Liquefaction of Ruscus aculeatus Branches into Bio-Polyols: Process Optimization and Polyol Characterization

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

• The novelty of the study is not clearly shown. Biomass liquefaction for bio-polyol production is already well studied. The authors should explain why Ruscus aculeatus is a better or unique biomass source.
• The introduction lists many studies but does not clearly state the research gap. The purpose of the study should be explained more clearly.
• The chemical composition of the biomass is not reported. Data on cellulose, hemicellulose, lignin, extractives, and ash would help explain the liquefaction results.
• The experimental results lack proper statistical analysis. Standard deviation or error bars are not included.
• The figures presenting liquefaction yield and other properties do not show variability. This makes it difficult to judge the reliability of the results.
• The effects of temperature, time, particle size, and solvent ratio are described, but the explanation of the chemical reactions during liquefaction is limited.
• Some explanations about depolymerization and condensation reactions appear speculative. Direct analytical evidence is not provided.
• The reported hydroxyl numbers are high. The influence of solvents such as glycerol and ethylene glycol on these values should be discussed.
• It is not clear whether the hydroxyl numbers were corrected for the presence of unreacted solvents. This may lead to overestimation of biomass-derived hydroxyl groups.
• Viscosity was measured using a Rapid Visco Analyzer. This instrument is mainly used for starch analysis. The authors should justify its use for polyol measurements.
• More details about the viscosity measurement conditions should be provided. Information such as shear rate and experimental parameters is needed for reproducibility.
• The FTIR analysis mainly lists functional groups. A deeper explanation of structural changes during liquefaction would strengthen the discussion.
• Thermal analysis results are presented clearly. However, the relationship between thermal behavior and chemical changes should be explained in more detail.
• Some figures lack clear labels and detailed descriptions. This reduces the clarity of the data.
• The manuscript mentions possible applications in polyurethane materials. However, no experimental validation is presented.
• Without polyurethane synthesis or performance testing, the practical application of the produced polyols remains uncertain.
• Some sentences in the manuscript are long and difficult to read. The writing should be simplified.
• Minor grammar errors and inconsistent terminology appear in several places. Careful language editing is needed.
• Parts of the discussion repeat results instead of providing deeper interpretation.
• The conclusion is too long and mostly repeats the results. It should focus on the key findings and their significance.

 

Comments on the Quality of English Language

Must be improved

Author Response

Dear Reviewer,

We sincerely thank you for your careful reading and valuable comments. We have addressed each point in detail below and revised the manuscript accordingly, as provided in the attached document.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Manuscript entitled "Liquefaction of Ruscus aculeatus Branches into Bio-Polyols: 2Process Optimization and Polyol Characterization" has been reviewed. Following points should be considered for further recommendations.

 

1. Clarify the influence of particle size on liquefaction efficiency and provide further justification for the chosen temperature conditions (140°C, 160°C, 180°C).
2. Include statistical analysis (e.g., standard deviations or error bars) to validate the significance of the results, particularly for liquefaction yields.
3. Expand on the chemical mechanisms causing the decrease in hydroxyl number with increased temperature, particularly regarding secondary reactions like condensation.
4. Provide more details on rheological testing methods, such as the type of rheometer used, and explore how the viscosity of polyols affects polyurethane foam production in more depth.
5. Discuss the scalability of the liquefaction process and its economic/environmental implications, especially with regards to solvent usage.
6. Strengthen the connection to broader bio-polymer research and suggest specific future research directions, such as experimenting with polyol blending to control viscosity.
7. Provide more detailed captions for figures, especially regarding experimental conditions and their industrial relevance.
8. Compare results with other lignocellulosic biomass liquefaction studies to broaden the scope of the conclusions.

Author Response

Dear reviewer,

We sincerely thank the reviewers for their careful evaluation of our manuscript and for their constructive comments and suggestions. All remarks were carefully considered, and the manuscript has been thoroughly revised accordingly. The reviewers’ comments are reproduced below in full, followed by our responses. All suggested modifications have been incorporated into the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Recommendation: Major revision

1. The abstract is too lengthy and lacks precision; the qualitative and quantitative data are not well presented.
2. In the introduction, the citations are improperly formatted, especially in the first three lines.
3. The introduction also needs to be revised to make it more concise.
4. All experimental conditions were tested in duplicate to ensure reproducibility; this should not be mentioned, as it is important. This is not a scientific way of writing
5. The reaction temperature was monitored via the thermal oil circulating in the reactor jacket. The effective liquefaction time was defined as starting once the system reached target temperatures of 140 °C, 160 °C, or 180 °C. Reaction durations varied between 15 and 60 minutes depending on the experimental conditions. This section also needs revision.
6. The term "hydroxyl index" (OH index) should be abbreviated appropriately.
7. Why did the authors choose to conduct experiments at the highest temperature of 180 °C?
8. Why did the authors not explore lower temperature optimization in these experiments?
9. As the authors mentioned, the results clearly demonstrate that increasing the reaction time leads to a slight improvement in liquefaction yield, increasing from 89% at 15 minutes to 90% at 30 minutes, and even to 92% at 60 minutes. However, they also state that the yield generally decreases over time. Can they provide the reasoning behind this?
10. If the yield increased with time, why did the authors not extend the duration to 70 or 80 minutes?
11. The liquefaction yield increases successively with a higher amount of solvent. At low solvent ratios (e.g., 1:3), the system likely becomes highly viscous early in the reaction, limiting mass transfer and diffusion of acid and solvent into biomass particles. The authors mentioned that, from an optimization perspective, the most suitable material-to-solvent ratios for industrial purposes range from 1:7 to 1:10. Please provide references and improve this explanation.

Author Response

We sincerely thank the reviewers for their careful evaluation of our manuscript and for their constructive comments and suggestions. All remarks were carefully considered, and the manuscript has been thoroughly revised accordingly. The reviewers’ comments are reproduced below in full, followed by our responses. All suggested modifications have been incorporated into the revised manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have meticulously answered the quieries.

Comments on the Quality of English Language

The authors have meticulously answered the quieries.

Author Response

Thank you for your positive evaluation. We appreciate your time and consideration.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have carefully revised the manuscript. Therefore, the manuscript should be accepted for publication. 

Author Response

Thank you for your positive assessment. We sincerely appreciate your time and support, and we are pleased that the manuscript meets the requirements for publication.

Reviewer 3 Report

Comments and Suggestions for Authors

NO

Author Response

Thank you for your evaluation. We appreciate your time and consideration.