Solubility investigations in the amorphous calcium magnesium carbonate system

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

Abstract

Amorphous precursors are known to occur in the early stages of carbonate mineral formation in both biotic and abiotic environments. Although the Mg content of amorphous calcium magnesium carbonate (ACMC) is a crucial factor for its temporal stabilization, to date little is known about its control on ACMC solubility. Therefore, amorphous Ca x Mg 1-x CO 3 ·nH 2 O solids with 0 ≤ x ≤ 1 and 0.4 ≤ n ≤ 0.8 were synthesized and dispersed in MgCl 2 -NaHCO 3 buffered solutions at 24.5 ± 0.5 °C. The chemical evolution of the solution and the precipitate clearly shows an instantaneous exchange of ions between ACMC and aqueous solution. The obtained ion activity product for ACMC (IAP ACMC = "solubility product") increases as a function of its Mg content ([Mg] ACMC = (1 - x) × 100 in mol%) according to the expression: log(IAP ACMC ) = 0.0174 (±0.0013) × [Mg] ACMC - 6.278 (±0.046) (R 2 = 0.98), where the log(IAP ACMC ) shift from Ca (-6.28 ± 0.05) to Mg (-4.54 ± 0.16) ACMC endmember, can be explained by the increasing water content and changes in short-range order, as Ca is substituted by Mg in the ACMC structure. The results of this study shed light on the factors controlling ACMC solubility and its temporal stability in aqueous solutions.

Originalspracheenglisch
Seiten (von - bis)155-164
Seitenumfang10
FachzeitschriftCrystEngComm
Jahrgang21
Ausgabenummer1
DOIs
PublikationsstatusVeröffentlicht - 2019

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Magnesium
magnesium
calcium
Carbonates
Calcium
carbonates
solubility
Solubility
calcium magnesium carbonate
aqueous solutions
Carbonate minerals
Ions
sheds
chemical evolution
products
Carbon Monoxide
moisture content
Water content
precipitates
ions

ASJC Scopus subject areas

  • !!Condensed Matter Physics
  • !!Chemistry(all)
  • !!Materials Science(all)

Fields of Expertise

  • Advanced Materials Science

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Solubility investigations in the amorphous calcium magnesium carbonate system. / Purgstaller, Bettina; Götschl, Katja; Mavromatis, Vasileios; Dietzel, Martin.

in: CrystEngComm , Jahrgang 21, Nr. 1, 2019, S. 155-164.

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

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