Effect of p-TsOH pretreatment on separation of bagasse components and preparation of nanocellulose filaments

The efficient separation of bagasse components was achieved by p-toluenesulfonic acid (p-TsOH) pretreatment. The effects of p-TsOH dosage, reaction temperature and reaction time on cellulose, hemicellulose and lignin contents were studied. Eighty-five per cent of lignin was dissolved, whereas the cellulose loss was minimal (less than 8.1%). Cellulose-rich water-insoluble residual solids were obtained. The degree of polymerization of cellulose decreased slightly, but the crystallinity index (CrI) increased from 52.0% to 68.1%. It indicated that the highly efficient delignification of bagasse was achieved by p-TsOH pretreatment. The nanocellulose filaments (CNFs) were produced by the treated samples. The physico-chemical properties of CNFs were characterized by transmission electron microscopy and thermogravimetric analysis. The results show that the CNFs have smaller average size and higher thermal stability. It provides a new method for CNFs.

Decision letter (RSOS-200967.R0) We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below.
Dear Dr Yao: Title: Effect of p-TsOH pretreatment on the bagasse delignification and preparation of lignincontaining nanocellulose filaments Manuscript ID: RSOS-200967 Thank you for your submission to Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry.
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Once again, thank you for submitting your manuscript to Royal Society Open Science and I look forward to receiving your revision. If you have any questions at all, please do not hesitate to get in touch. ********************************************** RSC Associate Editor: Comments to the Author: (There are no comments.) RSC Subject Editor: Comments to the Author: (There are no comments.) ********************************************** Reviewers' Comments to Author: Reviewer: 1 Comments to the Author(s) The manuscript entitled" Effect of p-TsOH pretreatment on the bagasse delignification and preparation of lignincontaining nanocellulose filaments" by Yao at el described the use of pTsOH in depolymerization of bagasse. The topic is interesting and can be useful for material chemists. the title says that delignification, but actually it appears to me that depolymerization reaction. Also, the results presented are not clear to some reproduced at other places. Also, need to rewrite many parts of the manuscript. Need to explain what happened to lignin. and many more Reviewer: 2 Comments to the Author(s) In this manuscript, the lignin-containing nanocellulose filaments (LCNFs) was prepared with bagasse which pretreated by p-toluenesulfonic acid (p-TsOH), then CNFs and LCNFs were compared. The study shows that this is indeed a novel and extremely efficient pretreatment method, the LCNFs has higher toughness, smaller average size and higher thermal stability. This work is interesting and inspiring to the field of guiding significance for LCNFs preparation. The followings are the suggestions, 1 In this manuscript, were LCNFs and CNFs prepared in the same way? 2 It is suggested that Fig. 4. and Fig. 5. should be combined together to facilitate the reader's observation. 3 It is recommended to unify the font, such as "℃" in the first paragraph of Section 4.2. 4 Please specify the reason why 80% p-toluenesulfonic acid (p-TsOH) is the optimal condition for the LCNFs production. 5 Are the three factors, the concentration of p-TsOH, temperature and time, worked independently? Please specify the reason why they were studied separatedly. 6 The images of the LCNFs and CNFs were highly recommended to be included in the manuscript.

Author's Response to Decision Letter for (RSOS-200967.R0)
See Appendix A.

RSOS-200967.R1 (Revision)
Review form: Reviewer 2 Is the manuscript scientifically sound in its present form? Yes

Are the interpretations and conclusions justified by the results? Yes
Is the language acceptable? Yes

Recommendation?
Accept as is

Comments to the Author(s) This manuscript is suitable for publication
Decision letter (RSOS-200967.R1) We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below.
Dear Dr Yao: Title: Effect of p-TsOH pretreatment on separation of bagasse components and preparation of nanocellulose filaments Manuscript ID: RSOS-200967.R1 It is a pleasure to accept your manuscript in its current form for publication in Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry.
The comments of the reviewer(s) who reviewed your manuscript are included at the end of this email.
Thank you for your fine contribution. On behalf of the Editors of Royal Society Open Science and the Royal Society of Chemistry, I look forward to your continued contributions to the Journal.

Yours sincerely, Dr Laura Smith Publishing Editor, Journals
Dear Reviewers, Thank you for your letter and for the comments concerning our manuscript entitled "Effect of p-TsOH pretreatment on the bagasse delignification and preparation of lignin-containing nanocellulose filaments". We have studied your comments carefully and have made corrections which we hope could meet your requirements. All changes have been highlighted in the revised version (red highlighting).
Questions you put forward are explained as follows:

Reviewer #1:
The title says that delignification, but actually it appears to me that depolymerization reaction. Also, the results presented are not clear to some reproduced at other places. Also, need to rewrite many parts of the manuscript.
Need to explain what happened to lignin. At present, we are studying the structural changes of lignin during p-TsOH pretreatment. Thank you very much for your valuable comments. It improves the quality of the manuscript. I hope the author's reply can meet your requirements.

Reviewer #2:
A) In this manuscript, were LCNFs and CNFs prepared in the same way?
In fact, most of the lignin and hemicellulose from bagasse were removed by pretreatment with p-TsOH. But the cellulose was also damaged in the process, and some lignin remains in the remaining raw material. Their impact on the preparation of CNFs needs to be assessed. In the same way, pretreated bagasse and bleached bagasse were used to prepare CNFs and the control CNFs, respectively. Thus, the application value of p-TsOH pretreatment in the preparation of CNFs was analyzed. Fig. 4. and Fig. 5. should be combined together to facilitate the reader's observation.

B) It is suggested that
It has been modified as suggested. Fig. 4. and Fig. 5 have been merged. The manuscript has been revised and marked accordingly.
C) It is recommended to unify the font, such as "℃" in the first paragraph of Section 4.2.
The font has been unified in revised version.

D) Please specify the reason why 80% p-toluenesulfonic acid (p-TsOH) is the optimal condition for the LCNFs production.
High performance CNFs need to be produced by p-TsOH pretreatment. This means that the lignin and hemicellulose content in the pretreatment samples should be reduced as much as possible, while the cellulose should be protected during the process. The results showed that the content of lignin and hemicellulose were significantly reduced with the increase of p-TsOH concentration. The concentration of p-TsOH concentration had little effect on cellulose content. The reduction of lignin and hemicellulose was effective when the concentration of p-TsOH exceeds 80%. It also causes waste of chemicals and higher disposal costs. Therefore, 80% p-TsOH is the optimal condition for the LCNFs production. E) Are the three factors, the concentration of p-TsOH, temperature and time, worked independently? Please specify the reason why they were studied separatedly.
The effects of the three factors on the reaction are not independent. The effects of p-TsOH dosage, pretreatment temperature and pretreatment time on bagasse components were analyzed by single factor experiment. The effects of p-TsOH on the main components of bagasse were studied at fixed temperature and time. Then the effect of pretreatment temperature on the main components of bagasse was studied under the optimal p-TsOH dosage. The effect of pretreatment time on the major components of bagasse was analyzed at optimal dosage and temperature. The optimal process of p-TsOH pretreatment was obtained. These three elements also interact in the process of single factor analysis. In the future, their interactions will be studied by response surface design. The process conditions will be further optimized.
F) The images of the LCNFs and CNFs were highly recommended to be included in the manuscript. Figure 4 shows the LCNFs and CNFs images.
As a whole, issues the reviewers suggested are very pertinent, which are very helpful to modified my entire paper and thank you very much again.