Coulometric generation of protons by oxidation of hydrogen dissolved in palladium, in non-aqueous media.
Coulometric generation of H(+) ions by the oxidation of hydrogen dissolved in palladium, in media such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetic anhydride and acetic acid-acetic anhydride mixture, for use in titration of bases, has been investigated. The hydrogen is oxidized at potentials which are much more negative than those of the bases and other components present in the solution. Titrations of numerous bases have established that the oxidation is quantitative and proceeds with 100% current efficiency.
Coulometric generation of hydrogen ions by oxidation of mercury in anhydrous acetone.
The application of a mercury anode for the quantitative generation of H(+) ions in anhydrous acetone has been investigated. From the changes of anode potential with current density in 0.25M sodium perehlorate in anhydrous acetone it has been established that in this solvent mercury is oxidized at a potential which is much more negative than the oxidation potentials of the bases to be titrated, the indicator used and the solvent. Protons generated in this way have been used for titration of some organic bases, with either visual or potentiometric end-point detection. The oxidation of mercury in anhydrous acetone and the reaction of mercury ions with acetone have been found to proceed with 100% current efficiency.
Influence of pressure and fluidization velocity on the hydrodynamics of a fluidized bed containing horizontal tubes
Abstract An experimental investigation of the influence of horizontal tubes on the bubble behaviour and through-flow velocity of gas inside bubbles was carried out and the influence of pressure and fluidization velocity was studied. The visible bubble flow rate and the gas velocity through the bubbles were measured simultaneously in a pressurized fluidized bed, using capacitance and Pitot-static pressures probes respectively. Silica sand with a mean particle diameter of 0.7 mm was fluidized at pressures between 01. and 1.6 MPa, in a bed of 0.2 × 0.3 m cross-section. Six different horizontal tube configurations were used and comparisons were made with results obtained in the same bed operated without tubes. The results from the bed with tubes show that the influence of pressure and fluidization velocity is basically the same as in the bed without tubes; an increase in pressure and fluidization velocity increases the bubble activity. At low excess gas velocities, the influence of immersed tubes on the bubble behaviour is less pronounced than at high excess gas velocities. Measurements and visual observations show that a small tube pitch gives a more uniform distribution of the visible bubble flow over the bed cross-section. At a combination of high pressure, high excess gas velocity and a large tube pitch, a preferred bubble path was observed in the centre of the bed cross-section. The pressure probe measurements show that the through-flow velocity of gas inside the bubbles is in most cases higher when tubes are present in the bed. The through-flow velocity consistently decreases with increasing pressure in the bed without tubes. The tendency is largely the same at a low excess gas velocity when tubes are present, but at a high excess gas velocity the through-flow velocity first decreases and then increases as the pressure is increased.