Research on the Preparation and Performance of Wood with High Negative Oxygen Ion Release Induced by Moisture

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Suggestions for the Abstract 

1. Refine the Problem Statement: The phrase "However, naturally occurring health-beneficial wood with human healthcare functions is still scarce" could be more specific about the research gap or unmet demand that the study aims to address.

2. Highlight Innovation More Directly: While the abstract mentions the successful preparation of healthy wood and the use of impregnation technology, the core innovation could be emphasized right at the beginning, perhaps connecting it directly to solving the mentioned scarcity.

3. Summarize Key Implications More Concisely: The abstract presents many detailed numerical data. While important, for an abstract, a more concise synthesis of the results and their practical implications ("improving indoor air quality and enhancing human health") can be more impactful. One could consider grouping some numbers or presenting a representative range.

Suggestions for the Introduction 

1. Argumentation Structure: The introduction could benefit from a smoother transition between paragraphs. Currently, the discussion about wood and its benefits moves to resource scarcity and then to negative oxygen ions. Connecting these themes more explicitly at the beginning of each paragraph could improve the flow.

2. Expand Literature Review on "Healthy Wood": The concept of "healthy wood" is introduced, but a deeper review of previous studies specifically focused on functionalizing wood for health benefits (beyond ion release) could strengthen the basis of the problem.

3. Contextualize "Hexagonal Stone" Earlier: "Hexagonal stone" is mentioned as a key material, but its relevance and unique properties could be introduced more prominently and substantiated in the literature before the section describing its use with poplar.

4. Clarity on Specific Study Objectives: Although the introduction mentions the development of new functional wood and the objective of releasing negative oxygen ions, the specific research objectives (e.g., which variables would be investigated, which technologies would be employed, which results would be quantified) could be more clearly articulated at the end of the introduction.

5. Review Redundancy in "Coatings 2025, 15, x": The repetition of "Coatings 2025, 15, x" and "FOR PEER REVIEW" on each page is an automatic watermark or header. However, the text preceding or following it can be adjusted to ensure that the content transition is smooth and not affected by these repetitions.

Suggestions for the Results and Discussion 

1. Deeper Interpretation of D50 Results: While section 3.1 discusses D50 values and dispersant effects, the discussion could delve deeper into why certain concentrations and dispersants are optimal. For example, exploring interaction mechanisms at a more molecular level or comparing with other studies that obtained similar or different results.

2. More Explicit Connection between D50 and Final Wood Performance: The results section shows the impact of dispersion on healthy wood. The discussion could create a more direct and elaborate bridge between dispersion properties (D50 particle size) and the final performance of the healthy wood (weight gain, liquid absorption rate, dimensional stability, and negative oxygen ion release).

3. Discussion of Implications of Swelling Rate Reductions: The significant reduction in hygroscopic swelling rates (e.g., 70.93% to 71.35% for PEG-treated samples) is an important result. The discussion should explore the practical implications of this improved dimensional stability for wood applications more deeply.

4. Robust Comparative Analysis with Literature: Although the text cites some references, the discussion of the results should include a more robust comparative analysis with the findings of other studies. How do the results of this work compare, surpass, or differ from those obtained by Gao et al., Chen et al., Wang et al., Yang et al., and Han et al. in terms of method, materials, and, most importantly, performance (especially in negative oxygen ion release)?

5. Deepen the Moisture Response Mechanism: The abstract and conclusion mention the "moisture response mechanism" leading to increased negative oxygen ion release when ambient humidity exceeds 70%. The discussion section could dedicate a more detailed paragraph to explain how humidity influences this process at a molecular or structural level in the modified wood.

6. Discuss Limitations and Future Challenges: It is important to acknowledge any limitations of the study, such as the duration of ion release tests, the applicability of the method to other wood types, or the scalability of production. Additionally, propose clear directions for future research based on these limitations and the achieved results.

7. Environmental Impact and Sustainability in More Detail: The work proposes a "sustainable and effective method" for preparing healthy wood. The discussion could expand on the environmental impact of hexagonal stone and the impregnation process, comparing it with other wood functionalization methods and highlighting sustainability benefits in more depth.

8. Improve Linking between Characterizations (FT-IR, XRD, SEM) and Properties: Sections 3.1.2 to 3.1.4 (assuming these are the discussions of FT-IR, XRD, and SEM, though not explicitly detailed in the snippets provided after 3.1.1) could have a more integrated discussion. For example, how do the observed changes in FT-IR and XRD analyses directly correlate with improvements in the physical properties and negative oxygen ion release capacity of the wood?

Comments on the Quality of English Language

Suggestions for the Abstract 

1. Refine the Problem Statement: The phrase "However, naturally occurring health-beneficial wood with human healthcare functions is still scarce" could be more specific about the research gap or unmet demand that the study aims to address.

2. Highlight Innovation More Directly: While the abstract mentions the successful preparation of healthy wood and the use of impregnation technology, the core innovation could be emphasized right at the beginning, perhaps connecting it directly to solving the mentioned scarcity.

3. Summarize Key Implications More Concisely: The abstract presents many detailed numerical data. While important, for an abstract, a more concise synthesis of the results and their practical implications ("improving indoor air quality and enhancing human health") can be more impactful. One could consider grouping some numbers or presenting a representative range.

Suggestions for the Introduction 

1. Argumentation Structure: The introduction could benefit from a smoother transition between paragraphs. Currently, the discussion about wood and its benefits moves to resource scarcity and then to negative oxygen ions. Connecting these themes more explicitly at the beginning of each paragraph could improve the flow.

2. Expand Literature Review on "Healthy Wood": The concept of "healthy wood" is introduced, but a deeper review of previous studies specifically focused on functionalizing wood for health benefits (beyond ion release) could strengthen the basis of the problem.

3. Contextualize "Hexagonal Stone" Earlier: "Hexagonal stone" is mentioned as a key material, but its relevance and unique properties could be introduced more prominently and substantiated in the literature before the section describing its use with poplar.

4. Clarity on Specific Study Objectives: Although the introduction mentions the development of new functional wood and the objective of releasing negative oxygen ions, the specific research objectives (e.g., which variables would be investigated, which technologies would be employed, which results would be quantified) could be more clearly articulated at the end of the introduction.

5. Review Redundancy in "Coatings 2025, 15, x": The repetition of "Coatings 2025, 15, x" and "FOR PEER REVIEW" on each page is an automatic watermark or header. However, the text preceding or following it can be adjusted to ensure that the content transition is smooth and not affected by these repetitions.

Suggestions for the Results and Discussion 

1. Deeper Interpretation of D50 Results: While section 3.1 discusses D50 values and dispersant effects, the discussion could delve deeper into why certain concentrations and dispersants are optimal. For example, exploring interaction mechanisms at a more molecular level or comparing with other studies that obtained similar or different results.

2. More Explicit Connection between D50 and Final Wood Performance: The results section shows the impact of dispersion on healthy wood. The discussion could create a more direct and elaborate bridge between dispersion properties (D50 particle size) and the final performance of the healthy wood (weight gain, liquid absorption rate, dimensional stability, and negative oxygen ion release).

3. Discussion of Implications of Swelling Rate Reductions: The significant reduction in hygroscopic swelling rates (e.g., 70.93% to 71.35% for PEG-treated samples) is an important result. The discussion should explore the practical implications of this improved dimensional stability for wood applications more deeply.

4. Robust Comparative Analysis with Literature: Although the text cites some references, the discussion of the results should include a more robust comparative analysis with the findings of other studies. How do the results of this work compare, surpass, or differ from those obtained by Gao et al., Chen et al., Wang et al., Yang et al., and Han et al. in terms of method, materials, and, most importantly, performance (especially in negative oxygen ion release)?

5. Deepen the Moisture Response Mechanism: The abstract and conclusion mention the "moisture response mechanism" leading to increased negative oxygen ion release when ambient humidity exceeds 70%. The discussion section could dedicate a more detailed paragraph to explain how humidity influences this process at a molecular or structural level in the modified wood.

6. Discuss Limitations and Future Challenges: It is important to acknowledge any limitations of the study, such as the duration of ion release tests, the applicability of the method to other wood types, or the scalability of production. Additionally, propose clear directions for future research based on these limitations and the achieved results.

7. Environmental Impact and Sustainability in More Detail: The work proposes a "sustainable and effective method" for preparing healthy wood. The discussion could expand on the environmental impact of hexagonal stone and the impregnation process, comparing it with other wood functionalization methods and highlighting sustainability benefits in more depth.

8. Improve Linking between Characterizations (FT-IR, XRD, SEM) and Properties: Sections 3.1.2 to 3.1.4 (assuming these are the discussions of FT-IR, XRD, and SEM, though not explicitly detailed in the snippets provided after 3.1.1) could have a more integrated discussion. For example, how do the observed changes in FT-IR and XRD analyses directly correlate with improvements in the physical properties and negative oxygen ion release capacity of the wood?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors propose a sustainable and effective method to prepare health wood with permanent negative oxygen ion release capability with scope to demonstrate the potential in improving indoor air quality with substantial impact on human health benefits. Using a type of hexagonal stone powder, the authors proposed a negative pressure impregnation modification method to develop the health wood. The materials and methods are well and proper described. The results indicate that a smaller median particle size in the powder generally results in better dispersibility, with little to no powder agglomeration. Additionally, it was studied the effect of dispersion treatment on the microstructure and the findings highlighted that negative oxygen ion release capability of hexagonal stone powder.

My recommendations are the following:

Line 17-18: I suggest reformulating the following:  “… six-ring stone powder …”, the words appear twice in the same sentence.

Line 23: The terms KH570, wt% PEG, Span60 are not defined in order to be discussed.

Line 29: What is imposed limit to demonstrate the affirmation “ a significant reduction”? The significant must be justified by statistically point of view.

Line 48: The word “possesses” is not proper used in this context.

Line 122: I think that it is not necessary to detail al the instruments used in experimentation. It is obvious that without these, the tests cannot be carried out.

Line 504: samples around 2θ = 16° and 22° --- °C.

Line 515: The same: 30.94° --- 30.94°C.

Line 615: This section could be improved to underline the innovative aspects of the study and results.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf