Channel flow cell studies of the inhibiting action of gypsum on the dissolution kinetics of calcite

a laboratory approach with implications for field monitoring

Shelley J. Wilkins, Richard G. Compton*, Mark A. Taylor, Heather A. Viles

*Corresponding author for this work

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

The rate of dissolution of surface-treated calcite crystals in aqueous acidic solution has been studied using an adaptation of the channel flow cell method with microdisc electrode detection. Surface treatments of calcite with sulfuric acid lead to the nucleation of gypsum overgrowths, which reduce the rate of dissolution of calcite. Rate constants for untreated calcite and calcite pretreated with sulfuric acid conditions of 0.01 M for 1 h, 0.05 M for 5 h, and 0.1 M for 21 h are found to be 0.035, 0.018, 0.006, and 0.004 cm s-1, respectively. Deterioration of calcite materials caused by acid deposition was investigated by field exposure of untreated and sulfate pretreated calcite rocks under urban conditions for 12 months. The rate constant for both pretreated and untreated calcite exposed to weathering is 0.003 cm s-1. This suggests that calcite self-passivates the surface from further reaction when exposed to acid deposition. However, surface studies indicate that the surface undergoes erosion and dissolution before passivation. Pretreatment of the surface with sulfate protects the surface from acid deposition so it remains less reactive toward acid compared with untreated calcite.

Original languageEnglish
Pages (from-to)354-361
Number of pages8
JournalJournal of Colloid and Interface Science
Volume236
Issue number2
DOIs
Publication statusPublished - 15 Apr 2001
Externally publishedYes

Keywords

  • Calcite dissolution
  • Channel flow cell
  • Gypsum
  • Pretreatments
  • Weathering

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