Papers by Author: Tong Jiang Peng

Abstract: As a new type of non-metallic mineral resource, serpentine has attracted more and more attentions. Serpentine mineral resources are abundant in China, with more than 5 billion tons reserves proved. However, most of them have not been used adequately except for some special serpentine, such as serpentine jade and chrysotile. The overview for status quo of serpentine utilization consists of the distribution, chemical compositions, crystal structure of serpentine, mature but not economic applications and some development of high-value utilization research. It is expected to provide some references for deeper research and promoting its applications.

Abstract: Spherical calcium carbonate (CaCO₃) is a potential component in many industrial fields such as high-grade papermaking, high-grade painting, environment, and pesticide. This paper describes a novel approach to synthesize spherical calcium carbonate (CaCO₃) particles via passing CO₂ bubbles into phosphogypsum salt leaching solution (CaSO₄) in the presence of ammonia (NH₃) at different temperatures. The influence of the initial solution pH and concentration of calcium ions on the polymorph and morphology of CaCO₃ was studied. The physical characteristics of the precipitate were evaluated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that compared with different calcium sources the phase and morphology of CaCO₃ synthesized by phosphogysum leaching solution had some regularity. The grain size of spherical CaCO₃ became bigger, surface became smoother, and particle dispersion became better with the increase of calcium ion concentration. The content of vaterite increased and particle grain size changed a little with the increase of pH. The research results had important environmental significance for phosphogysum resource utilization and CO₂ fixation.

Abstract: The effect of particle size of natural graphite on the size and structure of graphene oxide (GO) was investigated by using natural flake graphite (NFG) with different particle size. GO was prepared by modified Hummers method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, laser scattering particle size distribution analyzer and Atom force microscopy (AFM) were used to identify the characteristics of NFG and GO. The results provide evidence of how the graphite particle size affects the oxidation process and sheet size of the GO. Varies size monolayer GO sheets could be produced from the graphite with different particle size. The sheet size of GO is much smaller than that of the graphite, and the sheet size reduced multiple is proportional to the graphite particle size. The smaller particle size graphite is easily to be oxidized for a higher concentration GO suspension, and for more defect in the structure. Thus, this study leads to a better understanding of the preparation process of GO and provides a way to produce GO in different sheet size suitable for different applications.

Abstract: The fibri-form silica was successfully synthesized from the short chrysotile fibers by inorganic acid-leaching. X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and N₂ adsorption isotherms were used to characterize the products. The results indicate that the fibri-form silica is a kind of noncrystalline material, and the content of SiO₂ in the fibri-form silica is 98.30%. From 50°C to 1200°C, the structure of fibri-form silica is stable. The average diameter of single fiber range from 20 nm to 50nm and the lengths are 50nm to 3μm. The surface area and pore volume of fibri-form silica are 369.22m²/g and 0.43cc/g, respectively. And the size of pore diameters are different, is one of mesopore materials presenting high quality filler and catalyzer carrier.

Abstract: Fibri-form silica was extracted from short chrysotile fibers by mix-roasting with ammonium bisulfate. The fibri-form silica were characterized by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and N₂ adsorption isotherms. The results show that the fibri-form silica with disordered crystalline structure, but also in fibrous morphology. The surface area and pore volume of fibri-form silica are 181.66 m²/ g and 0.44 cc/ g, respectively. The structure of fibri-form silica is stable, no phase transformed from 50 to 1200 ^oC.

Abstract: By utilizing chrysotile asbestos tailing from Shannan ore in Sichuan as the main raw material, diopside-based glass-ceramics were successfully synthesized in the laboratory by adding some limestone, quartz sand, Al₂O₃, H₃BO₃, Na₂CO₃ and CaF₂. The optimum procedure for glass-ceramics was as follows: melting at 1400 for 60 min, sintering at 1100 for 120 min. Through the tests of physical and mechanical properties, the glass-ceramics materials with more crystalline phase had high density, fine performance of resisting compression (366MPa) and negligible water absorption. Through chemical resistance tests, the glass-ceramics samples showed strong corrosion resistance. Overall result indicated that it was a feasible attempt to produce glass-ceramics materials for building and decorative materials from chrysotile asbestos tailing.

Abstract: Graphite oxide samples with different oxidation levels were prepared by the oxidation of natural flake graphite based on a modified Hummers method, using different reaction temperatures and oxidation times followed by ultrasonication then centrifugation to obtain the corresponding graphene oxide nanosheet suspensions. The samples were characterized by XRD and AFM. The results show that the oxidation level of graphite oxide samples can be increased by increasing either the reaction temperature or the oxidation time. Well-dispersed suspensions of the graphite oxide samples can be formed in alkaline solution after ultrasonication, especially for samples with higher oxidation levels. A number of coarse particles are observed in the suspensions, particularly those derived from graphite oxide samples with lower oxidation levels, due to the lower degree of exfoliation in these samples, which is influenced by the oxidation level. Rapid sedimentation of these coarse particles can be achieved by high-speed centrifugation, yielding homogenous suspensions of graphite oxide comprising a mass of monolayer graphene oxide nanosheets with lateral dimensions of several hundred nanometers to several micrometers and thickness of ~1.0–1.4 nm.

Abstract: . In order to exploit a kind of low cost and environment-friendly humidity sensing materials, a series of Li-modified montmorillonite ion conductors were prepared using the montmorillonite form Jimusaer in Xinjiang Province of China. The montmorillonite humidity sensing elements were made by the thick film technique on mica substrates. Then the structures of the samples were investigated by X-ray diffraction (XRD) and the humidity sensing characteristics of the elements were tested by an equipment of the resistance testing. The results indicate that the resistances of the montmorillonite humidity elements all decrease with the increase of the system humidity. But there is a great discrepancy between the resistances of Na- montmorillonite humidity element when humidity adsorption and desorption. It was found that Li-modification montmorillonite ion conductors behave well as a humidity sensing material in 30～90% RH (relative humidity). The suitable experimental parameters of montmorillonite Li-modifying under ~ 80°Care obtained.

Abstract: Hydrophlogopite was modified with sodium and then organically intercalated with a series of alkyl quaternary ammonium salts. The organically intercalated samples were characterized by X-ray diffraction analysis (XRD) and the effect of alkyl quaternary ammonium salt on the interlayer spacing of hydrophlogopite was discussed. The results showed that if the same alkyl quaternary ammonium salt was used to intercalate hydrophlogopite, the interlayer spacing of hydrophlogopite increased gradually with the rise of the added amount of quaternary ammonium salt, and that if different quaternary ammonium salts with the same amount were used, the interlayer spacing increased gradually with the rise of the chain length of the alkyl quaternary ammonium salts. For the alkyl quaternary ammonium salts with large chain length (n>10), the inflection point for the increasing interlayer spacing of the intercalated hydrophlogopite is at about 0.5 times of CEC. When octadecyl trimethyl ammonium bromide is used as intercalation agent and the added amount is 5 times of CEC, the interlayer spacing of hydrophlogopite is relatively maximal.

Abstract: Chrysotile asbestos tailing was broken down into active magnesium oxide and silicon dioxide by roasting. The activation product of Chrysotile as raw materials was used to prepare acicular basic magnesium carbonate by the carbon–ammonia method. The effect of the carbonization temperature, aging temperature, aging time, and the mole ratio of NH3•H2O and Mg2+ were studied on the form and percent conversion of the acicular basic magnesium carbonate. The structure, thermal properties and crystal morphology of the sample were analyzed by XRD analysis, thermal analysis and optical microscope, respectively. The results show that acicular basic magnesium carbonate prepared at the best conditions: carbonization temperature is at 50°C, aging temperature is at 70°C, aging time is for 4-5 hours, and the molar ratio of NH3•H2O and Mg2+ is 2:1. In this condition, the formation rate of specula basic magnesium carbonate is more than 82%. Its chemical formula which is 4MgCO3•Mg(OH)2•4H2O is obtained by XRD and thermal analysis, and the aspect ratio of the sample of the acicular basic magnesium carbonate was about 30 which was tested by optical microscope.