Barite precipitation in porous media: Impact of pore structure and surface charge on ionic diffusion

Water and ion diffusion in partially-water saturated compacted kaolinite: Role played by vapor-phase diffusion in water mobility

“…diffusivities, are reported in Figure 3A. For the three tracers used, data are very similar, indicating that the electrostatic effects would be too low to significantly impact the diffusive rate of cation species via surface diffusion and anion species via anion exclusion, as already shown by Glaus et al (2010) and Rajyaguru et al (2021). Conversely, in other clay media dominated by illite layers (i.e., high charge layers), electrostatic effects become more pronounced, leading to significant differences for the diffusivities between anions, cations and neutral species.…”

“…The application of Jurin-Laplace's law for a suction of 1.9 MPa shows that pores with diameters less than 150 nm should be totally filled with liquid water, while the results of mercury intrusion porosimetry (MIP) indicated a mean pore throat value of approximately 35 nm for a sample of kaolinite compacted at a dried bulk density slightly lower than ours (1690 kg m -3 ) (Rajyaguru et al, 2021). This means that most of the pores would be filled with liquid water, thus excluding a possible continuity of the gas phase through the whole pore network at 1.9 MPa.…”

Diffusion driven barite front nucleation and crystallisation in sedimentary rocks

“…Barite precipitation in compacted kaolinite led to similar observations on anion transport and reduced barium diffusion due to barium sorption on kaolinite pores and lower self-diffusion compared to sulfate (e.g. Rajyaguru et al (2021)).…”

“…The samples used by Melkior et al (2009) and Chagneau et al (2015b) are respectively 80% and 70% rich in clay equilibrated with a sodium solution beforehand. Rajyaguru et al (2021) kaolinite is saturated with Na + . By comparaison, the experimental Vosges sample contains up to 10% of clay and Na + balancing was not carried out before diffusion.…”

“…Therefore, the clay adsorption site is occupied by a variety of cations. The electrolytes are concentrated two order of magnitude more than Melkior et al (2009) and Rajyaguru et al (2021).…”