Materials Science Forum Vols. 743-744

Abstract: Ti (OC₄H₉)₄ was used as the Ti precursor and titanium dioxide (TiO₂) was prepared by sol-gel method. During the preparation process, Fe³⁺ was doped and different surfactants, such as SDS, PEG, CTAB, were added to improve the photocatalytic activity of TiO₂. The effect of the different type of surfactants on the structure of Fe-doped TiO₂ was discussed. The photocatalysts were characterized by thermogravimetric thermal analysis, X-ray diffraction, scanning electron microscopy and UV-Vis spectrophotometer. The red shift of the absorption edge of the Fe-doped TiO₂ prepared by using different surfactants was observed. Methyl orange (MO) solution was degraded under sunlight irradiation to evaluate the photocatalytic performance. The results indicated that the photocatalyst prepared with PEG addition had the highest activity and MO degradation ratio could reach 90% after 4 hours irradiation with the best photocatalyst.

Abstract: Unlike photo-induced super-hydrophilic inorganic thin films, non-photoinduced innate super-hydrophilic TiO₂/SiO₂ thin films have been successfully prepared in this work. SiO₂/TiO₂ thin films were prepared by solgel method via adding hydrophilic fumed silica to TiO₂ sol and characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and contact angle meter. The results show that the super-hydrophilicity of the as-prepared thin films can maintain for one month without light irradiation, and the thin films have excellent antifogging property as well.

Abstract: Distinguished with photoinduced super-hydrophilic inorganic thin films, non-photoinduced innate super-hydrophilic SiO₂ thin films were successfully fabricated in this work. The SiO₂ sol was prepared by acid-base two-step sol-gel method. The mix solution containing SiO₂ sol and polyethylene glycol (PEG) was coated on glass substrate and then went through thermal treatment to obtain innate super-hydrophilic SiO₂ thin films. The films were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and contact angle meter. The results show that the surface concave-convex microstructure and the hydroxyl content are the factors that endow the SiO₂ coating films with innate super-hydrophilic property.

Abstract: Using space electromagnetic wave propagation principle, environment requirements of building protective engineering structure and performance characteristics of cement-based composites, a design idea of cement-based composite with electromagnetic protection is presented in the present study. This design idea was tested and verified. According to the proposed new designed method, by optimizing and selecting the wave-transparent aggregate and absorbing agent material, the absorbing composite materials of cement-based electromagnetic protection, electromagnetic wave absorbent, energy saving and environmental protection can be improved. A new cement-based composite with electromagnetic protection and microwave absorbing properties (the minimum reflectivity is-8.4dB), wide frequency bandwidth, and letter mechanical properties was prepared by using a 20 mm sample between 8-18 GHz. The results provide a basis design and preparation of cement-based composite with electromagnetic protection.

Abstract: Ultra-fine cerium dioxide precursor particles was prepared with cerium (III) nitrate hexahydrate (Ce (NO₃)₃6H₂O) and urea (CO(NH₂)₂) at 85°C by homogenous precipitation method. Effects of reaction and ageing time on the morphology of the precursor particles were studied, the morphology of precursor particles was characterized by scan electronic microscope and the crystallinity of the precursors was studied by X-ray diffraction. The result showed that the mono-dispersed spherical particles turned into flower and bundle-like particles as reaction time increasing, the particles turned into slice and rod-like particles as the ageing time increasing, the transition process occurred in ageing process was later than that in the reaction process, the spherical particles were less crystallization and the slice and the rod-like particles were at a state of fine crystallization.

Abstract: Thus, here, by using the sol-gel technique and spin coating technology, a series of mesoporous silica thin films doped by silylated naphthol fluorescence dye were successfully fabricated. By selecting the same surfactant triblock copolymer Pluronic F127 (EO₁₀₆-PO₇₀-EO₁₀₆) as structure-directing agent, films with different pore structure and similar aperture size were synthesized under different conditions. The films doping fluorescence dye toward nitro explosive 2, 4, 6-trinitrotoluene (TNT) vapor exhibited rapid response rate and extremely high fluorescent quenching efficiency, close to 96.4 % after 1200 s response. The results clearly showed that pore structure control of mesoporous film was an effective way to improve sensor performance. Mesoporous thin films, with different pore structure, easily to be prepared and owning high sensitivity, could be used as a new alternative of trace explosive detecting material.

Abstract: Nanomaterial is becoming an important adsorption or disinfection material for removing virus from drinking water. In this study, static and dynamic tests were used to examine adsorption and inhibition characteristics of carbon nanotubes (CNTs) on two model viruses -- f2 and MS2 bacteriophage. Controlling variate method was used to systematically investigate the adsorption kinetics and adsorption isotherms of CNTs on two model viruses; as well as to find the impact of different CNTs dosages on adsorption effect; and then to study the inhibitory effect of CNTs.The results showed that: (1) The adsorption process of f2 and MS2 bacteriophage on CNTs corresponded well with the pseudo-second-order kinetics equation. Time to reach a saturation equilibrium adsorption is about 30min. (2) Both the Langmuir and Freundlich isotherm adequately described two adsorption processes which indicated that the removal mechanism of virus was a mix of monolayer and multilayer adsorption. (3)The dosage of a single removal system should not be too high in practical application. (4) The inhibition of CNTs on model viruses exhibited.

Abstract: Lanthanum doped fly ash (La-FA) adsorbent was prepared using hydrothermal reaction method and applied to the removal of wool-used reactive red B (WRR B) dye from the aqueous solution. The preparation and adsorption conditions of the sorbent were investigated. The adsorption characteristics and mechanism were analyzed by X-ray diffraction (XRD) and discussed from kinetics viewpoint. The results show that: the removal rate of WRR B from the solution containing 150 mg/L at pH 6.0 by La-FA adsorbent, which obtained under the conditions of a certain ratio of mass to concentration of La³⁺ and stirring time of 6h at 60°C, is 94% with good adsorption effect when the contact time is 2.5h at temperature of 25°C. All sorption kinetic data at different temperature are found to be described by the pseudo-second order equation very well and the adsorption process is mainly controlled by intra-particle diffusion. The equilibrium adsorption amount (q_e) of the La-FA adsorbent for reactive dyes increased with increase in dye initial concentration and decreased with the rise of temperature. The adsorption activation energy obtained was 9.86kJ/mol. Combining with XRD analysis, the results indicate that the adsorption is mainly the physical sorption with exothermic nature. The room temperature is favorable to the adsorption and actual operation.

Abstract: Polypropylene pre-oriented multifilament were made by melt spinning with fast winding, and then hard elastic polypropylene fibers were made followed by annealing treatment under some conditions. The effects of the conditions of melt spinning and annealing process on the elasticity of polypropylene fibers were studied. The structure and property of hard elastic polypropylene fibers were analyzed by DSC,WAXD,SAXS and Sound velocity anisotropy. The results showed that the hard elasticity of annealed fibers increased with the improving of speed of winding, and the elasticity also increased with the improving of annealing temperature and extension of annealing time, and the elastic recovery rate of PP multifilament can be as high as 93.6%. The crystal phase of unannealed and annealed PP fibers did not change. Annealing leaded to form perfectly the characteristic crystalline structure of crystals of being perpendicular to fiber axis.

Abstract: The electrocatalytic degradation performances of the Ti/Sb-SnO₂ electrodes with Ni, Co and Mn intermediate layers prepared by thermal oxidation for phenol were studied. The microstructure and morphology of the intermediate layers and the outer active layers were characterized by XRD, SEM and EDX. The content of phenol and intermediate material degraded with different electrodes in the phenol solution was compared by UV-Vis spectrophotometer and measuring COD. In the meantime, the influence of different intermediate layers on the service life of anode was investigated by the accelerated life test. The experimental results showed that, after 10h, the phenol degradation efficiency with Ti/Ni/Sb-SnO₂ electrode almost reached 100% and the COD was 18mg/L, but the electrode was irreversibly damaged within 20min under the accelerated life test. Comparing with Ti/Ni/Sb-SnO₂, the degradation efficiency of phenol in Ti/Co/Sb-SnO₂ electrode was worse because the COD was 43mg/L, but the accelerated life was 20.8h. For Ti/Mn/Sb-SnO₂ electrode, the COD was only 50mg/L, but the accelerated life reached to 289h. Therefore it may be concluded that the different intermediate layers have a notable effect on the structure, morphology, service life and the electrocatalytic activity of anode.