to test the concentration of trace metal ions using PerkinElmer OPTIMA2000DV ICP instrument of PerkinElmer in the United States.
(6) UV-visible absorption spectroscopy test of organic dye aqueous solution UV-visible absorption spectrum test recorded in Japan HITACHI company U-4100UV/VIS/NIR spectrophotometer, the test wavelength range is 300-700nm, and based on the wavelength at 500nm absorbance, calibrate the concentration of Congo red (CR) in the solution.
