Alkaline Decomposition of Solid Solution of Ammonium-Sodium Jarosite with Arsenic
, Francisco Patiño 2, Antoni Roca 3, Mizraim U. Flores 4, Iván A. Reyes 5, Martin Reyes 6 and Hernán Islas 1
Round 1
Reviewer 1 Report
In this manuscript, the authors synthesized a solid solution of arsenical ammonium-sodium jarosite, with an approximate formula [(NH4)0.72Na0.06(H3O)0.21]Fe3(2.52) (SO4)1.85(AsO4)0.15[(OH)4.41(H2O)1.59]. The decomposition reaction in alkaline media was carried out; this decomposition shows three stages: an induction period, a progressive conversion and a stabilization periods. The process is controlled by the chemical reaction, and the progressive conversion period is consistent with the shrinking core model. Some critical issues should be properly addressed and I suggest the acceptance after a major revision. My specific questions/comments are listed as follows:
- The reason for choosing NaOH as media to study the kinetics of ammonium-sodium jarosite with arsenic should be specified to better guide the readers.
- The high-manification SEM and TEM images of samples should be provided to observe the microstructure of surface.
- On page 3, the authors stated that “Therefore, samples of the solution were taken at different times (≈5 mL) to monitor the progress of the reaction according to the conditions of each experiment.” How long are the different times?
- Please mark the corresponding phases on the peaks in Fig. 7 and explain in detail the reason for the phase transition and add standard PDF cards. The picture spacing is too narrow, please widen it.
- On page 7, the authors stated that “Particle size distribution results showed that the main sizes are retained in the meshes with diameters of between 25 and 38 μm, with a retained weight of 48.5% and 33.1% respectively (Table 4).” The authors should explain the reason of diameters of between 25 and 38 μm with a retained weight of 48.5% and 33.1% respectively of the manuscript to the reader.
- It is suggested to provide the mapping result of partially decomposed particle.
- On page 8, the authors stated that “In this stage, the difficulty of OH− ions to diffuse into the surface of the particles of ammonium-sodium jarosite with arsenic and the formation of active sites until the establishing of a reaction front was observed.” Please the authors explain the reason of the difficulty of OH− ions to diffuse into the surface of the particles of ammonium-sodium jarosite with arsenic and the formation of active sites.
Author Response
Dear Reviewer,
The authors appreciate the reviewer's recommendation. within the attached file you will find the answers to each comment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Interesting and valuable work that can have not only scientific value but also be valuable for practical management of mining residues and wastes.
The work was made in a very thorough and scientifically sound manner. I have only one worry - it seems that the experiments were made as single tests only. I expected that a scientific study of this dignity should be based on triplicate experiments to ensure statistical value of the data. If the authors can show (ad add to the manuscript) statistics for their results it would add a lot to the value of the paper.
Author Response
Dear Reviewer,
The authors appreciate the reviewer's recommendation. within the attached file you will find the answers to each comment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscript is advised to be accepted since all the problems have been addressed.
