Ultrasound-Assisted Cold Alkaline Extraction: Increasing Hemicellulose Extraction and Energy Production from Populus Wood

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Abstract: line 14: please rewrite the 1st sentence or correct it accordingly: Alkaline preteatments are considered highly effective for the separation of different components of lignocellulosic biomass.

Abstract: line 18: typing error: high-value.

Abstract: line 19: operating of what? (Subject missing).

Abstract: needs to be rewritten as there is not results mention in it.

Batter to write keywords in alphabetical order.

Keywords: should be different from the title so that your article may have may have more chance of access or search.

Citation 14: climate allowing plants like Robinia pseudoacacia, Ulmus pumila, Eucalyptus sp.
and/or Populus sp. to grow.

Citation 20: typing error: Among.

Citation 22-25: typing error: disadvantages.

Citation 26-27: batter to write pretreatment rather than treatment.

Add Citation: A. García et al., 2011 (30) right after the name, mentioned.

In last paragraph of introduction part: There are also no bibliographic references exploring its utilization for the simultaneous valorization of the hemicellulosic liquid and energy application of the solid residue.

Please rewrite this sentence “ as according to authors knowledge”………..  However, there has been enough work done on hemicellulosic liquid to produce value added products (Tareen, A. K., Punsuvon, V., & Parakulsuksatid, P. Conversion of steam exploded hydrolyzate of oil palm trunk to furfural by using sulfuric acid, solid acid, and base catalysts in one pot. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 1-12. doi:10.1080/15567036.2020.1741733)

Materials & methods: 2.1: utilized was a wood from...

Materials & methods: 2.1: second sentence seems to be un-necessary.

Materials & methods: 2.1 min-1

This analysis was conducted using high-performance liquid chromatography (HPLC) with an AMinex HPX-87H ion-ex-change column at 30 ºC as the stationary phase and 0.005 M H2SO4 at a flow rate of 0.6 mL min-1 as the mobile phase. Please add reference for HPLC conditions

Materials & methods: 2.2: As this is a multivariate modeling approach,

Material & methods: Plagiarism is very high in this part. Please reduce it.

Result & discussion: 3.1: typing error: 67.5% if the total biomass.

Result & discussion: The amount of lignin remaining in the solid was also interest. Cold alkaline extraction partially delignifies the raw material, (It would be better if you could mention the delignification in percentage on dry weight basis or weight weight basis? By explain how much of lignin has been removed using your method? Additionally, also mention the delignification mechanism using that method you have used)?

Result & discussion: 3.1: Constantí et al. 1998, Ebringerová et al. 2010.: Add Citation right after the name, mentioned. (throughout the manuscript).

Author Response

Thank you for your time and comments. The changes made to the manuscript corresponding to your feedback are underlined in yellow. In addition, the answers to each point are shown in this document in boldface type.

Reviewer 1: Comments and Suggestions for Authors

Abstract: line 14: please rewrite the 1st sentence or correct it accordingly: Alkaline preteatments are considered highly effective for the separation of different components of lignocellulosic biomass.

Abstract: line 18: typing error: high-value.

Abstract: line 19: operating of what? (Subject missing).

Abstract: needs to be rewritten as there is not results mention in it.

The typographical errors have been corrected and the recommendations have been introduced in the abstract of the manuscript. See the abstract.

Batter to write keywords in alphabetical order.

Keywords: should be different from the title so that your article may have more chance of access or search.

Thank you for your recommendation. See the keywords section.

Citation 14: climate allowing plants like Robinia pseudoacacia, Ulmus pumila, Eucalyptus sp.
and/or Populus sp. to grow.

Citation 20: typing error: Among.

Citation 22-25: typing error: disadvantages.

Citation 26-27: batter to write pretreatment rather than treatment.

Add Citation: A. García et al., 2011 (30) right after the name, mentioned.

All comments on previous citations in the manuscript have been corrected.

In last paragraph of introduction part: There are also no bibliographic references exploring its utilization for the simultaneous valorization of the hemicellulosic liquid and energy application of the solid residue.

Please rewrite this sentence “ as according to authors knowledge”………..  However, there has been enough work done on hemicellulosic liquid to produce value added products (Tareen, A. K., Punsuvon, V., & Parakulsuksatid, P. Conversion of steam exploded hydrolyzate of oil palm trunk to furfural by using sulfuric acid, solid acid, and base catalysts in one pot. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 1-12. doi:10.1080/15567036.2020.1741733).

The last paragraph of introduction has been rewritten to clarify the originality and scientific novelty of this work. You can see this paragraph underlined in blue, because we have added your and the other reviewer’s recommendations.

Materials & methods: 2.1: utilized was a wood from...

Materials & methods: 2.1: second sentence seems to be un-necessary.

Materials & methods: 2.1 min-1

This analysis was conducted using high-performance liquid chromatography (HPLC) with an AMinex HPX-87H ion-ex-change column at 30 ºC as the stationary phase and 0.005 M H2SO4 at a flow rate of 0.6 mL min-1 as the mobile phase. Please add reference for HPLC conditions

Materials & methods: 2.2: As this is a multivariate modeling approach,

Material & methods: Plagiarism is very high in this part. Please reduce it.

All typographical errors have been corrected, and the reference to the HPLC conditions has been added. Regarding plagiarism, as you mentioned, it is high in the methodology section. We used the Turnitin program provided by the University of Huelva to analyze such plagiarism. It is observed that most of the plagiarism is related to equations, acronyms of standards, statistical expressions, or combinations of 2-3 words, which cannot be altered.

Result & discussion: 3.1: typing error: 67.5% if the total biomass.

It is a typographical error; we have corrected it in the manuscript.

Result & discussion: The amount of lignin remaining in the solid was also interest. Cold alkaline extraction partially delignifies the raw material, (It would be better if you could mention the delignification in percentage on dry weight basis or weight weight basis? By explain how much of lignin has been removed using your method? Additionally, also mention the delignification mechanism using that method you have used)?

The next paragraph has been inserted in the manuscript, page 6:

The values in the table are expressed as a percentage of each polymer in the initial raw material. They could be converted into percentages relative to the raw material by multiplying the value by the corresponding amount in the initial raw material and dividing by 100. However, if this value is divided by the yield and then multiplied by 100, it would represent the percentage of the polymer relative to the solid phase.

 Result & discussion: 3.1: Constantí et al. 1998, Ebringerová et al. 2010.: Add Citation right after the name, mentioned. (throughout the manuscript).

It has been corrected throughout the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In my opinion, the topic of the manuscript has the potential to fit within the scope of the journal. The experimental part is, in my opinion, clear, and the modelling is interesting for biomass valorisation. However, I advise major revision. I recommend improving the literature in the introduction and improving how to report the references in the text.

Abstract, Line 1: “the separating the differents….”(remove “s” in “differents”) or write  “the separation of different…”.

Abstract Line 2: “These pretreatments exhibit minimal interaction with hemicelluloses…”. Some alkaline pretreatments at high temperatures and/or high alkali contents can remove high quantities of hemicellulose. I recommend to reformulate the sentence.

Abstract, Line 7: “Hihg-value products”.

Abstract, Last line: I suggest to remove the word “lower”.

Introduction, Page 2, Line 26: Based on the comment in Abstract Line 2, I suggest adding the main disadvantage of alkaline treatments at too high temperatures or too high concentrations of alkali, the degradation of three biopolymers (lignin, hemicellulose and partially cellulose) which allow obtaining fibres for papermaking but it limits the use of hemicellulose for high-value products. In my opinion, it will help the reader to understand why cold alkaline extraction works. I suggest adding literature.

Introduction, page 3: “The combination…not referenced…”. I found two articles: “Recovery of xylan from Acacia mearnsii using ultrasound-assisted alkaline extraction” DOI: https://doi.org/10.1002/bbb.2491.

“Optimisation of Alkaline Extraction of Xylan-Based Hemicelluloses from Wheat Straws: Effects of Microwave, Ultrasound, and Freeze–Thaw Cycles” Polymers 2023, 15(4), 1038; https://doi.org/10.3390/polym15041038

Xylan is a component of hemicelluloses. I suggest discussing these articles to specify the novelty of the proposed manuscript.

Introduction, end of the section: I suggest introducing that a work of modelling and optimisation by multiple regression is performed. Describing that this approach is useful and widely used for optimising biomass and waste stream valorisation. I advise adding literature. I suggest:

Tofani, G., Cornet, I. & Tavernier, S. Multiple linear regression to predict the brightness of waste fibres mixtures before bleaching. Chem. Pap. 76, 4351–4365 (2022). https://doi.org/10.1007/s11696-022-02181-5

Biomass to energy: a machine learning model for optimum gasification pathways, DigitalDiscovery,2023,2,929–940, DOI: 10.1039/D3DD00079F

Results and discussion, Page 5, from Line 19: add in the text the reference number to the references Constantí et al. 1998 and Ebringerová et al. 2010.

Results and discussion, Page 7, Line 1: Please be consistent with the references. For example, the reference [53] is not reported in the text of the manuscript (Carvalho et al. 2016 is named, but it is not reported as [53]). The same for Fernández et al. 2020. Please check the entire text.

Results and discussion, Page 7: I suggest to define the term “structural components”.

Results and discussion, Page 9: “García et al. 2013, and Carvalho et al. 2016”, it is necessary to add the reference number. Please check the entire text.

Results and discussion, Page 13: “…highest lower heating values…”. This definition is not clear to me. Can you please clarify?

Comments on the Quality of English Language

I found some minor errors in English. I reported them in the comments and suggestions for the authors.

Author Response

Thank you for your time and comments. The changes made to the manuscript corresponding to your feedback are underlined in green. In addition, the answers to each point are shown in this document in boldface type.

Reviewer 2: Comments and Suggestions for Authors

In my opinion, the topic of the manuscript has the potential to fit within the scope of the journal. The experimental part is, in my opinion, clear, and the modelling is interesting for biomass valorisation. However, I advise major revision. I recommend improving the literature in the introduction and improving how to report the references in the text.

Abstract, Line 1: “the separating the differents….”(remove “s” in “differents”) or write  “the separation of different…”.

Abstract Line 2: “These pretreatments exhibit minimal interaction with hemicelluloses…”. Some alkaline pretreatments at high temperatures and/or high alkali contents can remove high quantities of hemicellulose. I recommend to reformulate the sentence.

Abstract, Line 7: “Hihg-value products”.

Abstract, Last line: I suggest to remove the word “lower”.

Your suggestions have been entered in the abstract, you can see the changes underlined in green. In addition, the line 2 of the abstract has been rewritten.

Introduction, Page 2, Line 26: Based on the comment in Abstract Line 2, I suggest adding the main disadvantage of alkaline treatments at too high temperatures or too high concentrations of alkali, the degradation of three biopolymers (lignin, hemicellulose and partially cellulose) which allow obtaining fibres for papermaking but it limits the use of hemicellulose for high-value products. In my opinion, it will help the reader to understand why cold alkaline extraction works. I suggest adding literature.

The second line of the abstract has been rewritten to clarify the distinction between hemicellulose extraction efficiency and the absence of hemicellulose modification or degradation.

Introduction, page 3: “The combination…not referenced…”. I found two articles: “Recovery of xylan from Acacia mearnsii using ultrasound-assisted alkaline extraction” DOI: https://doi.org/10.1002/bbb.2491.

“Optimisation of Alkaline Extraction of Xylan-Based Hemicelluloses from Wheat Straws: Effects of Microwave, Ultrasound, and Freeze–Thaw Cycles” Polymers 2023, 15(4), 1038; https://doi.org/10.3390/polym15041038

Xylan is a component of hemicelluloses. I suggest discussing these articles to specify the novelty of the proposed manuscript.

The last paragraph of introduction has been rewritten to clarify the originality and scientific novelty of this work. You can see this paragraph underlined in blue, because we have added your and the other reviewer’s recommendations.

Introduction, end of the section: I suggest introducing that a work of modelling and optimisation by multiple regression is performed. Describing that this approach is useful and widely used for optimising biomass and waste stream valorisation. I advise adding literature. I suggest:

Tofani, G., Cornet, I. & Tavernier, S. Multiple linear regression to predict the brightness of waste fibres mixtures before bleaching. Chem. Pap. 76, 4351–4365 (2022). https://doi.org/10.1007/s11696-022-02181-5

Biomass to energy: a machine learning model for optimum gasification pathways, DigitalDiscovery,2023,2,929–940, DOI: 10.1039/D3DD00079F

Thank you for your suggestion, it has been entered into the manuscript.

Results and discussion, Page 5, from Line 19: add in the text the reference number to the references Constantí et al. 1998 and Ebringerová et al. 2010.

Results and discussion, Page 7, Line 1: Please be consistent with the references. For example, the reference [53] is not reported in the text of the manuscript (Carvalho et al. 2016 is named, but it is not reported as [53]). The same for Fernández et al. 2020. Please check the entire text.

Results and discussion, Page 7: I suggest to define the term “structural components”.

Results and discussion, Page 9: “García et al. 2013, and Carvalho et al. 2016”, it is necessary to add the reference number. Please check the entire text.

Results and discussion, Page 13: “…highest lower heating values…”. This definition is not clear to me. Can you please clarify?

 All references have been reviewed, and refence numbers have been added.

Structural components refer to the main fractions of lignocellulosic biomass, namely cellulose, hemicellulose, and lignin. This information has been incorporated into the manuscript after the term is introduced (page 7).

To enhance reader understanding, a definition of lower heating values has been included. This clarification is provided in the manuscript (Page 11).

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors replied to the comments. I have only one comment:

Page 3, blue part: "In this work, we incorporate the specificity of a cold alkaline treatment. The combination...". I advise modifying it: "In this work, we combined a cold alkaline treatment with ultrasound technology. This approach..."

Comments on the Quality of English Language

Only one comment was reported in the comments for the authors.

Author Response

Dear Reviewer.

Thank you for your careful review of our manuscript, and we appreciate your constructive comments. We have carefully considered your suggestion regarding the aim on Page 3.

Original Text:

"In this work, we incorporate the specificity of a cold alkaline treatment. The combination..."

Revised Text:

"In this work, we combined a cold alkaline treatment with ultrasound technology. This approach..."

You can see this change highlighted in green on page 3.

We have implemented the recommended modification to enhance clarity and precision in describing the aim. If you have any further suggestions or concerns, please don't hesitate to let us know.

Thank you once again for your valuable feedback.

Sincerely,

Susana Lozano Calvo,

Corresponding author

University of Huelva

Susana.lozano@diq.uhu.es

Author Response File: Author Response.pdf