Combined Adsorption and Photocatalytic Degradation for Ciprofloxacin Removal Using Sugarcane Bagasse/N,S-TiO₂ Powder Composite

Round 1

Reviewer 1 Report

1. The title should be revised. Replace the word antibiotic with the name of the antibiotic. What is power composite?

 

2. The abstract is poorly written, mainly there is no consistency in using different terminologies, for example, “scanning electron microscopy, X- ray diffractometry, infrared spectrometer analysis and photoluminescence spectra”. Quantitative information regarding the affecting parameters should be provided.

Introduction

3. Line 30, due to.

 

4. The introduction needs substantial improvement. It should give a piece of brief information on all the technologies used for water treatment before declaring photocatalytic oxidation as most promising. The adsorption technology, its popularity, and its limitations should be described. It should include basic information on ciprofloxacin and its uses.

 

5. Since authors describe that it has been detected at mg/L in Asian countries, they should provide some quantitative values. In my opinion, the authors should start the introduction by describing ciprofloxacin and then its water pollution. In short, they must establish a sequence and flow between the different components of the introduction.

 

Section 2.1 Chemicals

6. Tetraisopropyl orthotitanate (C12H28O4Ti); thiourea (CH4N2S); ethanol 99% (C2H5OH); nitric acid 65% (HNO3); hydrochloric acid (HCl); sodium hydroxide (NaOH); Please mention from where these chemicals were purchased because analytical grade may not be applicable to all these.

Section 2.2. Preparation materials

7. An appropriate amount was added is not enough; please mention the actual amounts.

 

8. How can you name nitric acid-treated sugarcane bagasse as “alkaline treated sugarcane bagasse”? This mistake is throughout the manuscript.

 

 

9. “All experiments were performed with 250 rpm stirring and at room temperature.” What does it mean when all the samples were dried using ovens?

Section 2.3. Characterization of materials

10. This section needs language correction

Section 2.4. Experimental approach

11. What is the novelty of this work compared to reference [20], when all the synthesis, experimental designed is followed from that work?

 

12. “100 mL CIP solution”, what was the concentration?

 

 

13. “absorption-desorption”, why absorption?

 

Section 3.1. Characterization of materials

 

14. Error! Reference source not found, what is this, as it has been appeared several times throughout the manuscript.

XRD

15. Acid and alkaline treatment does not affect the XRD of the composite; please elaborate in more detail.

SEM

16. SEM images with higher resolution should be shown; there is no point in showing SEM images of 10 µm when nanocomposites have been synthesized.

Photoluminescence

17. Why PL intensity is lowest for ASB/N,S-TiO2 compared to other composites. After calcination, all composites are converted to biochar, so this only explanation is not enough.

Section 3.2. Elimination of CIP

18. “This suggests that the antibiotic adsorption efficiency increased due to the presence of sugarcane bagasse.” This is Incorrect because composites other than ASB/N,S-TiO2 have sugarcane bagasse.

 

19. The description of experiments is not clear. For the optimization, the adsorption and photodegradation experiments were done in combination, or the only adsorption was performed. The design of the experiments needs a clear presentation throughout the manuscript. Partial information is provided in most of the instances.

 

 

20. What was the optimum dosage from these experiments?

 

21. What were the optimum conditions for all the parameters?
22. UV/Vis spectra of CIP should be shown before the treatment and after treating under the optimum conditions.
23. 
    Was this approach tested for real polluted water samples?

Author Response

Response to Reviewer 1 Comments

 

Old subject: Combined adsorption and photocatalytic degradation for antibiotic removal using sugarcane bagasse/N,S-TiO₂ power composite

New subject: Combined adsorption and photocatalytic degradation for ciprofloxacin removal using sugarcane bagasse/N,S-TiO₂ powder composite

Code: water-1338126

We thank the editors and reviewers for taking the time to consider our work. Here, we have carefully reviewed the comments and have addressed point-by-point responses to the reviewer’s comments. Parts of the manuscript have been modified and highlighted by the Track Changes command in response to the reviewers’ suggestions and comments. We trust that our responses are satisfactory to you and that it is now suitable for publication in the Water.

 

 

Point 1: The title should be revised. Replace the word antibiotic with the name of the antibiotic. What is power composite?

 

Response 1: Thank you for your kind suggestion. The new title is: “Combined adsorption and photocatalytic degradation for ciprofloxacin removal using sugarcane bagasse/N,S-TiO₂ powder composite”.

 

Point 2: The abstract is poorly written, mainly there is no consistency in using different terminologies, for example, “scanning electron microscopy, X- ray diffractometry, infrared spectrometer analysis and photoluminescence spectra”. Quantitative information regarding the affecting parameters should be provided

 

Response 2: The abstract was edited.

 

Introduction

 

Point 3: Line 30, due to.

 

Response 3: This sentence was corrected: “…due to their well-known properties…”

 

Point 4: The introduction needs substantial improvement. It should give a piece of brief information on all the technologies used for water treatment before declaring photocatalytic oxidation as most promising. The adsorption technology, its popularity, and its limitations should be described. It should include basic information on ciprofloxacin and its uses.

 

Response 4: This was made in the first paragraph of the introduction.

 

Point 5: Since authors describe that it has been detected at mg/L in Asian countries, they should provide some quantitative values. In my opinion, the authors should start the introduction by describing ciprofloxacin and then its water pollution. In short, they must establish a sequence and flow between the different components of the introduction.

 

Response 5: The brief introduction of ciprofloxacin and its water pollution was added (line 63-69)

 

Section 2.1 Chemicals

 

Point 6: Tetraisopropyl orthotitanate (C12H28O4Ti); thiourea (CH4N2S); ethanol 99% (C2H5OH); nitric acid 65% (HNO3); hydrochloric acid (HCl); sodium hydroxide (NaOH); Please mention from where these chemicals were purchased because analytical grade may not be applicable to all these.

 

Response 6: From the first manuscript they were mentioned and purchased from Sigma – Aldrich

 

Section 2.2. Preparation materials

Point 7: An appropriate amount was added is not enough; please mention the actual amounts

 

Response 7: The actual amounts (10g) was added

 

Point 8: How can you name nitric acid-treated sugarcane bagasse as “alkaline treated sugarcane bagasse”? This mistake is throughout the manuscript

 

Response 8: Thank you so much. This part was re-written (section 2.2.1)

 

Point 9: “All experiments were performed with 250 rpm stirring and at room temperature.” What does it mean when all the samples were dried using ovens?

 

Response 9: This sentence has been removed.

 

Section 2.3. Characterization of materials

 

Point 10: This section needs language correction

 

Response 10: This section was edited

 

Section 2.4. Experimental approach

 

Point 11: What is the novelty of this work compared to reference [20], when all the synthesis, experimental designed is followed from that work?

 

Response 11: In our previous work, N,S co-doped TiO₂ was synthesized and investigated for photocatalytic degradation of CIP, in comparison to synthesized TiO₂ and commercial TiO₂ (P25 Degussa). In this manuscript, sugarcane bagasse has been successfully used as support and as adsorbent enhancing the photo-efficiency of N,S-TiO₂ in applications of photocatalytic degradation of CIP in aqueous solution. In addition, it also shows that the pre-treatment of supported material affects the removal performance of CIP of material composite.

 

Point 12:  “100 mL CIP solution”, what was the concentration?

 

Response 12: It is not specifically mentioned due to the CIP concentration range of 5-50ppm being evaluated. The conditions of each experiment were noted below the graphs in section 3.2. We hope you will agree with our designed experiments.

 

Point 13:  “absorption-desorption”, why absorption?

 

Response 13: It was corrected “adsorption-desorption”

 

Section 3.1. Characterization of materials

 

Point 14: Error! Reference source not found, what is this, as it has been appeared several times throughout the manuscript.

 

Response 14: We apologize for this inconvenience. Our draft does not show this error, I will contact the assistant editor to correct it.

 

XRD

 

Point 15: Acid and alkaline treatment does not affect the XRD of the composite; please elaborate in more detail.

 

Response 15: RSB/N,S-TiO₂, ASB/N,S-TiO₂ and CSB/N,S-TiO₂ had a similar XRD pattern, leading to the pre-treatments of sugarcane bagasse did not change the crystal structure of the photocatalyst (line 142-144)

 

SEM

 

Point 16: SEM images with higher resolution should be shown; there is no point in showing SEM images of 10 µm when nanocomposites have been synthesized.

 

Response 16: Due to Covid, the laboratory was closed, resulting in SEM images with higher resolution could not carry out. This part was also edited.

 

Photoluminescence

 

Point 17: Why PL intensity is lowest for ASB/N,S-TiO2 compared to other composites. After calcination, all composites are converted to biochar, so this only explanation is not enough.

 

Response 17: This was changed: “The alkaline pre-treated sugarcane bagasse may strengthen the activated state of photocatalyst since vacant d orbitals of metals present in biochar act as electron acceptors that prevent recombination of e^-/h pairs.” (line 189-190)

 

Section 3.2. Elimination of CIP

 

Point 18: “This suggests that the antibiotic adsorption efficiency increased due to the presence of sugarcane bagasse.” This is Incorrect because composites other than ASB/N,S-TiO2 have sugarcane bagasse.

 

Response 18: This was changed: “This suggests that N,S-TiO₂ incorporation with alkaline pre-treated sugarcane bagasse improved the antibiotic adsorption capacity” (line 204-205)

 

Point 19: The description of experiments is not clear. For the optimization, the adsorption and photodegradation experiments were done in combination, or the only adsorption was performed. The design of the experiments needs a clear presentation throughout the manuscript. Partial information is provided in most of the instances.

 

Response 19: The design of the experiments was mentioned in section 2.4

 

Point 20: What was the optimum dosage from these experiments?

 

Response 20: 0.5 gL^-1 was the optimum dosage, and this was added.

 

Point 21: What were the optimum conditions for all the parameters?

 

Response 21: The optimum conditions were contact time 150-minute irradiation, pH 5.5-6, dosage 0.5 gL^-1 and the initial concentration CIP 30 ppm. This was also added in the abstract.

 

Point 22: UV/Vis spectra of CIP should be shown before the treatment and after treating under the optimum conditions.

 

Point 23: Was this approach tested for real polluted water samples?

 

Response 22 and 23: Due to Covid, the laboratory was closed, leading to those experiments could not carry out.

 

 

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript demonstrates a synthesis of sugarcane bagasse/N,S-TiO2 composite for photocatalytic degradation of antibiotics. It could be accepted for publication after a major revision.

1. In Line 17-19, errors in this sentence should be corrected because it is too elusive to be understood.
2. In the introduction part,  other AOPs, such as Fenton reaction (Applied Catalysis B: Environmental, 2021, 286, 119859) and catalytic ozonation (Chemical Engineering Journal, 2021, 404, 127075; Applied Catalysis B: Environmental, 2019, 251: 66-75) should be discussed to highlight the advantages of the photocatalytic oxidation process. 
3. The subtitle in part 2.2 (Line 73, 86) needs corresponding numbers. Similarly, subtitles in part 3.1 and others should be more specific and numbered.
4. EDS should be performed to verify the presence of N, S, Ti, O, and C elements.
5. In Figure 3, peaks in the FT-IR spectra should be assigned and marked accordingly.
6. Is there any residue pollutant in the adsorbed photocatalyst? The adsorption rate should be much faster than the photocatalysis reaction on the surface of the catalyst.
7. Line 115, reference was not found here.
8. English should be improved.

Author Response

Response to Reviewer 2 Comments

 

Old subject: Combined adsorption and photocatalytic degradation for antibiotic removal using sugarcane bagasse/N,S-TiO₂ power composite

New subject: Combined adsorption and photocatalytic degradation for ciprofloxacin antibiotic removal using sugarcane bagasse/N,S-TiO₂ powder composite

Code: water-1338126

We thank the editors and reviewers for taking the time to consider our work. Here, we have carefully reviewed the comments and have addressed point-by-point responses to the reviewer’s comments. Parts of the manuscript have been modified and highlighted by the Track Changes command in response to the reviewers’ suggestions and comments. We trust that our responses are satisfactory to you and that it is now suitable for publication in the Water.

 

Point 1: In Line 17-19, errors in this sentence should be corrected because it is too elusive to be understood.

 

Response 1: That sentence has been edited as follows: “The highest efficiency was observed for the alkaline pre-treated sugarcane bagasse combined with N,S-TiO₂, about 86% compared to other materials under optimal conditions”

 

Point 2: In the introduction part, other AOPs, such as Fenton reaction (Applied Catalysis B: Environmental, 2021, 286, 119859) and catalytic ozonation (Chemical Engineering Journal, 2021, 404, 127075; Applied Catalysis B: Environmental, 2019, 251: 66-75) should be discussed to highlight the advantages of the photocatalytic oxidation process. 

 

Response 2: This was made in the first paragraph (line 36-39) of the introduction.

 

Point 3: The subtitle in part 2.2 (Line 73, 86) needs corresponding numbers. Similarly, subtitles in part 3.1 and others should be more specific and numbered.

 

Response 3: Subsections in sections 2.2; 3.1 and 3.2 have been numbered.

 

Point 4: EDS should be performed to verify the presence of N, S, Ti, O, and C elements.

 

Response 4: Thank you for your kind suggestion. Due to Covid, the laboratory was closed, leading to this analysis could not carry out.

 

Point 5: In Figure 3, peaks in the FT-IR spectra should be assigned and marked accordingly.

 

Response 5: Some important peaks were made in Figure 3

 

Point 6: Is there any residue pollutant in the adsorbed photocatalyst? The adsorption rate should be much faster than the photocatalysis reaction on the surface of the catalyst.

 

Response 6: Due to Covid, the laboratory was closed, leading to this statement could not be tested. However, CIP removal efficiency of the composite material after 3 times is only reduced by 10%, which can be proved that it is durable and stable. We hope you will agree.

 

Point 7: Line 115, reference was not found here

 

Response 7: Line 115: “In Figure 1, XRD analysis was performed to characterize the nitrogen and sulfur co-doped TiO₂ and sugarcane bagasse/N,S-TiO₂ composite” which does not mention any references at all.

 

Point 8: English should be improved

 

Response 8: Thank you for your kind suggestion. The manuscript has been improved.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Authors should provide high-resolution SEM images that really indicate the formation of desired nanocomposites.

Authors should also demonstrate the applicability of their material for the removal of selected antibiotics from real wastewater. This is a very simple experiment. 

 

 

Author Response

Response to Reviewer 1 Comments

 

Title: Combined adsorption and photocatalytic degradation for ciprofloxacin removal using sugarcane bagasse/N,S-TiO₂ powder composite

Code: water-1338126

We thank the editors and reviewers for taking the time to consider our work. Here, we have carefully reviewed the comments and have addressed point-by-point responses to the reviewer’s comments. Parts of the manuscript have been modified and highlighted by the Track Changes command in response to the reviewers’ suggestions and comments. We trust that our responses are satisfactory to you and that it is now suitable for publication in the Water.

 

 

English language and style: English language and style are fine/minor spell check required

 

Response: The last manuscript has been checked.

Point 1: Authors should provide high-resolution SEM images that really indicate the formation of desired nanocomposites.

Point 2: Authors should also demonstrate the applicability of their material for the removal of selected antibiotics from real wastewater. This is a very simple experiment. 

 

Response 1 and 2: Thank you for your kind suggestions. Due to Covid, the laboratory is closed, no one is allowed access to the lab so that SEM images with higher resolution could not be obtained and those experiments currently cannot be carried out. We hope you will agree with our designed experiments.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

All my concerns have been well addressed and the current version of this manuscript was significantly improved. Therefore, it could be accepted for publication in Water.

Author Response

Response to Reviewer 2 Comments

 

Title: Combined adsorption and photocatalytic degradation for ciprofloxacin antibiotic removal using sugarcane bagasse/N,S-TiO₂ powder composite

Code: water-1338126

We thank the editors and reviewers for taking the time to consider our work. Here, we have carefully reviewed the comments and have addressed point-by-point responses to the reviewer’s comments. Parts of the manuscript have been modified and highlighted by the Track Changes command in response to the reviewers’ suggestions and comments. We trust that our responses are satisfactory to you and that it is now suitable for publication in the Water.

 

 

English language and style: English language and style are fine/minor spell check required

 

Response: The last manuscript has been checked.

 

 

Author Response File: Author Response.docx

Round 3

Reviewer 1 Report

Since I received the same response twice. I have suggested accepting the paper.