Porosities accessible to HTO and iodide on water - saturated compacted clay materials and relation with the forms of water : a low field proton NMR study

The aim of the present work was to quantify accessible porosities for iodide and for a water tracer (HTO) on water-saturated compacted clay samples (illite, montmorillonite and MX-80 bentonite) and to relate these macroscopic values to the forms of water in these porosities (surface/bulk water, external/internal water). Low field proton NMR was used to characterize and quantify the forms of water. This enabled the three different populations (structural OH, external surface and internal surface water) to be differentiated on hydrated clays by considering the difference in proton mobility. An accurate description of the water forms within the different populations did not appear possible when water molecules of these populations were in contact because of the occurrence of rapid exchange reactions. For this ha l-0 04 50 88 1, v er si on 1 27 J an 2 01 0 Author manuscript, published in "Geochimica et Cosmochimica Acta Acta 73, 24 (2009) 7290-7302" DOI : 10.1016/j.gca.2009.09.014