Decomposition of 2-naphthol in water and its antibacterial and antiviral activities by LaMnO<sub>3</sub> and LaCoO<sub>3</sub> in the dark
Ryuju Kiribayashi, Kayano Sunada, Yasuhide Mochizuki, Toshihiro Isobe, Sachiko Matsushita, Takeshi Nagai, Hitoshi Ishiguro, Akira Nakajima
Abstract
Single-phase powders of LaMnO3 and LaCoO3, lanthanum-based perovskites, were synthesized using the citric acid combustion method. The surface concentration of La in the obtained powder was higher in LaCoO3 than in LaMnO3. These samples decomposed 2-naphthol in water in the dark. The decomposition reaction is attributed to the Mars–van Krevelen (MvK) mechanism because of the temperature dependence, activation energy, valence change during the reaction, and the amount of ion elution into water. A disproportionation reaction was confirmed for Mn in LaMnO3. Both samples exhibited antibacterial and antiviral activity against Escherichia coli, Staphylococcus aureus, bacteriophage Qβ, and bacteriophage Φ6. The antibacterial activity was higher than the antiviral activity. LaCoO3 tended to have higher antibacterial and antiviral activity than LaMnO3 had. Results show that these materials had less ion leakage than that reported earlier for La2Mo2O9.