Layered metal uranyl phosphates. Retention of divalent ions by amine intercalates of uranyl phosphates

Abstract

HUO2PO4•4H2O (HUP) forms a laminar intercalate with butylamine, c = 29.30(5) Å, which accepts cationic metals in exchange for the n-butylammonium ions. Hydrated uranyl metal phosphates M(UO2PO4)2•nH2O (M = Mn, Co, Ni, Cu, Zn, Cd) are obtained by ionic exchange and were studied by thermal analysis and X-ray diffraction. The tetragonal structures of all these product compounds are derived from HUP. The diffuse electronic reflectance spectra of every sample show characteristic [Formula: see text] absorption bands. In the spectra of the Co, Ni, and Cu phosphates there are other bands in the 500–800 nm zone compatible with their observed aquocation transitions.

Microbially enhanced chemisorption of nickel into biologically synthesized hydrogen uranyl phosphate: A novel system for the removal and recovery of metals from aqueous solutions

“…More importantly, the samples in that study (Bonthrone et al, 1996) were mixed crystals of the HUP and Ni/HUP, with a low content of Ni 2+ only. In the present study, the crystal cell unit dimensions are very close to those found for Ni(UO 2 PO 4 ) 2 ⅐ 9H 2 O, which was prepared by intercalation of a chemically synthesized HUP and indexed as tetragonal: a = b = 6.907(9) Å; c ‫ס‬ 11.04(4) Å (Pozas-Tormo et al, 1986).…”

“…Transformation from a tetragonal metal uranyl phosphate crystal system to a less symmetric nontetragonal compound was observed when Mn(UO 2 PO 4 ) 2 ⅐ 9.5H 2 O was partially dehydrated (Pozas-Tormo et al, 1986). This also seems to be a plausible explanation for the different crystallographic cell units in the different hydrates of Ni(UO 2 PO 4 ) 2 .…”

“…PIXE spectra (B and C) were obtained from random points on the samples obtained from the columns described in Figure 2 [(B) regenerated with priming solution; (C) regenerated with citrate buffer] after the third challenge with Ni 2+ . Tormo et al, 1986Tormo et al, , 1987Tormo et al, , 1988. All the crystalline powders in these cases were indexed as a tetragonal unit cell in which the hk0 reflections of the HUP parent persist, but the hkl reflections, notably those of 00l, vary.…”

“…Heated overnight at 50°to 60°C, the uranyl metal phosphates lose one to three water molecules and contract by ca. 1 Å (Pozas-Tormo et al, 1986, 1988.…”

“…This can be described by: (Hunsberger and Ellis, 1990). The ability of chemically prepared HUP to intercalate Ni 2+ -cation and to remove Ni from the surrounding aqueous environment was experimentally proven (Pozas-Tormo et al, 1986, 1988. The identity of crystal structure of both chemically prepared and microbially created HUP (Macaskie et al, 1992) indicated a possibility for the exploitation of the intercalative ion-exchange property of cell-bound HUP, functioning as a biogenic ion-exchange material, as a means for the effective removal of Ni 2+ from wastewaters.…”