Crystal Nucleation and Growth

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Crystallography and Physical Chemistry of Minerals & Nanominerals".

Deadline for manuscript submissions: closed (15 September 2019) | Viewed by 5575

Special Issue Editor

Alfred Wegener Institute Helmholtz Centre for Polar and Marine Reserach, Section Biogeosciences, 27570 Bremerhaven, Germany
Interests: biomineralization; proxy development; low temperature geochemistry; Raman spectroscopy; crystal nucleation; crystal growth
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Special Issue Information

Dear Colleagues,

Advances in analytical methods that allow us to investigate solids on the nanoscale, in combination with the developments in computational methods, have significantly enhanced our knowledge on crystal nucleation and growth during the last decades. This Special Issue is dedicated to experimental and theoretical work on crystal nucleation and growth in purely inorganic and biogenic systems. Process based studies on the role of trace elements and organic molecules on crystal formation and transformation as well as their role in the formation of mesocrystals are welcome for this Special Issue. The focus of the studies should be on a process-based level, e.g., investigating the thermodynamics and kinetics of a system rather than presenting purely descriptive studies.

Dr. Gernot Nehrke
Guest Editor

Manuscript Submission Information

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Keywords

  • Crystal nucleation
  • Crystal growth
  • Phase transformation
  • Precursor phases
  • Biomineralization
  • Mesocrystals
  • Thermodynamics
  • Kinetics
  • Trace elements

Published Papers (1 paper)

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Research

18 pages, 5196 KiB  
Article
Struvite Crystallisation and the Effect of Co2+ Ions
by Jörn Hövelmann, Tomasz M. Stawski, Helen M. Freeman, Rogier Besselink, Sathish Mayanna, Jeffrey Paulo H. Perez, Nicole S. Hondow and Liane G. Benning
Minerals 2019, 9(9), 503; https://doi.org/10.3390/min9090503 - 22 Aug 2019
Cited by 11 | Viewed by 5157
Abstract
The controlled crystallisation of struvite (MgNH4PO4∙6H2O) is a viable means for the recovery and recycling of phosphorus (P) from municipal and industrial wastewaters. However, an efficient implementation of this recovery method in water treatment systems requires a [...] Read more.
The controlled crystallisation of struvite (MgNH4PO4∙6H2O) is a viable means for the recovery and recycling of phosphorus (P) from municipal and industrial wastewaters. However, an efficient implementation of this recovery method in water treatment systems requires a fundamental understanding of struvite crystallisation mechanisms, including the behavior and effect of metal contaminants during struvite precipitation. Here, we studied the crystallisation pathways of struvite from aqueous solutions using a combination of ex situ and in situ time-resolved synthesis and characterization techniques, including synchrotron-based small- and wide-angle X-ray scattering (SAXS/WAXS) and cryogenic transmission electron microscopy (cryo-TEM). Struvite syntheses were performed both in the pure Mg-NH4-PO4 system as well as in the presence of cobalt (Co), which, among other metals, is typically present in waste streams targeted for P-recovery. Our results show that in the pure system and at Co concentrations < 0.5 mM, struvite crystals nucleate and grow directly from solution, much in accordance with the classical notion of crystal formation. In contrast, at Co concentrations ≥ 1 mM, crystallisation was preceded by the transient formation of an amorphous nanoparticulate phosphate phase. Depending on the aqueous Co/P ratio, this amorphous precursor was found to transform into either (i) Co-bearing struvite (at Co/P < 0.3) or (ii) cobalt phosphate octahydrate (at Co/P > 0.3). These amorphous-to-crystalline transformations were accompanied by a marked colour change from blue to pink, indicating a change in Co2+ coordination in the formed solid from tetrahedral to octahedral. Our findings have implications for the recovery of nutrients and metals during struvite crystallisation and contribute to the ongoing general discussion about the mechanisms of crystal formation. Full article
(This article belongs to the Special Issue Crystal Nucleation and Growth)
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