Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum
Synchrotron-based small- and wide-angle X-ray scattering (SAXS/WAXS) was used to examine in situ the precipitation of gypsum (CaSO4·2H2O) from solution. We determined the role of (I) supersaturation, (II) temperature and (III) additives (Mg2+ and citric acid) on the precipitation mechanism and rate...
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doaj-c382c6e8fddc482d8c9b73cdc00cd5562020-11-24T22:52:54ZengMDPI AGMinerals2075-163X2017-08-017814010.3390/min7080140min7080140Physicochemical and Additive Controls on the Multistep Precipitation Pathway of GypsumMercedes Ossorio0Tomasz M. Stawski1Juan Diego Rodríguez-Blanco2Mike Sleutel3Juan Manuel García-Ruiz4Liane G. Benning5Alexander E. S. Van Driessche6LEC, IACT, CSIC, Universidad de Granada, 18100 Granada, SpainGFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, GermanyDepartment of Geology, Museum Building, Trinity College Dublin, 2 Dublin, IrelandStructural Biology Brussels, Flanders Interuniversity Institute for Biotechnology and Vrije Universiteit Brussel, 1050 Elsene, BelgiumLEC, IACT, CSIC, Universidad de Granada, 18100 Granada, SpainGFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, GermanyLEC, IACT, CSIC, Universidad de Granada, 18100 Granada, SpainSynchrotron-based small- and wide-angle X-ray scattering (SAXS/WAXS) was used to examine in situ the precipitation of gypsum (CaSO4·2H2O) from solution. We determined the role of (I) supersaturation, (II) temperature and (III) additives (Mg2+ and citric acid) on the precipitation mechanism and rate of gypsum. Detailed analysis of the SAXS data showed that for all tested supersaturations and temperatures the same nucleation pathway was maintained, i.e., formation of primary particles that aggregate and transform/re-organize into gypsum. In the presence of Mg2+ more primary particle are formed compared to the pure experiment, but the onset of their transformation/reorganization was slowed down. Citrate reduces the formation of primary particles resulting in a longer induction time of gypsum formation. Based on the WAXS data we determined that the precipitation rate of gypsum increased 5-fold from 4 to 40 °C, which results in an effective activation energy of ~30 kJ·mol−1. Mg2+ reduces the precipitation rate of gypsum by more than half, most likely by blocking the attachment sites of the growth units, while citric acid only weakly hampers the growth of gypsum by lowering the effective supersaturation. In short, our results show that the nucleation mechanism is independent of the solution conditions and that Mg2+ and citric acid influence differently the nucleation pathway and growth kinetics of gypsum. These insights are key for further improving our ability to control the crystallization process of calcium sulphate.https://www.mdpi.com/2075-163X/7/8/140nucleationmultistep pathwaycrystal growthgypsumadditives |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Mercedes Ossorio Tomasz M. Stawski Juan Diego Rodríguez-Blanco Mike Sleutel Juan Manuel García-Ruiz Liane G. Benning Alexander E. S. Van Driessche |
spellingShingle |
Mercedes Ossorio Tomasz M. Stawski Juan Diego Rodríguez-Blanco Mike Sleutel Juan Manuel García-Ruiz Liane G. Benning Alexander E. S. Van Driessche Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum Minerals nucleation multistep pathway crystal growth gypsum additives |
author_facet |
Mercedes Ossorio Tomasz M. Stawski Juan Diego Rodríguez-Blanco Mike Sleutel Juan Manuel García-Ruiz Liane G. Benning Alexander E. S. Van Driessche |
author_sort |
Mercedes Ossorio |
title |
Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum |
title_short |
Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum |
title_full |
Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum |
title_fullStr |
Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum |
title_full_unstemmed |
Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum |
title_sort |
physicochemical and additive controls on the multistep precipitation pathway of gypsum |
publisher |
MDPI AG |
series |
Minerals |
issn |
2075-163X |
publishDate |
2017-08-01 |
description |
Synchrotron-based small- and wide-angle X-ray scattering (SAXS/WAXS) was used to examine in situ the precipitation of gypsum (CaSO4·2H2O) from solution. We determined the role of (I) supersaturation, (II) temperature and (III) additives (Mg2+ and citric acid) on the precipitation mechanism and rate of gypsum. Detailed analysis of the SAXS data showed that for all tested supersaturations and temperatures the same nucleation pathway was maintained, i.e., formation of primary particles that aggregate and transform/re-organize into gypsum. In the presence of Mg2+ more primary particle are formed compared to the pure experiment, but the onset of their transformation/reorganization was slowed down. Citrate reduces the formation of primary particles resulting in a longer induction time of gypsum formation. Based on the WAXS data we determined that the precipitation rate of gypsum increased 5-fold from 4 to 40 °C, which results in an effective activation energy of ~30 kJ·mol−1. Mg2+ reduces the precipitation rate of gypsum by more than half, most likely by blocking the attachment sites of the growth units, while citric acid only weakly hampers the growth of gypsum by lowering the effective supersaturation. In short, our results show that the nucleation mechanism is independent of the solution conditions and that Mg2+ and citric acid influence differently the nucleation pathway and growth kinetics of gypsum. These insights are key for further improving our ability to control the crystallization process of calcium sulphate. |
topic |
nucleation multistep pathway crystal growth gypsum additives |
url |
https://www.mdpi.com/2075-163X/7/8/140 |
work_keys_str_mv |
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