Studies of the sorption of triethyl phosphate by ion-exchanged smectite clays

Abstract

The binding of triethyl phosphate (TEP) to smectites containing Bu₄N⁺, Mg²⁺ or Al³⁺ as the counter-ion has been studied. Solid-state ³¹P and ¹³C CPMAS and SPE-MAS NMR were used to observe both mobile and motion-restricted phases. Magnesium complexes of TEP and dimethylmethyl phosphonate (DMMP) have been prepared and used as models for the complexes formed in the clay matrix. These compounds were also investigated by solid-state ³¹P NMR and FTIR spectroscopies. TG, XRD and FTIR spectroscopy have also been used to study the sorbed TEP species. A number of sorption sites have been detected; one important mechanism of sorption involves coordination to the interlamellar cation.