Abstract
Understanding mineral growth mechanism is a key to understanding biomineralisation, fossilisation and diagenesis. The presence of trace compounds affect the growth and dissolution rates and the form of the crystals produced. Organisms use ions and organic molecules to control the growth of hard parts by inhibition and enhancement. Calcite growth in the presence of Mg2+ is a good example. Its inhibiting role in biomineralisation is well known, but the controlling mechanisms are still debated. Here, we use a microkinetic model for a series of inorganic and organic inhibitors of calcite growth. With one, single, nonempirical parameter per inhibitor, i.e. its adsorption energy, we can quantitatively reproduce the experimental data and unambiguously establish the inhibition mechanism(s) for each inhibitor. Our results provide molecular scale insight into the processes of crystal growth and biomineralisation, and open the door for logical design of mineral growth inhibitors through computational methods.
Highlights
Understanding mineral growth mechanism is a key to understanding biomineralisation, fossilisation and diagenesis
Magnesium is a known poison for calcite growth, and this is relevant for biomineralisation[19,20,21] as well as industrial materials synthesis[22], so we test the model with the recently published[23] experimental data for magnesium (Mg2+), sulphate (SO42−) and their ion pair (MgSO40)
In the form of humic and fulvic acids, are common in the earth’s surface waters, and the carboxyl functional group is active in molecules known to control calcite growth[11] and biomineralisation[12], so we test the model with new experimental data for calcite growth in ss(Cpole6ucHtiie5osCnOsMOg−2c+o).nOtaanuidnrinrSegOsu42lta−scesithsaotewcauths(eCadtHin3mChaOiibnOitlyi−o)nbybyaandtdhsoeripbnteoinorgnzoanaotinec calcite steps, which blocks kink nucleation
Summary
Understanding mineral growth mechanism is a key to understanding biomineralisation, fossilisation and diagenesis. The microkinetic model was developed for minerals consisting of two general components in equal stoichiometry, and should be generally applicable to the growth of any two components of a crystal, at elevated temperature and pressure This would, for example, include the most divalent metal carbonate and sulphate minerals, as long as kink nucleation is observed to be a rate-limiting step during growth. In the form of humic and fulvic acids, are common in the earth’s surface waters, and the carboxyl functional group is active in molecules known to control calcite growth[11] and biomineralisation[12], so we test the model with new experimental data for calcite growth in ss(Cpole6ucHtiie5osCnOsMOg−2c+o).nOtaanuidnrinrSegOsu42lta−scesithsaotewcauths(eCadtHin3mChaOiibnOitlyi−o)nbybyaandtdhsoeripbnteoinorgnzoanaotinec calcite steps, which blocks kink nucleation. We demonstrate that the minimal set of parameters used in the microkinetic model together with geochemical speciation modelling is enough to reproduce the observed behaviour for all inorganic and organic inhibitors in our study
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