The Addition of Anthocyanin as a Sensitizer for TiO2 Nanotubes in a Combined Process of Electrocoagulation and Photocatalysis for Methylene Blue Removal
Round 1
Reviewer 1 Report
I don’t see much novelty as photocatalysis with TiO2 has been published in thousands of articles. Authors tried to use anthocyanin as sensitizer to add novelty in the work.
Still, I believe this manuscript is far from publication. However, it can be recommended if authors add more novelty in the work. Authors must also report the photocatalysis activity against Rhodamine B and methyl orange and compare the results obtained.
I don’t see much novelty as photocatalysis with TiO2 has been published in thousands of articles. Authors tried to use anthocyanin as sensitizer to add novelty in the work.
Still, I believe this manuscript is far from publication. However, it can be recommended if authors add more novelty in the work. Authors must also report the photocatalysis activity against Rhodamine B and methyl orange and compare the results obtained.
Author Response
Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corrections highlighted in the re-submitted files
Author Response File: 
Author Response.pdf
Reviewer 2 Report
My suggestion is a major revision.
1- Synthesis is very interesting. Add the synthesis schematic to the article.
2- The quality of SEM images is very bad. Add new images to the article.
3- What exactly is your research innovation?
4- Interpretations and mechanisms are very weak.
5- Compare your research results with similar articles in the table.
6- Try to add a graphical abstract of the Photocatalysis mechanism to the article.
Moderate editing of English language required
Author Response
Thank you for taking the time to read this manuscript. Please see the full comments and corrections highlighted in the re-submitted files below.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript focuses on the task of removing of the chromaticity of model dye solutions by the combined action of electrocoagulation and photocatalysis. Despite the progress made, the work is replete with inaccuracies and errors. In its current form, the paper is not suitable for Sustainability.
In their further work, the authors may additionally take into account the following comments.
1. Line 29. The gross formula is clearly not enough for paper, it is necessary to give the structural formula of both the Dye and the Sensitizer, too, and also inside Section 3 to find a place for a scheme of the alleged processes of destruction of the Dye and a visual scheme of electrocoagulation and adsorption of the Dye.
2. Line 31-32 “ Because of the presence of aromatic amines, such as aromatic nitro and other phenolic compounds in the MB structure, the MB is difficult to decompose [3], [5]. The authors do not distinguish between aromatic amines, nitro groups and phenols. These are different classes of organic compounds.
3. It is desirable to give the spectra of dye solutions to justify the choice of wavelength. How does the spectrum change depending on the pH?
4. The form of the references similar to that indicated in line 112 (and further in many places), is unacceptable.
5. Section 2.6. In what form were TiO2 nanotubes used? Did they remain on the plate, how were they synthesized, were they transferred to the reaction medium or in some other way? It is recommended to provide the scheme of the installation used.
6. CIP and other abbreviations must be decrypted.
7. Many figures are distorted and excessively elongated horizontally.
8. It is generally assumed that data in Tables should not duplicate data from Figures.
9. The word ”Waste” in the names of Sections 2.5 and 2.6 and in some other places is confusing and superfluous.
10. Figure 3c. There is no dimension scale, (b) and (d) are very pale, no details are visible.
11. Figure 4. The graphs do not differ from each other and do not carry any information in this sense; there are no peaks of S on any chart at all.
12. Inserts inside some drawings in this form are not appropriate here, it is better to separate them into separate figures. In some figures, explanatory inscriptions climb on dependency graphs.
13. The authors should clearly understand and explain that the resulting experiment involves two essentially independent processes associated with photoelectrocatalysis (which the authors want to improve with the help of an activator) and electrocoagulation followed by adsorption of the original dye. In this regard, It is would like to see a schematic representation of the research process carried out in the work. Section 3.7.1 has redundant calculations in the form of equations 1 and 2, it is enough to leave equation 3 to calculate the first - order kinetics, bring the rate constants in standard form and do not forget to specify the temperature at which the experiments were made.
14. Line 393. And here the formation of Fe(OH)2 ? After all, stainless steel was used as a cathode.
15. Line 397 – 400. Equation 7 is not clear, because there is no interpretation of the designation “CIP". These equations are applicable only for an alkaline medium.
16. Equation 11, what is “OH•atau O2• " ?
17. The composition of the products of electro- and photocatalytic effects has not been studied. Figure 16 as presented is not informative.
18. Sections related to electrochemistry and Section 3.9 are recommended to be shown to specialists after reworking.
19. In general, the costs of the total synthesis of titanium nanotubes and photocatalysis are high, and the yield does not exceed 65%.
Author Response
Thank you for taking the time to evaluate this manuscript and providing helpful feedback so that we can revise it to a better version. Please see the full comments and corrections highlighted in the re-submitted files below.
Author Response File: Author Response.pdf
Reviewer 4 Report
The study addresses an important environmental issue related to the treatment of textile industry wastewater containing hazardous dyes. However, there are a few areas that require clarification and further elaboration:
Sensitizer Selection and Characterization: The study mentions the addition of anthocyanin sensitizers to enhance the photocatalytic activity of TiO2 nanotubes. It would be helpful to provide more details regarding the selection criteria for anthocyanin sensitizers and the specific type of anthocyanin used in the experiment. Additionally, information about the characterization techniques employed to confirm the presence and effectiveness of the sensitizers on the TiO2 nanotubes would be valuable.
Mechanistic Insights: While the study demonstrates the enhanced MB removal efficiency through the combined process of electrocoagulation and photocatalysis with sensitized TiO2 nanotubes, it would be beneficial to discuss the underlying mechanisms responsible for this improvement. Providing mechanistic insights into the interaction between the anthocyanin sensitizers, TiO2 nanotubes, and MB molecules would enhance the understanding of the observed results.
Furthermore, I have a couple of questions regarding the research:
Did the study investigate the stability and recyclability of the sensitized TiO2 nanotubes? Considering the potential application of the combined process in practical wastewater treatment, it would be interesting to know if the sensitizers remained effective after multiple cycles of operation and if there were any changes in their performance over time.
Were any intermediate degradation products identified during the MB removal process? Since the degradation of MB can lead to the formation of intermediate compounds, it would be informative to determine the nature and toxicity of these by-products. Identification and characterization of these intermediates would contribute to the overall assessment of the combined process's environmental impact.
I believe addressing these points will strengthen the manuscript and provide a more comprehensive understanding of the research findings.
Author Response
Thank you for taking the time to evaluate this manuscript and providing helpful feedback so that we can revise it to a better version. Please see the full comments and corrections highlighted in the re-submitted files below.
Author Response File: Author Response.pdf
Reviewer 5 Report
1.In the introduction section ,some related work is missed.Compared with the related work"CHEMICAL ENGINEERING JOURNAL,2020,390 : 124522;SEPARATION AND PURIFICATION TECHNOLOGY ,2020, 235 :116270; the author should empahsis the noverty of the manuscript.
2.The mechnism of TiO2 nanotubes is insufficient.The authors should add more details.
3.In Fig 13,It can be concluded that an initial pH of 10 can lower the MB concentration to the quality standards in less time than initial pHs of 5 and 7.what is the reason？
Minor editing of English language required
Author Response
Thank you for taking the time to evaluate this manuscript and providing helpful feedback so that we can revise it to a better version. Please see the full comments and corrections highlighted in the re-submitted files below.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have incorporated all suggested corrections. Now, manuscript looks suitable for acceptance.
Author Response
Thank you so much
Reviewer 2 Report
Accept in present gorm
Minor editing
Author Response
Thank you so much
Reviewer 3 Report
6. CIP and other abbreviations must be decrypted.
This question is mostly unanswered. So what is it CIP?
10. Figure 6b the font should be enlarged so that the inscriptions are legible.
13. In equations 5 and 6, it is recommended to use subscripts correctly, confusion occurs in the current form.
15. Line 397 – 400. Equation 7 is not clear, because there is no interpretation of the designation “CIP". These equations are applicable only for an alkaline medium.
This question is mostly unanswered.
19. In general, the costs of the total synthesis of titanium nanotubes and photocatalysis are high, and the yield does not exceed 65%.
The authors proposed two files with the corrected manuscript, which have differences. Which is the correct one? On one of them: t is usually customary to use a different language for the text than the authors have given in these lines.
References of literature: it is required to give correct abbreviations of journal titles and produce DOI indexes for all references.
Author Response
Thank you for taking the time to evaluate this manuscript and providing helpful feedback so that we can revise it to a better version. Please see the full comments and corrections highlighted in the re-submitted files below.
Author Response File: Author Response.pdf
Reviewer 4 Report
The authors have addressed all the questions I proposed, I would recommend it be published.
Author Response
Thank you so much
Round 3
Reviewer 3 Report
Now the paper is polished and ready for acceptance. But I would like to draw attention to Comment 15. Since the measurements were carried out not only in an alkaline medium (and pH5 for example), it may be necessary to add equations for this medium. Or at least mention it. If this caused difficulties, it was recommended to contact specialists in electrochemistry for this. I leave the answer to the discretion of the authors.
