Intercalation of melamine into layered zirconium phosphates and their adsorption properties of formaldehyde in gas and solution phase

The intercalations of melamine into alpha- and gamma-zirconium phosphates (alpha- and gamma-ZrP) were investigated. Melamine-intercalated alpha-ZrP afforded two phases with different interlayer distances (d = 1.30 and 1.55 nm). The phase with d = 1.30 nm was obtained as the mixture with original alpha-ZrP at 30 min reaction by batch method, whereas the single phase with d = 1.55 nm was obtained by decantation method in saturated melamine aqueous solution. Contrary to this, for gamma-ZrP a phase with d = 1.78 nm was obtained by both batch and decantation methods in saturated melamine aqueous solution. And new phase with d = 1.48 nm was formed in batch method at low pH or lower concentration of melamine aqueous solution. In these phases the arrangement of melamine changed from a monclayer structure to a bilayer structure with the increase of interlayer distance. Furthermore, melamine-intercalated alpha- and gamma-ZrP adsorbed formaldehyde gas and formaldehyde in formalm solution by interacting with melamine molecule in the interlayer region. In melamine-intercalated gamma-ZrP with d = 1.48 nm, the expansion of interlayer distance to around 1.6 nm was observed after the adsorption of formaldehyde gas and formaldehyde in formalin solution. The adsorption of formaldehyde in formalin solution was accompanied with the release of melamine in the interlayer region with increasing the concentration of formaldehyde at 65 degrees C. (C) 2009 Elsevier Masson SAS. All rights reserved.