Abstract
Fourier transform infrared (FT-IR) and Fourier transform nuclear magnetic resonance (FT-NMR) methods were used to examine the adsorption and reaction of diisopropyl fluorophosphate (DFP) on various solid adsorbents. Static and flow system experiments were monitored with the use of FT-IR to determine DFP adsorption rates and isotherms on silica, coated silicas, γ-alumina, coated aluminas, and activated charcoal. The adsorption of DFP(g) onto the solid adsorbents was generally very rapid, with a half-life of 20 s for 1 mg DFP onto 25 mg of 350 m<sup>2</sup>/g silica. The DFP adsorption isotherm on silica indicated chemisorption to a monolayer at <i>P/P</i><sub>0</sub> < 0.6, followed by increased coverage that appears to be physical adsorption. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, photoacoustic spectroscopy (PAS), and solid-state <sup>31</sup>P NMR of adsorbed DFP showed chemisorption on silica and on alumina. Bonding at the P=O of DFP was indicated by a −41 cm<sup>−1</sup> shift in the ν(P=O) and a 1-ppm upfield shift in the <sup>31</sup>P resonance. DRIFT, PAS kinetics, and <sup>31</sup>P NMR showed that DFP hydrolyzed after the initial adsorption on alumina and some coated materials but not on silica or activated charcoal. The rate of hydrolysis increased on alumina with addition of water and varied with different aluminas and coated silicas.
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription