Potentiometric acid-base titrations of barite powder suspensions dominated by the 001 crystal face reveal a small pH dependent surface charge that varies in systematic fashion with ionic strength (0.03 and 0.30 m NaCl), a divalent cation (0.001 and 0.002 m Ca2+), and temperature (10 to 50oC). A surface complexation model (SCM), as constrained by available x-ray reflectivity and molecular modeling information, was developed to rationalize the pH dependent surface charge. Model results suggest that the background electrolyte, Ba2+ and SO42-(present due to the finite solubility of barite), and Ca2+, all adsorb at the barite surface in various pH regimes, at concentrations in the nmols/m2 range. This presentation will highlight the SCM results, and discuss implications of those results for our efforts to better understand the barite-water interface.

On the nature of the pH dependent surface charge of barite

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.