Fangfei Li

Preparation and characterization of magnesium doped hydroxyapatite–gelatin nanocomposite

Magnesium (Mg) doped hydroxyapatite (HAP)–gelatin (GEL) one-dimensional nanofibers were prepared in the aqueous GEL solution at low temperature (38 °C). The influence of GEL and Mg on morphology and crystal structure was systematically investigated. Different amount Mg doped HAP–GEL and HAP–GEL nanofibrils doped with different amounts of Mg were obtained by self-assembly along with gelatin, and pure HAP and HAP doped with Mg were sphere nanoparticles in the absence of GEL. Fourier transform infrared (FT-IR) analysis showed that chemical bonding between calcium ions of HAP and carboxyl groups of GEL molecules led to a red shift of the 1395 cm−1 band of GEL. The incorporation of Mg ions into the composite phase caused the decrease of the lattice parameters and Ca/P molar ratio in the HAP solid samples. Differential thermal analysis and thermogravimetric analysis (DTA/TG) features and FT-IR spectra of HAPGEL composite materials were very similar to those of dentine.

A high-stability silica-clay composite: synthesis, characterization and combination with TiO2 as a novel photocatalyst for Azo dye.

A novel micro-mesopores composite material has successfully been synthesized at basic hydrothermal conditions using natural mineral montmorillonite (MMT) and tetraethoxysilane (TEOS). Two surfactants, cetyltrimethyl ammonium bromide (CTAB) and polyethylene glycol (PEG), have been employed in order to shape the pores in the composite. The resultant silica-clay has large surface area (472m(2)/g) and high hydrothermal stability, which makes it a potentially host-material for catalyst. The molecular size of different surfactant leads to the multi-peak distribution of pore size, and the surfactant of larger size (PEG) corresponds to the formation of larger pores. Moreover, the photocatalytic results show that, comparing with pure TiO(2) particles, the loaded TiO(2) on such silica-clay shows higher photodegradation rate of methyl orange (MO) in aqueous. And another porous aluminosilicate host, zeolite, was also discussed for comparison.

The interaction of cellulose and montmorillonite in a hydrothermal process

In this paper, the interaction of cellulose and montmorillonite in a hydrothermal process was discussed. The preparation of the composite was performed at 230 °C for different periods of time from 0.5 to 16 h. The hydroxypropyl methyl cellulose was set to 50 wt.% in the composite and multiple sets of data were compared. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry-differential thermal analysis, specific surface area and electric potential for evaluation of interactions. Hydrochar is a solid carbon-rich mixture produced from the hydrothermal carbonization of the cellulose. The cellulose can be adsorbed at the surface of montmorillonite. The pores of montmorillonite are partially blocked by the hydrochar. The state of the hydrochar has a significant effect on the order of montmorillonite. The zeta potential of the composite is mainly affected by hydrochar. In turn, the Fourier transform infrared spectroscopy results indicate that montmorillonite affects the hydrochar structure, and the thermal stability of hydrochar is improved. The experimental results show that the presence of hydrochar in the composite causes significant changes in surface properties and the interlayer structure. Meanwhile, montmorillonite plays a protective role on the hydrochar.Graphical Abstract

Occurrence and Distribution of Gallium, Scandium, and Rare Earth Elements in Coal Gangue Collected from Junggar Basin, China

ABSTRACT In order to extract precious metals from coal gangue (CG) collected from the Junggar coal mining fields, Inner Mongolia of China, the occurrence and distribution of elements including gallium (Ga), scandium (Sc), and rare earth elements (REE) were studied by means of sequential leaching procedures. Kaolinite and boehmite were identified as the major crystalline phases in the CG. No observable crystalline minerals were found for bearing Ga, Sc, or REE. The percentage of REE (~88.6%) were able to be leached out by acid (25%, HCl) treatment at room temperature, which indicates the REE are mainly present in the amorphous phases. The structure of boehmite was destroyed when the temperature of acid treatment was improved to 160°C, and about 85% of Ga together with 36.8% of Sc was leached out in this leaching step. The majority of Ga was indicated as isomorphic substitutions in kaolinite and boehmite. The 36.8% scandium was confirmed as Al-substitutions in the Al–O octahedrons of kaolinite, and others (55.6%) are present in boehmite. Only a little portion (1.9%) of scandium was found in the Si–O tetrahedrons. Therefore, this research provided basic data for occurrence and distribution of precious metals in view of the future industrialization.

Study of the dielectric constant of polyurethane/polybutyl‐methacrylate interpenetrating polymer networks using metal–insulator–semiconductor structure

Polyurethane/polybutyl-methacrylate interpenetrating polymer networks (IPNs) film was formed on n-Si substrate by the dropping technique. When aluminum (Al) was vacuum deposited on the top of the film, the Al/IPNs/n-Si (metal–insulator–semiconductor) structure was fabricated successfully. With the aid of the high-frequency capacitance–voltage (C-V) characteristics at room temperature, the dielectric constant of IPNs was obtained. In the C-V curves, an increased hysteresis at high sweep voltage and a plateau in the depletion region were observed. This plateau indicates that the unsaturated bonds beyond IPNs film could act as electron well at the applied voltage above 10 V.