The effects of (di-,tri-valent)-cation partitioning and intercalant anion-type on the solubility of hydrotalcites

Dale P. Prentice, Lauren Gomez-Zamorano, Magdalena Balonis, Bartu Erdemli, Kirk Ellison, Narayanan Neithalath, Dante Simonetti, Gaurav Sant

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Synthetic hydrotalcites were produced by a co-precipitation method. The hydrotalcites are represented by the general formula [MII(1-x)MIII(x)(OH)2][An−]x/n·zH2O, where MII is a divalent cation (eg, Mg2+or Ca2+), MIII is a trivalent cation (eg, Al3+) and An− is the interlayer anion. Herein, MII = Mg, and MIII = Al such that [Mg/Al] = [2, 3] (atomic units) and An−, represents intercalant species including: OH, SO42− and CO32− anions. The thermochemical data of each compound including their solubility constants (Kso), density and molar volume were quantified at T = 25 ± 0.5°C, and P = 1 bar. The solubilities of the synthetic hydrotalcites, irrespective of their divalent-trivalent cation partitioning ratio, scaled as CO32− < SO42− < OH; in order of decreasing solubility. The type of anion, very slightly, affected the solubility with less than ±1 log unit of variation for [Mg/Al] = 2, and ±2 log units of variation for [Mg/Al] = 3. The solubilities of these phases were strongly correlated with that of gibbsite (Al(OH)3); such that activity of the [AlO2] species was solubility determining with increasing pH. The tabulated thermodynamic data were used to construct solid-solution models for phases encompassing both cation distribution ratios and to calculate stable phase equilibria relevant to alkali-activated slag (AAS) systems for diverse activator compositions.

Original languageEnglish (US)
Pages (from-to)6025-6039
Number of pages15
JournalJournal of the American Ceramic Society
Volume103
Issue number10
DOIs
StatePublished - Sep 1 2020

Keywords

  • LDH
  • hydrotalcite-like minerals
  • solubility constant
  • thermodynamics

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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