Rapid AOP Method for Estrogens Removal via Persulfate Activated by Hydrodynamic Cavitation

Round 1

Reviewer 1 Report (Previous Reviewer 2)

The authors have corrected the work according to my comments. For example, they have calculated the reaction kinetics. Please note that during the proofs, the numbers in Table 2 should be corrected. For example, "1,24", you should use dots instead of commas.

Author Response

Dear reviewer, so many people read it and did not see it. Thanks a lot for the correction and kind comments.

Reviewer 2 Report (Previous Reviewer 3)

After modification, the author improved the content of the article and added the relevant content. The current status of the article can be accepted by the journal.

Author Response

Dear reviewer, we try to improve it qiuckly what was useful also thanks to your effert.

Thank you again !

Reviewer 3 Report (New Reviewer)

The reviewed manuscript entitled: “Rapid AOP method for estrogens removal via persulfate activated by hydrodynamic cavitation” deals with exploring advanced oxidation processes (AOPs) using sulphur-based radicals (inorganic persulfates source) for organic contaminants removal in wastewater treatment process. The authors investigated an economically and environmentally friendly solution based on hydrodynamic cavitation, which does not require heating or additional activation of the used persulfate salts which is the main novelty and scientific advance in the current suggest research. Estrogen compounds are chosen as target removal endocrine disruptors pollutants but the process is for sure applicable for broad spectrum of others.  The experimental design is appropriate and the scientific rigor is on a good level. I have only one small critical remark – if possible, the authors to provide a real picture of the used hydrodynamic cavitation laboratory equipment. Also, is it possible to combine HC simultaneously with some ultrasound treatment technology?

Author Response

Dear reviewer we did all corrections requested  with one exception – the equipment is actually continuously employed in the locality to decontaminate explosives and they would not take a picture, but we hope that it is clear, from the Figure 2  you can see all details to understand the principle of this technology.  Regarding the question, if HC can be combined with US, we can say that yes, can be combined, but the fact, that only HC is able to activated PS with results presented in this paper we proved, that it is not necessary. Thank you for the understanding.

Wishing you all the best!

B. Marsalek

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

• There is not enough data to support the results.

Reviewer 2 Report

The authors have applied persulfate activated by cavitation for estrogens removal. They have investigated hybrid activation, such as heat/cavitation as well.

The persulfate-based processes are a good topic to study, and the authors have partially done a good job presenting the next manuscript in this field. However, some comments below possess several shortcomings, and I am not sure if this work can be published after a standard major revision process.

·        The novelty of the work should be underlined. I think that PS + cavitation was studied extensively. Similarly, the removal of estrogens by sulfate radical-based processes.

·        Overall, the number of results should be increased. For example, you should examine the influence of dose (more on that comment below), maybe also pH, common anions etc.

·        „All the experiments were performed using persulphate concentration of 0.1 mM. I“ – why this one? It would help if you justified e.g., using relevant literature.

·        Kinetics could also be determined.

·        „After collection, the samples were untouched for 3 hours and <“ – this sentence is not finished, I suppose?

·        „Sadílek et al. (2016) [18].“ – you should not mix the citation styles, it should be unified according to the MDPI guidelines.

Reviewer 3 Report

Comments for author File: Comments.docx