Aluminum Oxide Coatings as Nanoadsorbents for the Treatment of Effluents Colored with Eriochrome Black T

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The first 4 paragraphs should be combined into 1 section, and they should be more comprehensive.
2. AAO is not a new material and was studied long time ago (>12-13 years). The characteristics of this material have been reported in the literature. Justification should be made of why AAO was selected as adsorbent and what research gap is to be filled in this study. Similar studies have been published (https://doi.org/10.1016/j.cscee.2023.100394, doi: 10.11648/j.ijec.20180201.13, DOI: 10.33224/rrch.2024.69.10-12.09)
3. FTIR analysis is needed to study the interaction between the dye and the adsorbent 
4. The authors reported in the abstract that the adsorption process was found to be dependent on the initial dye concentration. However, no such data was presented in text. 
5. Recyclability of adsorbent should be presented and explained. 
6. The adsorption efficiency of the AAO should be compared with other materials found in the literature. How is the performance of AAO thus far in dye degradation and what is the potential for commercialization? 
7. Most of the references used are old (>5 years). More recent references should be included to justify the importance of carrying out such a study. 
8. Conclusions should be written in one paragraph comprehensively and highlighting the major findings. 

Author Response

Answer to reviewers

 

 

• Journal: Coatings
• Ref. No.: coatings-3575587
• Title: Aluminum oxide coatings as nanoadsorbent for the treatment of
  effluents colored with eriochrome black T
• Authors: Gustavo R. Kramer, Florencia A. Bruera, Pedro D. Zapata, Alicia E.
  Ares

 

Coming up next we disaggregate the comments of the reviewers (in green text) and we answer each one separately (in bold black text).

The changes in the content in the new version of the manuscript (reviewed) were highlighted in green text.

 

We thank the reviewers for their comments and observations, we consider that the proposed contributions greatly enrich the manuscript's improvement.

Next, we have responded each reviewer comment:

 

 

Review 1:

1. The first 4 paragraphs should be combined into 1 section, and they should be more comprehensive.

 

We thank the reviewer for this appreciation. The first four paragraphs of the introduction were reviewed, modified, and combined into a single paragraph as suggested. The modifications are shown in the manuscript.

 

 

2. AAO is not a new material and was studied long time ago (>12-13 years). The characteristics of this material have been reported in the literature. Justification should be made of why AAO was selected as adsorbent and what research gap is to be filled in this study. Similar studies have been published (https://doi.org/10.1016/j.cscee.2023.100394, doi: 10.11648/j.ijec.20180201.13, DOI: 10.33224/rrch.2024.69.10-12.09)

 

We thank the reviewer for their comment. Aluminum oxide has been extensively studied in recent years regarding its synthesis as a nanoparticle or film and its characteristics for different applications (templates for the synthesis of other nanomaterials, sensors, drug delivery, medical applications, catalysis, etc.). However, its application as an adsorbent in its nanoporous film form has not yet been reported in the literature. The publications mentioned by the reviewer refer to the use of aluminum oxide nanoparticles as adsorbents, which behave very differently from the nanomaterial addressed in this work. The main differences are that AAO has a film morphology with closely packed pores, has an amorphous structure, and can coat parts or devices on a macro scale. It also adopts different geometries that facilitate the scaling up of the adsorption process, its separation, reuse, and recycling.

To clarify this issue, part of the introduction was modified, and a comment was added to the discussion (section 3.2.1).

 

 

 

 

3. FTIR analysis is needed to study the interaction between the dye and the adsorbent.

We thank the reviewer for pointing this out. We consider the study of the interactions between AAO and absorbate essential for this work, and therefore, FTIR analysis has been added to the manuscript as shown in the manuscript.

 

 

4. The authors reported in the abstract that the adsorption process was found to be dependent on the initial dye concentration. However, no such data was presented in text. 

 

We thank the reviewer for this comment and agree to add the missing analysis. Therefore, section 3.2.1 was modified with the addition of a new figure illustrating the effect of initial dye concentration on %R and qe (Fig. 4) and its corresponding analysis. The modifications are shown in the manuscript.

 

5. Recyclability of adsorbent should be presented and explained. 

We thank the reviewer for their comment. We believe that studying OAA reuse will provide fundamental information on adsorbent lifetime, so we have added an adsorbent regeneration analysis to the manuscript, as shown in the manuscript.

 

 

6. The adsorption efficiency of the AAO should be compared with other materials found in the literature. How is the performance of AAO thus far in dye degradation and what is the potential for commercialization?

 

We thank the reviewer for their attention to comparing our results with those published in the literature.

We do not consider it appropriate to elaborate on the comparison of this material with those reported in the literature because most of the adsorbents studied for the adsorption of Eriochrome Black T are particulate or nanoparticulate materials. In contrast, the AAO used in this work is a nanoporous film/coating formed on a substrate (commercial aluminum alloy AA1050). These differences are reflected in the units used to quantify the amount of adsorbed dye, which for the particulate adsorbent is mg of dye per gram of adsorbent, and in our case, mg of dye per unit area (cm²).

However, we have expanded the comparison of our results with those of other adsorbents with similar physicochemical characteristics to the nanoporous AAO. These changes were added to the manuscript.

 

 

7. Most of the references used are old (>5 years). More recent references should be included to justify the importance of carrying out such a study. 

 

We agree with the reviewer. New and more recent references (published less than 5 years ago) were incorporated into the manuscript. 

 

 

 

 

 

8. Conclusions should be written in one paragraph comprehensively and highlighting the major findings. 

 

We think the reviewer is right. The conclusions were rewritten and the modifications are shown in the manuscript.

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In this manuscript, anodized aluminum oxide (AAO) material was used for surface modification and showed good adsorption performance in the decolorization test of Eriochrome Black T (EBT). The authors also performed various kinetic analyses and comparisons of the adsorption process. I have some minor comments on this manuscript before it can be published in Coatings.

 

1. Does the author have any stability tests for the AAO coating or reproducibility?
2. Could the author include a comparison of your results with other known adsorbents to demonstrate the advantages more clearly?
3. Since the adsorption performance improves significantly with increasing temperature, can the authors provide an economic energy efficiency analysis of the use of this adsorbent on an industrial scale, considering the energy consumption?

Author Response

Answer to reviewers

 

 

• Journal: Coatings
• Ref. No.: coatings-3575587
• Title: Aluminum oxide coatings as nanoadsorbent for the treatment of
  effluents colored with eriochrome black T
• Authors: Gustavo R. Kramer, Florencia A. Bruera, Pedro D. Zapata, Alicia E.
  Ares

 

Coming up next we disaggregate the comments of the reviewers (in green text) and we answer each one separately (in bold black text).

The changes in the content in the new version of the manuscript (reviewed) were highlighted in green text.

 

We thank the reviewers for their comments and observations, we consider that the proposed contributions greatly enrich the manuscript's improvement.

Next, we have responded each reviewer comment:

 

 

Review 2:

1. Does the author have any stability tests for the AAO coating or reproducibility?

 

We appreciate the reviewer's comment. We understand that the reviewer is referring to the reproducibility of the tests and their ability to obtain similar results by slightly modifying the conditions under which they were obtained. In this work, most experiments were performed in triplicate, obtaining the corresponding means and standard deviations for each calculated or determined parameter. Therefore, the veracity and reproducibility of the results obtained have been verified.

Conversely, if the reviewer refers to the reuse of the adsorbent, we believe that studying OAA reuse will provide fundamental information on adsorbent lifetime, so we have added an adsorbent regeneration analysis to the manuscript.

 

 

 

Finally, we understand that stability tests are performed to evaluate the performance of a product under its optimal conditions over time. In this work, the potential of AAO to adsorb EBT at the laboratory scale was evaluated, demonstrating its effectiveness. However, the optimization of the adsorption process variables has not yet been studied and is planned to be carried out in future works that also involve scaling up the process.

 

2. Could the author include a comparison of your results with other known adsorbents to demonstrate the advantages more clearly?

 

We thank the reviewer for their attention to comparing our results with those published in the literature.

We do not consider it appropriate to elaborate on the comparison of this material with those reported in the literature because most of the adsorbents studied for the adsorption of Eriochrome Black T are particulate or nanoparticulate materials. In contrast, the AAO used in this work is a nanoporous film/coating formed on a substrate (commercial aluminum alloy AA1050). These differences are reflected in the units used to quantify the amount of adsorbed dye, which for the particulate adsorbent is mg of dye per gram of adsorbent, and in our case, mg of dye per unit area (cm²).

However, we have expanded the comparison of our results with those of other adsorbents with similar physicochemical characteristics to the nanoporous AAO. These changes were added to the manuscript.

 

 

3. Since the adsorption performance improves significantly with increasing temperature, can the authors provide an economic energy efficiency analysis of the use of this adsorbent on an industrial scale, considering the energy consumption?

 

We appreciate the reviewer's comments. It should be noted that this work was conducted under laboratory conditions. Based on these promising results, we are interested in further optimizing the adsorption process with AAO as an adsorbent and scaling up its application in the treatment of contaminated effluents. This would generate favorable conditions for a more precise energy-economic analysis (from adsorbent preparation to use), which can be extrapolated to industrial application conditions.

 

We thank again the reviewers by their comments. We hope that the doubts have been clarified.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors had made the necessary amendments as suggested.