| Title: | Multistep partitioning causes significant stable carbon and hydrogen isotope effects during volatilization of toluene and propan-2-ol from unsaturated sandy aquifer sediment |
| Author(s): | Zamane S; Gori D; Hohener P; |
| Address: | "Aix Marseille University - CNRS, UMR 7376, Laboratory of Environmental Chemistry, Marseille, France. Aix Marseille University - CNRS, UMR 7376, Laboratory of Environmental Chemistry, Marseille, France. Electronic address: patrick.hohener@univ-amu.fr" |
| DOI: | 10.1016/j.chemosphere.2020.126345 |
| ISSN/ISBN: | 1879-1298 (Electronic) 0045-6535 (Linking) |
| Abstract: | "This study aimed at investigating whether stable isotopes can be used to monitor the progress of volatile organic compounds (VOCs) volatilization from contaminated sediment during venting. Batches of a dry aquifer sediment were packed into stainless steel HPLC columns, humidified with distilled water and later contaminated by either liquid toluene or propan-2-ol. The VOCs were then volatilized by a stream of gas at room temperature, and the concentrations and stable isotope ratios of gaseous VOCs were recorded by isotope-ratio mass spectrometry. During early stages of volatilization of toluene, the isotope ratios Deltadelta(13)C shifted to more negative values by about -3 to -5 per thousand and the Deltadelta(2)H by more than -40 per thousand, while the concentration remained at or near initial saturated vapor concentration. Depletion of the isotope ratios in the gas was explained by the vapor-liquid fractionation process, which is amplified by successive self-partitioning steps of gaseous VOC into remaining liquid VOC. For propan-2-ol the carbon isotope shift was negative like for toluene, whereas the H shift was positive. Hydrogen bonding in the liquid propan-2-ol phase causes a normal vapor-liquid H isotope effect which was described already in classical literature. The isotope shifts in the present experiments are larger than previously reported shifts due to phase-change processes and reach the magnitude of shifts usually observed in kinetic isotope fractionation" |
| Keywords: | 2-Propanol/*chemistry Carbon Carbon Isotopes/analysis Chemical Fractionation/methods Gases/analysis Groundwater/*chemistry Hydrogen/analysis Hydrogen Bonding Sand Toluene/analysis/*chemistry Volatile Organic Compounds/analysis Volatilization Carbon-13 Deu; |
| Notes: | "MedlineZamane, Sarah Gori, Didier Hohener, Patrick eng England 2020/03/15 Chemosphere. 2020 Jul; 251:126345. doi: 10.1016/j.chemosphere.2020.126345. Epub 2020 Mar 4" |
