Observation of Distinct Surface AlIV Sites and Phosphonate Binding Modes in Gamma-Alumina and Concrete by High-Field 27Al and 31P MAS NMR
Abstract
High loadings of nerve agent-related phosphonic acids adsorbed on ?-Al2O3 and concrete examined by 31P MAS NMR and high-field 27Al MAS NMR reveal the presence of several phosphonate-surface binding modes and greatly improved resolution of multiple AlIV sites. Some of the resolved AlIV sites are sensitive to surface hydroxylation/dehydroxylation are attributed to surface AlIV-OH groups (apparently having been observed for the first time). Although the number of surface AlIV sites detected by high-field 27Al MAS NMR (three) is in agreement with current surface models, their dehydroxylation behavior does not entirely concur with proposed dehydroxylation mechanisms. The various phosphonate-alumina surface species detected by 31P MAS NMR are consistent with those previously observed by IR techniques. In concrete, the formation of an aluminophosphonate species is directly observed, consistent with the recalcitrant extraction behavior exhibited by adsorbed phosphonates in environmental matrices.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2009
- Accession Number
- ADA597437
Entities
People
- George W. Wagner
- Roderick A. Fry
Organizations
- New York Structural Biology Center