Reaction rates and dissolution mechanisms of quartz as a function of pH

Shikha Nangia, Barbara J. Garrison

Research output: Contribution to journalArticle

74 Scopus citations

Abstract

In this computational study, we present the dissolution rates for quartz as a function of pH at 298 K. At any given pH, the dissolution of the quartz surface depends on the distribution of protonated, deprotonated, or neutral species. The dissolution mechanism for each of these three species was investigated by ab initio electronic structure calculations to obtain the reaction profile. Using the barrier height along with the partition functions for the transition state and the reactants in the rate-limiting steps, we calculated the TST rate constants for the reactions for the temperature range of 200-500 K. At 298 K the rate constant (s-1) for the dissolution of neutral species was found to be several orders of magnitude smaller than the rate-limiting steps for the protonated and deprotonated species. The values of the rate constants were used in the rate law expression to calculate the overall dissolution rate (mol m-2 s-1) at a given pH. The calculated rates were compared to previously reported experimental and theoretical rates and were found to be in good agreement over 2-12 pH range.

Original languageEnglish (US)
Pages (from-to)2027-2033
Number of pages7
JournalJournal of Physical Chemistry A
Volume112
Issue number10
DOIs
StatePublished - Mar 13 2008
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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