Emissions and Fire Risk Assessment of Nitrocellulose as a Sustainable Alternative in Pyrotechnic Compositions

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Dear authors, thank you for the updated version of the manuscript. I think it is possible to proceed for publication

Author Response

Comments: Dear authors, thank you for the updated version of the manuscript. I think it is possible to proceed for publication

Response: The authors would like to thank the reviewer for considering that the manuscript presents the necessary improvements for publication.

Reviewer 2 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

The reviewer is satisfied with the changes made.

Author Response

Comments: The reviewer is satisfied with the changes made.

Response: The authors would like to thank the reviewer for considering that the manuscript presents the necessary improvements for publication.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

This work investigated the use of nitrocellulose as a substitute for traditional powders in pyrotechnic composites with the aim of evaluating its viability as a more sustainable and safer alternative. The results were obtained through thermogravimetric analysis, mass spectrometry and experimental emission tests. This work is well written.

 

1.       The cost of the substitute was not discussed.

2.       How is the safety of this substitute?

3.       Please check the units in Table 7.

4.       The author should submit a clean version of your manuscript.

Author Response

Responses to the reviewer's comments are included in the attached Word document.

Author Response File: Author Response.docx

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please find the comments of the reviewer in the Word document. There are serious concerns about the scientific novelty and the logic of this manuscript.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

See Word document

Author Response

Please find attached our response to your comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, thank you very much for your work. The scope is interesting, but I have to request a verification of the paper's claim and additional improvements before continuing with its revision.

In the case study, the authors want to propose nitrocellulose with 12.6% nitrogen content as a substitute of black powder for aerial fireworks. Actually, there is no proof that the setup proposed by the authors would function for an aerial firework. As the same authors stated, aerial fireworks require to be lifted up to a certain threshold, while nitrocellulose is used for indoor fountains, where no great lifts are required. In my opinion, the authors should at first discuss the efficacy of nitrocelluose as a black powder substitute for black powder. According to my knowldege, I'm afraid that 12.6% cellulose would not be sufficient to properly lift an aerial firework. Also, The choice fo subsitituing 1:1 the mass of black power with nitrocellulose should be discussed.

In addition, it would be nice if the authors could merge together the different aspects of the paper: the author propose a theoretical comparison of total emissions between aerial fireworks from a real case study and by imposing a substitution of . Then an experimental comparison of emissions from fountains made of nitrocellulose and perchlorates is presented, Finally, a risk assessment on nitrocellulose vs. black powder handling is reported.  The three topics are unmatched in the current work, they appear as part of different works.

Also, theoritcal predicitons between blackpowder and nitrocellulose are not so positive: it is true that CO2 emissions are reduced, but CO is an effective pollutant (and it partially converts to CO2 overtime), NO2 is also an hazardous gas.

Comments on the Quality of English Language

Minor corrections are required, English is fluent

Author Response

Please find attached our response to your comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

 

The paper describes emissions and assessment of nitrocellulose (NC) as a substitute for black powder (BP) and KClO₄ in firework compositions. The paper is well-written and attempts to convince the reader that substituting NC for BP and/or KCLO4 would be environmentally advantages. Some to the risks associated with this substitution are also addressed. However, the authors failed to comment on confinement issues which may cause significant safety issues if NC is substituted for BP. Would the confining shells need to be modified since the reactivity of NC (or smokeless powder, SP) is significantly higher than BP? This topic needs to be addressed. A good example in the literature can be found in Propellants Explos. Pyrotechn. 46, (2021) 484-493. The cover of this issues shows a failed BP gun when  SP was substituted for BP. The readers should be cautioned that there may be confinement modifications and/or quantity modifications if the substitution is made.

 

There are a few minor issues that I thought should be made. For example, the material used in the TGA and DTA curves in Fig. 4 should be included in the caption (e.g., Nitrocellulose). It would also be interesting to see a plot of the BP TGA/DTA on the same graph. Other than that, I thought the paper read well and would be a nice contribution to the literature.

Author Response

Please find attached our response to your comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

CO's half-life in the atmosphere is about three months [12], allowing it to slowly oxidation to form CO2 and contribute to the formation of tropospheric ozone [13], [14].

....allowing it to slowly oxidise......

According to [23], measurements 

Please mention the authors of [23] in a proper citation.

but none of them carries out

Replace 'carries' with 'carried'.

n environmental comparison with traditional powder by mass spectrometry.

Are the authors sure about this statement? See for instance:

Dahl, D. B., & Lott, P. F. (1985). The differentiation of black and smokeless gunpowders. Analytical Chemistry, 57(3), 446A-454A.

Dahl, D. B., & Lott, P. F. (1987). Determination of black and smokeless powder residues in firearms and improvised explosive devices. Microchemical journal, 35(1), 40-50.

It is assumed that the same amount of nitrocellulose is sufficient to replace black powder and achieve the same explosion heights, due to a 1:1 substitution ratio make easier to compare the environmental footprint, which is the main objective.

.....ratio making it easier to ....... 

based on its main products [2], [3], [52], [53], could be defined as:

Please replace the 'could' with 'can'.

Please note that the stoichiometry of reaction equation 2 is incorrect.

the only article for sale to the general public

Please add an 's' to 'article'.

The gas analyser belongs to the Laboratory of Gas Detectors of the Laboratorio Oficial J.M. Madariaga (LOM), in which calibrations of devices for the detection and measurement of gas concentrations are usually carried out.

Please delete this sentence. For a scientific article it is irrelevant who owns the analyser.

With respect to Table 4. The authors mention in the rebuttal that they have included the references to show where and how these substances were determined. The reviewer was unable to identify these references. 

It has to be pointed out that an decomposition reaction should not take place in an inert atmosphere, nevertheless, in this case an decomposition is indeed produced under argon atmosphere. Previous studies reported thermogravimetric curves for nitrocellulose in  which the inert atmosphere leads to a decomposition in which a progressive mass loss is  produced [65], however, as previously mentioned, in the present curve there is a fast oxidation which is more consistent to a combustion than a thermal degradation.

With all due respect: nitrocellulose is a well known explosive/energetic material. As it carries its own oxygen and some of the chemical bonds are not very strong, it is an inherent unstable substance - these are the exact requirements for an energetic material. As such it NEEDS to react under even an inert environment. Any comment to the contrary is strange. Furthermore, by claiming that the curve does not look like thermal decomposition may show to people knowledgeable in the field, that the state-of-the-art of nitro-cellulose reactions is not known to the authors. This may reflect oddly on the authors.

This fact can be explained due to the oxygen released during the thermal degradation of the sample. Indeed, the oxygen produced has been recorded during the mass spectrometry test, as shown in Figure 5, represented by amu 32. This fact shows the influence of the heating rate in the reaction [66], [67], and further studies should consider focusing on this parameter especially when addressing the FTIR assessment in order to clearly define each component released during the reaction.

There is a whole community that is involved in nitrocellulose with their own conference every two years. This aside from a (substantially larger) community that is focused on thermal analyses. Stating that the heating rate is of influence on the results is very well known and very well described in literature and even textbooks. Furthermore, stating that you have found oxygen sounds a bit odd. The authors present information that is well known in the community. You are stating the obvious here.

This exothermic stage continues up to 400oC when the DTA begins decrease again. This fact can be explained as once the reaction is completed, and the heat is released the ashes remaining does not undergo any further reaction, and only heat absorption takes place. Indeed, if the mass variations after 200oC are considered, it can be noticed that only small variations take place as only ashes remain.

As mentioned with the previous version as well as above - you are really stating the obvious. Be aware how this reflects on you as a scientist.

therefore the fact that the first step found in black powder TG curves does not appear in the nitrocellulose thermal degradation can be explained as the nitrocellulose composition does not include sulphur compounds. 

See comment with previous point and also some comments above. The authors are stating the obvious and make it look like a new scientific discovery has been made. This looks very odd indeed.

For the remainder of this section the reviewer will not comment anymore. It is the choice of the authors and the reviewer can only advise.

Indeed, previous research already reported improvements in nitrocellulose thermal stability by increasing the moisture content [69]. Nevertheless, if moisture content is increased further research should focus on the determination if this increase is adequate for every phase of use and handling of nitrocellulose as the moisture content significantly deteriorates pyrotechnic devices [79], [80].

The reviewer can give you the answer already as this is well known in the field already - the last thing you wish to do in actual devices like fireworks is to add moisture. Absolutely out of the question one will do that.

The present study has investigated the use of nitrocellulose as a substitute for tradional powders in pyrotechnic compositions with the aim of evaluating its viability as a more sustainable and safer alternative. The results obtained through thermogravimetric analysis, mass spectrometry and experimental emissions tests have provided valuable information on the advantages and limitations of nitrocellulose compared to traditional compositions.

Please replace with:

The use of nitrocellulose as a substitute for traditional powders in pyrotechnic compositions was investigated with the aim of evaluating its viability as a more sustainable and safer alternative. The results were obtained through thermogravimetric analysis, mass spectrometry and experimental emission tests. 

It was shown that nitrocellulose can significantly reduce greenhouse gas emissions, particularly carbon dioxide, by 42% compared to black powder. Although it is known that the reduction of carbon dioxide is only possible by increasing carbon monoxide, this finding highlights the potential contribution of nitrocellulose to climate change mitigation in the context of fireworks displays. CO emissions need to be addressed in future research to optimize nitrocellulose formulations and minimize their adverse environmental impact.

Please replace with:

It was shown that nitrocellulose can significantly reduce greenhouse gas emissions, compared to black powder. 

(the rest of the original text is not a conclusion, but are statements).

From the paragraph that follows, please delete these sentences:

The composition under study is already used as a substitute for perchlorates in certain pyrotechnic devices, so its application to a larger number of devices is environmentally feasible. 

The pargraph that follows (On the other hand....) is to be completely removed. These are not conclusions but statements and some of the statements are open doors - one can write them down without doing any analysis.

The same applies to the last paragraph. Please remove.

 

sd

Comments on the Quality of English Language

See comments above

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, thanks for clarifying many issues arose in the first revision. After reading the updated paper, I would ask you some additional clarification:

1. The authors made clear the limitations provided by the comparison, indicating the extent of the 1:1 black powder/nitrocellulose substitution. However, I would suggest to line the headings of chapters 2 and 3 for a better clarity: chapter 3.2 compares nitrocellulose with black powder, but then there is a reference with perchlorates, which is the following aspect studied. Please keep the following labeling: 2.1-3.1: comparison of balck powder vs. nitrocellulose in the Macy's Independence day, 2.2-3.2 experimental tests with fountains, 2.3-3.3, thermal analysis, 2.4-3.4, HAZOP. This will increse clarity while reading.

2. Lines 115-116, I think that a more suitable claim could be ".. the present study aims to show the advantages of the introduction of nitrocellulose..."

3. Please use full form of acronyms at their first appearance (GHG)

4. For what concerns the thermal analysis, why did the authors chose DTA instead of DSC? DTA often leads to imprecise results. Also, DTA test conditions were not clarified (only TGA is clearly stated). 

5. The authors provided results for nitrocellulose only. Since the authors used the information deducted from the thermal analysis in the construction of HazOP, same information should be provided for black powder (even from literature).

6. Is it possible to visualize the Annex 1 for the Hazop? Actually I could not find it 

Comments on the Quality of English Language

Minor editing is required. In the novel submission, some sentence is hard to read and should be revised.