Preparation, structure and photocatalytic properties of cancrinite encapsulating lead and sulfide ions

Cancrinites encapsulating Pb²⁺ and S^2- ions have been prepared by hydrothermal and cation-exchange processes, and their structures and photocatalytic properties have been investigated. The structure analyses revealed that Pb²⁺ ions exchanged with Na⁺ ions were statistically located around S^2- ions in the same micropore, and the mean Pb-S bond lengths were estimated to be about 3.0 Å. It was found that the resulting specimens had photocatalytic properties, corresponding to an absorption band based on an electron transition between Pb²⁺ and S^2- ions, from the decolorization of methylene blue aqueous solution under black light irradiation. Treating the specimens at 400 °C under an N₂ atmosphere enhanced the photocatalytic property.