Quantitative and qualitative analysis of hydrosoluble organic matter in bitumen leachates

Bitumen is currently used as an embedding matrix for low and intermediate l evel radioactive waste disposal in deep sediments. High impermeability and a great resistance to most chemicals are the two main properties sought. In deed, the generation of water-soluble organic complexing agents could affec t the integrity of the wasteform due to an increase of radionuclide solubil ity. Therefore, the aim of this study is the quantitative and qualitative c haracterisation of soluble organic matter in bitumen leachates. Different c onditions of leaching solutions were tested such as various pHs, ionic stre ngths and S/V ratios), in order to simulate the expected deep environment o f bitumen waste disposal. In water, at neutral pH, the amount of soluble or ganic matter released is very low. However, the amount of soluble total org anic carbon released increased with pH. Nonetheless, in alkaline solutions (pH 13.5), the effect of the ionic strength leads to a decrease of soluble organic matter released. Several classes of organic compounds such as napht halene, alcohols, linear carboxylic acids, aromatics, glycols, and nitrogen compounds were identified by GC-MS.