Effect of Acid on Surface Hydroxyl Groups on Kaolinite and Montmorillonite

Sarah K. Sihvonen, Kelly A. Murphy, Nancy M. Washton, Muhammad Bilal Altaf, Karl T. Mueller, Miriam Arak Freedman

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Mineral dust aerosol participates in heterogeneous chemistry in the atmosphere. In particular, the hydroxyl groups on the surface of aluminosilicate clay minerals are important for heterogeneous atmospheric processes. These functional groups may be altered by acidic processing during atmospheric transport. In this study, we exposed kaolinite (KGa-1b) and montmorillonite (STx-1b) to aqueous sulfuric acid and then rinsed the soluble reactants and products off in order to explore changes to functional groups on the mineral surface. To quantify the changes due to acid treatment of edge hydroxyl groups, we use 19F magic angle spinning nuclear magnetic resonance spectroscopy and a probe molecule, 3,3,3-trifluoropropyldimethylchlorosilane. We find that the edge hydroxyl groups (OH) increase in both number and density with acid treatment. Chemical reactions in the atmosphere may be impacted by the increase in OH at the mineral edge.

Original languageEnglish (US)
Pages (from-to)409-430
Number of pages22
JournalZeitschrift fur Physikalische Chemie
Volume232
Issue number3
DOIs
StatePublished - Mar 28 2018

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

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