• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.517-520
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• 2006

The leaching behaviors of zinc and manganese oxides of spent alkaline manganeses battery in sulfuric acid solution by using $H_{2}O_{2}$ as a reducing agent were investigated according to the concentration of $H_{2}SO_{4}$, temperature, reaction time, and the amount of $H_{2}O_{2}$. The experimental results of zinc and manganeses dissolution rates obtained without a reducing agent at 100 g/L solid/liquid ratio, 3.0 M $H_{2}SO_{4}$, $60^{\circ}C$ and 200 r.p.m. were 97.7% and 43.5%, respectively. On the other hand, zinc and manganeses dissolution rates obtained by adding 30 mL reducing agent at $60^{\circ}C$ were 99.6% and 97.1%, respectively. The addition of the reducing agent increased the leaching of manganese by two-fold compared to the absence of a reducing agent. In case of adding over 30 mL $H_{2}O_{2}$, however, the leaching rates of zinc and manganeses were independent of reducing agent amounts.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.139-143
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• 1997

The photoluminescence characteristics of the zinc gallate have been investigated as a function of the composition and the firing atmosphere. Two distinct emission bands were observed whose peaks are 360 nm and 430 nm respectively. These emission bands are considered to be from two different emission centers. For $ZnO/Ga_2O_3$=49.3/50.7 or higher, 430 nm band is predominant and for $ZnO/Ga_2O_3$=49.2/50.8 or lower, 360nm band becomes predominant, whereas 430 nm band is almost completely suppressed. The shift of emission peak is though to be due to the change of the cation distribution with the zinc content in the spinel zinc gallate. Also, the emission centers responsible for the 360nm band are considered to be more efficient energy absorbers than the ones for the 430 nm band. Highly efficient green emitting phosphor was obtained by activating Zn-deficient zinc gallate with manganeses.