Morphological and phase changes in calcium oxalate crystals grown in the presence of sodium diisooctyl sulfosuccinate

L. Tunik, L. Addadi, N. Garti*, H. Füredi-Milhofer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Calcium oxalate was crystallized in the presence of the anionic surfactant dioctyl sulphosuccinate, AOT, and the phase composition of the precipitates (by X-ray diffraction powder patterns and thermal analysis) and their crystal growth morphology (by scanning electron microscopy and electron diffraction) were determined. In the control systems and in the presence of low concentrations of AOT (below the critical micellar concentration, CMC) calcium oxalate monohydrate (CaC2O4 · H2O, COM) was the dominant crystal phase. Crystals grown in the presence of C(AOT) > 0.75 CMC were thinner and more elongated than in the controls, indicating preferential adsorption of the surfactant at the 1̄01 and {010} crystal faces. When the AOT concentration exceeded the critical micellar concentration, the morphological changes in COM crystals became more intense and the composition of the precipitates abruptly changed to mixtures of COM and calcium oxalate dihydrate (CaC2O4 · (2 + x)H2O, x < 0.5; COD) with a COM/COD ratio up to 50 wt%. The morphology of the COD crystals was mostly unaffected. The phase change was attributed to preferential adsorption of AOT - in the form of surface aggregates - at the crystal faces of COM with the consequence of strong inhibition of nucleation and crystal growth of this crystal type and growth of the kinetically less favored COD crystals.

Original languageEnglish
Pages (from-to)748-755
Number of pages8
JournalJournal of Crystal Growth
Volume167
Issue number3-4
DOIs
StatePublished - Oct 1996

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