High Yield Super-Hydrophobic Carbon Nanomaterials Using Cobalt/Iron Co-Catalyst Impregnated on Powder Activated Carbon

Round 1

Reviewer 1 Report

This paper summarises the formulation of super-hydrophobic carbon nanomaterials through CVD process using a cobalt/iron as co-catalyst impregnated on powder activated carbon. The paper detailed the effect of catalyst compound combination to the formulated material in terms of carbon yield and contact angle respond of the material. Suitable test has been conducted to verify the material produced and the functionality of the material. The paper is well written and my comments are as follow:

Line 68: The statement on temperature restriction for PLV is not true as the pre-heating chamber is only operating at 1200^oC according to ref 12 and the main interaction of the material is with the laser. Hence the restriction is purely down to the availability of the laser source. Currently, you can easily get a laser source in multi kW power range and hence from productivity and efficiency point of view, it is not a restriction. Line 276: Can the author explain why the water droplet shown in Figure 3 is attached to the tip of the middle when the measurement was taken? Based on the description of the test in the methodology section, it seems that the angle was taken when a 4uL water droplet is dropped onto the surface which deviate from the image shown. Line378: Can the author mark the peak of interest with the relevant elemental species on Figure 7 to ease the reader when reading the article Line 391: Typo. One of the S5 should be S5. In the analysis section, the number of samples presented on the test from TEM to Raman to TGA has been reduced from 5 to 2. Can the author explain why the TGA and Raman results of S1, S6 and S10 were excluded from the paper? It will be interesting to include those and discuss the differences between the different samples produced with different catalyst composition. 

Author Response

Reviewer Report 1:

Reviewer 1: Comment (1)

This paper summarises the formulation of super-hydrophobic carbon nanomaterials through CVD process using a cobalt/iron as co-catalyst impregnated on powder activated carbon. The paper detailed the effect of catalyst compound combination to the formulated material in terms of carbon yield and contact angle respond of the material. Suitable test has been conducted to verify the material produced and the functionality of the material. The paper is well written.

Response to reviewer

Sincerest appreciation for your review on our manuscript ‘High yield super-hydrophobic carbon nanomaterials using cobalt/iron co-catalyst impregnated on powder activated carbon”.

Reviewer 1: Comment (2)

Line 68: The statement on temperature restriction for PLV is not true as the pre-heating chamber is only operating at 1200 ^oC according to ref 12 and the main interaction of the material is with the laser. Hence the restriction is purely down to the availability of the laser source. Currently, you can easily get a laser source in multi kW power range and hence from productivity and efficiency point of view, it is not a restriction.

Response to reviewer

Thank you so much for this insightful observation. We agree with the reviewer that our statement could be misunderstood and we have changed to make it clearer in the text.

Reviewer 1: Comment (3)

Can the author explain why the water droplet shown in Figure 3 is attached to the tip of the middle when the measurement was taken? Based on the description of the test in the methodology section, it seems that the angle was taken when a 4uL water droplet is dropped onto the surface which deviate from the image shown.

Response to reviewer

Thank you very much for this insightful observation. The contact angle of liquid drop is based on the adhesive forces between the liquid and the surface. In our samples, the material is super-hydrophobic as such the surface of the material is so hateful to water. Taking in the consideration the restrictions of the measuring instrument especially the distance between the needle and the surface and due to the high repulsion force between water drop and the material surface, it was not possible to freely deposit the water drop on the surface of the sample as the water drop refuses to rest on the surface of the material and remains stick to the needle. We have tried several times to do that, but the same phenomena were observed.

Reviewer 1: Comment (4)

Line378: Can the author mark the peak of interest with the relevant elemental species on Figure 7 to ease the reader when reading the article.

Response to reviewer

Thank you for this suggestion. We agree with the reviewer and have marked the peak of interest with the relevant elemental species on Figure 7 accordingly in response to this comment.

Reviewer 1: Comment (5)

Line 391: Typo. One of the S5 should be S5.

Response to reviewer

Thank you for this suggestion. In the revision, we have revised and corrected all the typos and sentences structure in the manuscript.

Reviewer 1: Comment (6)

In the analysis section, the number of samples presented on the test from TEM to Raman to TGA has been reduced from 5 to 2. Can the author explain why the TGA and Raman results of S1, S6 and S10 were excluded from the paper? It will be interesting to include those and discuss the differences between the different samples produced with different catalyst composition.

Response to reviewer

We would like to thank the reviewer for this suggestion. FESEM analysis was carried out for several samples to confirm that the synthesized materials are in nano-scale level. However, upon confirmation, the other characterizations were carried out for the samples that gave the highest yield (for both single and bimetallic catalysts) as well as the highest contact angle. These two desired outputs in this study were set in order to meet the requirements for our application as this material to be used in seawater membrane distillation. The comparison of the other materials characteristics was not included in this manuscript to avoid complexity and confusion as well as elongating the manuscript unnecessarily.

Author Response File: Author Response.docx

Reviewer 2 Report

General comments:

The article is generally interesting, contains new information that is of interest to the scientific community and is generally written and structured in a correct manner. Only errors in the use of abbreviations, capital letters in the headings and tables and inconsistency in the way of citing the bibliographical references used, especially in the abbreviations of the journals (sometimes with dots, sometimes without dots, etc) are perceived as quite common. The similarity index with previous works is acceptable.

 

Specific comments:

Abstract section: Please, avoid the use of abbreviations in abstract section. This section is excessive and could be widely shortened. In example, “Analysis of…statistically significant”. It is not necessary for an abstract to describe such basic aspects that can be perfectly explained in the main text.

 

Page 2, line 54: “CNMs” was already defined in line 50. It is unnecessary to repeat the definition.

Page 2, line 75: Please define “SWNTs” and “MWNTs”.

Page 3, line 127 and afterwards: Please, avoid the use of abbreviations such as “PAC” from subheadings.

Page 3, line 128: “PAC” was already defined in line 75.

Page 3, line 132: “the mixture was crushed to powder” How was the procedure and equipment employed? Was there any size of dust considered acceptable?

Page 4, line 170: ImageJ software webpage should be not cited in the main text. If you consider necessary, please state it in the references section.

Page 5, line 208: Improper use of capital letters. The same in page 6, line 221 and page 7, line 230.

 

 

Author Response

Reviewer Report 2:

Reviewer 2: Comment (1)

The article is generally interesting, contains new information that is of interest to the scientific community and is generally written and structured in a correct manner. Only errors in the use of abbreviations, capital letters in the headings and tables and inconsistency in the way of citing the bibliographical references used, especially in the abbreviations of the journals (sometimes with dots, sometimes without dots, etc) are perceived as quite common. The similarity index with previous works is acceptable.

Response to reviewer

Sincerest appreciation for your review on our manuscript ‘High yield super-hydrophobic carbon nanomaterials using cobalt/iron co-catalyst impregnated on powder activated carbon”. Thank you for this suggestion. In the revision, we have corrected all the errors in according to the reviewer comments.

Reviewer 2: Comment (2)

Abstract section: Please, avoid the use of abbreviations in abstract section. This section is excessive and could be widely shortened. In example, “Analysis of…statistically significant”. It is not necessary for an abstract to describe such basic aspects that can be perfectly explained in the main text.

Response to reviewer

Thank you for this suggestion. In the revision, we have revised the abstract and removed the abbreviations whenever is necessary. In addition, for the long sentence “Analysis of…statistically significant”, has been replaced with short statement.

Reviewer 2: Comment (3)

Page 2, line 54: “CNMs” was already defined in line 50. It is unnecessary to repeat the definition.

Response to reviewer

Thank you for this suggestion. We agree with the reviewer and have corrected that in the text.

Reviewer 2: Comment (4)

Page 2, line 75: Please define “SWNTs” and “MWNTs”.

Response to reviewer

Thank you so much for this insightful observation. We agree with the reviewer and have defined these abbreviations in the text.

Reviewer 2: Comment (5)

Page 3, line 127 and afterwards: Please, avoid the use of abbreviations such as “PAC” from subheadings.

Response to reviewer

Thank you for this suggestion. We agree with the reviewer and have corrected that accordingly in response to this comment.

Reviewer 2: Comment (6)

Page 3, line 128: “PAC” was already defined in line 75.

Response to reviewer

Thank you for this suggestion. We agree with the reviewer and have corrected that accordingly in response to this comment.

Reviewer 2: Comment (7)

Page 3, line 132: “the mixture was crushed to powder” How was the procedure and equipment employed? Was there any size of dust considered acceptable?

Response to reviewer

Thank you very much for this observation. The mixture was crushed to powder using sterilized (to avoid any contamination) glass mortar and pestle. The crashing was conducted in order to minimize the size of the powder in addition to provide extra homogeneity to the mixture. The crushing was conducted very softly and the sample weight was measured before and after crashing, however, the dust loss was negligible.

Reviewer 2: Comment (8)

Page 4, line 170: ImageJ software webpage should be not cited in the main text. If you consider necessary, please state it in the references section.

Response to reviewer

Thank you for this suggestion. We agree with the reviewer and we think is not really necessary to include the webpage of the software, as such it was removed accordingly in response to this comment.

Reviewer 2: Comment (9)

Page 5, line 208: Improper use of capital letters. The same in page 6, line 221 and page 7, line 230.

Response to reviewer

Thank you for this suggestion. We agree with the reviewer and these errors were corrected accordingly in response to this comment.

Author Response File: Author Response.docx