In this section
@article{Al:2016:10.1016/j.cis.2016.12.006,
author = {Al, Mahrouqi D and Vinogradov, J and Jackson, MD},
doi = {10.1016/j.cis.2016.12.006},
journal = {Adv Colloid Interface Sci},
pages = {60--76},
title = {Zeta potential of artificial and natural calcite in aqueous solution.},
url = {http://dx.doi.org/10.1016/j.cis.2016.12.006},
volume = {240},
year = {2016}
}
TY - JOUR
AB - Despite the broad range of interest and applications, controls on calcite surface charge in aqueous solution, especially at conditions relevant to natural systems, remain poorly understood. The primary data source to understand calcite surface charge comprises measurements of zeta potential. Here we collate and review previous measurements of zeta potential on natural and artificial calcite and carbonate as a resource for future studies, compare and contrast the results of these studies to determine key controls on zeta potential and where uncertainties remain, and report new measurements of zeta potential relevant to natural subsurface systems. The results show that the potential determining ions (PDIs) for the carbonate mineral surface are the lattice ions Ca(2+), Mg(2+) and CO3(2-). The zeta potential is controlled by the concentration-dependent adsorption of these ions within the Stern layer, primarily at the Outer Helmholtz Plane (OHP). Given this, the Iso-Electric Point (IEP) at which the zeta potential is zero should be expressed as pCa (or pMg). It should not be reported as pH, similar to most metal oxides. The pH does not directly control the zeta potential. Varying the pH whilst holding pCa constant yields constant zeta potential. The pH affects the zeta potential only by moderating the equilibrium pCa for a given CO2 partial pressure (pCO2). Experimental studies that appear to yield a systematic relationship between pH and zeta potential are most likely observing the relationship between pCa and zeta potential, with pCa responding to the change in pH. New data presented here show a consistent linear relationship between equilibrium pH and equilibrium pCa or pMg irrespective of sample used or solution ionic strength. The surface charge of calcite is weakly dependent on pH, through protonation and deprotonation reactions that occur within a hydrolysis layer immediately adjacent to the mineral surface. The Point of Zero Charge (PZC) at which the surface char
AU - Al,Mahrouqi D
AU - Vinogradov,J
AU - Jackson,MD
DO - 10.1016/j.cis.2016.12.006
EP - 76
PY - 2016///
SP - 60
TI - Zeta potential of artificial and natural calcite in aqueous solution.
T2 - Adv Colloid Interface Sci
UR - http://dx.doi.org/10.1016/j.cis.2016.12.006
UR - https://www.ncbi.nlm.nih.gov/pubmed/28063520
VL - 240
ER -