Chen Yunfa

Extraction of scandium from red mud by modified activated carbon and kinetics study

Activated carbon (AC) was modified by tri-butyl phosphate (TBP) for selectively extracting scandium, from red mud and characterized by BET (Brunauer-Emmett-Teller) surface area. The modified AC had a preferential adsorption to scandium. The influences of adsorbent dosage, adsorption temperature, and time on adsorption capacity and selectivity to scandium were examined. An optimum adsorbent dosage (similar to 6.25 g/L), adsorption temperature (308 K), and adsorption time (40 min) were figured out. A pseudo-second-order kinetics model was employed for describing the adsorption process of scandium.

Shape-Controlled Synthesis of ZnS Nanostructures: A Simple and Rapid Method for One-Dimensional Materials by Plasma

In this paper, ZnS one-dimensional (1D) nanostructures including tetrapods, nanorods, nanobelts, and nanoslices were selectively synthesized by using RF thermal plasma in a wall-free way. The feeding rate and the cooling flow rate were the critical experimental parameters for defining the morphology of the final products. The detailed structures of synthesized ZnS nanostructures were studied through transmission electron microscope, X-ray diffraction, and high-resolution transmission electron microscope. A collision-controlled growth mechanism was proposed to explain the growth process that occurred exclusively in the gas current by a flowing way, and the whole process was completed in several seconds. In conclusion, the present synthetic route provides a facile way to synthesize ZnS and other hexagonal-structured 1D nanostructures in a rapid and scalable way.

Effect of Plasma Spheroidization Process on the Microstructure and Crystallographic Phases of Silica, Alumina and Nickel Particles

During the plasma spheroidization process powders undergo different changes in their microstructures and crystal phases. In this paper, simple calculation of heat transfer between the plasma and a suspended particle was performed based on three hypotheses for the purpose of guiding experiments. Experimental investigation of the crystal phases and microstructural changes during the plasma processing was made using silica, alumina and nickel powders as starting materials. It has been revealed from the experimental results that these materials undergo different changes in crystal phases and microstructures, and these changes are essentially determined by the structures, properties and aggregate states of the starting materials.

Preparation and Properties of Anti-oxidation Inorganic Nano-coating for Low Carbon Steel at an Elevated Temperature

A new kind of anti-oxidation inorganic nano-coating for the common low carbon steel was prepared. It included magnesite mineral, metallurgic dust and silicate adhesive as the main raw materials. The nano-coating could be sprayed directly onto the low carbon steel slab even though with hot surface as far as under 1000°C. And at the same time, a compact thin nano-film was formed, and the film would inhibit the oxygen into the interface of the steel body and decrease the loss of weight because of oxidation. The loss was decreased by about 60% or more. The properties and mechanism of oxidation resistance of the coating were discussed through XRD, TG-DTA and SEM. The experimental results show that many reactions woulld happen among the components of the coating and then many microspheres with the size of 80–100 nm generated in the system. By using the heat of the steel body, the silicate adhesive would interact with the microspheres, and the other components of the coating would be soft and sintered so that when the coating was sprayed onto the surface of the steel slab, the intact and compact film could be formed and adhesive with the steel body. Besides the special properties of anti-oxidation, the coating could prevent the volatilization of microelement in the steel such as silicate and carbon at a high temperature. So it can improve the quality and output of steel with this new kind of nano-coating.

Formation and Thermal Stabilities Research of Ionic Liquids/alpha-ZrP Antibacterial Materials

Three different ionic liquids/alpha-zirconium phosphonates (IL-ZrP) composites antibacterial materials were prepared by introducing quarternary ammonium type ionic liquids (1-hexadecyl-3-methylimidazolium bromide, C(16)MIMBr; hexadecyl dimethyl benzyl ammonium chloride, C(16)HDBACCl; hexadecyl trimethyl ammonium chloride, C(16)CTACCl) into the interlayer of alpha-zirconium phosphonates (alpha-ZrP). The structure, components and thermal stability of composites was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), Thermogravimetric-Fourier transform infrared spectroscope analysis (TG-FTIR). XRD patterns show that the interlayer spacing of IL-ZrP are larger than the original alpha-ZrP. It represents that the ionic liquids are intercalated into the layer of alpha-ZrP. TG-FTIR shows that the mass fraction of C(16)MIMBr, C(16)HDBACCl and C(16)CTACCl in three IL-ZrP are 53.11wt%, 50.65wt% and 51.25wt%, respectively. The onset temperatures of the decomposition for C(16)MIMBr, C(16)HDBACCl and C(16)CTACCl are 174 degrees C, 198 degrees C and 219 degrees C, while the onset temperatures of the decomposition for C(16)MIMBr-ZrP, C(16)HDBACCl-ZrP and C(16)CTACCl-ZrP are 219 degrees C, 225 degrees C and 263 degrees C. The existing of alpha-ZrP improves the thermal stability of ionic liquids. Among the three IL-ZrP, the C(16)MIMBr-ZrP has excellent antibacterial activity, (i.e. within 24 h, the minimal inhibitory concentration of C(16)MIMBr pillared alpha-zirconium phosphonates against S. aureus and E. coli is less than 19 mg/L).

Characteristics and reactivities of solid wastes sorbent for medium-temperature flue gas desulfurization

Abstract In this study, sorbent for flue gas desulfurization is prepared using metallurgical dusts (MD) abundant in iron oxides as the main active component, lime as promoter, and amylum as special additive. The reactivity of the sorbent is conducted in a quartz fixed-bed reactor within the medium temperature range of 300°C–750°C under heating and isothermal conditions, while the physical and chemical properties of the sorbent are measured using ICP-AAS, SEM, XRD, and so on. The experimental results indicate that with temperature increasing from 300°C to 750°C, breakthrough sulfur capacity of the sorbent increases from 0.0257 gS/gSorbent at 300°C to 0.1391 gS/gSorbent at 650°C, then decreases to 0.0836 gS/gSorbent at 750°C, and that the removal efficiency of SO2 and breakthrough sulfur capacity of the sorbent depend on the chemical kinetics of Fe2O3 and CaO in the temperature range of lower than 600°C, but on the thermodynamic equilibrium of sulfuration of Fe2O3, the thermal stability of the Fe2(SO4)3 and content of CaO in the range of higher than 650°C. Physical and chemical analyses of the fresh and reacted sorents further verify that the effective and dominating component of the sorbent is Fe2O3 within the temperature range of lower than 650°C, while is CaO in higher than 650°C.