Investigation of the Interaction of γ-Al2O3 with Aqueous Solutions of Dimethyl Methylphosphonate Using Infrared Multiple Internal Reflection Spectroscopy

Abstract

The interaction of dilute solutions of dimethyl methylphosphonate (DMMP) in H(2)O with thin porous layers of γ-Al(2)O(3) has been studied under steady-state conditions using infrared multiple-internal-reflection spectroscopy. Upon the initial introduction of the DMMP solution to a previously H(2)O-saturated surface, DMMP diffuses into the porous layer and displaces weakly hydrogen-bonded H(2)O molecules. This is accompanied by hydrolysis of the γ-Al(2)O(3) to form Al(OH)(3) and/or AlO(OH). The P═O group of DMMP interacts predominantly with H(2)O and gives no clear indication of bonding to the oxide surface itself, from which it is inferred that the displacement of weakly adsorbed H(2)O results from the interaction of acidic Al-OH sites with the methoxy O atoms of DMMP. No hydrolysis of the DMMP, either in solution or in contact with the oxide, was detectable under the present conditions. The results have practical implications in the decontamination of materials following exposure to toxic reagents related to DMMP.