Effects of Magnetic Field on Nickel-Catalyzed Oxidation of Hypophosphite Ion by Water/Deuterium Oxide

Abstract

The effect of a magnetic field on the oxidation of hypophosphite ion catalyzed by electrolessly deposited nickel in aqueous deuterium oxide solution was studied. The steady rate of gas evolution was affected by both the magnetic field and the concentration of deuterium oxide. Such an effect was due to the magnetic spin rephasing of a radical pair of atomic hydrogen and atomic deuterium. The ratio of fractions of active sites occupied by atomic hydrogen and deuterium increased with magnetic flux density, but decreased with the mole percentage of deuterium oxide. The results indicated that the recombination rate of the radical pair of atomic hydrogen and atomic deuterium was affected by the magnetic field. A reaction mechanism of the oxidation of hypophosphite ion based on adsorption was proposed, and a steady rate equation was obtained experimentally. Based on the results of the steady rate, an empirical rate equation was obtained for the magnetic flux density B in the range 0.15−0.30 T, r s = 6.20(0.965 × exp(5.62B)[H2O]/[D2O])/(1 + 0.965 exp(5.62B)[H2O]/[D2O]) + (2.92 exp(1.46B))/(1 + 0.965 × exp(5.62B)[H2O]/[D2O]).

Effects of Magnetic Field on the Electroless Nickel/Cobalt Deposition

“…The effects of magnetic field on the electroless nickel deposition were well reported in our previous studies (Lee and Chou, 1994, 1995, 1996. These results indicated that the reaction order of the hypophosphite ion (Lee and Chou, 1994), the rate constants of electroless deposition of the nickel ion (Lee and Chou, 1995), and the rate constants of oxidation of hypophosphite ion (Lee and Chou, 1996) were affected by the magnetic field. These results revealed that the reaction behavior of electroless nickel deposition was affected by the magnetic field.…”

“…These results revealed that the reaction behavior of electroless nickel deposition was affected by the magnetic field. Besides our previous studies (Lee and Chou, 1994, 1995, 1996, there are many reports on the magnetic field effects on electroless metal depositions (Chiba and Ogawa, 1989;Osaka et al, 1992;Takebayashi et al, 1993;Tabulina et al, 1993;Mogi et al, 1993). These results revealed that the deposition rate and the morphology of the deposit were affected by the magnetic field.…”

“…The Langmuir-Hinshelwood adsorption model and the magnetic-induced spin rephasing were well applied to reveal the magnetic field effects on the electroless nickel deposition in our previous studies (Lee and Chou, 1994, 1995, 1996. The electroless nickel/cobalt deposition was similar to electroless nickel deposition except that two metal ions, the nickel ion and the cobalt ion, coexisted in the deposition solution.…”

“…Accordingly, the Langmuir-Hinshelwood adsorption model was applied to the nickel ion, cobalt ion, and hypophosphite ion, respectively. In our previous studies (Lee and Chou, 1994, 1995, 1996, the active sites were divided into two types that were occupied by the nickel ion and hypophosphite ion, respectively. The types of active sites were assumed to be four cases in the electroless nickel/ cobalt deposition.…”

“…The lower hydrogenation rates of cyclohexene and benzaldehyde catalyzed by the electroless nickel catalyst prepared within a magnetic field were due to the magnetic-field-induced changes of morphology and size of electroless nickel grains. Based on the magnetic field effects on the electroless nickel deposition in our previous studies (Lee and Chou, 1994, 1995, 1996, the electroless nickel/cobalt deposition was assumed to be affected by the magnetic field. Accordingly, the effects of magnetic field on the electroless nickel/cobalt deposition are explored in this study.…”