A highly sensitive differential pulse polarographic (DPP) method has been developed for the determination of trace amounts of osmium, based on the catalytic effect of osmium (VIII) on the oxidation of pyrogallol red (PGR) by sodium bromate at pH 7.00 and 25.0 0.1 ? C. The reaction rate was monitored by measuring the differential pulse cathodic current of the oxidation product of PGR and broma...

A kinetic method developed for the determination of ultra-trace amounts of nitrite based on its catalytic effect on the reaction between potassium bromate and Nile blue A in strongly acidic media is reported. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Nile blue A at 645 nm by the fixed-time method. The decrease in absorbance during the first...

Catalytic and catalytic photo-assisted hydration of propene to form 2-propanol in gas-solid regime at atmospheric pressure and 85 °C were carried out by using a heteropolyacid (POM) supported on different oxides. Binary materials were prepared by impregnation of H3PW12O40 on different commercial and home prepared supports (TiO2, SiO2, WO3, ZrO2, ZnO, Al2O3). Some of the composites were active b...

A new kinetic spectrophotometic method for the determination of trace amount manganese(II) in Tea real samples has been described based on it s the catalytic effect on the oxidations of 1 - (2 – Pyridyl Azo) - 2 - Naphthol, (PAN), by potassium bromated in sulfuric acid. The reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 547.5 nm. Under the optimum con...

Electrochemical oxidation of iodide has been studied in the presence of 2-thioborbituric acid using cyclic voltammetry and controlled-potential coulometry. The results indicate that, the resulting iodine takes part in halogenations reaction with 2-thiobarbituric acid. In addition, the present data are indicative of the suitability of iodide as a quasi mediator for determination of 2-thiobar...

A new kinetic spectrophotometic method for the determination of trace amount Chromium (III) in Teareal samples has been described based on it s the catalytic effect on the oxidations of 1 - ( 2 –PyridylAzo ) - 2 - Naphthol, (PAN), by potassium bromated in sulfuric acid. The reaction is followedspec- trophotometrically by measuring the decrease in the absorbance at 469 nm. Under the optimumcondi...

Different experimental approaches to measuring catalytic reaction efficiencies on thermal protection system materials are reviewed. Special emphasis is given to the theory and application of the diffusion tube side-arm reactor technique. In this technique, reactants diffuse into a dead-end tube and are progressively removed from the gas phase by surface reactions on the walls, establishing uniq...

The catalytic base in family 48 glycosyl hydrolases has not been previously established experimentally. Based on structural and modeling data published to date, we used site-directed mutagenesis and azide rescue activity assays to show definitively that the catalytic base in Thermobifida fusca Cel48A is aspartic acid 225. Of the tested mutants, only Cel48A with the D225E mutation retained parti...

Knowledge of the structure of catalysts is essential to understand their behavior, which further facilitates development of an active, selective, and stable catalyst. Determining the structure of a functioning catalyst is essential in this regard. The structure of a catalyst is prone to change during the catalytic process and needs to be determined in its working conditions. In this tutorial re...

A procedure is described for the determination of selenium in natural waters using cathodic stripping voltammetry in the presence of rhodium. Advantage is taken from a catalytic effect on the electrochemical reduction of protons in the presence of a mixed complex of selenide with rhodium and chloride, containing Cl–Rh–SeH species. The catalysis causes a very large peak-current at a negative pea...