Hybridization of layered zirconium phosphate with azo compounds and its photoresponsivity and adsorption of rare earth elements

Abstract

Intercalation treatments of azo compounds were performed in the interlayer space of α- and γ-zirconium phosphates (ZrP). X-ray diffraction patterns confirmed that the intercalation of the azo compounds into α-ZrP occurred via an octylamine intercalated intermediate. CHN elemental analysis indicated that the azo compounds were substituted for pre-intercalated octylamine. In contrast, all azo compounds tested except for p-hydroxyazobenzene were directly intercalated into the interlayer space of γ-ZrP without octylamine. Photoisomerization of p-aminoazobenzene and p-hydroxyazobenzene included in γ-ZrP was observed along with their reversibility, as determined by alternate ultraviolet and visible photoirradiation for 30 min. The adsorption competency of the prepared materials for rare earth cation significantly increased depending on the azo molecule density.