Interaction of titanium oxide with sodium hydroxide at hydrothermal conditions

Sodium titanates were obtained by hydrothermal treatment using titanium tetrabutoxide (ТBT), titanium tetroisopropoxide (TIPT), hydrated titanium dioxide (prepared by hydrolysis of titanium alkoxide) or air-dried TiO2 sol with a molar ratio of TBT/TIPT/TiO2: NaOH equal to 1:10–80, at the temperature 130–180 °C and treatment time 24–72 h. Samples were characterized by the adsorption method, X-ray phase analysis, scanning electron microscopy. The photocatalytic properties of nanostructured titanate in the H-form in the process of Rhodamine FL–BM photodegradation under UV-irradiation (K = 0.03–0.05 min–1), as well as the electrorheological properties, were evaluated. Partially hydrated sodium titanates as a filler of the electrorheological dispersion (the filler content of dispersion was 5 %) exhibited the shear stress of 50–60 Pa and the leakage current density of 1.0–1.5 μA/cm2 at an electric field strength of E = 4 kV/cm at a shear rate of 17.1 s–1.

Synthesis of Titanium Oxide Nanoparticles Using Root Extract of Kniphofia foliosa as a Template, Characterization, and Its Application on Drug Resistance Bacteria

Biogenic methods of synthesis of nanoparticles (NPs) using plant extracts have been given a great attention due to its nontoxicity and environmental friendliness. In this study, TiO2 NPs were synthesized from titanium tetrabutoxide and extract of root of Kniphofia foliosa. NPs of TiO2 were biosynthesized at different volume compositions of titanium tetrabutoxide to the plant extract with a ratio of 1 : 2, 1 : 1, and 2 : 1, respectively. These green synthesized NPs of TiO2 were characterized by thermogravimetric analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. TGA/DTA analysis has confirmed that the synthesized NPs of TiO2 were stable above the temperature of 500°C. The sharp and intense peaks at 2θ values of 25.3, 38.0, 47.9, 53.2, 54.8862, 62.7, 70.2, and 75.0 have confirmed formation of crystalline NPs of TiO2 in the sample of 1 : 1 and 2 : 1 ratios, and less crystalline samples for TiO2 NPs prepared in a 1 : 2 ratio. Comparison between FT-IR absorption bands of the plant extract and that of calcined NPs of TiO2 confirmed the purity of synthesized nanomaterials, except unavoidable adsorption of moisture on the surface of TiO2 NPs in an open air. The antibacterial activity of biosynthesized TiO2 NPs and that of ethanolic root extract of Kniphofia foliosa was investigated via the disc diffusion method against human pathogen bacteria strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Streptococcus pyogenes. Among the different ratios, TiO2 (1 : 1) NP shows better performance towards Gram-negative bacteria due to its smaller average crystalline size and uniform morphology observed in SEM image relative to the other two ratios of TiO2 NPs. Antibacterial activity of the ethanolic root extract of Kniphofia foliosa itself showed better performance towards Gram-negative bacteria than NPs of TiO2 that might be due to antibacterial activity of residue of ethanol left with the plant extract.

Pengaruh Suhu Sintering Pada Pembuatan Strontium Titanat (SrTiO3) Terhadap Konstanta Dielektrik Menggunakan Metode Co-Precipitation

<p>Strontium Titanate (SrTiO₃) with variation of sintering temperatures were prepared by co-precipitation methods. Sintering temperature were varied at 700^oC, 800^oC, and 900^oC for 4 hours. SrTiO₃ samples were prepared by Strontium Nitrate and Titanium Tetrabutoxide. SrTiO₃ samples were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Resistance Capacitance Inductance (RCL) meter, and Sawyer Tower. SEM images show that the sintering temperatures could affect the grain size of SrTiO₃. In addition, crystal size of SrTiO₃ (110) affected by sintering temperature. The highest of dielectric constant is 137 on SrTiO₃ at sintering temperature of 900^oC. Sawyer Tower curves confirmed that SrTiO3 has paraelectric property.</p><p>Keyword: Strontium Titanate, Co-precipitation, dielectrics constant, paraelectrics</p><p> </p>

Study on the Preparation of BaTiO3 Nano Powder via Non-Hydrolytic Sol-Gel Method

BaTiO3 (BT) nano powder was prepared via non-hydrolytic sol-gel (NHSG) method by using barium acetate, titanium tetrabutoxide as precursors, glycerol and ethanol as solvents. The samples were characterized by DTA-TG, XRD, FT-IR and TEM. The influences of heat treatment temperature on the morphology and the microstructure of powder were studied, and the mechanism of low temperature synthesis was discussed. In addition, the de-esterification action between the precursors was also described in detail. The results show that the formation of Ba-O-Ti bond in the xerogel via NHSG route is duo to the de-esterification polycondensation of barium acetate and titanium tetrabutoxide, which plays the key role in the low temperature synthesis of BT powder. With the temperature rising to 700 °C, BT nano powder with good dispersion and even size distribution can be acquired and the average particle diameter is about 25 nm. Overlow and overhigh heat treatment temperatures are both not beneficial to the preparation of BT nano powder.

Enhanced UV Photo-Stabilization of PBO Fibers via Sol-Gel Surface Modification

PBO fiber is the most excellent high performance fiber. But it is a kind of photosensitive material and is prone to degrade under ultraviolet (UV) radiation, which results in the changes of the fiber mechanical properties, finally affects the using of the material. In present paper, Titanium tetrabutoxide was used as solgel precursor of a nanosized TiO2coating to improve the photostability of PBO fibers. The nanosized TiO2coating was characterized by XRD. The influence of the coating on UV-durability of PBO was investigated by an accelerated UV-ageing method. Results of mechanical measurement showed that after exposing to UV light for 160 h, the fibers without TiO2coating degraded sharply, 7.01% of strength and 11.42% of break extension only remained, whereas 45.61% of strength and 68.56% of break extension still remained for the TiO2coated fibers. SEM analysis showed no significant surface morphological change on the coated fibers after the exposure, while some latitudinal crack fractures appeared on the uncoated PBO fibers.

New Reactor Fabricated Using Light Leakage Fiber for Azo Dye Degradation

Lanthanum-doped anatase TiO2coatings, which are composed of assemble crystalline of 50 nm diameter particles, when the percentage of dopant is 0.5 wt%, have been successfully fabricated by solgel dip-coating process on light leakage silica fiber (LSF) which length is 15cm and diameter is 125μm. This was achieved by adjustment of the lanthanum-doped solgel parameters such as molar ratio of precursors in lanthanum-doped TiO2-sols, the ratio of titanium tetrabutoxide to polyvinyl alcohol, dip-coating velocity, drying duration in air, thermal treatment and number of cyclical time of the process. Titania nanocrystals were prepared at ambient temperature in a liquid media using titanium tetrabutoxide as precursor, and the crystallization of amorphous precursor was preceded by peptizing with acid and then refluxing for a periodic time in homothermal water-bath. The photocatalytic properties of the La-TiO2films had been testified by the photo degradation of methyl orange. The lanthanum-doped anatase TiO2thin films were characterized by XRD and TEM. The products show much improved photocatalytic activity that will be useful in the design of a novel antibacterial, deodorant and antipollution new photo reactor.

Development of Nano-TiO2 Coating on Titanium Alloy Substrate for Biomedical Applications

Nanometer titanium dioxide powders were prepared by hydrolysis of titanium-tetrabutoxide with ethanol. The powder particle size of TiO2 in the structure of anatase-type is mainly between 5 and 10 nm. Using the process that titanium alloys were embedded by the nanometer TiO2 powders and sintered in the high temperature furnace, the nano-TiO2/titanium alloy biomaterials was fabricated out. The particle size of TiO2 particles on the surface of Ti alloy was mainly 50-70 nm. The method is a simple and adaptable technique for surface modification of the titanium alloys.