CO₂ Adsorption Reactions of Synthetic Calcium Aluminum Ferrite (CAF)

Round 1

Reviewer 1 Report

The author investigated a mechanism of carbonation reaction by CO₂ capture through the synthesis of ternary (CaO-Al₂O₃-Fe₂O₃) compounds and investigated the amount of CF and CA produced at sintering temperature 1,000 ℃ and 1,100 ℃, respectively. Although the article is written well, it could be difficult to accept in its current form as the article needs more characterization to prove the claims. My comments are mentioned below.

1.     The author reported the quantitative determination of calcium aluminum compounds from XRD analysis. It would be recommended to provide JCPDS file no about peak analysis.

2.     What about the crystallinity of the phase produced during different sintering temperatures (1,000 ℃ and 1,100 ℃) and how is its relevance to carbonation reaction?

3.     In the introduction, can it be possible to draw a reaction scheme between CO2 and ternary Ca-Al-based compound?

4.     It would be better to give space between ℃ and number.

5.     The author should mention TGA in place of DTA in section 3.2.1.

6.     Supplementary characterizations such as XPS, Raman, and EDS should be used to justify the compound produced during the sintering and carbonation reaction.

7.     The figures (especially 3 and 4) need to be revised and the fonts need to be the same as the text and should be visible.

8.     Refer few articles to revise your manuscript in better form (Minerals 2019, 9, 101; doi:10.3390/min9020101, ACS Appl. Mater. Interfaces 2017, 9, 11587−11598).

Author Response

Thank you very much for your kind review to complete this thesis. The contents of paper have been revised according to your comments, and as a papers for the examination of Woong-geol Lee's doctoral qualifications, I ask for your deep help so that this papers can be published as soon as possible.

Best regards,

 

 

Review 1.

1. The author reported the quantitative determination of calcium aluminum compounds from XRD analysis. It would be recommended to provide JCPDS file no about peak analysis. Done
2. What about the crystallinity of the phase produced during different sintering temperatures (1,000 ℃and 1,100 ℃) and how is its relevance to carbonation reaction?

Based on the cement clinker sintering temperature 1450℃, experiments were conducted for sintering temperatures of 900, 1000, and 1100℃. Unreacted raw materials in the calcined products at temperature of 900°C were present in a large amount, so it was excluded from carbo-reaction analyze.

The results of phase produced during different sintering temperatures (1,000 ℃ and 1,100 ℃) are shown in figure 2.  The results of carbonation reaction are shown in figure 5 and figure 6.

3. In the introduction, can it be possible to draw a reaction scheme between CO2 and ternary Ca-Al-based compound?

• 4CaO + Al₂O₃ → 4CaO·Al₂O₃ + CO₂ → Ca₄Al₂O₆CO₃
• 4CaO + Fe₂O₃ → 4CaO·Fe₂O₃ + CO₂ → Ca₄Fe₂O₆CO₃
• 4CaO + Al₂O₃ + Fe₂O₃ → 4CaO·Al₂O₃Fe₂O₃ + CO₂ → Ca₄Al₂Fe₂O₉·CO₃

4. It would be better to give space between ℃and number. Done
5. The author should mention TGA in place of DTA in section 3.2.1. Done
6. Supplementary characterizations such as XPS, Raman, and EDS should be used to justify the compound produced during the sintering and carbonation reaction.

In this study, these analyses were not performed. We will analyze them in next study related to this study.

7. The figures (especially 3 and 4) need to be revised and the fonts need to be the same as the text and should be visible. Done
8. Refer few articles to revise your manuscript in better form (Minerals 2019, 9, 101; doi:10.3390/min9020101, ACS Appl. Mater. Interfaces 2017, 9, 11587−11598). Done

Reviewer 2 Report

CO2 adsorption reactions of synthetic calcium alumino ferrite (CAF)
The manuscript focuses on the study of a mechanism of carbonation reaction by CO2 capture through synthesis of ternary (CaO-Al2O3-Fe2O3) compounds.
The work is interesting, however the paper needs significant improvement before being accepted for publication. In particular:
- Details of the considered technology are reported, however only a very quick mention of other possible technologies for separating carbon dioxide can be found. Considering the importance of the topic in the scientific and industrial sector and the relevance of traditional and innovative chemical absorption (for instance https://doi.org/10.1007/s11705-016-1555-5 and
https://doi.org/10.1016/j.cherd.2019.04.035), a section focusing on technologies for CO2  removal must be added in the introduction in the paper.
- The experimental procedure must be described with all details.
- The size of Figure 2, Figure 5 and Figure 6 with XRD patterns must be increased.
- Figure 3 is not easily readable.
- A careful reading of the manuscript is suggested, for instance some “.” are missing

Author Response

Thank you for your kindly review for this papers. The contents of papers have been revised according to your comments, and as a thesis for the examination of Woong-geol Lee's doctoral qualifications, I ask for your deep help so that this papers can be published as soon as possible.

Best regards,

 

Review 2

1. Details of the considered technology are reported, however only a very quick mention of other possible technologies for separating carbon dioxide can be found. Considering the importance of the topic in the scientific and industrial sector and the relevance of traditional and innovative chemical absorption (for instance https://doi.org/10.1007/s11705-016-1555-5 and
   https://doi.org/10.1016/j.cherd.2019.04.035), a section focusing on technologies for CO₂removal must be added in the introduction in the paper.

This study is a study on carbon dioxide adsorption in cement-based materials, which emits large amounts of carbon dioxide. This is a study of cement-based materials for carbon dioxide adsorption by a mechanism different from carbon dioxide adsorption by conventional amine compounds.

2. The experimental procedure must be described with all details.

The experimental progress was explained in detail through pictures and explanations. Please let me know if there is anything that needs further explanation.

3. The size of Figure 2, Figure 5 and Figure 6 with XRD patterns must be increased. Done
4. Figure 3 is not easily readable. Done
5. A careful reading of the manuscript is suggested, for instance some “.” are missing Done

Round 2

Reviewer 1 Report

Figure 3. DTA carves of carbonation with a) dry method and b) wet method. (It should change to curve)

According to Equation 1, Possible reactions (Please lowercase P)

of CF-based compounds was 57.1wt.%, 5.2wt.%, respectively. (Please provide gap on number and wt%)

Figure 1 Calcite generation based on reaction time (Change figure number, check the font)

The article looks fine to me and can be acceptable in revised form.

Author Response

Thank you for the reviewer's heartfelt advice.

I learned a lot and the completion of the thesis improved.

Thank you so much again.

 

1. Figure 3. DTA carves of carbonation with a) dry method and b) wet method. (It should change to curve)

Change DTA to TGA and change to curve

2. According to Equation 1, Possible reactions (Please lowercase P)

Change to the lowercase P

3. of CF-based compounds was 57.1wt.%, 5.2wt.%, respectively. (Please provide gap on number and wt%)

Change gap on number and wt% for all units. Also °C.

Provide JCPDS file no about peak analysis

4. Figure 1 Calcite generation based on reaction time (Change figure number, check the font)

Check the font and figure number.

Author Response File: Author Response.docx