Advanced Materials Research Vols. 512-515

Abstract: The glass ceramics were prepared by using molybdenum slag (90wt% added) as the raw materials, in which TiO₂ functioned as the nucleation agent. The effect of TiO₂ additions on the crystallization was studied. The crystallization process was investigated by DTA, XRD and SEM. It was showed that TiO₂ can effectively promote the glass formation when the content of TiO₂ is 5wt %. The activation energy for crystal growth E=280.46kJ/mol was evaluated by DTA and kinetic method. The glass ceramic has good properties with main crystal phase of wollastonite.

Abstract: Two series of nickel-based catalyst, NiO/Al₂O₃ and NiO/MgO/Al₂O₃ were prepared by the impregnation and step-by-step impregnation methods in the experiment. Toluene as the tar model compounds, the effect of catalyst composition and reaction condition on the catalytic conversion of tar components in coke oven gas were investigated. The results showed that to get more methane at higher reaction temperature, catalyst of 0.1% NiO loading is prefered. MgO could reduce the carbon deposition on the catalyst surface. The high temperature was conducive to the formation of H₂ and CO, but was not favorable for the CH₄ formation in the investigated temperature. The space velocity had little influence on the production of H₂ and CO, but the larger space velocity was good for the formation of CH₄. In addition, higher H2O /toluene ratio brought a higher H₂ production, but lower CO and CH₄ production.

Abstract: The methane transport was effected by the oxygen reaction across the cover soil. The air flow into the cover could be contribute to methane oxidation, when the extraction working. The gas flow and transport were the coupling process, which must be considered to evaluate the methane reaction in landfill cover. Both of the maximum oxidation rate and permeability of the soil was the critical index for assessing the methane outflow the cover from the landfill. It will provide technological support and theoretical evidence for the evaluation of the methane removal under the gas extraction system in landfill cover.

Abstract: The effect of KBrO₃ on catalytic wet air oxidation to be used in azo dye C.I. Reactive Brilliant Red K-2G decolorization under different conditions is evaluated. The reaction temperature, oxygen partial pressure, pH and catalyst dosage were studied. The optimal conditions of applying KBrO3/O₂ system were: reaction temperature 150°C, oxygen partial pre_{Subscript text}ssure 1.0 Mpa, pH 4 and Reactive Brilliant Red K-2G: KBrO₃ (mole ratio) 1:0.5. Under the optimal conditions, the color removal rate was 98.9%. KBrO₃/O₂ system was efficient in azo dye Reactive Brilliant Red K-2G decolorrization.

Abstract: In this research a laboratory model recirculating cooling water system was applied to investigate the effects of four kinds of inorganic ion concentrations on extracellular polymeric substances (EPS) content, the ration of proteins and polysaccharides ratio in EPS (PR/PS) and dehydrogenase activity (DHA) in the attached biofilms. The results showed that the low Na+ concentration was beneficial to EPS production and biofilms DHA. With Ca2+ concentration increasing, EPS content first increased and then decreased as a whole. Mg2+ showed no obvious effect on biofilms EPS content, while had the effect on PR/PS and DHA. The increase of Fe3+ concentration was beneficial for EPS formation and DHA when Fe3+ concentration was below 1.5 mg/L.

Abstract: Platinum particles modified glassy carbon electrode（Pt/GCE）was prepared by electrochemically deposite. The electrochemica1 behaviors of nitrite on Pt/GCE were studied by cyclic voltammetry. The influence factors of electrocatalysis for nitrite oxidation on Pt/GCE were studied. The result showed that Pt/GCE has favorable electrocatalysis for nitrite. oxidation, which was effected by the amount of platinum particles and the pH of base solution

Abstract: This paper describes the electrocatalytic oxidation of nitrite by poly-thionine /gold nanoparticle modified glassy carbon electrode. Due to the synergistic effect of poly-thionine and gold nanoparticle, the modied electrodes could oxide nitrite with enhanced oxidation current and a decrease in the required overpotential compared with bare electrode without poly-thionine and gold nanoparticles layer coated. The influence factors for nitrite assay such as polymer film thickness, adsorption time of gold nanoparticles onto the poly-thionine film, different buffers and pH，interferent ions were discussed elaborately. Under the optimal conditions, the oxidation current signal was proportional to the concentration of nitrite from 3.0×10-6 to 1.0×10-3 mol/L with a detection limit of 1.0×10-6 mol/L. The proposed method has been applied to determine nitrite concentration in real samples and the results were satisfactory. The poly-thionine/gold nanoparticles composites modied electrode has been proved to possess high sensitivity, good storage stability, reproducibility and anti-interference ability.

Abstract: The acid dissociation equilibria of typical linear weak acid polyelectrolytes, polyacrylic acid (PAA), were investigated by a potentiometric titration method. The electrostatic effects on the equilibria have been rationalized based on a Gibbs-Donnan concept. The apparent acid dissociation constant of PAA at completely neutralized condition determined by extrapolation are quite close to acid dissociation constant of their monomeric acid. The effective volume and the radius of polyelectrolyte phase of PAA have been calculated experimentally by the non-ideality term of ΔpK values with an iterative procedure. The radiuses increase with increasing at α 0.2 region. It is attributable to the repulsion between negatively charged carboxylate groups is weak at lowly dissociated state, whereas the repulsion is strong in highly dissociated state.

Abstract: Spillways or chutes have been used for over 3000 years. Recently, new construction materials and design techniques have increased the interest in spillways and chutes to increase dissolved oxygen concentration in water, especially for contaminated city rivers. A series of laboratory experiments were operated to obtain the efficiency of DO mass transfer over roughened spillway. Two kinds of roughened spillway were considered, i.e., stepped and semi-balled spillways. By means of measuring the DO concentration at the crest and downstream of spillways, the experimental results showed that the more the flow rate is, the less the re-aeration ability of roughened spillway is. Compared with the smooth spillway, stepped spillway has the best reoxygenation effect, followed by the spillway whose bottom is pasted some semi-tennis balls, the worst is the smooth spillway. The results highlight that appropriate artificial roughness on the bottom of spillways or chutes may play an important role to increase dissolved oxygen content and improve water quality.

Abstract: Absorption of carbon dioxide (CO2) by blended diethanolamine (DEA) + 2-amino-2- methyl-1-propanol (AMP) and single DEA solvents were compared using hollow fiber membrane contactor (HFMC). Experimental results showed AMP additive has positive influence to improve CO2 absorption flux and the optimum AMP/DEA mass concentration ratio is between 0.2 and 0.4. Decreasing gas liquid ratio could greatly promote CO2 absorption, and operating temperature has weak effect on CO2 flux. Besides, large CO2 flux can be achieved with high concentration of DEA+0.2AMP solution due to the decrease of liquid phase resistance to mass transfer, but the optimal DEA concentration was recommended to be about 15% for DEA+0.2AMP solution considering the costs of amines in HFMC.