Effect of Photocatalyst on Rheological Behavior and NO Degradation Capacity of Asphalt Binder
, Yanhui Niu 1,2,*, Huiyun Xia 1,2 and Yue Wang 1,2Round 1
Reviewer 1 Report
Report on the manuscript catalysts-2461719 entitled “Effect of Photocatalyst on Rheological Behavior and NO degradation Capacity of Asphalt Binder”.
The submitted manuscript should be revised. The following points should be addressed:
1. The language of the manuscript should be revised.
2. The discussion of figure 2 (SEM morphology) has strange statement: “sample exhibits a well-dispersed lamellar morphology, high surface area, mesoporous structure, and crystallinity”, how the authors know the crystallinity from SEM.
3. References for the absorption peaks of the sulfoxide (suggested one: Inorganic Chemistry Communications
Volume 148, February 2023, 110320) and carbonyl (suggested one: Chemical Engineering Journal, Volume 304, 2016, Pages 48-60) and C-H vibrational absorption peak (suggested one: Journal of Molecular Liquids, 345, 2022, 118249) and other FT-IR absorption peaks.
4. “No new characteristic absorption peaks were generated. This proved that adding nano-TiO2 and g-C3N4 into BA was only a physical modification process” Even it physical modification, the bonds of Ti-O should be appeared in FT-IR.
5. Could the authors identify the reaction order of NO degradation effect of photocatalytic asphalt binders to understand its mechanism which should be clear.
6. figure 10 title should be clearer.
The language of the manuscript should be revised.
Author Response
Thanks for your comments on our manuscript entitled " Effect of Photocatalyst on Rheological Behavior and NO Degradation Capacity of Asphalt Binder ". Those comments are very helpful for revising and improving our paper, as well as the important guiding significance to our other research work. We have studied the comments carefully and made revisions which are marked in yellow on the paper. We have tried our best to revise our manuscript according to the comments. The revisions are in the manuscript and the responses to the reviewers’ comments are as follows (the replies are highlighted in blue).
- The language of the manuscript should be revised.
Reply: Thank you for bringing this to our attention. We apologize for the oversight in our manuscript. We have carefully revised the language of our manuscript. In the future, we will take extra care to ensure that our papers are thoroughly reviewed before submission.
- The discussion of figure 2 (SEM morphology) has strange statement: “sample exhibits a well-dispersed lamellar morphology, high surface area, mesoporous structure, and crystallinity”, how the authors know the crystallinity from SEM.
Reply: Thanks very much for your comment! We apologize for the mistakes created by the discussion of SEM morphology here. We have revised the statement of morphology analysis of SEM. As we moved ‘Results and discussion’ before ‘Experimental part’ during revision, so Figure 2 were renamed as Figure 18.
- References for the absorption peaks of the sulfoxide (suggested one: Inorganic Chemistry Communications Volume 148, February 2023, 110320) and carbonyl (suggested one: Chemical Engineering Journal, Volume 304, 2016, Pages 48-60) and C-H vibrational absorption peak (suggested one: Journal of Molecular Liquids, 345, 2022, 118249) and other FT-IR absorption peaks.
Reply: We would like to thank you for the suggestion. We have carefully read the articles that reviewer suggested, which were so related to our articles. Thus, we added these articles to our references (Line 378-Line 371). Thank you again for such valuable comments!
- “No new characteristic absorption peaks were generated. This proved that adding nano-TiO2 and g-C3N4 into BA was only a physical modification process” Even it physical modification, the bonds of Ti-O should be appeared in FT-IR.
Reply: Thanks very much for your comment. We apologize for the mistakes created by the improper handling during the FTIR test, which caused the bond of Ti-O didn’t presented. For this, we have prepared three more nano-TiO2 modified asphalt binder samples to observe their FTIR spectra. Fortunately, we have found the bonding Ti-O peak at 483 cm-1 for three samples this time. We have corrected these spectra and related presentation in our article. (Figure 1- Figure 3).
- Could the authors identify the reaction order of NO degradation effect of photocatalytic asphalt binders to understand its mechanism which should be clear.
Reply: Thanks very much for your valuable comment. According to your suggestion, we have calculated the catalytic rates by the slope of NO2 concentration ratio curve. We have presented and discussed them in our article. (Figure 14, Figure 15)
- Figure 10 title should be clearer.
Reply: Thanks very much for your comment! We are sorry for the ambiguity caused by the unclear expressions here. We have made clearer adjustment to Figure 10 title. As we moved ‘Results and discussion’ before ‘Experimental part’ during revision, so Figure 10 were renamed as Figure 7.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This work aims to evaluate the rheological properties and the air cleaning capability of asphalt binder using g-C3N4 and TiO2. It is well written needing some adjustments:
The literature review could be improved regarding the results of air cleaning using photocatalytic asphalt.
What was the band gap value of the TiO2 used? Please, present it.
Why 5 h of RTFOT and 20 h for PAV? Any reason or reference for this?
Please, present the FTIR after RTFOT before PAV and discuss it.
Usually, in these spectra, there is the peak related to the particles. For the bonding metal-O, this is presented around 500 cm-1. Why didn't this peak appear?
The authors discuss about the catalytic rates but did not present the reaction rates. Please calculate, present and discuss them.
What was the amount of NOx removed in ppb?
I expected to see the NO2 concentration ratio for the sample without photocatalysts.
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Author Response
Dear reviewers:
Thanks for your comments on our manuscript entitled " Effect of Photocatalyst on Rheological Behavior and NO Degradation Capacity of Asphalt Binder ". Those comments are very helpful for revising and improving our paper, as well as the important guiding significance to our other research work. We have studied the comments carefully and made revisions which are marked in yellow on the paper. We have tried our best to revise our manuscript according to the comments. The revisions are in the manuscript and the responses to the reviewers’ comments are as follows (the replies are highlighted in blue).
1.The literature review could be improved regarding the results of air cleaning using photocatalytic asphalt.
Reply: We appreciate the reviewer's insightful comment regarding our literature review! We have widely concluded the recent research results about photocatalytic asphalt materials. Based on this, we have improved the literature review considering the results of air cleaning using photocatalytic asphalt.
2.What was the band gap value of the TiO2 used? Please, present it.
Reply: Thanks very much for your comment. The anatase TiO2 was provided by Shanghai Jianghu Industrial Company, which had band gap value of 3.2 eV. We have presented it in Table 2.
3.Why 5 h of RTFOT and 20 h for PAV? Any reason or reference for this? Please, present the FTIR after RTFOT before PAV and discuss it.
Reply: Thank you for bringing this to our attention. We apologize for the ambiguity caused by the lack of clarity of expression here. According to American Society of Testing Materials (ASTM) D1754, 5 h of RTFOT and 20 h for PAV are the standard requirements. The RTFOT method indicates approximate change in properties of asphalt during conventional hot-mixing at about 150°C as indicated by viscosity, penetration, or ductility measurements. The aim of PAV method is to simulate the oxidative ageing of asphalt during road use and to evaluate the oxidative ageing capacity of different asphalts under test temperature and pressure conditions.
We have presented the FTIR after RTFOT before PAV and discussed it in our article. (Figure 2)
4.Usually, in these spectra, there is the peak related to the particles. For the bonding metal-O, this is presented around 500 cm-1. Why didn't this peak appear?
Reply: We would like to thank you for the valuable suggestion! We apologize for the mistakes created by the improper handling during the FTIR test, which caused the bonding metal-O didn’t presented around 500 cm-1. For this, we have prepared three more nano-TiO2 modified asphalt binder samples to observe their FTIR spectra. Fortunately, we have found the bonding Ti-O peak at 483 cm-1 for three samples this time.
We have corrected these spectra and related presentation in our article. (Figure 1- Figure 3)
5.The authors discuss about the catalytic rates but did not present the reaction rates. Please calculate, present and discuss them.
Reply: Thanks for your thought-provoking comments! According to your suggestion, we have calculated the catalytic rates by the slope of NO2 concentration ratio curve. We have presented and discussed them in our article. (Figure 14)
6.What was the amount of NOx removed in ppb?
Reply: Thanks very much for your comment! According to earlier research results, the initial NO concentration reached dynamic equilibrium at around 500 ppb before the photocatalytic reaction started. We controlled the standard air flow rate of 2.4 L/min and standard NO flow rate of 15 mL/min (concentration of 125 mg/m³), the NO concentration in the mixed gas was approximately 625 µg/m³. The amount of NOx removed was then recorded and calculated as in equation (6). (Line 448)
7.I expected to see the NO2 concentration ratio for the sample without photocatalysts.
Reply: Thanks very much for your comment. Asphalt binder samples without photocatalysts did not exhibit the ability to degrade NO2, thus showed zero NO2 concentration ratio. We have added the NO2 concentration ratio for the sample without photocatalysts in Figure 13.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
It could be accepted.
