Effects of Phosphate and Thermal Treatments on the Characteristics of Activated Carbon Manufactured from Durian (Durio zibethinus) Peel
Round 1
Reviewer 1 Report (New Reviewer)
The manuscript addresses the Effect of Phosphate and Thermal Treatments on the Characteristics of Activated Carbon Manufactured from Durian Peel. It covers a suitable research gap, but the direct application and benefit of this paper is not clearly stated at the end of the Introduction.
The paper is well structured and it is easy to follow.
Methodology is clear. Reproducibility aspects must be clarified as for performance of the activated carbon.
Table 9 must contain a reference value to compare with. How is the adsorption efficiency compared to previous research? Benefits over literature? How were these values calculated? Steady state? Reproducibility? Standard deviation? Same for Table 10 in terms of yield.
Quality of figures is good and they match the main findings and explanations in the discussion.
Conclusions are too broad and they must include main findings and values obtained from the results. This way they could suggest future work recommendations.
Author Response
Thank you very much for the constructive comments. We would like to inform you that we have already revised the manuscript the suggestions.
Author Response File: 
Author Response.docx
Reviewer 2 Report (New Reviewer)
Damayanti et al., produced activated carbon from Durian peels and activated the biochar via phosphoric acid. Subsequently the authors performed ethanol adsorption using the activated carbon derived from Durian peels. The authors claim that the novelty of their research lies in the chemical activation using phosphoric acid in contrast to the literature where only H2SO4 and KOH is used (according to the authors). However, a quick look into the literature learns that chemical activation using phosphoric acid on durian peel derived biochar is already performed quite a few times (Please see: (i) Journal of Scientific & Industrial Research; 70, 2011; pp 554-560, (ii) Kuwait J. Sci. Eng. 2012, (1B) pp37-58, (iii) Ionics, 22, pages1209–1216 (2016) (iv) https://doi.org/10.1016/j.biortech.2010.08.068 , (v) Indo. J. Chem., 2010, 10 (1), 36 - 40, (vi) https://doi.org/10.1080/15226514.2023.2175780, but not limited to these examples). Therefore the novelty of this article is very limited. Moreover, the article is full of grammar and spelling mistakes, that requires an extensive English language revision. For these reasons I reject this article for publication in chemengineering.
Author Response
Thank you very much for the constructive comments. We would like to inform you that we have already revised the manuscript the suggestions.
Author Response File: Author Response.docx
Reviewer 3 Report (New Reviewer)
Authors have polished the text however it does not bring anything new except maybe the use of a new species (waste from a specific plant).
1. „the wavelength“ when dealing with the cm-1 should be termed wavenumbers as this is standard spectroscopic terminology
Minor typos:
Title 2.6. “dan” is typo for “and”
„H3PO4“ numbers are not subscripted in some places (line 369)
Author Response
Thank you very much for the constructive comments. We would like to inform you that we have already revised the manuscript the suggestions.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report (New Reviewer)
Damayanti et al., produced activated carbon from Durian peels and activated the biochar via phosphoric acid. Subsequently the authors performed ethanol adsorption using the activated carbon derived from Durian peels. Although the manuscript already improved compared to the previous version, there a still some major and minor comments to address before publication in ChemEngineering. Herewith you can find my comments:
- - Not needed to add (400-500-40%) in Line 18 as the information is already mentioned in the sentence before (and it is also not mentioned later).
- - Line 64: absorb or adsorb?
- - Typo Line 66 “present”.
- - Reformulate Line 70-71, for example: “AC was characterized, its yield was optimized and adsorption efficiency were investigated for its ability to adsorb ethanol.”
- - Typo Line 74
- - Line 75-76: “Furthermore, the raw material was dried at 70°C for 12 hours to reduce the moisture content.” Was it reduced or removed. If only reduced, please mention moisture content after drying.
- - Did the authors determine the (bio-)chemical composition of the durian peel before the carbonization process (cellulose, hemicellulose, lignin, etc)?
- - Is there a specific reason why the AC is washed/neutralized at elevated temperature (85 °C)? Please elaborate in the text.
- - Line 92-93: please add temperature.
- - The authors used 100 rpm during the adsorption experiments. Did the authors consider other stirring speeds (to make sure there are no mass transfer limitation)?
- - Please add a section in Materials and methods that lists all chemicals/materials (i.e., CAC) used.
- - Subscrips of H3PO4 in Table 4.
- - There are 2 equations used to describe the AC yield (equation 1 and equation 2). Which one of the 2 is used in the manuscript? Also there seems to be missing text in the description of equation 2.
- - Please go through the text (and tables/figures) and make sure that the same (relevant) significant numbering is being used (also in accordance with standard deviations).
- - The authors already use the abbreviations “K” and “KA” before mentioning them in full. Is it also not more logical to use abbreviations “C” for carbon and “AC” for activated carbon? Now there are 2 abbreviations for the same name (i.e, AC, KA). This would facilitate reading.
- - Line 245, crystallized or crystalline?
- - Please increase the (font)size of Figure 3 and remove the grey box surrounding the Figure.
- - Please make sure that all SEM pictures in Figure 4 have the same size.
- - Remove grey box surrounding Figure 5.
- - Enlarge Figure 7 and remove grey box surrounding the Figure.
- - Line 302, not necessary to add H3PO4 as it is already mentioned earlier in the manuscript.
- - Line 317; replace coconut shell activated carbon by CAC?
- - Typo Line 370 “°C”.
- - Spacing missing in Line 373.
- - Line 374: activated carbon à “AC”.
- - Line 392 commercial AC à CAC.
Author Response
Dear Reviewer,
Thank you for giving us the opportunity to submit a revised draft of the manuscript “Effect of Phosphate and Thermal Treatments on the Characteristics of Activated Carbon Manufactured from Durian (Durio zibethinus) Peel” for publication in the ChemEngineering. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Those changes are highlighted within the manuscript. Please see below, in red, for a point-by-point response to the reviewers’ comments and concerns. All page numbers refer to the revised manuscript file with tracked changes.
Point 1: Not needed to add (400-500-40%) in Line 18 as the information is already mentioned in the sentence before (and it is also not mentioned later)
Response 1: Thank you very much for the constructive comments. Line 18 is not (400-500-40%) but (400-800-40%) and I have deleted it.
Point 2: Line 64: absorb or adsorb?.
Response 2: Thanks for the suggestion to check the spelling concord of the manuscript for better comprehension of its readership. Therefore, we have writen “adsorp” (not “absorp”)
Point 3: Typo Line 66 “present”
Response 3: Thanks for the suggestion to check the spelling concord of the manuscript for better comprehension of its readership. Therefore, we have writen “presence” (not “present”)
Point 4: Reformulate Line 70-71, for example: “AC was characterized, its yield was optimized and adsorption efficiency were investigated for its ability to adsorb ethanol.”
Response 4: Thanks for the suggestion to check the grammar and spelling concord of the manuscript for better comprehension of its readership. We have reformulated Line 70-71 from “The AC was characterized and its yield and adsorption efficiency were investigated for its ability to adsorb ethanol “ to “AC was characterized, its yield was optimized and adsorption efficiency were investigated for its ability to adsorb ethanol.
Point 5: Typo Line 74
Response 5: Thanks for the suggestion to check the grammar concord of the manuscript for better comprehension of its readership. Therefore, we have writen “on Gunungpati area (Semarang City)” (not “at Gunungpati (Semarang Municipality”)
Point 6: - Line 75-76: “Furthermore, the raw material was dried at 70°C for 12 hours to reduce the moisture content.” Was it reduced or removed. If only reduced, please mention moisture content after drying
Response 6: Thank you very much for the constructive comments. We have changed from “Furthermore, the raw material was dried at 70°C for 12 hours to reduce the moisture content.” to “Furthermore, the raw material was dried at 70oC until a constant weight was reached.”
Point 7: Did the authors determine the (bio-)chemical composition of the durian peel before the carbonization process (cellulose, hemicellulose, lignin, etc)?
Response 7: Thank you very much for the constructive comments. We did not collect data on the primary (bio-)chemical composition of durian peel before the carbonization process (cellulose, hemicellulose, lignin, etc.)
Point 8: Is there a specific reason why the AC is washed/neutralized at elevated temperature (85 °C)? Please elaborate in the text
Response 8: Thank you very much for the constructive comments. We have added “until no longer detectable phosphor ions or other contaminants are found in the wash water” after “the AC produced was then neutralized with distilled water for 30 minutes at 85oC”.
Point 9: Line 92-93: please add temperature
Response 9: Thank you very much for the constructive comments. We have added temperature= at 110oC
Point 10: The authors used 100 rpm during the adsorption experiments. Did the authors consider other stirring speeds (to make sure there are no mass transfer limitation)?
Response 10: Thank you very much for the constructive comments. We only consider that the adsorbate is adsorbed onto the activated carbon well. If the stirring exceeds 100 rpm, the adsorbate is most likely not adsorbed onto the activated carbon. Conversely, if the stirring is less than 100 rpm, the adsorption process takes a long time.
Point 11: Please add a section in Materials and methods that lists all chemicals/materials (i.e., CAC) used
Response 11: Thank you very much for the constructive comments. We have added commercial activated carbon (CAC) in 2.1. Material Pretreatment
Point 12: Subscript of H3PO4 in Table 4
Response 12: Thank you very much for the constructive comments. We have changed H3PO4 to H3PO4
Point 13: There are 2 equations used to describe the AC yield (equation 1 and equation 2). Which one of the 2 is used in the manuscript? Also there seems to be missing text in the description of equation 2
Response 13: Thank you very much for the constructive comments. The initial equation in the text is Equation (1) = Equation (3), not Equation (2). Therefore, Equation (1) is being omitted because this study is not only limited to the yield of neutralization results from activated carbon but also focuses on the processing of durian peels into activated carbon.
Point 14: - Please go through the text (and tables/figures) and make sure that the same (relevant) significant numbering is being used (also in accordance with standard deviations).
Response 14: Thank you very much for the constructive comments. The tracking of writing faults suggested by reviewers has been enhanced. It is evident from the track modifications we made.
Point 15: The authors already use the abbreviations “K” and “KA” before mentioning them in full. Is it also not more logical to use abbreviations “C” for carbon and “AC” for activated carbon? Now there are 2 abbreviations for the same name (i.e, AC, KA). This would facilitate reading
Response 15: Thank you very much for the constructive comments. We have prepared abbreviations consistently throughout the text, for example, carbonization changed to CN, KA changed to AC, and commercial activated carbon changed to CAC.
Point 16: Line 245, crystallized or crystalline?
Response 16: Thank you very much for the constructive comments. We have changed the word from more crystallized to more crystalline.
Point 17: Please increase the (font)size of Figure 3 and remove the grey box surrounding the Figure
Response 17: Thank you very much for the constructive comments. We have enlarged the size (font) of Figure 3 and removed the gray box surrounding the Figure
Point 18: Please make sure that all SEM pictures in Figure 4 have the same size
Response 18: Thank you very much for the constructive comments. We have made sure that all SEM pictures in Figure 4 have the same size
Point 19: Remove grey box surrounding Figure 5
Response 19: Thank you very much for the constructive comments. We have removed grey box surrounding Figure 5
Point 20: Enlarge Figure 7 and remove grey box surrounding the Figure
Response 20: Thank you very much for the constructive comments. We have enlarged Figure 7 and remove grey box surrounding the Figure
Point 21: Line 302, not necessary to add H3PO4 as it is already mentioned earlier in the manuscript
Response 21: Thank you very much for the constructive comments. We have changed from “caused by phosphoric acid activator (H3PO4)” to “caused by phosphoric acid activator”
Point 22: - Line 317; replace coconut shell activated carbon by CAC?
Response 22: Thank you very much for the constructive comments. We have replaced coconut shell activated carbon by CAC
Point 23: Typo Line 370 “°C”.
Response 23: Thank you very much for the constructive comments. We have changed from “600oC” to “600oC”
Point 24: Spacing missing in Line 373
Response 24: Thank you very much for the constructive comments. We have changed from “aresimilar” to “are similar”
Point 25: Line 374: activated carbon à “AC”.
Response 25: Thank you very much for the constructive comments. We have changed from “activated carbon” to “AC”
Point 26: Line 392 commercial AC à CAC
Response 26: Thank you very much for the constructive comments. We have changed from “commercial AC” to “CAC”
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
The manuscript “Effect of Phosphate and Thermal Treatments on the Characteristics of Activated Carbon Manufactured from Durian (Durio zibethinus) Peel” by Damayanti et al. is a normal study. No novelty is there in the work as this type of work is available in literature. Moreover, it lacks proper justification and reasoning. Here are few comments:
1. Abstract is poorly written.
2. Introduction doesn’t seem to fit as per title need.
3. Make of furnace must be given. What was the heating rate, was the furnace closed enough to control the atmosphere?
4. The surface area of the carbon prepared is not good and the authors made comparson with CAC which has very low surface area, why?
5. SEM pics doesn’t show porosity. Fig 3b shows some spherical shapes which are not discussed.
Merely giving this information is not enough for a journal like ChemEngineering and authors are suggested to give more characterization results with some application
Author Response
Thank you for the suggestion to improve the quality of the manuscript. We have added the explanation in our manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
1. There are numerous studies on phosphoric acid activation, I would like to see a discussion comparing the resulting values (Yield, surface area, etc.)
2. please try to generalize possible applications of AC. Your introduction was too focused on ethanol and energy application but nothing on the results or scope of the study on this application. It was misleading.
3. Countercheck the values on the resulting surface area on existing literature. I am having a feeling that the values are lower than I expected.
Author Response
Thank you for the suggestion to improve the quality of the manuscript. We have added the explanation in our manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper about the production of activated carbon from durian peel needs to be revised before its publication. Here is the list of errors and questions:
- line 14: double word
- line 73-78: Is the temperature kept constant during 1-hour carbonization or activation? Is 1h enough for complete carbonization at these temperatures? how much material is used? How about the heat and mass transfer effects during this isothermal heating process? This section should be explained in more detail.
- Section 2.3: Details of characterization experiments may be included. For example, was coating applied to samples before SEM analysis ?, waht was the particle size of the materials?, Which gas was used for adsorption desorption analysis (BET)?
- line 102: Which commercial activated carbon was used?
- Lines 120-124: This explanation should be reconsidered.
- Figure 1: Check the symbols on the figure. C never makes 4 bonds and never has a peak around 2662 1/cm. (Line 148)
- Line 163: XRF gives the inorganic content? How did you calculate C content? And why the C content of first carbonization products is higher than activated samples? The carbon content of the 300-400 C carbonization products should be lower than 90 %. Typical biochar contains approximately 55-75 % elemental carbon. These findings seem to be unclear.
- line 202, Table 9. The results of EDX are not enough to explain the elemental content of any material. It may give idea, but giving the results in tables is not appropriate for biomass-based materials since biomass is a heterogeneous material. These tables can be removed or the results can be given in graphics just for a simple explanation of the material.
- Line 232: The neutralization process should be explained in detail in the methods section.
- The number of references is too much for a research paper.
- English grammar must be checked by a native speaker.
- For all numerical results, authors must pay attention to significant figures.
- Although the work seems to be original, the methodology and the results have little contribution to the literature. Previous work on phosphoric activation gave more porous activated carbons with larger surface areas of around 1500 m2/g from durian plants. The reason for the low surface areas in this study should be explained.
- The novelty of the study should be more explained in the introduction section by giving the results from similar work (phosphoric acid activation).
Author Response
Thank you for the suggestion to improve the quality of the manuscript. We have added the explanation in our manuscript.
Author Response File: Author Response.pdf
Reviewer 4 Report
There are too many researches on the preparation of activated carbon from different raw materials, including coal, biomass, and solid waste. The idea of the study is not new, nor is the methodology novel, and the results obtained are common. Besides, there are some problems in the manuscript, some of these problems are listed below.
1. The purpose of the manuscript is to use activated carbon to purify ethanol, but this study did not mention the effect of using activated carbon prepared from durian to purify ethanol. Is the prepared activated carbon effective for ethanol purification? The study did not provide an answer.
2. There are many preparation methods of activated carbon, including physical activation method and chemical activation method. Why choose chemical activation method to prepare activated carbon from durian peel? The specific surface area of activated carbon prepared by chemical method is usually large, but that prepared by H3PO4 activation in this paper is not high, so it is unlikely to achieve ethanol separation and achieve good results.
3. In addition, many analytical methods were adopted in this manuscript, such as FTIR, SEM-EDX, XRF, and BET. However, the obtained results are common. Therefore, the obtained results should be deeply analyzed to get some new insights.
Author Response
Thank you for the suggestion to improve the quality of the manuscript. We have added the explanation in our manuscript.
Author Response File: Author Response.pdf
Reviewer 5 Report
It was written in the article this study was the only that studied carbonization temperatures 300 and 400. Why did they chose to study 300C?
Also, according to results, pore formation is observed at 400C. Why didn’t they consider to study the temperature of 500C?
Author Response
Thank you for the suggestion to improve the quality of the manuscript. We have added the explanation in our manuscript.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
1. The context of using the AC doe ethanol adsorption was lacking in the introduction.
2. There was no clear account of the mechanism of ethanol adsorption onto the AC.
3. I think the results on the surface area are very low. Discussion and emphasis on the (carbon) AC yield were insufficient.
Reviewer 3 Report
Here is the list of comments and questions:
- Since the origin of the commercial AC is not given in detail, the data about its surface area should be removed from the abstract.
- The introduction section is better but still needs to be improved to give more results from previous studies. not only with KOH activation but also with H3PO4 activation too.
- What is the particle size of the AC and CAC?
- It is unbelievable that the ACs produced at 800 C have lower surface areas at lower acid concentrations. Around 2 m2/g is very low, even lower than K400. What is the reason?
- Fig.1 a. % is written, and should be removed.
- Fig.1 b, c, and d: 800-400 sample has more absorption bands than te others, which is impossible. When the temperature increases the functional groups are removed leaving a solid carbonaceous material behind. And hence, no peaks are observed in FTIR. FTIR analysis should be re-done.
- the explanations on Fig. 1 are not enough and do not give data/knowledge on the functional group-adsorption relationship.
- XRF is not the correct technique to determine the elemental content of ACs. Elemental C should be detected by an elemental analyzer. The inorganic content is nearly the same after carbonization and/or activation. Therefore tables 5-8 are not necessary.
- The titles of the tables and figures are not meaningful.
- EDX may give idea on the composition, however for heterogeneous materials like AC, it does not give certain results on the elemental composition.
- Section 3.5 should be given as the first results
- There are many typing errors in the text even in the titles, please read again and correct them.
- More data on ethanol adsorption is required. What is the effect of adsorption T on the yield? Thermodynamics and kinetics of adsorption may be studied as well.
- The novelty of the paper is ethanol adsorption rather than AC production. I ask authors to add new data on ethanol adsorption instead of giving FTIR, XRF, or EDX results of all ACs.
- I suggest a major revision if the authors can add new data on ethanol adsorption. If not, my decision is to reject it.
Reviewer 4 Report
Compared with the previous manuscript, it is improved.
Reviewer 5 Report
The authors have added all suggestions to improve the manuscript. It can be acceptable.
