FACTORS INFLUENCING THE PREPARATION OF TiO2 NANOPOWDERS FROM TITANIA SOL

Titania nanoparticles with high photocatalytic activity were prepared from titanium alkoxide dissolved in alcohol and water under acidic conditions. The effects of the key parameters including (alkoxide/water) ratio, (alkoxide/alcohol) ratio, precursor type, solvent type, type and concentration of stabilizer, calcination temperature, presence of methylcellulose (MC) and hydrothermal treatment were studied. The optimal conditions were obtained through an experimental design technique. This technique is also used to find the main factors influencing the degradation of methylene blue (MB) and mass percent of anatase phase. The powders characteristics were investigated by XRD and Brunauer-Emmett-Teller (BET) methods. The X-ray diffraction studies showed that the product has anatase crystal structure with average particle size below 13 nm. The photocatalytic activities of the TiO2 nanoparticles were assessed by the degradation of MB in aqueous solution. According to the obtained results, the kinetics of photocatalytic reaction followed pseudo-first-order model. The results showed that the main factors influencing the degradation of MB were the type of stabilizer, presence of MC, hydrothermal treatment, solvent type and calcination temperature. Specific surface areas of the nanoparticles were between 76-198 m2/g

Characterization and photocatalytic activities of nanosized titanium dioxide thin films

Thin films of titanium dioxide with high surface area are prepared by sol-gel dip-coating technique. In this regards, Titania nano sols with high photocatalytic activity were prepared by dissolving titanium alkoxide in alcohol and water under acidic conditions. Photocatalytic activities of titanium dioxide thin films were measured in the presence of methylene blue. Microstructure and photocatalytic activity of the films, nanopowders and titanium dioxide sols were investigated using X-ray diffraction, scanning electron microscopy, specific surface area, zeta sizer and ultraviolet_visible spectrometry techniques. Particle size analysis of sols showed that the mean particle sizes were 15 to 128 nm. X-ray diffraction analyses revealed that anatase crystal structure was produced with crystallite size below 11 nm. Increasing mass percent of anatase phase and specific surface area, enhance the photocatalytic activity. Scanning electron microscopy images showed that the addition of methylcellulose as a dispersant, not only produced rough texture in the thin film, but also enhanced photocatalytic activity. The thin films prepared by using nitric acid as a stabilizer, revealed higher photocatalytic activity, surface area and sol stability and these data were more than those prepared with acetic acid

The Effect of Malting Process on Physicochemical and Aerodynamic Characteristics of Two Barley Line of Golestan Province

Malting is one of the biotechnological processes that includes steeping, germination and killing of cereal. This process is performed in controlled environment in which hydrolytic enzymes are synthesized and cell wall, protein and starch of endosperm are largely digested. In this study the malting quality was evaluated in order to select the best line for malt production. The effects of malting process, on terminal velocity and physicochemical characteristics included volume, 1000 kernel weight, protein content, β-glucanase activity and cold water extract of two barely lines (EBYT-88-17 and EBYT-88-20) of Golestan Province were investigated. The experiments were done in a completely randomized design with three replications. The results of the analysis of variance showed that the type of sample (line) has a very significant impact on physicochemical and terminal velocity factors (P<0.01). Maximum and minimum volume of malt and barley corresponded to EBYT-88-20 and EBYT-88-17 respectively. The malting process reduced 1000 kernel weight, terminal velocity and increased protein amount, beta glucanase enzyme activity and cold water extraction efficiencies. The level of enzyme activity in malt resulted from EBYT-88-17 line higher than malt prepared of EBYT-88-20 line. Therefore, this line is better to use in preparation of enzyme extracts therefore in the confectionary industry, cakes and cookie