A Review on the Lignin Biopolymer and Its Integration in the Elaboration of Sustainable Materials
, Mirko Faccini 1 and Regis Teixeira Mendonça 2,3
Round 1
Reviewer 1 Report
Manuscript ID: Sustainability-1097899
A review on the lignin biopolymer and its integration in sustainable materials
This manuscript is a review on R and D of lignin incorporated materials, such as phenolic resins, epoxy resins, polyurethane foams, carbon fibers, hydrogels, and composites by citing several references. Giving concise information of above R and D fields to the reader is the main task of review manuscript. Therefore, a simple sentence with scientific soundness is very important.
Some major concern and specific suggestions, which must be revised prior to publication are mentioned in the attached pdf file.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 2 Report
I reviewed article entitle “A review on the lignin biopolymer and its integration in sustainable materials”
I think this is an informative work rather than a review article. I would expect much longer introduction in a review article than what the authors have. Lignin chemistry and structure and some other sections are some kind of superficially presented. El Mansouri et al. have one article published, I think it was published in 2006 but not sure, related to lignin based adhesives, I don’t see that work here. I also believe A. Pizzi did some work on utilization of lignin as adhesive to be used in wood based composite manufacture. These are missing in literature cited. Review article is challenging, and one should not miss almost any previous work carried out. I suggest that the authors should revise the manuscript extensively and resubmit their work so that it may attract more attention in enhanced format.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Paper contains comprehensive review not only on the different application of lignin, but also a detailed information about the needed modification methods of lignin to be used for different applications as partial replacement of fossil-based chemicals.
However, the title makes reader to think of comprehensive review of lignin as biopolymer, explaining specific characteristics, however the paper does not give sufficient insight in methods for lignin extraction, including non-commercial methods. Paper contains only general aspects of main industrial technologies in Section 3. More detailed information about non-commercial methods has to be added to show the options. Or title has to be changed giving the correct information about the focus on industrial area only. However, it would contradict with information given further in review, because several non-commercial applications have been described in section 4.
Noticeable difference in manner of presentation of information among sections. Sections 2 and 3 are very general and superficial, while Section 4 explains better and goes into details and gives surnames of separate researches published. Paper has to be reviewed and the style has to be synced across the whole document.
Visualisation of rection mechanisms during extraction of lignin and breakage of lignin bonds would improve the review in Section 3.
Summarising scheme or table for all the lignin applications would improve the readability of review and would make it more attractive to readers in Section 4.
Line 43. 70 million tons per what period of time? A year? A Month?
Line 45. Please review properties listed. Antioxidant is not a property. Antioxidant activity is property. Consider the use of “biodegradability” instead of biodegradable.
Lines 61-82. The addition of picture or scheme of lignin biosynthesis and structure, functional groups etc would improve this section significantly.
Line 100. I suggest replace term black liquor with term pulping/cooking liquor or white liquor here (line 100), because the pH of pulping process is based on the pH and composition of initial solution, which is not black liquor. Solution becomes black liquor only in the end of process, when contains all the extracted substances.
Please, check the language, preferably by native speaker or professional language editor.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Authors did revised article based on the comments and questions of the reviewers.
Reviewer 3 Report
The manuscript has been improved significantly by adding figures explaining structure of liginin, by adding schemes of lignin extraction processes and applications described in manuscript.
Authors have answered and explained all the comments. Additional information has been added to manuscript and improved title has made the concept of the manuscript clearer.
