Relative Contributions of Mg Hydration and Molecular Structural Restraints to the Barrier of Dolomite Crystallization: A Comparison of Aqueous and Non-Aqueous Crystallization in (BaMg)CO₃ and (CaMg)CO₃ Systems

Round 1

Reviewer 1 Report

The article “Relative contributions of Mg hydration and molecular structural restraints to the barrier of dolomite crystallization” is interesting and presents novel results on the crystallization of Mg-Ba-CO2 system in non-aqueous and aqueous environment. I consider that the work is well presented and referenced, although it could be improved and I present some comments in that regard.

Comments:

Would it be possible to refer to obtaining norsethite or the presence of Ba in this study in the title of the work? Although the introduction places the reader on the objective of the study, I believe that the title directs attention mainly to the crystallization of dolomite, while the study focuses on norsethite.

Line 57: overwhelminglFy must be overwhelmingly.

Line 154: power must be powder.

In the diffraction patterns presented in Fig. 1, appear peaks that have not been identified. Could an identification be made of the phases that coexist with norsethite and whiterite in the cases 1 Mg: 5 Ba, 1 Mg: 2 Ba and 1 Mg: 1 Ba? Please, carry out a discussion of the origin of these phases.

XRD results are not shown in the work for the H2O case. Did any additional phase appear besides norsethite or whiterite? It would be of interest to show some of the cases obtained with the presence of both phases together or separately.

Was any chemical analysis carried out on the samples obtained from the preparation in the presence of water and without the presence of water, to verify that the cleaning of Na, Cs and Cl had been completely achieved?  I think would be of interest the inclusion of a comment about it or the results of the analysis in the work.

The images shown in Fig. 2 do not present any discussion, except for the reference to the amorphous case at line 198. A more in-depth discussion of the figure would also improve the work.

Author Response

see file attached

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript is devoted to the study of the well-known "dolomite problem" - why dolomite crystallizes under atmospheric conditions, while norsetite, similar in structure and Gibbs energy, according to (Zhang et al., 2021), demonstrates direct precipitation at ambient temperature. I am unable to assess the details and subtleties of experimental techniques, however, the conclusion that the inability of dolomite to crystallize in aqueous solutions is due to the higher Gibbs energy of the formation of an activated complex than in norsetite. I support the thesis that the activated complex of the dolomite crystallization reaction is entropically preferable to the formation of norsetite, but is much less stable due to the weak chemical bond (dissociation energy 366 464 kJ/mol and 563 kJ/mol, respectively for Ca-O bond and Ba-O bond).

Please clarify why on page 10, line 372 it is written “ΔS ‡ N = -18.1 J / mol and ΔS ‡ D = 29.7 J / mol” .

I recommend the manuscript for publication in the form as it is presented.

Author Response

Thank your very much for your encouraging comments.

Please clarify why on page 10, line 372 it is written “ΔS ‡ N = -18.1 J / mol and ΔS ‡ D = 29.7 J / mol” .

 

Thanks very much for noticing and pointing out the typo.  The dimension is now given in the correct form of JK^-1mol^-1.