Advanced Materials Research Vols. 356-360

Abstract: Biomorphic ceramics is a novel inorganic materials with hierarchical structures derived from natural biological structures. In this paper, the properties of biomorphic materials are described. The preparation technologies of converting biological structures into biomorphic ceramics are summarized. At last the application and prospects of the ceramics in this field also are analyzed.

Abstract: A magnetically separable photocatalyst silver vanadates@SiO₂/Fe₃O₄ was prepared by hydrothermal process. The prepared sample was composed of mixed phases of a–Ag₃VO₄ and Ag₄V₂O₄, and the main phase was a–Ag₃VO₄. The bandgap of the synthesized sample was 2.2 eV. In the degradation of methyl orange (MO) solution under the visible light (l>420 nm), the silver vanadates@SiO₂/Fe₃O₄ showed high photocatalytic activity in two-cycle photocatalytic test.

Abstract: The excess nitrate in groundwater could be removed by heterotrophic denitrifying bacteria, though often limited by scarce carbon source present. Denitrification in two columns filled with walnut shell and its mixture with silica sand was studied. Both media showed high nitrate removal (>90%) with trace amounts of nitrite left over. The nitrate removal rates of two columns, 0.039±0.003, 0.029±0.003 g N L^-1d^-1, respectively, were zero order (r²=0.9181, 0.9998 for each column) in kinetics, which demonstrated a low C/N ratio herein. Despite of the implication that denitrification was carbon-limited, the organic matter residue in both columns, especially in pure walnut shell, were still problematic. The mixture media was suggested as potential PRB media for its satisfactory nitrate removal and relatively low COD residue; though we believed these hardly degradable organic residues require more study.

Abstract: Water Storage and Controlled-release Film (WSCF) is a new kind of polymer composite with the function of releasing water slowly in a given period. This paper resumptively introduces the importance of water storage and controlled-release film (WSCF) material for tree planning in desertified regions. Microstructures of WSCF were studied and experiments were also carried out successively in various environmental conditions.

Abstract: N/TiO₂ photocatalyst was synthesized by modified sol–gel method and characterized by XRD, XPS and DRS. The photoactivity of N/TiO₂ were evaluated by the degradation of 2-naphthalenesulfonate (2-NS) under different light sources. The results showed that nitrogen doping may cause band gap narrowing of TiO₂, and therefore increase the photocatalytivity of N/TiO₂ under visible-light. The average particle size of the N/TiO₂ synthesized is about 10 nm, and the N/TiO₂ contains 100% anatase phase of TiO₂. The dopant is found mainly to be NOx and the doping concentration in NT is 1.30%. The NT shows very high efficiency for the catalysis of the degradation of 2-NS. The degradation efficiency of 2-NS using NT under visible light for 5 h is 47.29%, much higher than 2.5% of the pure TiO₂.

Abstract: TiO₂ nanoparticles are prone to aggregate in aqueous solution, which limits its extensive application. Several researches have been carried on the stability of TiO₂ suspensions. In this study, four common dispersants including ethanol, tetrahydrofuran (THF), polyvinylpyrrolidone (PVP), and sodium hexametaphosphate (SHMP) have been chosen to detect their effects on stability of TiO₂ aqueous suspensions. The experimental results showed that THF and SHMP were efficient dispersants for TiO₂ nanoparticles in aqueous solution.

Abstract: A simple method was developed for the preparation of zinc oxide (ZnO) nanofibers grafted on the expanded graphite(EG) under routine conditions. The synthesized materials were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The results show that the ZnO nanofibers, with a diameter of 50-150 nm, were randomly deposited on the expanded graphite.

Abstract: Water Storage and Controlled-release Film (WSCF) is a new kind of polymer composite with the function of releasing water slowly in a given period. Micro-organism culture was carried out to study the process of film’s degradation. The results showed that the degradation rate of WSCF added with fungi suspension was increased by 0.6% more than that of WSCF without fungi suspension. The degradation rate of WSCF added with soil suspension was increased by about 1% more than the film without soil suspension. Compared different culture mediums, the order of degradation rates of WSCF was: bacteria medium > actinomyces medium > fungi medium. The degradation rate of WSCF with field soil suspension was the highest one. The degradation rate of WSCF was higher than ordinary plastic film, increased by 3-5%. The results of tests under liquid culture indicated that mixed bacterium were helpful to the degradation of WSCF, the degradation rate of WSCF under liquid culture was higher than that of soil culture, increased by about 2%.

Abstract: Thiol-functionalized poly (acrylic acid)/SiO₂ (PAA/SiO₂) composite nanofiber membranes have been fabricated by a sol-gel electrospinning method and their adsorption capacity for Ag⁺, Cu²⁺ was investigated. Results showed the PAA/SiO₂ fibers had a diameter between 300 nm-700 nm. FTIR results demonstrated that the mercapto groups have been introduced into the silica skeleton. The adsorption of Ag⁺, Cu²⁺ on the membranes fit the Redlich-Peterson isotherm model best. The equilibrium adsorption capacity of Ag⁺ (575.64 mg/g) on PAA/SiO₂ nanofiber membranes is higher than Cu²⁺ (331.52 mg/g). The desorption rate reached 98% in 30 min. The removal rate of Ag⁺, Cu²⁺ still maintained above 75% after six regeneration cycles. Adsorption kinetics of Ag⁺, Cu²⁺ followed a pseudo-second-order model.

Abstract: The influences of adsorption temperature, adsorption time, dosing quantity, adsorption environment pH value, initial concentration and bamboo charcoal type on adsorption of bamboo charcoal adsorb ammonia nitrogen in wastewater are studied. The result shows that the maximum adsorption values are 1.1715 mg/g and 0.9115 mg/g respectively at 25°C and 40°C. Bamboo charcoal can easily absorb ammonia nitrogen at low temperature condition. 180 min is a suitable adsorption time. Increasing bamboo charcoal dosing quantity is helpful to improve efficiencies of ammonia nitrogen removal in wastewater, but the adsorption capacity is declining as bamboo charcoal dosing quantity increasing. Solution pH value has a great impact on the adsorbed amount, the adsorbed effect in alkaline solution is much better than in acid one’s. The adsorption ability of the moderate temperature bamboo charcoal is higher than the high temperature one’s.