Review Reports - Parabens and Methylisotiazolinone (MIT): Preservatives with Different Behaviors When Subjected to Ozone and Ultraviolet Light Treatments

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

This paper reports the degradation of 102 parabens, MIT, and mixtures of both by UVC (254 nm) light treatment, ozone treatment 103 or a combination of both processes, which is an interesting development but the reviewer identifies some moderate issues to attend to, as follows:

1) please, describe the mechanism of degradation and interaction among the species and the treatments applied. here, a figure can be developed.

2) Interesting to see any degradation; however, as reactive species, some are degraded but some others are generated as part of chemical reactions, therefore, authors need to give further feedback on this matter.

3) Are there any other potential advanced processes (e.g. hydrodynamic cavitation) for the degradation of these compounds? please read and give feedback accordingly:

The role of hydrodynamic cavitation in tuning physicochemical properties of food items: A comprehensive review

Cavitation based cleaner technologies for biodiesel production and processing of hydrocarbon streams: A perspective on key fundamentals, missing process data and economic feasibility – A review

4) Please, give the perspectives of this work

Author Response

Reviewer 1

Comments and Suggestions for Authors

This paper reports the degradation of parabens, MIT, and mixtures of both by UVC (254 nm) light treatment, ozone treatment or a combination of both processes, which is an interesting development but the reviewer identifies some moderate issues to attend to, as follows:

The authors would like to thank the Reviewers for their useful and constructive comments and the Editor for giving us the chance to revise the manuscript. The replies are given in blue in the following paragraphs and the corresponding changes in the revised manuscript can be checked as changes marked.

1) please, describe the mechanism of degradation and interaction among the species and the treatments applied here, a figure can be developed.

We would like to thank the referee for the suggestion. He is right that in these treatments where different reactive species are involved, it is interesting to clarify which species are responsible for the degradation of the pollutants in each treatment. A figure has been added to clarify this: Figure 3. Schematic description of the main mechanisms or reactive species involved in the three processes applied (UV, O₃ and O₃+UV) at the different pH tested (3, 5 and 9).

The referee is right. As mentioned in the previous answer and in the new figure provided, depending on the treatment applied, different reactive species are generated. The transformation of the different reactive species has been previously described in the literature, for this reason we have not gone into this discussion in this paper. However, it is interesting to note that there are different reactive species in these treatments and a sentence has been added in the paper after the referee's suggestion. See L 107-114

3) Are there any other potential advanced processes (e.g. hydrodynamic cavitation) for the degradation of these compounds? please read and give feedback accordingly:

The role of hydrodynamic cavitation in tuning physicochemical properties of food items: A comprehensive review

Cavitation based cleaner technologies for biodiesel production and processing of hydrocarbon streams: A perspective on key fundamentals, missing process data and economic feasibility – A review

We would like to thank the reviewer for the suggestion to complete the review of the state of the art. A paragraph has now been added to include the suggested papers on cavitation studies and the 2 suggested references have been added [21-22] . See L.71-74

4) Please, give the perspectives of this work

The reviewer is right, it is interesting to conclude an article by clarifying the perspectives of the work. In the conclusion section, the authors state "further studies on the treatment of mixed contaminants are necessary to select the most suitable effluent treatment for cases involving both types of contaminants". A sentence has now been added to further clarify these perspectives: “Interactions between reactive species and some contaminants are capable of modifying the degradation of other compounds. The degradation of pollutants by different degradation techniques in isolation and in mixtures with other pollutants will be further investigated”. See L.622-625

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

The manuscript submitted for review concerns the neutralization of some sewage pollutants that also hinder the work of biological treatment plants, which are preservatives used in the cosmetics and food industries.

The authors used three "green" methods: UVC and ozonation (O3), discovering the synergy of UVC and O3 in relation to parabens, as well as hindering this process by the simultaneous presence of methylisothiazolinone (MIT). Well-designed experiments were conducted and their effects were properly explained, with two caveats.

The first concerns the lack of representation of the full UV spectra of these compounds, or even molar extinction coefficients at 254 nm, because the discussion of MIT's obstruction of complex degradation is devoid of valid evidence.

The second concerns the fact that parabens are esters and in an aqueous alkaline environment as such should be split into an acid salt and a suitable alcohol. Some of the measurements were made in an environment with pH 9. A mention should be made on this subject, because it cannot be ruled out that under these conditions the double salt of p-hydroxybenzoic acid was destroyed each time, and not any of the parabens.

I used the word "green" in the review because the proposed methods require significant amounts of electricity, which should also be "green".

I do not deny the veracity of the explanation, but both additional information should be included in the text, then I wholeheartedly recommend printing it.

Author Response

Reviewer 2:

We would like to thank the reviewer for the suggestion. Full UV spectra have been carried out for all compounds separately and for the mixture of all of them. A table with the molar extinction coefficients has been included in the text (Table 3) and the figure of the spectra is added as supplementary information (Figure S2).

Thanks to the referee for his comment. He is right, normally esters at basic pH could undergo hydrolysis of the ester group generating the corresponding acid and alcohol. However, in this case, we have checked, doing parallel experiments, leaving the mixture at basic pH without ozone or UV light treatment and have not observed any apparent decrease in the concentration of any paraben. In a previous paper [16], where we treated this same mixture of parabens by photo-Fenton process, we also checked the photolysis of this solution with sunlight, and no degradation of any compound was observed (see first paragraph of Results and discussion in Catalysts, 2022, 12, 1390). See L. 199-202.

I used the word "green" in the review because the proposed methods require significant amounts of electricity, which should also be "green".

I do not deny the veracity of the explanation, but both additional information should be included in the text, then I wholeheartedly recommend printing it.

We would like to thank the referee for his suggestion. We agree with him that these methods consume a large amount of energy and that it should be noted that nowadays this energy can be obtained from renewable sources that make these processes "greener" and can compete with other green technologies. A sentence has been added at the end of the introduction section (L. 117-119) clarifying this aspect.

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

The paper is well written and designed but might need to be revised quickly for minor English editing. All the best!

Comments on the Quality of English Language

The paper is well written and designed but might need to be revised quickly for minor English editing. All the best!

Author Response

The paper is well written and designed but might need to be revised quickly for minor English editing. All the best!

The authors would like to thank the Reviewers for their useful and constructive comments and the Editor for giving us the chance to revise the manuscript. The replies are given in blue in the following paragraphs and the corresponding changes in the revised manuscript can be checked as changes marked.
Following the indications of the reviewer, we have revised the English of the manuscript and eliminated as many errors as we have detected.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

The paper is ready for acceptance. It has enough quality to be published!

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript reports the description of a study carried out on additives subjected to treatments to check their degradability.

The research is very interesting and deals with a topical subject that is of practical relevance.

The parts of the text are all well written and in harmony with each other.

The introduction explains the scenario and previous research very clearly.

The methodology applied appears consistent with what has been applied in similar studies.

The manuscript therefore appears ready for publication, however it would be appropriate to clearly indicate the number of repetitions with which each value was obtained.

Figures 2 and 4 show histograms, which I imagine are the average values of several repetitions.

It would then be necessary to indicate the number of repetitions by which the values were achieved. Then it would be correct to indicate whether statistical tests were carried out to check the significant difference between the trials. Furthermore, it would be good to express the results with the variability obtained in the results, for example with the standard deviation or standard error.

Otherwise, the manuscript and the research reported are admirable and I congratulate the authors.

Author Response

Reviewer 1

The manuscript reports the description of a study carried out on additives subjected to treatments to check their degradability. The research is very interesting and deals with a topical subject that is of practical relevance. The parts of the text are all well written and in harmony with each other. The introduction explains the scenario and previous research very clearly. The methodology applied appears consistent with what has been applied in similar studies.

The manuscript therefore appears ready for publication, however it would be appropriate to clearly indicate the number of repetitions with which each value was obtained.

Figures 2 and 4 show histograms, which I imagine are the average values of several repetitions.

The authors would like to thank the Reviewers for their useful and constructive comments and the Editor for giving us the chance to revise the manuscript. The replies are given in blue in the following paragraphs and the corresponding changes in the revised manuscript can be checked as changes marked.
The referee is right. Standard deviations for individual measurement points were not included. However, all experiments were repeated twice. This information has now been added in section 2.3 (line 158-159). Standard deviation bars have been included in all graphs.

Otherwise, the manuscript and the research reported are admirable and I congratulate the authors.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Parabens and Methylisotiazolinone (MIT), preservatives with different behaviors when subjected to ozone and ultraviolet light treatments.

Comments

This study, which aims to investigate the simultaneous degradation of preservatives such as parabens and methylisothiazolinone (MIT)." I believe that the manuscript has the potential to be a valuable contribution to the field of environmental science. However, I have a few concerns that I believe need to be addressed before the manuscript is ready for publication.

First, I am not convinced that the authors have adequately addressed the limitations of their study. For example, the authors state that "the results of this study are limited by the small sample size and the lack of long-term data." However, the authors do not discuss how these limitations could affect the interpretation of the results.

Second, I am concerned about the authors' use of the term "degradation." The authors define degradation as "the process of breaking down a substance into smaller molecules." However, this definition is not consistent with the definition of degradation that is used in the environmental science literature. The most common definition of degradation in the environmental science literature is "the process of converting a substance into a form that is less harmful to the environment." The authors should clarify their definition of degradation and explain how it is consistent with the more common definition.

Third, I am concerned about the authors' use of the term "contaminant." The authors define contaminant as "a substance that is harmful to the environment." However, this definition is not consistent with the definition of contaminant that is used in the environmental science literature. The most common definition of contaminant in the environmental science literature is "a substance that is present in the environment at a concentration that is harmful to human health or the environment." The authors should clarify their definition of contaminant and explain how it is consistent with the more common definition.

Fourth, I am concerned about the authors' use of the term "parabens." The authors define parabens as "a group of chemicals that are used as preservatives in cosmetics and other products." However, this definition is not consistent with the definition of parabens that is used in the environmental science literature. The most common definition of parabens in the environmental science literature is "a group of chemicals that are used as preservatives in cosmetics and other products and that have been shown to be harmful to the environment." The authors should clarify their definition of parabens and explain how it is consistent with the more common definition.

Fifth, I am concerned about the authors' use of the term "methylisothiazolinone (MIT)." The authors define MIT as "a chemical that is used as a preservative in cosmetics and other products." However, this definition is not consistent with the definition of MIT that is used in the environmental science literature. The most common definition of MIT in the environmental science literature is "a chemical that is used as a preservative in cosmetics and other products and that has been shown to be harmful to the environment." The authors should clarify their definition of MIT and explain how it is consistent with the more common definition.

Overall, I believe that the manuscript has the potential to be a valuable contribution to the field of environmental science. However, I believe that the authors need to address the concerns that I have raised before the manuscript is ready for publication.

· Specifically, I recommend that the authors:

few comments are also enclosed in the attached file

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Parabens and Methylisotiazolinone (MIT), preservatives with different behaviors when subjected to ozone and ultraviolet light treatments.

Comments

· Specifically, I recommend that the authors:

here few comments are there in enclosed file.

Author Response

Reviewer 2

Parabens and Methylisotiazolinone (MIT), preservatives with different behaviors when subjected to ozone and ultraviolet light treatments.

Comments

The authors would like to thank the Reviewers for their useful and constructive comments and the Editor for giving us the chance to revise the manuscript. The replies are given in blue in the following paragraphs and the corresponding changes in the revised manuscript can be checked as changes marked.

First, I am not convinced that the authors have adequately addressed the limitations of their study. For example, the authors state that "the results of this study are limited by the long-term sample size and the lack of long-term data." However, the authors do not discuss how these limitations could affect the interpretation of the results.

We are very sorry, but after checking the whole paper we have not found that sentence. Is it possible that it is a confusion of the referee?

This definition of degradation has now been introduced in the introduction section, the first time the term is mentioned. (L.66-67)

The authors agree with this definition of contaminant proposed by the reviewer and it has been applied in the paper. These contaminants (parabens and MIT) are substances at certain concentrations in the environment can be harmful to human health”. (L.133-134)

We agree with the definition proposed by the reviewer and have included it in the introduction section (L. 49-51)

The authors agree with this definition of "methylisothiazolinone (MIT)" proposed by the reviewer and it has been applied in the paper. MIT are a chemical that is used as a preservative in cosmetics and other products and that has been shown to be harmful to the environment. (L. 58-59)

Specifically, I recommend that the authors:
The manuscript should be formatted according to the journal's style guide.

The manuscript has been formatted according to the journal's style guide.

The reference section should be increased with the number of recent studies. I would like to suggest to the author to include the following published article to cover more work in ozone/PM/BC and ultraviolet light treatments the author’s study of articles. May be cited in your work. o COVID-19 lockdowns reduce the Black carbon and polycyclic aromatic hydrocarbons of the Asian atmosphere: source apportionment and health hazard evaluation o Characterization, seasonal variation, source apportionment and health risk assessment of black carbon over an urban region of East India o Source apportionment and health risks assessment of black carbon aerosols in an urban atmosphere in East India o Emissions of black carbon and polycyclic aromatic hydrocarbons: Potential implications of cultural practices during the Covid-19 pandemic o Understanding Sources and Composition of Black Carbon and PM2.5 in Urban Environments in East India o Characterization of PAHs and n-alkanes in atmospheric aerosol of Jamshedpur City, India o Black Carbon Emissions from Traffic Contribute Sustainability to Air Pollution in Urban Cities. Many old references are there in the introduction section are completely removed.

The paper includes a comprehensive literature review focusing on preservative degradation: 39 bibliographic citations, of which, 17 are after 2020. Only 5 citations are prior to 2015 and are considered necessary because they are either reference books in the field or they are articles extremely related to this work and it is considered important to consider them for this study.

We have carefully read the suggested references, which we consider very interesting and we will take them into account for future publications we are preparing on nanoparticles.

- COVID-19 lockdowns reduce the Black carbon and polycyclic aromatic hydrocarbons of the Asian atmosphere: source apportionment and health hazard evaluation. Balram Ambade, Tapan Kumar Sankar, Amit Kumar, Alok Sagar Gautam, Sneha Gautam Environ Dev Sustain 2021;23(8):12252-12271. doi: 10.1007/s10668-020-01167-1. Epub 2021 Jan 3.
- Characterization, seasonal variation, source apportionment and health risk assessment of black carbon over an urban region of East India o Source apportionment and health risks assessment of black carbon aerosols in an urban atmosphere in East India. Balram Ambade, Tapan Kumar Sankar, S. Panicker. 2021 Urban Climate38(4):100896
- Source apportionment and health risks assessment of black carbon Aerosols in an urban atmosphere in East India. Balram Ambade & Tapan Kumar Sankar. Journal of Atmospheric Chemistry volume 78, pages177–191 (2021)
- Emissions of black carbon and polycyclic aromatic hydrocarbons: Potential implications of cultural practices during the Covid-19 pandemic. Sudarshan Kurwadkar, Tapan Kumar Sankar, Amit Kumar, Balram Ambade, Sneha Gautam, Alok Sagar Gautam, Jayanta Kumar Biswas, Mohammed Abdus Salam. Gondwana Research. Volume 114, February 2023, Pages 4-14.
- Understanding Sources and Composition of Black Carbon and PM2.5 in Urban Environments in East India o Characterization of PAHs and n-alkanes in atmospheric aerosol of Jamshedpur City, India. by Balram Ambade, Tapan Kumar Sankar, Lokesh K. Sahu and Umesh Chandra Dumka. Urban Sci. 2022, 6(3), 60.
- Black Carbon Emissions from Traffic Contribute Sustainability to Air Pollution in Urban Cities. Ali Jaan Hussain, Tapan Kumar Sankar, Meththika Vithanage, Balram Ambade & Sneha Gautam. Water, Air, & Soil Pollution volume 234, 217 (2023).

However, since all of them refer to black carbon as a pollutant in the atmosphere and our paper is about paraben degradation in aqueous media, we did not find where to fit these references. Anyway, we are grateful to the reviewer for the suggestions that we will consider for future papers.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Author has not significantly improved the reviewers comments. I must reject it in present form.

Following point to be noted:

Simplistic approach: The experiments were conducted using 254 nm UV light, ozone treatments, and simultaneous ozone and UV light treatments at three different pH levels. While these methods are commonly used, they may not be the most effective or efficient for treating all types of contaminants. A more extensive range of treatment methods could be explored.
Limited experimental design: The experiments were conducted using mixtures of parabens and MIT, but not in the presence of other common contaminants found in water bodies. Including these additional contaminants would provide a more realistic representation of the degradation processes occurring in natural environments.
Lack of discussion on real-world applications: The paper primarily focuses on the theoretical aspects of contaminant degradation without discussing potential real-world applications or implications. Expanding the discussion to include potential uses for the findings or addressing potential challenges in implementing the proposed treatment methods would strengthen the paper.

Comments on the Quality of English Language

Introduction & result and discussion