Water uptake and salt leaching of two simulated French Bituminized Waste Products (BWP) have been investigated under nearly constant volume conditions. The resulting pressure development was monitored during 5 to 6 years for two simulated BWP samples, varying one from the other by their inorganic load and composition. Pressure development induced by water uptake is mainly the result of two processes: (1) an osmotic phenomenon due to the presence of soluble and hygroscopic salts (NaNO3 and Na2SO4) embedded in the bitumen matrix and (2) recrystallization of anhydrous Na2SO4 into its decahydrate form, leading to an important volumetric expansion. After a certain hydration period, the pressure exerted by the hydrating BWP stabilizes when the pressure generating phenomena are fully counteracted by the leaching of soluble salts via out-diffusion, reconsolidation of pores in highly leached parts of the BWP, and/or some creep of the BWP into the technical voids of the water uptake cells. For one of the French BWP, this already occurred after 1 year of hydration. Differences are found in the pressure evolution and increase rate of the two studied BWP, though a much larger difference is observed when comparing the results of the French BWP to a Belgian BWP, i.e. Eurobitum. The faster pressure development observed for the French BWPs can be attributed to the differences in the soluble salt content, the inorganic load, the content of recrystallizing salts, but also to the presence of insoluble salts such as BaSO4, which seems to facilitate the water uptake rate in the French BWP. The faster hydration in French BWP results in a larger fraction of salts becoming available for osmosis and recrystallization within a relatively short time frame, thereby explaining the faster pressure build-up. On the other hand, BaSO4 does not seem to affect the leaching of soluble salts from BWP directly.

We investigate water infiltration in porous matrices made of bitumen and salts with different solubilities. Dispersion, inside bitumen, of either SrSO4 or MgSO4 at 40% mass fraction was achieved, as a way to model materials used in the context of nuclear waste conditioning. Pulsed field gradient nuclear magnetic resonance (PFG-NMR) and environmental scanning electron microscopy (ESEM) measurements allow us to characterize the evolution of the porous structure as a consequence of water infiltration (due to a leaching phenomenon) for durations up to 1.5 year. PFG-NMR enables performing 1D-imaging of water at different times to monitor its slow seeping inside the material. Profiles observed at the maximum time interval (1.5 year) demonstrate that different leaching behaviors exist depending on whether the salts dispersed inside bitumen are of the soluble or insoluble type. NMR relaxation and diffusion measurements were also taken. Remarkably, when performed in combination with 1D-imaging, such measurements yield information on the surface-to-volume ratio of the water-filled porous network, at different times, as a function of depth. In the case of the matrix-containing insoluble salts, relaxation measurements lead to discrimination between two different water populations differing by their T-2 or T-1 values. These values are described in the framework of surface-driven relaxation. A two-step model of leaching is proposed that globally accounts for the different observations (NMR 1D-imaging, relaxation/diffusion, as well as ESEM). The present work gives insight into the leaching behavior of porous bitumen-salt matrices and could be used as an input for modeling their evolution on longer timescales.

An exhaustive GC–MS sample preparation, derivatization, mass fragmentation and acquisition study was performed, for the simultaneous analysis of chlorophenols (CPs). Selected species were 2-CP, 3-CP, 4-CP, 3,5-dichlorophenol (diCP), 2,5-diCP, 2,6-diCP, 2,4-diCP, 2,3-diCP, 3,4-diCP 2,4,6-trichlorophenol (triCP), 2,4,5-triCP, 2,3,4-triCP, 2,3,4,6-tetrachlorophenol (tetraCP) and pentachlorophenol (pentaCP), in total 14 compounds. As novelties to the field, basic researches, like systematic derivatization, mass fragmentation and acquisition methods have been optimized for the trimethylsilyl (TMS) ether derivatives of CPs. The reactivity of chlorophenols with silylating agents has not been systematically analyzed. Here, we studied the reactivity of 14 chlorophenols with five silylating reagents. The three acquisition techniques, the full scan (FS), the multiple ion monitoring (MIM), and the currently optimized multiple reaction monitoring (MRM) methods, have been compared. We developed a new analytical approach, simultaneously monitoring the fragmentation pattern of the 35Cl and the 37Cl containing fragment ions both as precursor and as product ions. This principle resulted in remarkable specificity and sensitivity of detection and quantification; particularly in the cases of the tetraCP and pentaCP derivatives containing the 35Cl and the 37Cl fragment ions at an approximate ratio of <1:1. Detailed documentation of the loss of HCl via fragmentation processes, without decomposition of the benzene ring, was attributed to the “ring-walk” mechanism described first for monochlorophenol. Critical evaluation of the derivatization and acquisition protocols was collated and validated with the same characteristics. Data of six point calibration along with the corresponding relative standard deviation percentage (RSD%) values, in the line of FS, MIM and MRM methods (r2: 0.9987, 0.9992, 0.9989; RSD%: 8.7, 5.6, 8.1), proved to be independent on the acquisition processes. The practical utility of the optimized MRM acquisition techniques was confirmed by the quantitation of the CP contents of Danube River, tap water and distilled water samples. Results confirmed at the first time the primary importance of the MRM acquisition method, even in comparison to the MIM one: we revealed that distilled water contains higher chlorophenol content than tap water, which might have a great significance for the water industry.