Water purification in a solar reactor incorporating TiO2 coated mesh structures

The rate of photocatalytic oxidation of contaminants in drinking water using an immobilized catalyst can be increased by properly designing the catalyst structure. By creating a solar reactor in which meshes coated with TiO2 were stacked, we demonstrated that degradation of humic acids with four superimposed stainless steel meshes was up to 3.4 times faster than in a single plate flat-bed reactor. Incorporation of TiO2 coated mesh structures resulted in a high specific photocatalytically active surface area with sufficient light penetration in the reactor, while the coated area for one mesh was 0.77 m2 per m2 projected area. This brought the photocatalytic efficiency of such reactors closer to that of dispersed-phase reactors, but without the complex separation of the very fine TiO2 particles from the treated water.

Anchoring ultra-fine TiO2–SnO2solid solution particles onto graphene by one-pot ball-milling for long-life lithium-ion batteries

A low cost, up-scalable and one-pot wet-mechanochemical approach is designed for fabricating TiO2–SnO2@graphene nanocomposites where TiO2and SnO2solid solution nanoparticles are evenly anchored on graphene sheets.

Low Temperature Synthesis of TiO2 from Acid Solution

Fine TiO2 particles were synthesized from titanate precursor, Na16Ti10O28, dissolved in aqueous HNO3 solution. Crystalline rutile TiO2 powders were prepared by reflux of dissolved powders in the aqueous HNO3 solution under 100 °C. Prepared TiO2 powders were characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy and BET specific surface area analysis.

Genotoxic effects of nanosized and fine TiO2

The in-vitro genotoxicity of nanosized TiO2 rutile and anatase was assessed in comparison with fine TiO2 rutile in human bronchial epithelial BEAS 2B cells using the single-cell gel electrophoresis (comet) assay and the cytokinesis-block micronucleus test. BEAS 2B cells were exposed to eight doses (1—100 μg/cm2) of titanium(IV) oxide nanosized rutile (>95%, <5% amorphous SiO2 coating; 10 × 40 nm), nanosized anatase (99.7%; <25 nm), or fine rutile (99.9%; <5 μm) for 24, 48, and 72 h. Fine rutile reduced cell viability at lower doses than nanosized anatase, which was more cytotoxic than nanosized rutile. In the comet assay, nanosized anatase and fine rutile induced DNA damage at several doses with all treatment times. Dose-dependent effects were seen after the 48- and 72-h treatments with nanosized anatase and after the 24-, 48- (in one out of two experiments), and 72-h treatments (one experiment) with fine rutile. The lowest doses inducing DNA damage were 1 μg/cm2 for fine rutile and 10 μg/cm 2 for nanosized anatase. Nanosized rutile showed a significant induction in DNA damage only at 80 μg/cm2 in the 24-h treatment and at 80 and 100 μg/ cm2 in the 72-h treatment (with a dose-dependent effect). Only nanosized anatase could elevate the frequency of micronucleated BEAS 2B cells, producing a significant increase at 10 and 60 μg/cm 2 after the 72-h treatment (no dose-dependency). At increasing doses of all the particles, MN analysis became difficult due to the presence of TiO2 on the microscopic slides. In conclusion, our studies in human bronchial epithelial BEAS 2B cells showed that uncoated nanosized anatase TiO2 and fine rutile TiO2 are more efficient than SiO 2-coated nanosized rutile TiO2 in inducing DNA damage, whereas only nanosized anatase is able to slightly induce micronuclei.

Hydrothermal Synthesis of TiO2/SiO2 Hybrid Photocatalyst from Rice Husk Ash

Photocatalyst materials were prepared as a hybrid between TiO2 /SiO2 via low temperature hydrothermal method (150oC) without further heat treatment. Porous silica from rice husk ash was used as a support for fine TiO2 particles which acted as a photocatalyst when radiated with a UV light. TiO2-deposited SiO2 was successfully prepared through hydrolysis of TiOSO4 solution by controlling synthesis parameters such as pH ,concentration of TiOSO4, temperature and time under hydrothermal treatment. The obtained products were characterized for physical and chemical properties by means of XRD, XRF, BET and TEM . It was found that pH had an influence on the crystallization of TiO2, and under an appropriated pH, only anatase presented along with amorphous phase. High crystallinity of nano-crystalline anatase ( about 5 nm) deposited on silica surface was observed through TEM. Adsorption and photocatalytic performances of the prepared catalyst were evaluated in methylene blue aqueous solution in the dark and under ultraviolet ray irradiation, respectively. Due to the synergetic functions of adsorption by porous substrate and decomposition by TiO2 photocatalyst, an enhancing of photocatalytic activity for decomposition of organic pollutants in water under UV rays was obtained.

Effect of Additives on Hydrolysis of Ti Alkoxide and Microstructural Observation of TiO2

By the usage of the hydrolysis of Ti alkoxide, various types of TiO2 were obtained through the addition of catalyst (HCl, NH4OH, and CH3COONH4) and some additives into Ti alkoxide solution at room temperature. In special, the effect of two additives, diethylene glycol (DEG) and hexamethylphospheric triamide (HMPA), on hydrolysis behaviors and microstructure with various catalyst for hydrolysis of Ti-tetraisopropoxide was in detail investigated. In case of TiO2 powder with HMPA as an additive, the crystallinity of TiO2 except with NH4OH as a catalyst decreased in XRD patterns, compared to those of products with no additive and with DEG as an additive. The addition of HMPA prohibited the growth of TiO2 and led to fine TiO2 with the average particle size of approximately 10nm.