Cluster Analysis of Soluble Organic Fractions in Two Low-Rank Coals
Round 1
Reviewer 1 Report
Dear Author,
I have investigated your manuscript. Please find my comments in the attached file.
Regards.
Comments for author File: 
Comments.pdf
Author Response
Point 1: Please use also the full names of the abbreviations in the first appearance.
Response 1: Abbreviations have been changed to full names for the first occurrence of the noun.
Point 2: Sometimes you left a space before the citations, sometimes you didn't. Please use journal format. Please check the full text.
Response 2: All citations have been prefixed with a space.
Point 3: information. Ju
Do the first names of the Authors used in Author [number] format?
Please check the full text.
Response 3: All authors' names have been used in author [number] format.
Point 4: Include a space after the colon. Insert a space after the semi-colon.
Response 4: A space has been added after all colons and semicolons.
Point 5: The bottom axes are difficult to read.
Response 5: A projection to PC1,PC2,PC3 has been added to address this issue.
Point 6: Please increase the font size in the horizontal axis.
Response 6: The image has been redrawn with the horizontal text enlarged.
Point 7: Is there no space between the surname and initials of the first name?
Response 7: A space has been added between the surname and the first letter of the name.
Reviewer 2 Report
The paper is very well written, including format, text, figure, and tables. About references, I suggest that can be improved with other papers around of the world. Thus, the review will be extended globally.
Another point is the method don’t show how many repetitions are prepared and analysed (14 sample). This is very important to evaluate the z-score and normal distributions (sample more than 30 unities)
And last contribution I suggest that the review bring the idea about amount of the organic fractions can be recovery from coal low rank and if this can be applied in local industry, for the other hand, if this analytical process can indicate an economical application to organic fractions from low coal.
I didn´t found major problems and the references are all in the text. The Figures are clear. But if author can, I suggest put a legend in the abbreviations in the lines 98 - 100, and 110 - 112. The comprehension of the terms will easier.
Author Response
Point 1: The paper is very well written, including format text, figure, and tables. About references, I suggest that can be improved with other papers around of the world. Thus, the review will be extended globally.
Response 1: The format of the paper has been reworked to conform to the journal format.
Point 2: Another point is the method don't show how many repetitions are prepared and analysed (14 sample). This is very important to evaluate the z-score and normal distributions (sample more than 30 unities).
Response 2: The experimental coal samples are prepared in accordance with the national standard, and the samples are used for extraction .
Point 3: And last contribution I suggest that the review bring the idea about amount of the organic fractions can be recovery from coal low rank and if this can be applied in local industry, for the other hand, if this analytical process can indicate an economical application to organic fractions from low coal.
Response 3: Under the backgroud of low carbon utilization of coal, Main chemical problem for improve the comprehensive utilization efficiency of low-rank coals as chemical raw materials is to know the composition of organic matter in the coals. Our work could provide effective theoretical basis for clean and non-fuel use of low-rank coals.
Point 4: I didn't found major problems and the references are all in the text. The Figures are clear. But if author can, I suggest put a legend in the abbreviations in the lines 98- 100, and 110- 112. The comprehension of the terms will easier.
Response 4: Explanations have been added after the abbreviations in lines 103 - 105 and 118 - 125.
Reviewer 3 Report
The Authors investigated the roles of different organic solvents in extracting organic compounds from low-rank coals. They performed a series of sequential extraction tests and found out the best organic solvent for each organic compound presented in the low-rank coal. For example, the Authors suggested that carbon disulfide (CS2) can efficiently extract the aromatic hydrocarbon, but hexane and petroleum ether are good for extracting aliphatic hydrocarbons. The topic of this paper is relative to Applied Science Journal. However, the Reviewer would like to reject this paper for the following reasons,
A. The Reviewer had a major concern on the experimental design shown in this paper. The procedure of extraction shown in Fig. 1 suggests that the coal sample was extracted using seven organic solvents in a typical sequence, i.e., CS2 à hexane à…à THF and methanol, but the Authors did not provide any explanations why using this sequence. The sequence of organic solvents can have big impacts on the extraction performance, which can lead to different conclusions.
The Reviewer did not understand the rationale of conducting sequential extraction tests in this work. Theoretically, one should use a single solvent in each extraction test so that the performance of each solvent can be compared fairly because in this way there will be no synergistic effect between two or more organic solvents.
B. In the Materials and Methods section (Section 2), some important information is not provided. Where did the Authors obtain the chemicals used in this work? What is the grade of each chemical? The properties of as-received low-rank coal samples are missing, i.e., moisture content in the as-received sample. What is the dosage of organic solvent used in the extraction test?
C. The quality of figures presented in this paper is not high-enough. For example, Figs. 4 and 5 are not easy to read. The legend in Figs. 6 and 7 are too small to see.
D. In many places of this paper, the citation format is inappropriate. Usually only the last name of the author should be shown in the citation. For example, line 40, “Ju Caixia et al.” should be “Ju et al.”.
E. Many typos throughout the paper:
a. Line 115-116, spacing is not right. “g;A_ad” should be “g; A_ad”
b. CS2 should be CS_2
c. Line 168, “he could not”?
d. Line 184, “Holingole” should be “Huolinguole”
Author Response
Point 1: The Reviewer had a major concern on the experimental design shown in this paper. The procedure of extraction shown in Fig.1 suggests that the coal sample was extracted using seven organic solvents in a typical sequence, ie. CS2，hexane ... a THF and methanol, but the Authors did not provide any explanations why using this sequence. The sequence of organic solvents can have big impacts on the extraction performance, which can lead to different conclusions.
The Reviewer did not understand the rationale of conducting sequential extraction tests in this work. Theoretically. one should use a single solvent in each extraction test so that the performance of each solvent can be compared fairly because in this way there will be no synergistic effect between two or more organic solvents .
Response 1: Since there are multiple non-covalent interactions between coal molecules and a single solvent is often not effective in weakening several forces at the same time, so the coals were sequentially extracted with seven solvents with the aim of breaking these forces one by one under mild conditions.
This extraction sequence was chosen because 1. polarity of the solvents 2. the solvents are stable 3. the solvents have a low boiling point and can be recycled 4. the solvents are relatively common 5. the solvents have a good selective uptake of specific components of the coal and there are significant differences in solubility.
Point 2: In the Materials and Methods section (Section 2), some important information is not provided.Where did the Authors obtain the chemicals used in this work? What is the grade of each chemical? The properies of as-received low-rank coal samples are missing, ie. Moisture content in the as-recelved sample. What is the dosage of organic solvent used in the extraction test?
Response 2: The solvents are commercially available analytical pure reagents, all purchased from Sinopharm. Experimental coal samples were prepared by reduction in accordance with national standards and extracted and tested using this sample. With regard to coal analysis: ar is the received basis and ad is the air-dried basis. According to the national standard, coal samples are air dried for coal quality analysis, therefore the moisture of received coal samples is not measured. Each stage of extraction was repeatedly replaced with fresh reagents until the extract was colourless, and the combined filtrate was concentrated to 2~3mL using a rotary evaporator to obtain the extract of the stage, with 100mL of extraction solvent each time.
Point 3: The quality of figures presented in this paper is not high-enough. For example, Figs. 4 and 5 are not easy to read. The legend in Figs.6 and 7 are too small to see.
Response 3: In response to the small size of the text in the horizontal or vertical coordinates depicted in the image, the drawing has been redrawn to enlarge the text size. For Figure 5, a projection section has been added to project the individual data onto PC1, PC2 and PC3.
Point 4: In many places of this paper. the citation format is inappropriate. Usually only the last name of the author should be shown in the citation. For example, line 40, "Ju Caixia et al." should be "Ju et al."
Response 4: To address the issue of poor citation formatting, all citations have been changed to show only the author's surname.
Point 5: Many typos throughout the paper.
a.Line 115-116, spacing is not right. "g:A_ ad" should be "g;A_ ad"
b.CS2 should be CS_ 2
c.Line 168. "he could not ?
d.Line 184. "Holingole" should be "Huolinguole"
Response 5: Typographical errors in the article have been corrected, including the lowering of chemical formulae, grammatical errors, the inclusion of spaces after inverted commas and the English writing of names.
Reviewer 4 Report
It is of great importance to investigate the composition and structure of soluble organic compounds as well as organic macromolecules in coal. The authors systematically studied 14 groups of extracts and seven stages of solvent graded extraction. From this point of view, this manuscript is recommended to be considered for publication in the Journal.
Author Response
The reviewer did not suggest any comment.
Round 2
Reviewer 3 Report
The Reviewer appreciates the response from the Authors. The Reviewer also appreciates the explanation about the extraction sequence used in this work.
The Reviewer suggests publish this work after fixing the following typos,
Line 194: "he" should be "it"
Line 203: "Shen Fu" should be "Shenfu"
The name of second coal sample was not consistent in this paper. The Authors sometimes named it as "Honglinguole Coal", while sometimes naming it as "Khoringole coal".
Author Response
Point 1: The Reviewer suggests publish this work after fixing the following typos,
Line 194: "he" should be "it"
Line 203: "Shen Fu" should be "Shenfu"
The name of second coal sample was not consistent in this paper. The Authors sometimes named it as "Honglinguole Coal", while sometimes naming it as "Khoringole coal".
Response 1:
It has been amended for line 194
The name of Shenfu Coal has been revised in full
The name of Huolinguole coal has been unified in its entirety
