Physical Properties of Plasma-Activated Water

Round 1

Reviewer 1 Report

The authors have conducted a systematic investigation of the physical properties of PAW.

A few questions are given as below.

1.         Like the Viscosity measurement, has the author considered the surface tension and contact angle at different temperatures?

2.         The authors should improve the scientific English writing in this paper.

3.         The viscosity increase with temperature can also be attributed to sub-micron bubbles. However, the experimental observation should be provided as a prove.

Author Response

Dear Reviewer, 

We Thank you for your insightful comments and recommendations, it has greatly helped to revise this work to the better form it is now. While the paper was revisited by us, we have tried to address all the comments you have mentioned. We have worked on improving the English language writing in the paper to make the paper more coherent and readable. 

Kindly see our responses to your comments below: 

1. The surface tension and contact angle investigations in this study were limited to room temperature due to the limitations presented by cost of systems required for accurately measuring these properties at varying temperatures.

2. We have worked on the paper to greatly improve the English scientific writing in it.  
3. As further experiments were need to prove sub-micron bubble presence in PAW, we have omitted the viscosity influence we had earlier attributed to submicron bubbles. 

Kindly review this revised version of "Physical Properties of Plasma Activated Water" and let us know your valuable comments. 

Best, 

Authors

Reviewer 2 Report

Dear Authors,

I reviewed the manuscript: plasma-2147430, line by line, and I found that the manuscript has a potential scientific contribution, and the topic is interesting. The authors aim to investigate the physical properties of plasma activated water. However, the manuscript needs to be improved from different aspects including write up, conclusions, coherent, and literature enrichment.

I have comments on the manuscript as follows:

1-      Abstract is very short. Authors need to improve the abstract.

2-      Introduction. Authors need to enrich the introduction with literature and include the importance of the PAW.

3-      The viscosity of PAW and normal water is similar in almost similar under temperature 10-20 (figure 10). However, under temperature more than 20 there is a clear difference in PAW viscosity. Is that the conclusion about viscosity difference between two types of water.  Please reflect it in the conclusion.

4-      Author find lower contact angles of PAW in comparison with normal water (DW), how significant that the results will add for the scientific contribution and advantages of PAW?

5-      The same for surface tension. It displays decreasing with Plasma activation. Authors should illustrate the importance of their results for water treatment industry.

6-      The conclusion section should be paraphrased to be readable and reflect the results and application.

Thank you

Author Response

Dear Reviewer, 

We Thank you for your insightful comments and recommendations, it has greatly helped to revise this work to the better form it is now. While the paper was revisited by us, we have tried to address all the comments you have mentioned. We have worked on improving the English language writing in the paper to make the paper more  coherent and readable. 

Kindly see our responses to your comments below: 

1. We have worked on the abstract to enhance it with the background, aim, results and significance of this work
2. The Introduction have been reworked to provide a better understanding of PAW, its importance, current applications, review of research done in relation to it, significance of physical properties investigated in this study and their potential applications, with inputs from literature.
3. The viscosity results section (3.2), discussions (4) and conclusion (5) have been reworked to better describe the viscosity behavior of PAW. A detailed explanation to your question is given in Notes #1 attached.
4. The contact angle results section (3.3) and discussions (4) have been reworked to discuss the application of lowered contact angle of PAW. Lower contact angles indicates that plasma activation increased the adhesion and wettability of water, which have applications in surface treatments industry. Example, in painting and dyes. 
5. The surface tension results section (3.1) and discussions (4) have been reworked to discuss the application of decreased surface tension of PAW. The low surface tension characteristic of PAW indicates potential surfactancy behavior. Surfactants are required for numerous industrial processes including but not limited to detergents, paints, food emulsion, biotechnological processes, etc.  
6. The conclusion have been reworked to be more readable and more reflective of results.

Kindly review this revised version of "Physical Properties of Plasma Activated Water" and let us know your valuable comments. 

Best, 

Authors

Notes:

1. The plasma additives lead to increased viscosity in PAW; at low temperatures the amorphous structure of PAW causes it to be of low viscosity when compared to normal water at crystalline structure. As temperature increase, the crystalline structure of water transitions to amorphous; when both PAW and normal water are at amorphous structure, the friction inducing plasma additives will result in PAW to have higher viscosity.  The viscosity behavior exhibited by PAW, from low values of viscosities to high,  describe how the mesoscopic structure change and foreign plasma additives influence the viscosity of water. 

Reviewer 3 Report

I have read manuscript number: plasma-2147430 with the title:"  Physical Properties of Plasma Activated Water", and I found that the authors are focusing on experimental investigations and results of physical properties of plasma-activated water, such as – surface tension, viscosity, and contact angle. The investigation showed that the physical properties of plasma-activated water differ from normal water and the properties are significantly different for kinematic viscosity at higher temperatures and contact angles. I would like the authors to consider the following points before I recommend the publication

1-The abstract of the manuscript must be rewritten in a compact form. The authors must mention the main findings.

2-The introduction must be rewritten.

3-The equations present in section 4 must be taken numbers and written references.

4-All symbols in equations must be defined.

5-All references must be written in the same style and according to the style of the journal.

6-The presentation and grammar need improvement.

Author Response

Dear Reviewer, 

We Thank you for your insightful comments and recommendations, it has greatly helped to revise this work to the better form it is now. While the paper was revisited by us, we have tried to address all the comments you have mentioned. We have worked on improving the English language writing in the paper to make the paper more  coherent, readable, enriched in literature; the introduction have been reworked as well.  

Kindly see our responses to your comments below: 

1. We have worked on the abstract to enhance it with the background,  aim, results and significance of this work.
2. The Introduction have been reworked to provide a better understanding of PAW, its importance, current applications, review of research done in relation to it, significance of physical properties investigated in this study and their potential applications, with inputs from literature.
3. The equations have been given numbers now and the source of the equation is cited prior including them. 
4. All symbols in equations have been defined now. 
5. The references have been formatted according to journal style now. 
6. The paper was reworked in its entirety to improve the presentation and grammar usage in it. 

Kindly review this revised version of "Physical Properties of Plasma Activated Water" and let us know your valuable comments. 

Best, 

Authors

Round 2

Reviewer 2 Report

The author improved the manuscript. So, I recommend accepting the manuscript for publication.