Platinized titanium dioxide

Spin trapping by PBN has also been employed to detect radical formation in a photo-Kolbe reaction in which acetic acid is irradiated (A > 360 nm) in the presence of platinized titanium dioxide powder (Kraeutler et al, 1978). The nitroxide observed was considered to be (PBN—Me ), but the published spectrum clearly shows the presence of a second species spectral overlap might therefore be an alternative to solvent polarity as an explanation of the discrepancy between the observed splitting parameters and those previously reported for this species. Where poor resolution obtains, it is important that... 

Since Bahnemann and co-workers have observed that a comparatively high amount of trapped holes are formed when partially platinized titanium dioxide particles are subjected to ultra band gap irradiation (cf. Fig. 7.6), they have chosen this system to study the dynamics of the photocatalytic oxidation of the model compounds dichloroacetate, DCA", and SCN- [7]. To explain their experimental observations these authors have used a model assuming two energetically different types of hole traps (see our detailed discussion above). 

Vorontsov A.V., Stoyanova I.V., Kozlov D.V. et al. (2000) Kinetics of the Photocatalytic Oxidation of Gaseous Acetone over Platinized Titanium Dioxide, J. Catal. 189(2), 360-369. 

This current-control feature can be illustrated in the electrochemical decarboxylation of vicinal diacids. These reagents have long been used as protecting groups for double bonds, since electrochemical deprotection by two-electron oxidation causes bis-decarboxylation and production of a C=C double bond [60]. In contrast, when platinized titanium dioxide is irradiated in the presence of one such vicinal diacid (cyclohexenedicarboxylic acid), the major reaction pathway leads to monodecarboxylation, rather than to benzene formation (Eq. 12). 

The molecular weight distribution of the peptides could be partially controlled by choice of the sensitizer diglycine was formed twice as efficiently on platinized titanium dioxide as on platinized cadmium sulfide, whereas the yield of pentaglycine was four times higher on CdS/Pt than on Ti02/Pt. 

Kunioka M, Nakamura Y, Doi Y (1988) New bacterial copolyesters produced in Alcaligenes eutrophus from organic acids. Polym commun 29 174-176 Kuo CY, Lin HY (2009) Photodegration of C.I. Reactive Red 2 by platinized titanium dioxide. J Hazard Mater 165 1243-1247... 

S. Sato, J. M. White, Photoassisted water-gas shift reaction over platinized titanium dioxide catalysts, J. Am. Chem. Soc. 102 (1980) 7206-7210. 

Kondelka, M., A. Monnier, and J. Augustyniski (1984). Electrocatalysis of the cathodic rednction of carbon dioxide on platinized titanium dioxide film electrode. 

Izumi 1, Dunn WW, Wilboum KO, Fan F-RF, Bard AJ. (1980) Heterogeneous photocatalytic oxidation of hydrocarbons on platinized titanium dioxide powders. J. Phys. Chem., 84 3207-3210. 

Takeda K. and Fujiwara K. 1996. Characteristics on the determination of dissolved organic nitrogen compounds in natural waters using titanium dioxide and platinized titanium dioxide mediated photocatalytic degradation. Water Res. 30 323-330. 

E. Borgarello, J. Kiwi, E. Pelizzetti, M. Visca, M. Qratzel, Hydrogen production from water by visible light using zinc porphyrin-sensitized platinized titanium dioxide. J. Am Chem. Soc. 103(1981)6324. 

Bahnemann, D.W., J. Monig and R. Chapman (1987b). Efficient photocatalysis of the irreversible one-electron and two-electron reduction of halothane on platinized colloidal titanium dioxide in aqueous suspension. Journal of Physical Chemistry, 91(14), 3872-3788. 

The cathode material is usually stainless steel, a nickel alloy, or titanium. Graphite, lead dioxide, platinized titanium, and DSA are some of the materials that have been used as an anode. The cells are operated at a current density of between 0.1 and 0.5 A/cm. The majority of the cells used to produce hypochlorite have the parallel-plate type of geometry [81]. 

As anode material, smooth platinum, as foil or net, is most widely used. In nonaqueous solvents, additionally, platinized titanium, gold, hard graphite and ruthenium dioxide on titanium have been employed. To keep the amount of the costly platinum low, the foils have been glued to a graphite support. With vitreous or baked carbon in protic solvents (methanol, ethanol, water) dimer yields nearly comparable to those at platinum have been obtained. ... 

Titanium covered by platinum or by dioxide of manganese, ruthenium, iridium or other substances is most commonly used as an anode. Graphite and graphite covered with lead dioxide have also been used as anodes. Under some conditions, high pH and absence of salts in the anolyte, nickel can be used as the anode. Stainless steel is commonly used as the cathode. If current reversal is employed, the same material, platinized titanium or graphite, is used for both electrodes. Electrode chambers should be flushed with a large flow of rinse solution in order to remove the electrode reaction products. 

Other alkali-metal chlorates are produced by analogous technology while sodium and potassium bromate are produced electrolytically starting both from bromide ion and bromine solutions. The production of bromate is, however, a very small-scale process and the cells have not been optimized to any extent for example while cells with lead dioxide and platinized titanium have been described, some plants still use solid platinum electrodes The mechanism of bromate formation is identical to that described for chlorate by reactions (5.10)—(5.13) the kinetics are, however, different. The hydrolysis of bromine is slower than chlorine but the disproportionation step is much faster (by a factor of 100) and it is therefore advisable to use a more alkaline electrolyte, about pH 11. 

For small-scale electrolysis units, energy consumption will be much less important than in a chlor-alkali process ease of operation with a minimum of maintenance and replacement of components and the initial cost of the total unit will more often determine the choice of the cell. As a result, for example, while the cathode will generally be steel, a wide range of anode materials including graphite, lead dioxide and platinized titanium have been used as well as dimension-ally stable anodes. Hence the quoted energy consumptions of hypochlorite cells lie in the range 4.5—7.0 kWh kg , considerably above those for a chlor-alkali cell. 

Electroflotation cells vary in capacity between 1 and 50 m, the largest size giving the capability of dealing with up to 150 m of water per hour. In a typical specification the plant will reduce 1000 p.p.m. solids and 600 p.p.m. oils to 30 p.p.m. and 40 p.p.m. respectively. The components of the cell will be selected mainly for durability and low cost. The tank will be steel or a cheap plastic depending on size the cathode will be a steel and the anode platinized titanium or lead dioxide on titanium. 

A2Pt207, similar to those reported for tin, ruthenium, titanium, and several other tetravalent ions. Trivalent ions which form cubic platinum pyrochlores range from Sc(III) at 0.87 A to Pr(III) at X.14 A. Distorted pyrochlore structures are formed by lanthanum (1.18 A) and by bismuth (1.11 A). Platinum dioxide oxidizes Sb203 to Sb2(>4 at high pressure. The infrared spectra and thermal stability of the rare earth platinates have been reported previously and will not be repeated here, except to point out the rather remarkable thermal stability of these compounds decomposition to the rare earth sesquioxide and platinum requires temperatures in excess of 1200 °C. 

About 50 g. of titanium(IV) bromide is poured or distilled into flask A, in an atmosphere of carbon dioxide.f Hydrogen, freed from oxygen by passage over platinized asbestos at 300° (or copper at 425 to 450°) and dried by sulfuric acid, is passed from tube I through the apparatus... 

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