Solid-state deuterium NMR spectroscopy of d5-phenol in white portland cement: a new method for assessing solidification/stabilization

Abstract

We have developed a new NMR-based procedure for studying waste/cement interactions. This is the first use of deuterium NMR spectroscopy to study waste solidification/stabilization (S/S). The main feature of deuterium NMR spectroscopy is the ability to monitor molecular reorientations over a wide range of reorientation rates. This technique allows one to determine if a particular deuterated organic waste is effectively solidified/stabilized and to determine the lower limit of the bond strength between the waste and the cement matrix. Comparison of the predicted and experimental deuterium NMR spectra show that phenol is mainly dissolved in pore waters and, thus, poorly immobilized by white portland cement, at least for cure times up to 1 year. After evaporation of the pore water from the cement matrix the 2H line shape and 2' 1 were measured at 230-360 K; the maximum activation energy for the 180' ring flip process is 5.5 kcal/mol. Hence, the lower limit of the bond strength between phenol and the cement matrix is approximately 5.5 kcal/mol.

Interpretation of Electric Field Gradients at Deuterium as Measured by Solid-State NMR Spectroscopy

“…Because of the well-defined values for C-D bonds (C,, q, orientation of the tensor), motional averaging effects are relatively easy to observe in the form of partially reduced values of C,, changes in the apparent value of q, or more rapid spinlattice relaxation times. L9*38, 42 In organometallic complexes, the cyclopentadienyl ring is relatively free to rotate, even in the solid state.43944 Solid-state deuterium NMR is an ideal method for measuring Cp-ring rotation rates over a very wide range. In Cp-ring rotation rate constants of 2.4 x 10" s -(300 K) down to 1.2 x lo7 s -' ( I 10 K) were measured from a combination of line shape and T I data4' As an aside.…”

Hydrogen isotope exchange reactions involving C–H (D, T) bonds

“…1 This trend is strongly supported by the emergence of analytical methods which simplify product analyses, including the availability of bench top mass spectrometry, 2 H and 3 H NMR spectroscopy in solution and in the solid state as readily accessible tools. 13 Deuterium is available at low cost and in high isotopic purity, facilitating H ? D exchange experiments.…”

Sequential Diffusion Spectra as a Tool for Studying Time-Dependent Translational Molecular Dynamics: A Cement Hydration Study

“…A popular porous material often studied by NMR is cement. Several different NMR methods were used in these studies, including the solid-state NMR spectroscopy [15] of different nuclei in cement compounds, e.g., 29 Si [16], 27 Al [17] and 2 H [18]. This method can also be optimized to allow in situ applications [19].…”