Degradation of Plastic Materials through Small-Scale Pyrolysis: Characterization of the Obtained Hydrocarbons and Life Cycle Analysis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Degradation of Plastic Materials through Small-Scale Pyrolysis: Characterization of the Obtained Hydrocarbons and Life Cycle Analysis is interesting.

The work presented here is exciting but requires major revisions before it can be accepted for publication. My comments are as follows:

1. What does it add to the subject area compared with other published material? Please add more details about it. (Pyrolysis of waste plastics into fuels and chemicals: A review (https://doi.org/10.1016/j.rser.2023.113799), some works are already reported)

2. Authors need to be more careful about referencing.

 (a) “Therefore, humanity must turn to renewable energy sources or other alternative energies” Please add more than one reference.

(b) “The process used to convert plastics into aromatic oils is based on the pyrolysis of plastics.”- Please add references.

(c) “On the other hand, the catalysts used in the pyrolysis of plastics include metallic oxides and activated clays”- Please add reference.

3.  The author needs to pay attention to the format of the figures, such

(i) Please increase the font size of the Figures 1, 2, 5 & 7

(ii) Please remove the some excel chart boxes from the inside of the figures (Figure 1, 2 & 7)

4. In Figure 3, a is present but b is missing. Please add the caption of b. Please also modify the caption also by separating a, and b.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. The authors developed a good work, the weak point of the manuscript is a lack of deep discussion compared to literature results. The authors should include a table showing what is their best result and compare it with literature results in the background section. 

2. The authors must bring a comparison with literature by data, tables, etc...Some discussion about their results is necessary to answer what is their major contribution to the knowledge in this area. 

3. The author needs to add more recent references (last 10 years).

4. Please verify some typos in the text.

5. Please rearrange the 3. MATERIALS AND METHODS section before the 2. RESULTS section. 

 

Comments on the Quality of English Language

1. The manuscript is well written and the quality of English is acceptable verify some typos in the text.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors This manuscript deals with the degradation of low-density plastic materials via pyrolysis in the presence of zeolite catalysts for energy recovery. This study aims at characterizing aromatic oils, further distilled to produce light hydrocarbons, which are valuable chemicals. Presentation of the content is not well-organized, but confused. The usual sequence of sections should be: Introduction, Materials and method (or Experimental), Results and discussion (or 2 separate sections), Conclusion. The authors must follow this scheme. The level of English is sufficient in my opinion, although I am not a native English speaker.

 

Many papers were published in the recent years on the recovery of plastic waste by thermal and catalytic pyrolysis, and it is not clear in this case which is the novelty and the relevance of the current study with respect to those available in the literature, which are more than those mentioned by the authors.   Introduction Some data regarding plastic waste are referred to several years ago. Data must be referred to more recent times. As stated previously, the authors must state clearly (in the second part of this section) the novelty and the relevance of the current study with respect to those already published.   Experimental Description of the experimental procedures is found, although many details are missed. The sample size used for pyrolysis is not reported.   Results and discussion I don't understand the meaning of using 5 decimals to express energy (see paragraph 2.1., two times). The number of digits must reflect the precision with which the value of a quantity is known. The results obtained seems to be in agreement with some of those available in literature, but no comparison has been made by the authors in this respect. I don't find any sentence provided by the authors in which the relevance of the results obtained is stressed, thus giving an idea of a poor quality (low degree of novelty) of this manuscript.   Conclusions Units for mass is g, not gr. Please, check it and revise. It seems that the results are expected on the basis of the results of previous studies, without any substantial relevance. The contribution of this manuscript to the development of this research topic is very limited.   Reference List The papers cited in the reference list seem to be not enough to give an idea of the current status of the art on this topic. Furthermore, I found several references of journals or references to documents written in Spanish. This could be a problem for readers that are not familiar with this language.
In addition, the format used is not that recommended by the MDPI's journals. Please, check and revise accordingly.

Taking into account all the above mentioned comments, I can't recommend the publication of this manuscript in its present form, and major revision is needed.   On the other hand, minor (but important) changes must be considered in the revision process.

The style used for the title of sections and subsections (with the use of capital letters) is not correct. Please, check the correct style from the MDPI's guide for authors and revise accordingly. Also the form of the text is often incorrect. Please, check the formula of CO2 and put the number in subscript (as usual). Check and revise all details like this. Furthermore, use k for kilo instead of K (not capital letter). Page 4 of 15: The acronym of the equation is Eq. (rather than Ec.). In addition, each equation must be numbered (from Eq. 1 to Eq. 6).
Furthermore, k1...k7 parameters cannot be considered as "rapid", but rate constants, provided that a physical meaning can be attributed to each of them (I am not sure about this). Figure 2, Page 5 of 15: units must not be expressed with dots. So, please, delete dot after min in both plots (X-axes). Page 9 of 15, Section 3 - Materials and methods: The first sentence is incomplete. Some words are missed. Please, check it and rewrite it. Page 12 of 15, paragraph 3.3. Replace Espectroscopy with Spectroscopy.

  I did not find the Authors' contributions, in which each contribution to the development of the manuscript is related to each author. Please, write it according to the MDPI's usual format. Comments on the Quality of English Language

see the Comments and Suggestions for Authors attached above

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Recommendation: Publish as is; no revisions needed.

 

Comments:

After carefully reading the manuscript, I can fully understand the authors' argument and purpose. Thus, I recommend this article for publication without further modification.

 

Author Response

Thank you very much for taking the time to review this manuscript. 

Reviewer 3 Report

Comments and Suggestions for Authors The authors addressed almost all questionable points and the revised version shows a significant improvement in the quality and clarity of presentation. Nevertheless, only some (mainly formal or grammar) changes must be made.    I have listed them as follows.   line 247: Replace "Next" with "Subsequently". line 248: Replace "After" with "Afterwords,". line 254: I suggest adding "and carbon dioxide" after "water vapor". line 271: the content of Goal and Scope Definition seems to be missed. Please, check and revise it accordingly. line 286: In my opinion "according" is more suitable than "regarding". Figure 4: labels of axes are incorrect. The Y-axis needs a "/" that separates the measured quantity from its unity, while units for the Time must be reported without dots. Figure 5: The Y-axis needs a "/" that separates the measured quantity from its unity line 347: Please, delete "°C" after "40". line 348: Please, delete "°C" after "60". Figures 7 and 8: it is better to uniform the style of reporting the measured quantity and its units, always separated by a "/". Furthermore, "-1" of the units for wavelength must be reported in superscript. Table 1: I don't understand the use of a capital letter for toluene. If it is not the case, please delete it and replace it with a normal one. The same situation is found in Tables 3 and 4. Please, add a comment and revise if needed. Figures 9 and 10:  "-1" of the units for wavelength must be reported in superscript. line 444: Please, replace K with k for kilo. Table 5: Please, check the alignment of the data reported in the last column (on the right) and revise them. Line 498: Please, check the correctness of the formula of the catalyst. Maybe a subscript is not correct. Comments on the Quality of English Language

I am not a native English speaker, Nevertheless, I believe some minor editing is required.

Author Response

Thank you very much for taking the time to review this manuscript. 

Author Response File: Author Response.docx