ZnO Promoted Persulfate Activation in Discharge Plasma System for Ofloxacin Degradation
Round 1
Reviewer 1 Report
In this manuscript, the degradation effect of plasma/persulfate/ZnO system on ofloxacin was investigated. ZnO is used to further improve the activation efficiency of plasma on persulfate.
1. Researchers have not mentioned the importance of this work?
2. Plasma interactions on the catalyst have not been studied.
3. The limitations of the work should also be mentioned at the end.
ØŒThe quality of English Language should be improved.
Author Response
Please see the attached file
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Article entitled ZnO promoted persulfate activation in discharge plasma system for ofloxacin degradaion written by Zhen Li, Wenxuan Jiang, Jingwen Huang, Yawen Wang, He Guo and submitted to Catalysts journal as a draft no catalysts-2363767 deals with an important issue of antibiotic decomposition in water.
The article is in journal’s scope. Therefore, it could be considered for publication in Catalysts journal. As English is not my native language, I am not able to assess language correctness. However, while reading, I found some statements missing, confusing or unclear. Below I enclose the list of my comments.
It is worth adding the literature review in the introduction with the methods of OFX elimination used so far and the concentrations of OFX expected in the environment.
Chapter 3 is written very imprecisely. A lot of key information about experimental setup is missing.
Paragraph 3.2 – more detailed description is needed. Reactor geometry, flows and other important parameters should be given.
Details of the radical scavenging experiment are not given.
Merely breaking up an OFX is not everything. Decomposition products and their concentrations should be given. A OFX degradation scheme/pathway should be proposed.
Line 314: What is the relationship between biodegrability and COD? If anything, the BOD5/COD ratio should be determined.
The understanding of COD is completely different, it is not biodegrability. It makes no sense to use COD when TOC is determined. TOC is a measure of the content of organic compounds, while COD is a measure of the content of compounds susceptible to oxidation using potassium dichromate. Therefore, potentially reduced inorganic compounds (which should not be here) could be determined as COD. COD is vulnerable for disruptions - the presence of other substances entering redox systems interferes with the correct determination - here we have radicals and PS.
The Authors write about biodegradability. However, no biodegrability tests have been performed. This also needs to be supplemented. In this context, it is also worth performing toxicity tests.
Why persulfate is doses are given in mM while other doses/concentrations are given in mg/L. This should be unified to mg/L.
How the Authors determine the content of/influence of ·O2- and 1O2 as only Et-OH and TBA were used?
The concept of research is interesting, but many things in experimental control is missing. Fortunately, the Authors performed a very simple experiment on a model compound, so it is possible to repeat the experiment and complete the missing information.
Based on my comments and general impression, I suggest major revision.
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript deals with the degradation of ofloxacin using ZnO and persulfate in a plasma discharge system. The results look promising and well described. The manuscript is well written and is acceptable for publishing in Catalysts after minor revision.
1) Please verify the kinetic constant value for ZnO dosage of 0.35 g/L on page 4, line 120. There seems to be an error.
2) Clarify the unit of energy efficiency; the unit is mg/kWh on writing (page 5, line 139) and g/kWh in figure 4.
3) What are the active substances produced by plasma? Add those with proper reference on page 6, line 157.
4) Mention the trapping agent used to capture OH radical for ESR analysis.
5) Define TOC and COD at their first appearance on the manuscript.
6) Recheck the unit of energy efficiency on page 9, lines 253-254 “Sm2Ti2O7 photocatalyst can degrade 99.2% OFX, and its energy efficiency can reach 42.5 kWh”.
7) Provide the dimensions of the plasma reactor in experimental system section and improve the schematic diagram of the reactor with a 2-D reactor image on the side for clear picture.
8) Describe the type of power supply used (sinusoidal, pulse, ac, dc etc.) along with image of oscilloscope wave data and photo of plasma discharge on the side of figure 9.
9) It is also advised to add optical emission spectra (OES) data of the plasma discharge.
10) Also mention the pumping speed of the water sample to the reactor and its effect on OFX degradation.
11) English should be checked by a native speaker before publication.
English should be checked by a native speaker before publication.
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
This is my second review of this article. The Authors answered all of my questions. Suggested corrections have been applied. I suggest to accept this article in its present form.
