Extraction of Rare Earth Elements from Chloride Solutions Using Mixtures of P507 and Cyanex 272
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe version is OK and could be accepted. It's better to polish the paper.
Comments on the Quality of English LanguageGood
Author Response
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Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper describes the extraction of rare earth metals with a mixture of P507 and Cyanex 272. This paper is a mere technical report with only a tabulation of the experimental results and no discussion at all, which is necessary for a paper.
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsIn REE processing, REEs are most often separated and purified using solvent extraction with organophosphorus reagents such as P507 (PC88A), DEHPA, and Cyanex 272. Also, the mixtures of these reagents are of great concern. As the present authors mentioned, the mixture of P507 and Cyanex 272 is one of these.
However, in this manuscript (communication), the readers cannot understand the relative advantage of using this mixed extractant in comparison with the cases using each single extractant. The general effects of the initial metal concentrations, extractant concentrations, and pH would be similar between single and mixed extractants. Thus, the readers would want to see more detailed comparison with single extractant systems and to know the technological advantages of the mixed extractants. Unfortunately, the present manuscript does not show the data for single extractant systems and seems to be just lists of experimental data without technological novelity.
It is a pity but this MS should be rejected.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsCOMPOUNDS 2793528: The manuscript titled “Extraction of rare earth elements from chloride solutions using mixtures of P507 and Cyanex 272” submitted by Afonin et al. is a classical study of solvent extraction applying the well-known extracting molecules. Nonetheless, in my opinion, in its current form, the manuscript cannot be published in the Journal Compounds and some extensive changes and clarifications are needed.
1. The authors must write something about the novelty of their work, clearly.
2. What was the basis of selection of the explored organic solvent?
3. Write the name of the compounds P507 and Cyanex 272 in the section abstract.
4. Distribution ratio is the correct term according IUPAC. Please make changes in Tables, etc.
5. “The total concentration of REE chlorides in the initial solutions and aqueous phases after extraction was determined via titration with a standard solution of EDTA at pH 5.6, using xylenol orange as an indicator.” Include reference, literature source for the detail procedure.
6. Why the CREE initial is different during the experimental work i.e. Tables 1-3, although in the range 0.05-0.9 M.
7. Include 1 for figure.
8. Make comparable the results obtained for SF 0.16; 0.30.
9. It will be more perfect if adding the related discussions about the comparison between the obtained results in the manuscript and other reported results in literature.
10. Please enlarge the section results and discussion.
11. Include one more figure based on the date presented in Tables 5-8.
12. Include one more figure based on the Experimental data as a model of extraction cascade to obtain individual rare earth elements using a mixture of P507 and Cyanex 272.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe corrections to the paper make it look more like a paper. Although it is a technical effort with little academic aspect, it is probably a technically meaningful study. It is considered acceptable as a paper.
Author Response
Thank you for your positive review of our manuscript.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have added the results of the simulation of their proposed process. Thus, the manuscript seems to be publishable as communication in the journal, if the following points are reconsidered:
(1) L54-57: Ref. [19] was published in 2005. We cannot say that this is a “recent” publication.
(2) L182-183: Is there any evidence that isooctanol as an additive causes the decrease in separation factors of adjacent REEs with increasing metal concentration of initial aqueous solution? They should show it and explain the possible mechanism of this suppression.
(3) L194: Did the precipitation occur at higher extractant concentrations? If occurred, it should be noted in Table 1, and why did the precipitation occur?
(4) L196-L217: The authors have added this part in the present version. The authors should explain the assumptions and method of calculation more. For example, the following points are lacking:
(i) In order to calculate the extraction behavior of the process, distribution ratios should be represented by some empirical equations with the initial metal and extractant concentrations by least squares fitting using the data in Table 1. They should describe the equations used and the results of the fitting.
(ii) They do not show the distribution ratios under high HCl concentrations. They should explain how they calculated the stripping behavior.
(iii) It seems that the processing is assumed to be carried out using multistage countercurrent extraction and stripping (and scrubbing?). They should mention it with the number of stages in each cascade.
(5) L216: According to Wang [20], the stripping percentage of Lu with 2 mol/L HCl is less than 60%. Is it really appropriate to use 2 mol/L HCl to strip Lu?
(6) Refs. [22] and [23] are exactly the same. Please delete either one.
Author Response
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Author Response File: Author Response.pdf
Round 3
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have corrected some parts according to my comments. Although I do not necessarily agree with the author_response to my 2nd review, I respect their opinions. Basically, I will not request further correction nor further discussion. But, please reconsider the following minor points.
(1) As for the item (1) of author_response to my 2nd review, I did not suggest Ref. [19] to be deleted. What I wanted to point out was that the term “recently” was not appropriate because Ref. [19] was published 19 years ago. I fully agree with the authors’ reply that this reference is important and should be included. But what about deleting the term “Recently” on L54?
(2) In the red parts of the text, the expression “rare earth elements” should be corrected as “REEs”.
(3) L233: “Table 1-8” should probably be “Tables 2, 6”.
Comments on the Quality of English LanguagePlease see (2) of "Comments and Suggestions for Authors".
Author Response
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Author Response File: Author Response.pdf
