Novel AOPs-Based Dual-Environmental Digestion Method for Determination of Total Dissolved Nitrogen in Water

Round 1

Reviewer 1 Report

The manuscript entitled “ Novel AOPs-Based Dual Environmental Digestion Method for Determination of Total Dissolved Nitrogen in Waters” deals with the problem of environmental pollution by nitrogen compounds from agriculture. The authors were designed and tested homemade apparatus. In my opinion, they have been obtained reliable results.  The manuscript is written correctly and can be published after minor revision.
 line 43, word nitrite repetition.
In figure 2 there is a lack of an explanation of solid line meaning. As, it is extrapolation by a polynomial of the measurements points.
Line 235,  extra word - This

Author Response

Dear reviewer,

Thank you for your comments and suggestions about our manuscript-ID: Water-1379861 entitled “Novel AOPs-Based Dual Environmental Digestion Method for Determination of Total Dissolved Nitrogen in Waters”.

We are very grateful to you for your good comments and suggestions, and we have updated our manuscript carefully according to your comments and suggestions. Please review the highlighted version again, thank you very much!

The attachment is the corresponding point-by-point replies to your comments.

Thank you very much for your time and consideration!

Yours Sincerely,
Xiaofang Sun

Corresponding author: Xiaofang Sun at College of Chemical Engineering,

Zhejiang University of Technology, Hangzhou 310014, China,

Email: [email protected],

Phone number: +86-0571-88320329; fax number: +86-0571-88320329

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

your study of the digestion method is interesting and extensive. The estimations of the influence of pH, time of digestion, chloride, carbonate, and hydrogen carbonate on digestion efficiency are thorough. Unfortunately, I miss the use of certified reference materials, method validation, uncertainty estimation, and LOD/LOQ calculation in your method development. There are suitable certified reference materials for Total Nitrogen in surface waters and for wastewater effluent to be used for such purposes.

According to the Water template, the Results and Discussion should be divided into different sections in the MS, which was not done in your case.

My specific comments are:

1. Line 180: Please add the reference for the work of Sun et al.
2. Use the same expression for the concentration of the compounds used - either the mass concentration (mg/L) or the molar concentration (mmol/L) throughout.
3. Line 377, table 2: Please add the units for the concentration of carbonate (column 2). I suppose it is "mmol/L".
4. Please rephrase paragraph 2.3 (lines 140-160) - present the procedure in narrative text. 
5. Please rephrase the sentence (lines 49-52) and check lines 235 and 297 for unnecessary wording.

Author Response

Dear reviewer,

Thank you for your comments and suggestions about our manuscript-ID: Water-1379861 entitled “Novel AOPs-Based Dual Environmental Digestion Method for Determination of Total Dissolved Nitrogen in Waters”.

We are very grateful to you for your good comments and suggestions, and we have updated our manuscript carefully according to your comments and suggestions. Please review the highlighted version again, thank you very much!

The attachment is the corresponding point-by-point replies to your comments.

Thank you very much for your time and consideration!

Yours Sincerely,
Xiaofang Sun

Corresponding author: Xiaofang Sun at College of Chemical Engineering,

Zhejiang University of Technology, Hangzhou 310014, China,

Email: [email protected],

Phone number: +86-0571-88320329; fax number: +86-0571-88320329

Author Response File: Author Response.docx

Reviewer 3 Report

Authors demonstrated the application of ultraviolet combined with ozone (UV/O3) synergistic digestion method for estimating the total dissolved nitrogen in waters and the influence of ions on digestion efficiency were also investigated. Authors systematically carried out the experiments and the results are discussed appropriately. Manuscript can be acceptable after addressing the following comments.  

1. In the introduction section, mention the conventional methods of digestion and compare its advantage and disadvantages with the UV/O3 digestion method.
2. In the introduction, elaborate HPLC when used for the first time
3. At section 2.2, elaborate PTFE when used for the first time
4. At section 2.3. authors can mention the reference of standard method used for the analysis of digested samples
5. Figure 3, were the calibration curve plotted using the triplicate samples?
6. Authors should also add the molecular formula of glycine for better understanding of readers

Author Response

Dear reviewer,

Thank you for your comments and suggestions about our manuscript-ID: Water-1379861 entitled “Novel AOPs-Based Dual Environmental Digestion Method for Determination of Total Dissolved Nitrogen in Waters”.

We are very grateful to you for your good comments and suggestions, and we have updated our manuscript carefully according to your comments and suggestions. Please review the highlighted version again, thank you very much!

The attachment is the corresponding point-by-point replies to your comments.

Thank you very much for your time and consideration!

Yours Sincerely,
Xiaofang Sun

Corresponding author: Xiaofang Sun at College of Chemical Engineering,

Zhejiang University of Technology, Hangzhou 310014, China,

Email: [email protected],

Phone number: +86-0571-88320329; fax number: +86-0571-88320329

Author Response File: Author Response.docx

Reviewer 4 Report

Comment to the paper: “Novel AOPs-Based Dual Environmental Digestion Method for Dermination of Total Dissolved Nitrogen in Waters” by Rongyao Cai et al.

General comment:

The manuscript deals with investigations on total dissolved nitrogen by using AOPs-based dual environmental digestion method. The effect of flow rate, pH of water sample and reaction time on digestion efficiency of dissolved N-compounds was investigated.

The manuscript is suitable to be published in this journal; however, some points should be addressed before publication.

Some minor language mistakes are present that should anyway be corrected.

1. Introduction

AOPs are usually used for the treatment of wastewater. Please, improve the introduction by including a short overview on water treatment by AOPs. Please, consider the following manuscripts:

• Electro-oxidation of humic acids using platinum electrodes: An experimental approach and kinetic modelling (2020) Water (Switzerland), 12 (8), art. no. 2250.
• A critical review on ibuprofen removal from synthetic waters, natural waters, and real wastewaters by advanced oxidation processes (2022) Chemosphere, 286, art. no. 131849.
• Comparison of hydrogen peroxide-based advanced oxidation processes for the treatment of azole-containing industrial wastewater (2021) Chemical Engineering Journal, 425, art. no. 131785.

2. Materials and methods

Please, specify if investigations were carried out in duplicate/triplicate etc.

Please, include statistical analysis (i.e. ANOVA).

Please, clarify if NOx measurements were carried out.

Please, specify the parameter of the assessment of the performance of the methodology proposed (i.e. conversion rate, %).

3. Results and discussion

Please, improve comparison between experimental findings and literature data.

Please, include statistical analysis results.

The validation of the proposed methodology should be performed by comparing it with conventional methods.

Error and reliability of the proposed method should be assessed.

NOx measurements should be reported

Nitrogen balance should be included.

The complete characterization of the water solution should be included.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thank you for your comments and suggestions about our manuscript-ID: Water-1379861 entitled “Novel AOPs-Based Dual Environmental Digestion Method for Determination of Total Dissolved Nitrogen in Waters”.

We are very grateful to you for your good comments and suggestions, and we have updated our manuscript carefully according to your comments and suggestions. Please review the highlighted version again, thank you very much!

The attachment is the corresponding point-by-point replies to your comments.

Thank you very much for your time and consideration!

Yours Sincerely,
Xiaofang Sun

Corresponding author: Xiaofang Sun at College of Chemical Engineering,

Zhejiang University of Technology, Hangzhou 310014, China,

Email: [email protected],

Phone number: +86-0571-88320329; fax number: +86-0571-88320329

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear authors,

your paper was improved in the revised form, but you did not address the issue of using certified reference materials in method validation, nor you have included the method parameters (such as LOD/LOQ, repeatability, etc.). Please be more thorough in your future works.

Reviewer 4 Report

The authors revised the manuscript according to the comments/changes suggested. The paper is suitable to be published in this journal in the current form.