The determination of the optimal distribution of the catalytic activity profile, whichmaximizes the catalytic effectiveness, in created unsteady state conditions, is analyzed andtreated numerically for the case of a simple reaction. It was proven that the modulation, of thetemperature and the reactant concentration of the external bulk fluid, leads to a considerableincrease of the catalytic eff...

chromium(III) up to 100 ng mL−1, and for chromium(VI) up to 200 ng mL−1) were obtained, using the “fixed time” method with detection limits of 4.9 ng mL−1 and 3.8 ng mL−1, respectively. The results suggest that at the reaction conditions chromium(VI) is reduced and chromium(III) is oxidized to an intermediate oxidation state and the catalytic action of chromium is due to the formation of an act...

a simple and reliable electrochemical sensor based on cobalt oxide nanoparticles modified glassy carbon electrode (gce/cooxnps) for determination of butylated hydroxyanisole is presented here. the nanoparticles were fabricated by electrodepositing method. the modified electrode shows excellent catalytic activity toward butylated hydroxyanisole oxidation in ph 12.0 phosphate buffer solution (pbs...

nanostructured iron oxide powder that has been recovered from waste pickling liquor unit of steel industry was studied for oxidation catalytic applications. in this research, the powder was characterized by x-ray diffraction (xrd) and transition electron microscopy (tem) for determination of phase structure, morphology and particle size. furthermore, the specific surface area of the powder was ...

This study describes a new simple, sensitive and selective catalytic kinetic spectrophotometricmethod for the determination of vanadium (V). The method is based upon the catalytic effect ofvanadium (V) on the oxidation of Carminic acid by bromate in sulfuric acid media. The reaction wasfollowed spectrophotometrically by measuring the decrease in absorbance at 490 nm and thedependence of sensiti...

A new catalytic kinetic spectrophotometric procedure for determination of trace quantities of zirconium was proposed. Janus Green was oxidized by potassium bromate and zirconium catalyst which then converted to a colorless product in acidic media. Reaction rate was monitored spectrophotometrically at 606 nm. It relies on the linear relationship between the absorbance difference (ΔAt) and Zr(IV)...

a simple, selective and sensitive method for the determination of trace amount of titanium (iv) based on its catalytic effect on methylene blue- ascorbic acid redox reaction has been reported. the reaction was followed spectrophotometrically by measuring the change in absorbance of methylene blue at 665 nm, 5 minutes after the initiation of the reaction. in this study experimental parameters we...

sulphide was determined spectrophotometrically at 628 nm and ph 6.7 based on its catalytic reduction of toluidine blue in the presence of se(iv) using a flow injection system. after optimization of the measuring conditions the calibration curve was found linear up to 25 mg/ml and the detection limit was 0.3 mg/ml (30 ml injections). the relative standard deviation for the determination of 10 mg...

A highly selective and sensitive catalytic spectrophotometric method was developed for the determination of nitrite in water samples. The method is based on its catalytic effect on the nuclear fast red–potassium bromate redox reaction in acidic medium. The reaction was followed spectrophotometrically by measuring the change in the absorbance at 518 nm of nuclear fast red 5 min after initiation ...

a kinetic-spectrophotometric procedure is reported for determination of trace amounts of ag(i). this method is based on catalytic effect of silver ion on the oxidation of congo red by potassium peroxodisulphate at ph=3.4 and 30 oc in the presence of 1,10-phenanthroline as an activator. the reaction was followed spectrophotometrically by measuring the rate of change in absorbance of congo red at...