Preparation of Bentonite Supported Nano Titanium Dioxide Photocatalysts by Electrostatic Self-assembly Method

Electrostatic self-assembly method （ESAM） was used to prepare bentonite supported-nano titanium dioxide photocatalysts. The materials were characterized by X-ray diffraction （XRD）, fourier transform infrared spectroscopy （FT-IR） and scanning electron microscopy （SEM）. Methyl orange was used to estimate the photocatalytic activity of the materials. The effects of the calcination temperature and silane dosage on the photocatalytic activity of the samples were investigated. The experimental results show that the bentonite facilitates the formation of anatase and restrains the transformation of anatase to rutile. Part of nano-size TiO2 particles insert into the galleries of bentonite. The photocatalysts exhibit a synergistic effect of adsorption and photocatalysis on methyl orange. Photocatalysts prepared by ESAM method exhibit higher photocatalytic activity and better recycle ability than those of the traditional method.

New Applications of Nano Titanium Dioxide

New applications and research progress of nano titanium dioxide （TiO2） in coating, environmental protection, chemical industries, cos- metics industry, electronic industrial products, medicine, health and food processing fields were summarized in the paper. The results showed that nano TiO2 is the most dynamic one in the new nano material study today, which will have a very important impact on our social economic develop- ment in future. The research and utilization will give people＇s lives enormous changes.

Nano-cerium-element-doped titanium dioxide induces apoptosis of Bel 7402 human hepatoma cells in the presence of visible light

AIM： To investigate the apoptotic effect of photoexcited titanium dioxide （TiO2） nanoparticles in the presence of visible light on human hepatoma cell line （Bel 7402） and to study the underlying mechanism. METHODS： Cerium-element-doped titanium dioxide nanoparticles were prepared by impregnation method. Bel 7402 human hepatoma cells were cultured in RPMI 1640 medium in a humidified incubator with 50 mL/L COL at 37℃. A 15 W fluorescent lamp with continuous wavelength light was used as light source in the photocatalytic test. Fluorescence morphology and agarose gel eletrophoresis pattern were performed to analyze apoptotic cells. RESULTS： The Ce （Ⅳ）-doped TiO2 nanoparticles displayed their superiority. The adsorption edge shifted to the 400-450 nm region. With visible light illuminated for 10 min, 10 μg/cm^3 Ce （lV）-doped TiO2 induced micronuclei and significant apoptosis in 4 and 24 h, respectively. Hochest 33 258 staining of the fixed cells revealed typical apoptotic structures （apoptotic bodies）, agarose gel electrophoresis showed typical DNA ladder pattern in treated cells but not in untreated ones. CONCLUSION： Ce （Ⅳ） doped TiO2 nanoparticles can induce apoptosis of Bel 7402 human hepatoma cells in the presence of visible light.

Preparation of nano-TiO_2/diatomite-based porous ceramics and their photocatalytic kinetics for formaldehyde degradation

Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650~C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic （PC） activity of the composites was investigated un- der UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were k = 0.576 mg＇m3·min^-1 and K = 0.048 m3/mg.

Preparation,characterization of Y^(3+)-doped TiO_2 nanoparticles and their photocatalytic activities for methyl orange degradation

A series of pure and Y3＋-doped TiO2 nanoparticles with high photocatalytic activities were prepared by a sol-gel method using tetra-n-butyl titanate as precursor.The as-prepared catalysts were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and diffuse reflectance spectroscopy（DRS）.The results indicated that yttrium doping could effectively reduce the crystalline size,inhibit the anatase-to-rutile phase transformation and surppress the recombination of the photogenerated electron-hole pairs.The DRS results showed that the optical absorption edge shifted to red direction owing to yttrium ion doping.The photocatalytic activities of samples were evaluated by the photodegradation of methyl orange（MO） aqueous solution under 300 W high pressure mercury lamp irradiation.Photodegradation results revealed that Y3＋ doping could greatly improve the photocatalytic activity of TiO2.In this experiment,the optimal dosage was 1.5 mol.% when samples were calcined at 773 K for 2 h,which caused a MO photodegradation rate of 99.8% under UV irradiation for 70 min.

Surface characterization of steel/steel contact lubricated by PA06 with novel black phosphorus nanocomposites

In the present work,two types of novel nano additives,titanium sulfonate ligand/black phosphorus(TiLi/BP)and titanium dioxide/black phosphorus(TiCVBP)nanocomposites,were prepared.The tribological behavior of the steel/steel friction pairs lubricated by polyalphaolefins type 6(PA06)containing the nanocomposites under boundary lubrication was studied.The worn surfaces were analyzed using modem surface techniques.The experimental results show that the rubbed surfaces became smooth and showed little wear with the addition of the nanocomposites.TiO_(2)/BP nanocomposites can significantly improve the lubricity of BP nanosheets under high contact stress.The synergistic roles of the load-bearing abilities and rolling effect of TiO_(2) nanoparticles,the slip induced by the BP with its layered structure,and the establishment of a tribofilm on the sliding interface are the basis of the tribological mechanisms.