Review Reports - Biodiesel Production through the Transesterification of Non-Edible Plant Oils Using Glycerol Separation Technique with AC High Voltage

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This contribution does quite fit within the scope of the journal.

The article shows findings related to the ideal operating parameters for the trans-esterification of two non-food oils, as well as how these variables affected the characteristics of the biodiesel that was produced

The organization of the article is satisfactory and figures & tables are necessary.

The introduction stated in an organized fashion the goals of the research.

The following issues need to be improved:

Title, in general, reflects the content.

The abstract is informative but is not well structured. It begins (first 7 lines: "The term "biodiesel"...and ponemia oil. ") with a general description more appropriate for the Introduction chapter. The reader is not located where the research was carried out, the period it covered, or the objectives that are proposed. Results are presented "The results showed that the optimal conditions..." and then procedures are presented "A high voltage procedure was used to separate glycerol and biodiesel..." Other results are presented later "The results showed that, for a batch of 15 liters..." etc.

The authors do not provide research highlights, which would offer an overview of their research.

Keywords are proper but it should be placed in alphabetical order and avoid using words that are already in the title.

The material and methods outline properly what was done and how it was done. However, authors should focus more on how the method was used to fulfil the objectives and less on a broadly detailed description of the procedures.

The results are in line with the theme and proposed objectives.

In tables 1, 2 and 3, the numbers after the decimal point must be standardized ( 1, 2 or 3 oof these numbers appear indistinctly)

The discussion is adequate based on the results obtained.

The authors have drawn up acceptable conclusions. However, they should take into account that conclusions should not significantly repeat material from the other sections of the article.

The references are acceptable.

(In the future add line numbers to text to facilitate review)

Author Response

Response to Reviewer 1 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Can be improved	We improved abstract section, all figures, materials and method section, and conclusion section in track change
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Can be improved	We checked the research design in track change
Are the arguments and discussion of findings coherent, balanced and compelling?	Can be improved	We reviewed the all manuscript in track change
For empirical research, are the results clearly presented?	Can be improved	We reviewed the all manuscript in track change
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Can be improved	we modify the conclusion section to remove material

3. Point-by-point response to Comments and Suggestions for Authors

General Comments:

This contribution does quite fit within the scope of the journal.

The organization of the article is satisfactory and figures & tables are necessary.

The introduction stated in an organized fashion the goals of the research.

Response: Thank you for pointing this out.

The following issues need to be improved:

Comment 1: Title, in general, reflects the content.

Response1: Thank you for pointing this out.

Comment 2:

The authors do not provide research highlights, which would offer an overview of their research.

Response2: Thank you for pointing this out. We agree with this comment. In the revised version, we modify the abstract section.

Comment 3:

Keywords are proper but it should be placed in alphabetical order and avoid using words that are already in the title.

Response3: Thank you for pointing this out. We agree with this comment. In the revised version, we modify the keywords.

Comment 4:

Response4: Thank you for pointing this out. We agree with this comment. In the revised version, we modify the material and methods section to fulfil the objectives and less on a broadly detailed description of the procedures.

Comment 5:

The results are in line with the theme and proposed objectives.

Response5: Thank you for pointing this out.

Comment 6:

In tables 1, 2 and 3, the numbers after the decimal point must be standardized ( 1, 2 or 3 of these numbers appear indistinctly)

Response6: Thank you for pointing this out. We agree with this comment. In the revised version, we modify the numbers after the decimal point to be standardized in table 1,2, and 3.

Comment 7:

The discussion is adequate based on the results obtained.

Response7: Thank you for pointing this out.

Comment 8:

The authors have drawn up acceptable conclusions. However, they should take into account that conclusions should not significantly repeat material from the other sections of the article

Response8: Thank you for pointing this out. We agree with this comment. In the revised version, we modify the conclusion section to remove materials.

Comment 9:

The references are acceptable.

Response9: Thank you for pointing this out.

Comment 10:

(In the future add line numbers to text to facilitate review)

Response10: Thank you for pointing this out. In the revised version, line numbers are added.

4. Response to Comments on the Quality of English Language

Point 1: English language fine. No issues detected

We made English editing by mpdi office (English-76206)

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

1. Figures No. 1, 2, 4, 6, 7, 9, 10-16 are very poor quality.

2. For some reason, Section 3.1 "Separation Time" is the very first in Section 3, although the glycerol separation process is carried out after the synthesis of biodiesel fuel and it would be more logical to move this section before 3.4.4.

3. The article is titled "Biodiesel Production Through the Transesterification of Non-Edible Plant Oils using Glycerol Separation Technique with AC High Voltage". I don’t quite understand why there’s a part about the engine here at all?

4. During what reaction time were the results presented in sections 3,4,1 and 3,4,2 was obtained?

5. The article presents the properties of the resulting biodiesel fuel, but does not provide the properties of fuel blends B10, B20, B30. At the same time, the engines use blends rather than pure biodiesel fuel.

My final opinion: the article has 2 not very related sections. One is devoted to the synthesis of biodiesel fuel and the study of its properties and fuel blends obtained with its participation. 2. Dedicated to studying how fuel behaves when burned in an engine.

The article is called “using Glycerol Separation Technique with AC High Voltage”, which is actually devoted to a couple of paragraphs and 1 graph out of 10.

I would recommend that the authors choose one of two options to refine it and rename the article.

Author Response

Response to Reviewer 2 Comments

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Yes	We improved abstract section materials and method section, and conclusion section in track change
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Must be improved	We checked the research design and some words were added to materials and method section in track change
Are the arguments and discussion of findings coherent, balanced and compelling?	Must be improved	We reviewed the all manuscript in track change
For empirical research, are the results clearly presented?	Must be improved	We reviewed the all manuscript in track change
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Can be improved	we modify the conclusion section to remove material

3. Point-by-point response to Comments and Suggestions for Authors

Comment 1:

Figures No. 1, 2, 4, 6, 7, 9, 10-16 are very poor quality.

Response1: Thank you for pointing this out. We improved the quality of Figures No. 1, 2, 4, 6, 7, 9, 10-16

Comment 2:

For some reason, Section 3.1 "Separation Time" is the very first in Section 3, although the glycerol separation process is carried out after the synthesis of biodiesel fuel and it would be more logical to move this before 3.4.4.

Response2: Thank you for pointing this out. We moved Section 3.1 "Separation Time before section 3.4.4.

Comment 3:

The article is titled "Biodiesel Production Through the Transesterification of Non-Edible Plant Oils using Glycerol Separation Technique with AC High Voltage". I don’t quite understand why there’s a part about the engine here at all?

Response3: Thank you for pointing this out. We added the engine performance in this manuscript to support the sustainable biodiesel industry and the sustainability of biodiesel production as the production biodiesel can run engines. Thus under section 3.7. Engine Performance, we addeded” The investigated engine performance with the produced biodiesel to support the sustainable biodiesel industry and the sustainability of biodiesel production as the production biodiesel can run a diesel engine”.

Comment 4:

During what reaction time were the results presented in sections 3,4,1 and 3,4,2 was obtained?

Response4: Thank you for pointing this out. We added stirring time was 60 minutes under graphs of sections 3,4,1 and 3,4,2

Comment 5:

The article presents the properties of the resulting biodiesel fuel, but does not provide the properties of fuel blends B10, B20, B30. At the same time, the engines use blends rather than pure biodiesel fuel.

Response 5: Thank you for pointing this out. The properties of the resulting biodiesel fuel B100 was presented in Table 3 as well as Diesel fuel B0 according to ASTM. However, we did not investigate the combustion and emission characteristics of the produced biodiesel, we only focused on fuel consumption and generated power, thus the properties of B10, B20, B30 were not included due to cost.

Comment 6:

The article is called “using Glycerol Separation Technique with AC High Voltage”, which is actually devoted to a couple of paragraphs and 1 graph out of 10.

I would recommend that the authors choose one of two options to refine it and rename the article.

Response 6: Thank you for pointing this out. We clear the objectives of our research paper in abstract section as follows:

Thus, the research highlights biodiesel synthesis from non-edible plant oils such as pongamia and jatropha using glycerol separation technique with AC high voltage method through the transesterification reaction. In this context, non-edible plant oil has emerged as an alternative with a high potential for making the biodiesel process sustainable. Moreover, the study introduces how fuel behaves when burned in a diesel engine.

4. Response to Comments on the Quality of English Language

Point 1: I am not qualified to assess the quality of English in this paper

We made English editing by mdpi office (English-76206)

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

This paper proposed a production method for a kind of promising biodiesel made from non-edible plant oils such as pongamia and jatropha, as good alternatives to diesel. A revision is required to improve the quality of this article as follows:

1. There are several spoken languages found in this article. For example, it would be better to replace “makeup” with “composition” in the line “Numerous factors, including the quality of the raw materials, the makeup of...” in the second paragraph on Page 3.

2. Please describe the information of fuel injection system in the section of 2.3 measurements.

3. Please describe the details of devices used such as individual brand trademark and specification in the section of 2.4 referring to the description of test bench.

4. Please add the base experimental data injected with diesel alone in Figure 16 and Figure 17.

5. The conclusion is unclear and lengthy. Please summarize the results into several points segmented with paragraphs.

Comments on the Quality of English Language

Minor editing of English language is required

Author Response

Response to Reviewer 3 Comments

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Yes
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Can be improved	We checked the research design and some words were added to materials and method section in track change
Are the arguments and discussion of findings coherent, balanced and compelling?	Can be improved	We reviewed the all manuscript in track change
For empirical research, are the results clearly presented?	Can be improved	We reviewed the all manuscript in track change
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Can be improved	we modify the conclusion section to remove material

3. Point-by-point response to Comments and Suggestions for Authors

Comment 1:

There are several spoken languages found in this article. For example, it would be better to replace “makeup” with “composition” in the line “Numerous factors, including the quality of the raw materials, the makeup of...” in the second paragraph on Page 3.

Response1: Thank you for pointing this out. We replaced “makeup” with “composition.

Comment 2:

Please describe the information of fuel injection system in the section of 2.3 measurements.

Response2: Thank you for pointing this out. We wrote under section 2.4 however, type of injection was direct injection.

Comment 3:

Please describe the details of devices used such as individual brand trademark and specification in the section of 2.4 referring to the description of test bench.

Response3: Thank you for pointing this out. Due to plagiarism behavior, we omitted the details of devices used such as individual brand trademark and specification in the section of 2.4 referring to the description of test bench and the details of the schematic diagram of the tested engine and its specifications are shown by Khalaf et al. [30], who used the same engine in their study.

Khalaf, M.; Abdel-Fadeel, W.; Abd Elhady, S.; Esmail M, F. C. Performance and emissions of a diesel engine fueled with a biofuel extracted from jatropha seeds. International Journal of Applied Energy Systems 2022; 4(2),40-50.

Comment 4:

Please add the base experimental data injected with diesel alone in Figure 16 and Figure 17.

Response4: Thank you for pointing this out. We changed the graphs to include data injected with diesel alone B0

Comment 5:

The conclusion is unclear and lengthy. Please summarize the results into several points segmented with paragraphs.

Response 5: Thank you for pointing this out. In the revised manuscript we summarized the conclusions in points.

4. Response to Comments on the Quality of English Language

Point 1: Minor editing of English language required

We made English editing by mdpi office (English-76206)

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

1) I think the work undertaken by the authors is important for sustainability and combating fuel shortages. However, while there are a lot of interesting results/findings presented in this work from the manufacturing lens, more implications/impact need to be discussed. Furthermore, there needs to be a discussion on the practical scalabbility of the process including what could be the potential limitations to making this process feasible

2) Authors make the claim in 2.2.4 and 3.1 that glycerol separation is faster with high voltage device than gravity approach. While it does make sense, do they have in-house experimental data or another source they can cite to quantitatively establish the difference/impact?

3) In section 3.6, the authors discuss the quantitative change in proprerties but it is missing the resulting implications. What is the upside and downside of the observations? Why discuss the 42 cST of rapeseed oil when it is not included in the table - what is the context behind that comparison?

4) In section 3.7, it would be better to include data on the graphs for 0% biodiesel as a yardstick for performance.

Author Response

Response to Reviewer 4 Comments

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Yes
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Yes
Are the arguments and discussion of findings coherent, balanced and compelling?	Can be improved	We reviewed the all manuscript in track change
For empirical research, are the results clearly presented?	Can be improved	We reviewed the all manuscript in track change
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Can be improved	we modify the conclusion section to remove material

3. Point-by-point response to Comments and Suggestions for Authors

Comment 1:

I think the work undertaken by the authors is important for sustainability and combating fuel shortages. However, while there are a lot of interesting results/findings presented in this work from the manufacturing lens, more implications/impact need to be discussed. Furthermore, there needs to be a discussion on the practical scalability of the process including what could be the potential limitations to making this process feasible.

Response1: Thank you for pointing this out. Under section 3.2, we added” To unlock the complexity and improve system performances, it is crucial to consider the complexity of the biodiesel production processes. This includes process design, quantitative evaluation, and optimization of the biodiesel from entire systems perspectives. The primary obstacle to the broad commercialization of biodiesel is its restricted feedstock and the several processes involved in producing it, including pre-treatment of the feedstock, transesterification reactions, and biodiesel purification. Therefore, to make biodiesel and its blend a sustainable commercial fuel, it is important to have detailed knowledge about such processes.

Comment 2:

Authors make the claim in 2.2.4 and 3.1 that glycerol separation is faster with high voltage device than gravity approach. While it does make sense, do they have in-house experimental data or another source they can cite to quantitatively establish the difference/impact?

Response2: Thank you for pointing this out. Yes, in different studies, glycerol separation is faster with high voltage device than gravity approach such as Ampairojanawong, et al. (2023) and Isamil et al. Thus, under section 3.4.4 we added” However, compared to a traditional gravitational settling separation, the electrically driven separation technology with a high voltage alternating current source technique had a better efficiency to remove glycerol and other pollutants [41]. Moreover, high voltage technique has been demonstrated to be capable of quickly inducing glycerol fallout, according to Isamil et al.

Ampairojanawong, R.; Boripun, A.; Ruankon, S.; Suwanasri, T.; Cheenkachorn, K.; Kangsadan, T. Separation Process of Biodiesel-Product Mixture from Crude Glycerol and Other Contaminants Using Electrically Driven Separation Technique with AC High Voltage. Electrochem 2023, 4, 123-144. https://doi.org/10.3390/electrochem4010011

Ismail, Z. E.; Moussa, A. I.; Deef, M. M. Utilization of high voltage to separate glycerol during producing biodiesel. J.Soil Sci. and Agric. Eng., Mansoura Univ. 2018; 9 (8), 329 –332.

Comment 3:

In section 3.6, the authors discuss the quantitative change in properties but it is missing the resulting implications. What is the upside and downside of the observations? Why discuss the 42 cST of rapeseed oil when it is not included in the table - what is the context behind that comparison?

Response3: Thank you for pointing this out. We wrote under section 3.6,” however, kinematic viscosity of pure biodiesels is higher than that of petrol diesels and according to the ASTM guidelines, the kinematic viscosity should be between 1.9 and 6.0 cST. The obtained viscosity from jatropha and pongamia oils was within the recommended guidelines. Kinematic viscosity, however, is a crucial and significant aspect of an engine fuel's flow. Also, the 42 cST of rapeseed oil removed and put general statement “In general, biodiesel derived from different feedstock generations has a density ranging from 832 to 982 kg/m³. Regular diesel has a flashpoint of 55–65 °C, but biodiesel fuels have a flashpoint of above 150 °C. 47 is the lowest figure for the cetane number. The calorific value of biodiesel fuels is often lower than that of petroleum diesel [45].

Comment 4:

4) In section 3.7, it would be better to include data on the graphs for 0% biodiesel as a yardstick for performance.

Response4: Thank you for pointing this out. We modified the graphs of generated power and fuel consumption to include B0.

4. Response to Comments on the Quality of English Language

Point 1: English language fine. No issues detected

We made English editing by mdpi office (English-76206)

Author Response File: Author Response.docx

Reviewer 5 Report

Comments and Suggestions for Authors

1. Page 4, bottom. The reaction equation is written in unclear form. Please rewrite it.

2. Page 5, 2.2.3, the last step: please explain how the biodiesel was washed to eliminate any impurities

3. Section 2.3, first paragraph. The authors list the ``attributes’’ (physical properties) that “were assessed using A UV-visible detector coupled with a high-pressure liquid chromatograph … to measure the quantity of free glycerol existing in the biodiesel trial”.

a. Please explain how all these physical properties (of very different nature) can be measured using the above equipment. Or why all these properties are determined by the quantity of free glycerol only?

b. What do the designations like D129 (in %) mean? 0.129%, 1.29% or 12.9%?

4. The manuscript contains a lot of graphs showing some properties of two biodiesels fabricated from Jatropha and Pongamia. If these graphs are intended to compare these two species (with respect to the corresponding biodiesel features), a reader cannot make such a comparison until the uncertainties of the measured quantities are explicitly given.

5. The biodiesel production described by the authors implies some energy consumption. For example, ahigh-voltage device is used to separate glycerol, some energy is used to gather the seeds, roast and squeeze them to obtain the oil. Did the authors impose a simple question: given all these energy consumption sources, is the resulted biodiesel is justified (i) energetically and (ii) economically?

Author Response

Response to Reviewer 5 Comments

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Can be improved	We reviewed the all manuscript in track change
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Can be improved	We reviewed the all manuscript in track change
Are the arguments and discussion of findings coherent, balanced and compelling?	Yes
For empirical research, are the results clearly presented?	Can be improved	We reviewed the all manuscript in track change
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Yes

3. Point-by-point response to Comments and Suggestions for Authors

Comment 1:

Page 4, bottom. The reaction equation is written in unclear form. Please rewrite it.

Response1: Thank you for pointing this out. We removed the reaction equation

Comment 2:

Page 5, 2.2.3, the last step: please explain how the biodiesel was washed to eliminate any impurities

Response2: Thank you for pointing this out. Under section 2.2.5. Dry Washing, we wrote “the produced biodiesel was passed through two filters to eliminate any impurities. The filters were filled until they reached up to 2/3 of the total volume with sawdust, with a little press carried out by hand (Figure 6).

Comment 3:

Section 2.3, first paragraph. The authors list the ``attributes’’ (physical properties) that “were assessed using A UV-visible detector coupled with a high-pressure liquid chromatograph … to measure the quantity of free glycerol existing in the biodiesel trial”.

Please explain how all these physical properties (of very different nature) can be measured using the above equipment. Or why all these properties are determined by the quantity of free glycerol only?

Response 3-a: Thank you for pointing this out. Since glycerin is the main byproduct of biodiesel production.

What do the designations like D129 (in %) mean? 0.129%, 1.29% or 12.9%?

Response 3-b: Thank you for pointing this out. We remove the unused propertied however, they are D1298 for density kg/m³ at 15 °C; D445 for viscosity (cSt) at 40 °C mm²/s; D93 for flash point (°C); D613 for cetane no.; and D240 for calorific value (MJ/L).

Comment 4:

The manuscript contains a lot of graphs showing some properties of two biodiesels fabricated from Jatropha and Pongamia. If these graphs are intended to compare these two species (with respect to the corresponding biodiesel features), a reader cannot make such a comparison until the uncertainties of the measured quantities are explicitly given.

Response 4: Thank you for pointing this out. We used calibrated devices and the graphs showing some properties of two biodiesels created from Jatropha and Pongamia to see the differences between them

Comment 5:

The biodiesel production described by the authors implies some energy consumption. For example, a high-voltage device is used to separate glycerol, some energy is used to gather the seeds, roast and squeeze them to obtain the oil. Did the authors impose a simple question: given all these energy consumption sources, is the resulted biodiesel is justified (i) energetically and (ii) economically?

Response 5: Thank you for pointing this out. Your opinion is right , but to be a viable substitute for a fossil fuel, an alternative fuel should not only have superior environmental benefits over the fossil fuel it displaces, be economically competitive with it, and be producible in sufficient quantities to make a meaningful impact on energy demands, but it should also provide a net energy gain over the energy sources used to produce it (https://doi.org/10.1073/pnas.0604600103). Also, we added “The three main facets of sustainability that are addressed by global biodiesel issues are social, environmental, and economic [29]. Profit maximization and reduced manufacturing costs are the main goals of economic sustainability. This calls for the development of new, ideally inedible raw materials and the application of waste- and energy-saving technology [29]. The reduced environmental burden is the main component of environmental sustainability. Employment and the utilization of local resources for the benefit of the community were the two main components of social sustainability. The research that have been examined indicate that microalgae, fat, oils, and grease, various solid wastes, and other non-edible raw materials are viable and promising biodiesel substitutes [29] at the end of introduction

4. Response to Comments on the Quality of English Language

Point 1: I am not qualified to assess the quality of English in this paper

We made English editing by mdpi office (English-76206)

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

This new version of the scientific paper includes all the improvements based on the points out and suggestions made by this reviewer. I am satisfied with the whole changes made. Then, in conclusion the article is accepted for publication in its present form.

Author Response

Response to Reviewer 1 Comments R

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Yes
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Yes
Are the arguments and discussion of findings coherent, balanced and compelling?	Yes
For empirical research, are the results clearly presented?	Yes
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Yes

3. Point-by-point response to Comments and Suggestions for Authors

General

Response: Thank you for pointing this out. We are appreciated for your conclusion

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Unfortunately, in my opinion, the article cannot be published in this form.

Author Response

Response to Reviewer 2 Comments

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
Are the arguments and discussion of findings coherent, balanced and compelling?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
For empirical research, are the results clearly presented?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors

3. Point-by-point response to Comments and Suggestions for Authors

General

Unfortunately, in my opinion, the article cannot be published in this form.

Response: Thank you for pointing this out.

For Materials and Method section Under 2.2.2. Transesterification

we added” The principle of the transesterification process is shown in Zhang et al. [30].

Zhang, W.; Wang, C.; Luo, B.; He, P.; Zhang, L.; Wu, G. Efficient and economic transesterification of waste cooking soybean oil to biodiesel catalyzed by outer surface of ZSM-22 supported different Mo catalyst. Biomass Bioenergy 2022, 167, 106646

For results and discussion section, under section of 3.6. Oil and its Biodiesel Properties, we added”

In general, biodiesel derived from different feedstock generations has a density ranging from 832 to 982 kg/m³. Regular diesel has a flashpoint of 55–65 °C, but biodiesel fuels have a flashpoint of above 150 °C. 47 is the lowest figure for the cetane number. The calorific value of biodiesel fuels is often lower than that of petroleum diesel [44]. However, kinematic viscosity of pure biodiesels is higher than that of petrol diesels [45] and according to the ASTM guidelines, the kinematic viscosity should be between 1.9 and 6.0 cST [46]. The obtained viscosity from jatropha and pongamia oils was within the recommended guidelines. Kinematic viscosity, however, is a crucial and significant aspect of an engine fuel's flow [46].

Furthermore, Table 4 and Table 5 show fuel properties of jatropha and pongamia biodiesel and their blends, respectively. By inspection Table 4 and Table 5, it can be seen that the kinematic viscosity and density of jatropha and pongamia biodiesels are higher than those of diesel fuel, however, this fact was reported by Zheng and Cho [47], who reported that these properties have a certain impact on the flow and atomization of the fuel. In addition, the calorific value of jatropha and pongamia biodiesels is generally lower than that of diesel fuel, however, this fact was reported by Zheng and Cho [47], who reported that it makes the fuel consumption of biodiesel blends higher than that of diesel fuel. The flash point value of jatropha and pongamia biodiesels is higher than those of diesel fuel, however, biodiesel has a major benefit in storage and transportation due to its high flash point [47]. The cloud point value of jatropha and pongamia biodiesels is higher than those of diesel fuel as shown in Tables 4 and 5, however, in the study of Sarin et al. [48], the jatropha and pongamia biodiesels had cloud points of 4.0 and −1.0 °C, respectively. General, blends of jatropha and pongamia biodiesels and diesel share many physical and chemical characteristics, which makes them a great substitute fuel”.

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

Thank you for addressing my comments. No further questions or concerns.

Author Response

Response to Reviewer 4 Comments

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Yes
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Yes
Are the arguments and discussion of findings coherent, balanced and compelling?	Yes
For empirical research, are the results clearly presented?	Yes
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Yes

3. Point-by-point response to Comments and Suggestions for Authors

General

Thank you for addressing my comments. No further questions or concerns.

Response: Thank you for pointing this out. We are appreciated for your conclusion

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

Author Response

Response to Reviewer 2 Comments

1. Summary

2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
Are all the cited references relevant to the research?	Yes
Are the research design, questions, hypotheses and methods clearly stated?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
Are the arguments and discussion of findings coherent, balanced and compelling?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
For empirical research, are the results clearly presented?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors
Is the article adequately referenced?	Yes
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	Must be improved	The response is Under Point-by-point response to Comments and Suggestions for Authors

3. Point-by-point response to Comments and Suggestions for Authors

General

Unfortunately, in my opinion, the article cannot be published in this form.

Response: Thank you for pointing this out.

For Materials and Method section Under 2.2.2. Transesterification

we added” The principle of the transesterification process is shown in Zhang et al. [30].

For results and discussion section, under section of 3.6. Oil and its Biodiesel Properties, we added”