Green Development of Natural Fibre-Based Paper Mulch from Recyclable Cow Dung and Flax Straw Waste

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. Appropriate papers in this field (recovery of cellulose fibres from vegetation digested and excreted by animals) must be reviewed and cited. 

2. The ecological problems are not solved as claimed because there is little mention of the treatment of the waste that is generated in the process.

3. Whilst the analytical techniques used is good, the economic case is not made (given the waste streams that are created).

4. The analytical techniques and the results obtained must be compared with other publication that deal with this subject.

5. Claiming that this is a Circular process need to be demonstrated.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

I reviewed the manuscript titled “Green Development of Natural Fibre-Based Paper Films from Recyclable Cow dung and Flax Straw Waste”. Despite the interesting and promising topic, the manuscript left a poor impression.

First and foremost, the authors need to clearly explain what they mean by 'paper films'. I have never heard it before. I searched on google scholar and found almost no mentions of 'paper films'. It is quite confusing when from the beginning of the article you have no idea about the material discussed. What it exactly is, according to the authors?

Additionally, the text needs proofreading and language improvement. Other comments are provided below.

Entire manuscript. The reference formatting lacks the brackets.

Line 18. Isn't newton per square meter (N/m²) the unit of tensile strength?

Lines 20-22. It would be better not to use abbreviations in the abstract (AKD). Further in the text, there is no decryption for a number of abbreviations, including CDPF, MPF, etc. I can guess what is it, but should I?

Lines 20-22. Try paraphrasing this sentence to make it clearer.

Line 55. The clarity of the information attributed to reference [12] is insufficient. Typically, when authors insert a reference in the middle of a sentence, it pertains specifically to the mentioned aspect. In this instance, I read this as [12] is associated with air quality solely, leaving the numbers in the preceding sentence (definitely requiring citation!), as well as groundwater pollution and ecological balance in the instance sentence unsupported.

Line 59. What few reports? Please list (cite) them too.

Line 67. Italic in a Latin name is missed.

Line 71. The term 'corrosion resistance' is not suitable. Corrosion is a phenomenon associated exclusively with metals.

Line 84. Before claiming low cost, it should be calculated, shouldn't it? When I see a comparison of laboratory-made techniques with an industrial one (petroleum-made PE), I have very serious doubts about its real 'low cost'.
It is low comparing to what? To the industrially produced PE films, which costs almost nothing? Understand me right, I vote for all the new laboratory-made green improvements and sustainability. But the authors should be very careful with terms they use to emphasize the impact of their technology. 

The same goes for 'pollution-free'. To be honest, as one ecologist to another, can we say that any technology can be pollution-free? Here, it looks a bit like greenwashing, although I believe it was not in purpose.

Line 87. "High-quality organic fertilizer" - was it proved in the study or just a prediction?

Line 90. The phrase "protect the ecological environment" looks redundant

Lines 100-102. Please, use the IUPAC names of the organic reagents. Brutto formulas says nothing to the reader, that is why they are not commonly used in organic chemistry.

Line 109. method... method... method

Line 116. Which exactly neutral detergent was used?

I would recommend proofreading of 2.2.2 for the aim of improving the clearness. For now, I failed to comprehend the connection of the beating degrees (lines 142-143) and in what proportions they were mixed with each other in the machine. Were the dung and the straw beating separately or together? If together (how I imagine), then how you measured the beating degree of each type of material? 

Lines 134-135. Do I understand correctly - the dung was used without any pretreatments from the researchers? It was just "cleaned from soil and sand" (see line 94). It doesn't seem correct to call the processes of digestion inside the cow a pretreatment of the dung for pulping. It is just my opinion...

Line 143. Please provide clarification regarding the meaning of "the paper basis weights of 50, 60, 70, 80, 90g". What exactly was used as paper basis? Are those g - grams per m² (grammage of the papersheets)? 
It would be beneficial to rephrase the entire sentence for improved coherence. Is the sentence referring to the composition for film preparation? Note that the dung is in SR, the paper basis (whatever it means) is in g, while the straw is in percentage... The current formulation appears inconsistent. It would be better to provide a table for the content of the ingredients for all the samples discussed.

Flow chart (fig 2). Why is it a paper film? It is an ordinary handsheet of paper, isn't it?

Line 157. Decrypt the abbreviation AKD and provide the brand of the lotion and initial percentage of AKD in it (if possible).

Line 163. Typically, FTIR is used to determine not chemical structure of the material, but rather its functional group content.

Line 164. Provide the country of FTIR spectrometer's origin.

Lines 170-171. Check the sentence. The terms "calculation formula", "equation", and "empirical formula" are referred to one thing. Also, it would be better to cite the source of this formula. 

Line 177. Gold spray? It seems this part lacks the details. The same in 2.2.4, 2).

Line 268. Are flax fibers representing amorphous structure? It would be better to provide the crystallinity for both initial materials too.

Lines 307-309. Paraphrase the sentence.

Line 350. Nowhere in the article is the Kaiser method described or even mentioned, except for in the abstract.

Lines 358-363. Even if the drying temperature is lower than the decomposition temperature, it doesn't necessarily mean that no damage or reactions occur. To clarify this fact, it is advisable to perform a comparison between the FTIR spectra of the pulp and the handsheet prepared from it.

Line 368. Is 'paper membrane', according to the authors, the same as paper film (whatever it means)?

Subsection 3.4.1. There is nothing new that AKD coating makes paper hydrophobic. I suppose it is its main purpose, isn't it? It is recommended to reduce the amount of text in this section. Briefly mention that the coating performs its function, provide the measured angles. Figure 6 can also be condensed, as a and b depicts approximately the same as c and d.
It would be interesting to compare the angles for the studied samples and ordinary papersheets (without the dung and flax straw) with the same grammage. 

I don't understand how paper sheets (even AKD coated) can replace transparent polyethylene mulching film. What specific effect is expected from your so-called paper films? The greenhouse effect, which is crucial, as far as I understand, will not be present. Is it about a shading effect? But then, this should have been mentioned in the introduction.

What is the purpose of making this coating impermeable to water?

Lines 408-410. Please give examples why/when/how water resistance can be beneficial for the climatic conditions and production environment in the context of agriculture. As far as I understand, not water resistance is responsible for a microclimate under the PE film.  

The XPS section (3.4.3) requires improvement in the discussion of the results, as well as general proofreading.

Line 440. Check the formula of AKD: there are C=O and C-O presented. And all fiber components do contain C-C and C-H.

Line 443. What can be a source of N in the flax straw?

Lines 445-446. Paraphrase the sentence.

3.4.4. When the numbers are organized in a table, it is so much easier to comprehend them and compare. 

In general, since the authors propose their so-called paper film instead of PE films it would be interesting to compare their basic properties. 

Lines 464-466. I am looking at the formula of AKD (https://en.wikipedia.org/wiki/Alkyl_ketene_dimer#/media/File:AKDstructure.png) and I can't see any groups which could react with carbonyl groups of the fibers (forming covalent bonds) without special conditions. Can the authors provide some examples of such reactions?

Line 478. And how it will affect the proposed biodegradability of the material?

Fig. 8. What is the difference between a and b; c and d?

Line 485. What exactly do the authors mean by "film-forming properties"?

Comments on the Quality of English Language

The language is understandable, although there are many instances of grammatical and punctuational problems: "paper film takes a vital role in future", "livestock dung consists plenty of fibres, especially in cow dung", "the mixed pulps exist cellulose I, cellulose II and amorphous structure", "the AKD-coated paper film hydrophobic properties", etc.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript titled “Green Development of Natural Fibre-Based Paper Films from Recyclable Cow dung and Flax Straw Waste” by Cao, X.; et al. is an original scientific work where the authors study how producing blends of flax fibers with cow manure enhances the formation of paper films with suitable properties for their use minimizing the use of fossil fuel derived products. The authors employed many complementary techniques such as tensile test, scanning electron microscopy, FTIR, XRD and TGA to fully characterize the examined paper films

However, it exists some points that need to be addressed (please, see them below detailed point-by-point) to improve the scientific quality of the submitted manuscript paper before this article will be consider for its publication in Agronomy.

1) KEYWORDS (OPTIONAL). The authors should consider to add the term “plant-based fibres” in the keyword list.

 

2) INTRODUCTION. “Film mulching is an essential (…) areas 1” (lines 29-30). Please, the authors should place the reference citations between brackets. This comment should be taken into account for the rest of the main manuscript body text.

 

3) “Traditional plastic mulch film is prepared using polyethylene (PE) (…) caused severe environmental problems (…) damages soil structure, affects crop water and fertilizer absorption, hinders crop root growth, and causes soil compaction” (lines 36-40). Could the authors provide some quantitative information about the non-desirable effects caused by the used of fossil fuel based materials and their degradation conditions? [1]

[1] https://doi.org/10.1016/j.ecoenv.2022.113933

 

4) “The accumulation of cow dung generates greenhouse and foul gases (…) disrupting ecological balance” (lines 54-56). Please, the authors should furnish the chemical nature of the GHG formation and some quantitative details about their negative impact on the nature.

 

5) “Currently, cow dung is still used for fertilization, fermentation and there are few reports on its application in other fields” (lines 58-60). Here, it may be advisable to mention the rich content of phosphorous [2] which makes possible the use of cow dung in the aforementioned applications mentioned by the authors.           

[2] https://doi.org/10.3390/agronomy11081483

 

6) MATERIALS AND METHODS. “Cow dung (…) pur-chased from (…)” (lines 94-95). Please, the authors should erase the hyphen placed in the term “purchased”. Then, the significant figures should be homogenized along the manuscript text (e.g. “solid content 15±0.5% in line 102).

 

7) Figure 1 (line 111). What are the reaction yields associated to each indicated process? This information should be devoted in the main manuscript body text. Then, did the authors observe any degradation stability issue in any of these above described process steps? In case affirmative, a brief statement should be provided in this regard.

 

8) “2) SEM analyses of paper film samples (…) All samples were treated with gold spray before detection” (lines 184-187). Did the gold sputtering step negative interfere in the data interpretation of the examined film samples (e.g. by enlarging their critical morphology dimensions)? In case affirmative, what strategy was used by the authors in order to minimize this detrimental effect.

 

9) RESULTS AND ANALYSES. Figure 3 (OPTIONAL). Could the authors homogenize the scale bar of the shown SEM images (panel e with respect to panel c and d)? This will greatly benefit to the potential authors to better compare the analogies and differences between the different examined conditions. Same comment for the Figure 5, panels a-d (line 387).

 

10) “Therefore, (…) addition of flaw straw fibres has a more significant improvement in the strength of the paper film” (lines 367-370). Here, even if I agree with this statement furnished by the authors it may be opportune to highlight the pivotal role of the interfacial adhesion forces exerted between flax fibers (with rich-content of cellulose) and the matrix of interest [3]. For this reason, flax offers better performance in comparison to other lignified plant fibers like jute or kenaf.

[3] https://doi.org/10.3390/ma16062440

 

11) Figure 6, panel c (line 411). The standar deviation (SD) bars should be added to the depicted contact angle measurements carried out for both films according to the population size gathered by the authors.

 

12) CONCLUSIONS. This section perfectly remarks the most relevant outcomes found by the authors in this research. The authors should add a brief statement to discuss about the future line actions to pursue this research. Finally, the references are in the proper format of Agronomy journal (No actions are requested from the authors).

Comments on the Quality of English Language

The manuscript is generally well-written albeit a final check it would be desirable in order to polish final details.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, thank you for thorough answers, you did a great job.

I am generally satisfied with the quality of the manuscript now, however, in line 80, 'corrosion resistance' still remains.

In both line 72 and line 383, it is written 'rapid-KO then method'. Correct name is Rapid-Kothen method.

Also, please correct the description of the methods applied. E.g., in lines 199-202 (and in other places), the description now is like in a manual for students: "place the sample, turn on the device". The imperative mood is inappropriate in the article. Just describe how it was done, without abundant details about pressing the buttons and turning the device on. 

My question about film-forming properties was not if/why cellulose can form films. I know that well :) The problem was that your material is not a film, it is a paper, so, it is not clear enough why the film-forming properties are mentioned (lines 258-259). 

Line 101. "the product will be a high-quality organic fertilizer". If, according to your answer, it is a prediction, it should be "the product can be a high-quality organic fertilizer", isn't it?

Author Response

请参阅附件。

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The authors did a great effort to cover all the suggestions raised by the Reviewers. For this reason, the quality of the scientific manuscript was greatly improved. I warmly endorse the publication of this work in Agronomy journal.

Author Response

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Author Response File: Author Response.docx