Kinetics and mechanism of the reaction of acetonyl radical, CH3(CO)CH2, with Br2

The low pressure fast discharge flow method with laser induced fluorescence detection of CH3C(O)CH2 was employed to study the kinetics of the reaction CH3C(O)CH2 + Br2 → CH3C(O)CH2Br + Br (1) at 298, 323 and 365 K. The rate coefficient at room temperature is k1 = (2.33 ± 0.04 (2σ)) 10–12 cm3 molecule–1 s–1, which increases slightly with increasing temperature. Quantum chemistry (G2) and theoretical rate theory (conventional TST) computations have supplied results in qualitative agreement with experiment. The relatively slow rate of reaction (1) can be due to the resonance stabilization of the acetonyl radical. Keywords: reaction kinetics, acetonyl radical, Br2 molecule, resonance stabilizatio

Elimination of Zinc from Aluminum During Remelting in an Vacuum Induction Furnace

In this paper, the results of the study on aluminium evaporation from the Al-Zn alloys (4.2% weight) during remelting in a vacuum induction furnace (VIM) are presented. The evaporation of components of liquid metal alloys is complex due to its heterogeneous nature. Apart from chemical affinity, its speed is determined by the phenomena of mass transport, both in the liquid and gas phase. The experiments were performed at 10-1000 Pa for 953 K - 1103 K. A significant degree of zinc loss has been demonstrated during the analysed process. The relative values of zinc loss ranged from 4 to 92%. Lowering the pressure in the melting system from 1000 Pa to 10 Pa caused an increase in the value of density of the zinc evaporating stream from 3.8210-5 to 0.000564 gcm-2s-1 at 953 K and 3.3210-5 to 0.000421 gcm-2s-1 for 1103 K. Based on the results of the conducted experiments. it was found that evaporation of zinc was largely controlled by mass transfer in the gas phase and only for pressure 10 Pa this process was controlled by combination of both liquid and gas phase mass transfer

Comparative Analysis of Lead Removal from Liquid Copper by ICF and CCF Refining Technologies

Innovative technologies require the use of materials that meet increasingly high requirements; one such requirement is the purity of metals. In the case of copper, this translates into a parameter related to electrical conductivity. Traditional metal refining technologies have some limitations that can be eliminated through the use of modern melting aggregates. Such solutions include vacuum induction furnaces, comprising an induction furnace with a cold crucible. As part of this work, the possibilities of refining copper and lead alloys were investigated. In addition, the research was carried out with the use of two induction vacuum aggregates, allowing us to compare their effectiveness. The tests were carried out in a pressure range of 10–1000 Pa and at temperatures of 1273–1473 K. The results obtained made it possible to determine the mass transport coefficient of lead from an alloy with copper, and to determine the share of resistance in individual stages of the process. For experiments conducted inside an induction crucible furnace, lowering the working pressure inside the furnace chamber from 1000 to 10 Pa while increasing the temperature from 1323 to 1473 K was accompanied by a drop in the lead concentration inside the alloy of 69 to 96%, compared to its initial mass. For experiments conducted inside a cold crucible furnace, approximate values of lead removal appeared for lower temperatures (1273 to 1323 K), confirming that the analyzed process happens faster in this aggregate

Kinetics and mechanism of the reaction of acetonyl radical, CH3C(O)CH2, with Br2

The low pressure fast discharge flow method with laser induced fluorescence detection of CH3C(O)CH2 was employed to study the kinetics of the reaction CH3 C (O) CH2 + Br2 → CH3 C (O) CH2 Br + Br(1) at 298, 323 and 365 K. The rate coefficient at room temperature is k1 = (2.33 ± 0.04 (2σ)) × 10-12 cm3 molecule-1 s-1, which increases slightly with increasing temperature. Quantum chemistry (G2) and theoretical rate theory (conventional TST) computations have supplied results in qualitative agreement with experiment. The relatively slow rate of reaction (1) can be due to the resonance stabilization of the acetonyl radical. © 2013 Elsevier B.V. All rights reserved