Jin Hui Peng

Dielectric Properties and Temperature Increase of Zinc Oxide Dust Derived from Volatilization in Rotary Kilns

Abstract The present study measures dielectric properties (ε´, ε″ and tanδ) of zinc oxide dust produced in a rotary kiln, using a cavity perturbation method with microwaves at 2.45 GHz. The effect of apparent density of the dust on the dielectric properties was determined. The results indicated that zinc oxide dust has excellent absorbing performance and can reach 800 ºC in 6 minutes. The apparent density of zinc oxide dust and the microwave penetration depth were also related.

Characterizations of Novel Binuclear Transition Metal Polynitrogen Compounds: M2(N5)4 (M=Co, Rh and Ir)

Theoretical studies on a series of binuclear transition metal pentazolides M2(N5)4 (M=Co, Rh and Ir) predict Paddlewheel-type structures with very short metal-metal distances suggesting high-order metal-metal multiple bonds. Natural Bonding Orbital (NBO) analysis have indicated that the bonding between the metal atom and the five-membered ring is predominantly ionic for each M2(N5)4 species, and a high-order metal-metal multiple bonding exists between the two metal atoms, in addition, the presence of the delocalized π orbital plays an important role in the stabilization of this metal-polynitrogen species. Nucleus independent chemical shift (NICS) values confirm that the planar N5 exhibits aromaticity in these M2(N5)4 species. The values of NICS(0.0), NICS(0.5) and NICS(1.0) for Co2(N5)4 are larger than those of the other two M2(N5)4 species (M=Rh and Ir), with the order of Co2(N5)4>Rh2(N5)4>Ir2(N5)4. The dissociation energies into Mononuclear Fragments for M2(N5)4 (M=Co, Rh and Ir) are predicted to be 82.9 (85.7), 139.9 (113.2), and 155.1 (149.7) kcal/mol, respectively. However, the dissociation energies for the loss of one pentazolato group from the M2(N5)4 analysis have indicated that the Co2(N5)4 is relatively higher at ~40 kcal/mol. Thermochemistry suggests Co2(N5)4 to be a viable species.

Optimization of Microwave Drying of CuCl Residue Using Response Surface Methodology

Abstract: The technology that CuCl residue from Zn hydrometallurgy was dried by microwave heating was studied. The influence of the drying duration, drying temperature and material thickness on dehydration rate was investigated. The response surface methodology (RSM) technique was utilized to optimize the process conditions. The optimum conditions for drying CuCl residue have been identified to be an drying temperature of 80°C, drying duration of 11 min and material thickness of 16 mm. The optimum conditions resulted in an CuCl residue with moisture content of 4.97%, which could ensure remove chlorine of CuCl residue by microwave roasting.

Study on Furfural Production from Hemicelluloses

In this paper, furfural was produced from hemicelluloses of bagass by hydrolization reaction with sulfuric acid and acetic acid respectively. The effect of several variables such as temperature , liquid-to-solid ratio ,time and catalyst charge（KCL） on furfural yield was studied. The results showed that the better yield of furfural was obtained in acetic acid hydrolysis system. However, compared to yield of acetic acid hydrolysis system, it need more time and higher temperature at the same liquid-to-solid ratio. At last, when sulfuric acid as catalyst, liquid-to-solid ratio was 1:6 and time was 5h at 150°C, furfural yield can reach 75 %.

Microwave-Assisted Preparation and Physical Characterisation of Iron Oxyhydroxides Adsorbents for Arsenic Removal from Aqueous Solutions

A novel method for preparation of iron oxyhydroxide materials, involving aqueous precipitation followed by microwave assisted aging is investigated. The produced materials are characterized by XRD, SEM, EDX and TEM spectroscopy and BET analysis. The materials show physical characteristics dependent on preparation procedure. The adsorptive properties of the materials for arsenic are studied by batch adsorption techniques. It is found that the rate of arsenic upload depends strongly on the degree of crystallinity of the materials. The adsorption capacity is approximately 55 mg/g. The physical characterization of the arsenic loaded adsorbents show that the adsorption process modifies the morphology of the materials. Over 4% of arsenic atoms are incorporated into the particle matrix.

A Theoretical Investigation of the Thermal Decomposition of Zinc Acetate and Zn-Oxo Complex Based on the Pyrolysis Characteristics of the Zinc-Containing Spent Catalyst

Zinc acetate and Zn-oxo complex of Zn4O(CH3COO)6 containing in the spent catalyst of vinyl synthesis were investigated by means of the first principles of density functional (DFT) methods. The geometries, energies, charge populations and local electron density distributions of the two compounds and their formate analogues were analyzed. Based on the pyrolysis characteristics of the spent catalyst, the thermodynamic properties of ΔG, ΔH and ΔS for possible decomposition reactions of zinc acetate and Zn4O(CH3COO)6 were calculated as functions of temperature. The results provide a theoretical evidence that Zn4O(CH3COO)6 is more stable than zinc acetate due to the regular Zn4O and ZnO4 tetrahedral coordination between Zn atoms and two kinds of O atoms. The preparation of Zn4O(CH3COO)6 via the hydrolysis of zinc acetate is thermodynamically feasible. Zn4O(CH3COO)6 is further decomposed into ZnO via a decarboxylation reaction rather than a hydrolysis reaction.

Adsorption Characteristics of Nitric Oxide and Sulfur Dioxide on Coal Activated Carbon

The aim of this paper is to study the adsorption characteristics of nitric oxide (NO) and sulfur dioxide (SO2) on raw coal activated carbon over temperature ranged 298～343K using a static volumetric adsorption apparatus. The adsorption equilibrium data for NO and SO2 were fitted to Freundlich, Dubinin-Radushkevich (D-R) and Sips adsorption isotherm model. Isosteric heat of adsorption was determined by the Clausius-Clapeyron equation. It was found that Sips adsorption isotherm model is more suitable for description of NO adsorption process at 298K, 313K and 328K and SO2 adsorption process at 313K, 328K and 343K, however, D-R adsorption isotherm model is more suitable for description of the NO adsorption process at 343K and SO2 adsorption process at 298K. The isosteric heat of adsorption values of SO2 increase slightly as the adsorbed amounts increasing from 0.8 to 1.6mg/g, but the isosteric heat of adsorption values of NO show a converse trend. Meanwhile, NO and SO2 adsorbed on coal activated carbon at the four temperatures may be a dominant of physical adsorption.

Pyrolysis Kinetic of Basic Zinc Carbonate from Spent Catalyst and Preparation of Active ZnO by Microwave Heating

The TG and DTG curves of self-made ZnO precursor were studied by the thermo-gravimetric analysis method in N2 atmosphere from 25°C to 650°C at the heating rate of 5, 10 and 15°C/min. The TG curve showed that the decomposition process started at about 150°C and finished at 300°C, in accordance with the temperature range of the decomposition from basic zinc carbonate to zinc oxide. The first level chemical reaction based on Coats-Redfern method was applied to estimate the activation energy of the decomposition. The correlation factor was about 0.99, and the calculated average activation energy was 33.89kJ/mol. Active zinc oxides were perpetrated by microwave heating at 350°C for 30min. Their composition and surface morphology were investigated by using scanning electron microscope and X-ray diffraction and its quality can reach the first-grade standard of HG/T2572-94.

Optimization on Influencing Factors of Fracture Toughness of Corundum-Mullite Toughened by In Situ Synthesized Mullite Whiskers by Response Surface Methodology

The corundum-mullite was toughened by in-situ synthesized mullite whiskers and the process parameters influencing the fracture toughness of corundum-mullite, such as sintering temperature, addition amount of AlF3 and V2O5, were optimized by means of response surface method. Corundum-mullite with fracture toughness of 9.44 MPa.m-1/2 could be obtained under the optimized conditions, i.e. sintering temperature of 1400°C, 4.8 wt.% of AlF3 and 5.8 wt.% of V2O5. The results showed that it was feasible to prepare corundum-mullite toughened by in-situ synthesized mullite whiskers by the optimized parameters. In addition, an accurate model based on response surface method was proposed to predict the experimental results.

Recovery Methods of Germanium

The paper overviewed the recovery methods of germanium, summarized the feature of those methods such as leaching with sulphuric acid, chlorination leaching- distillation, alkali decomposion, leaching with hydrofluoric acid, extracting, reduction and leaching germanium with microorganism. And introduced the principles ,technologies and disadvantages of those methods. Finally, prospected that microwave pretreatment technology and microwave directly leaching can be used in traditional methods such as acid leaching and alkali decomposion to improve the recovery rate of germanium by change insoluable germanium into soluble germanium and upgrade the leaching rate of germanium.