Reactive Transport of Protons in Electro-Osmotic Displacements with Electrolyte Concentration Difference in a Microcapillary.

In this work, we model electro-osmotic displacement with electrolyte concentration difference in a microcapillary by incorporating proton transport coupled with surface complexation reaction and carbonate equilibrium. The hysteretic effect observed in experiments is well-captured by the model. By deriving the semianalytical solution of the nonlinear transport equation using method of characteristics, we elucidate the transport mechanism of protons by classifying their nonlinear transport behavior (shock/rarefaction/discontinuity) into several regimes depending on the concentration ratio and the pH.

Chromatographic analysis of the acidity-salinity transport system.

The effects of acidity and salinity on solute transport in porous media are important to a diverse range of fields from seawater intrusion to nuclear waste storage. Recent transport experiments in quartz sand show the difficulty in capturing the coupling of acidity and salinity under acidic conditions for this system. Here we study the ability of different surface complexation models to capture this coupling, through an analysis of the reactive transport equations in the limit of no diffusion.

Challenges in Coupling Acidity and Salinity Transport in Porous Media.

Salinity is an increasingly prescient issue in reactive transport, from low salinity water flooding to fracking brine leakage. Of primary concern is the effect of salinity on surface chemistry. Transport and batch experiments show a strong coupling of salinity and acidity through chemical interactions at the mineral-liquid interface.