Advanced Materials Research Vols. 652-654

Abstract: Coal gangue is a kind of solid waste which is discharged from coal mining and coal washing. Dumped gangues do not only take a large land occupation but also pollute air and water. Treatment and utilizing of coal gangues has become the major issue for the coal industry to resolve. As major experimental material in this study, the coal gangue from Dawukou, Shizuishan, Ningxia province, China had been analyzed to have high-alumina content, and it could been used as alumina constituent for the preparation of sulphoaluminate cement. In this paper, alite-sulphoaluminate cements were prepared at 1330°C using coal gangue, limestone and gypsum as major main materials, fluorite and barite as minor materials. The result shows that major clinker minerals of the cement are sulphoaluminate, alite and belite, while major hydrate is ettringite, compressive strength of the cement is 48.9MPa after 7d. These experiments provide a new method of coal gangue comprehensive utilization.

Abstract: Catalytic hydrolysis decomposition of dichlorodifluoromethane (CCl2F2) in the presence of water vapor and oxygen was studied over a series of solid base that have different ZrO2 content using a fixed-bed reactor. CO2 and CClF3 were the main-products and no CO was detected as by-product. The decomposition activity depended on the calcination temperature and the Zr:Ca. Calcined at 650 °C and Zr:Ca=1:0.35 were the best catalyst preparation conditions. Adopting low concentration of oxygen and CCl2F2 and high concentration of water vapor is preferable to the achievement of high conversion of CCl2F2 and selectivity for CO2. The catalytic activity of CaO/ZrO2 remained steady for 20 h on stream.

Abstract: In this paper, regeneration of reed leaf fibers that have been degummed pretreatment in high temperature and pressure dissolved in 1-butyl-3-methylimidazolium chloride ionic liquids was studied. The samples containing 5% or 10%(wt/wt)reed leaf fibers in the ionic liquids, at 90°C for 7h.The dissolution process was viewed by polarizing microscope. Fourier-transform infrared spectroscopy(FT-IR) and X-ray diffraction were used to visualize the crystalline of reed leaf fiber transformed completely from cellulose I to cellulose Ⅱ after regenerated directly from 1-butyl-3-methylimidazolium chloride solution.

Abstract: Sm0.3Ce(0.7-x)MoxO(1.85+δ) yellow pigments were prepared by solid-state synthesis method, which were obtained by doping molybdenum for substitution of Ce4+ in Sm0.3Ce0.7O1.85. Effects of Molybdenum doping amount on crystal structure of the pigments were investigated and the coloring mechanism of the pigments was analyzed. The results show that molybdenum doping has markedly changed the color of the pigments. The color of pigments changed from cream to yellow as molybdenum doping amount increased from x=0.00 to x=0.04. And the color changed from yellow to yellow green when x was adjusted from x=0.05 to x=0.07. When x=0.08, the color of pigments changed to gray.

Abstract: A pot experiment was conducted to investigate the effect of nano particle hydroxyapatite (nHAP) on Cadmium(Cd) contaminated soil. The Cd uptake of pakchoi in Cd polluted soil treated with various concentration of nHAP were studied. In addition, the effect of nHAP on chemical fraction distribution in Cd contaminated soil was evaluated. Results indicated that by adding the nHAP, the Cd level in pakchoi shoots and roots decreased significantly compared to the control. The mechanism of this treatment involved bioavailability reduction and immobilization of Cd in soil, resulting in the transformation of available fractions to unavailable fractions. In conclusion, with the addition of nHAP, the resistance to Cd of pakchoi in contaminated soil could be significantly enhanced and the quality of the plants improved.

Abstract: This study aimed to that waste circuit boards in batches were incinerated by thermal plasma. Firstly, the working principle of plasma incinerator and the exhaust gas treatment main process were introduced, then, the experimental results was analyzed and discussed. Due to the thermal plasma processing waste incineration furnace has high temperature (1200 0C above), all the organic ingredients in waste circuit boards, including dioxin, can be decomposed completely in a few milliseconds, no showing the secondary pollution and no producing furans and other carcinogens. In addition, after main exhaust gas (CO, NO) concentration change with time was carefully tracked, it was found that a large amount of CO gas was produced and NO gas concentration was within national safety limits during experiment. Although 44.4 kg sample was incinerated, more than 1 kg of small pieces of metal like Copper was obtained from the cooling molten slag. Finally, it was obvious that the volume and weight of molten slag was far less than the ones of sample. The experimental result has important practical significance for protecting the environment, obtaining more CO gas resource and retrieving a variety of rare metals (such as Gold, Copper, Silver, Platinum, etc.).

Abstract: Alginate/polyvinyl alcohol (PVA) composite fibers containing copper ions were prepared by wet spinning. The spinning solution and manufacturing process were researched. The composite fibers were characterized by Tensile Strength Tester, SEM and TGA. This report shows that the spinning solution is a typical kind of pseudoplastic fluid. Adding boric acid to coagulation bath and putting Cu ions into composite fibers can improve the strength. The structure of composite fibers with Cu ions is denser and there are grooves on the fiber surface. In addition, the thermal property of composite fibers is steady.

Abstract: In order to make the reed leaf fiber soft, increase its separating degree and remove impurities, the method of pretreatment in removing impurity was studied. The orthogonal method was used to optimize the treatment condition and the optimal conditions were obtained at a concentration of sodium hydroxide of 18g/L, treating temperature of 100°C and holding time of 90min. It also revealed that temperature holding time had the greatest influence on the degumming effect of the fibers. Under these conditions, the content of pectin and hemicellulose could reach about 2.6% and the content of cellulose could come up to 92.8%. Furthermore, the binary quadratic orthogonal regressive experiment was used to optimize the degumming process. The longitudinal directions of the fibers were examined by SEM before and after the processing.

Abstract: CaF₂/AG25 (CFA) hybrid sorbent formed by hybrid reaction with activated calcium fluoride of low cost and anionic dye wastewater-Acid Green 25 (AG25) was used for the treatment of cationic dye wastewater. The adsorption of two cationic dyes methyl violet (MV) and Neutral Red (NR) from aqueous solutions was examined using a batch sorption technique. The effects of time, pH, ionic strength and temperature on the adsorption were also examined. It exhibited a faster adsorption to cationic dyes and hardly affected in pH over 3.5, ionic strength low 0.04 mol/L and temperature between 20 oC and 60 oC. The adsorption behavior of the NR and MV on CFA is in good agreement with the Langmiur isotherms model with the correlation coefficients of R 0.9948 for NR and 0.9992 for MV and the maximum adsorption capacity of NR (39.22 mg/g) and MV (48.78 mg/g). Finally, this sorbent was used in treatment of two practical cationic dye wastewaters with satisfactory results.

Abstract: N-doped Titanium dioxide (TiO2) nanotube arrays were characterized by scanning electron microscope (SEM)，X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to analyse its surface morphology, crystal types and the doping behavior of nitrogen. The material was used as electrode for photoelectrocatalytic degradation of hexachlorobenzen under irradiation of simulated sunlight. The effects of photocatalysis, electrocatalysis, photoelectrocatalysis, the concentration of Na2SO4 and pH value on degradation of HCB were investigated.