Preparation and Characterization of Corn Straw-Based Graphitized Carbon with Ferric Acetylacetonate as Catalyst

Round 1

Reviewer 1 Report

The manuscript describes the study of the synthesis of CSBGC (corn straw based graphitized carbon) by catalyst assisted graphitisation of carbonized corn straw. The corn straw consituate a significant part of agroindustrial wasted bio-mass, and its valorisation is an important research challenge.

The innovation of the approach proposed by authors is utilisation of Fe acetylacetonate as a catalyst of graphitization. The authors describe in details the synthesis and present a sutyd of  optimization of its conditions.

The following points should be taken into account for possible improvement of the work.

1. Since the main conclusion of the work is a catalytic action of Fe(acac) complex, it would be more conclusive to compare the synthesis with non-catalytic graphitization, e.g. by performing the experiment under the same condition in the absence of of Fe catalyst. It is moreover important since  a 7-fold increase of catalyst concentration (from 1 to 7 mmol/g) results in a systematic, but small (less than 10%)  increase in the graphitization yield.

2. FTIR attribution should be more precise. Namely, the mode of vibrations at 1000 and 1250 cm-1 should be proposed. The attribution of vibrations in 1300-1400 and 1550-1750 cm-1 ranges is also confusing, as it is presented : what peaks exactly can be attributed to stretching of C=O, C-OH, and C-O-C? 

3. Raman spectra of both graphitized and non-graphitized (i.e. product before graphitization step) carbons could be presented for more conclusive analysis of graphitization degree.

4. TGA axis should be presented in the relative weight units (referred to initial mass) rather than absolute masses.    

English of the manuscript needs improvement. 

Line 67 : Tube furnace was used to heat samples.

All parts of 2.3 are written in present tense, while the rest of the manuscript is in past tense. It should be corrected for the sake of consistency.

Line 100 : ... and wrap carbon particles, Llayered between carbon...

Line 252 (bibliography, Ref.2) : Journal title is repeated.

   

Author Response

Dear editor and Reviewers

I am the writer of the article "Preparation and Characterization of Corn Straw-based Graphitized Carbon with Ferric Acetylacetonate as Catalyst" (ID:2552218). I am grateful to the editors and reviewers for their suggestions for the revision of this article, and according to the suggestions careful modifications have been made. We will now report to you the status of the revision of this article.

For language, we have invited professionals to make modifications.

1. Since the main conclusion of the work is a catalytic action of Fe(acac) complex, it would be more conclusive to compare the synthesis with non-catalytic graphitization, e.g. by performing the experiment under the same condition in the absence of of Fe catalyst. It is moreover important since a 7-fold increase of catalyst concentration (from 1 to 7 mmol/g) results in a systematic, but small (less than 10%)  increase in the graphitization yield.

 

Both yield and graphitization are the focus of our work, this work we have an increase in yield, as you said the increase is really small, we will be based on your suggestions in the future work, and strive to get a higher increase.

 

2. FTIR attribution should be more precise. Namely, the mode of vibrations at 1000 and 1250 cm-1 should be proposed. The attribution of vibrations in 1300-1400 and 1550-1750 cm-1 ranges is also confusing, as it is presented : what peaks exactly can be attributed to stretching of C=O, C-OH, and C-O-C?

 

The problem has been corrected.

 

the symmetric absorption peak of ether bond at 1208 cm^-1, the antisymmetric absorption peak of ether bond at 1248 cm^-1, CH₃ of polyether polyol at 1380 cm^-1, methylene group of polyether polyol at 1455.cm^-1, and a more obvious bending vibration peak at 1500-2500 cm^-1, indicating the low content of unsaturated bonds such as carbon-carbon double bond and carbon-carbon triple bond, and a stretching vibration peak of CH₃ at 2856 cm^-1, and the methylidene of polyether polyol at 3310 cm^-1. A more obvious bending vibration peak, indicating that the content of unsaturated bonds such as carbon-carbon double bond and carbon-carbon triple bond is low, and the telescopic vibration peak of CH₃ appeared at 2856 cm^-1, and the telescopic vibration peak of the hydroxyl group in polyether polyol appeared at 3310 cm^-1（line167-175）

 

3.Raman spectra of both graphitized and non-graphitized (i.e. product before graphitization step) carbons could be presented for more conclusive analysis of graphitization degree.

 

We have added and replaced the corresponding Raman spectra as you suggested.

 

Figure 6. Raman Spectra of CSBGC.and CS（line222-223）

 

4.TGA axis should be presented in the relative weight units (referred to initial mass) rather than absolute masses.

 

Based on your suggestions we have modified the TG charts.

 

Figure 8. Thermogravimetric diagrams of liquefied products(a) and liquefied products with Fe(acac)₃ catalyst(b).（line258）

 

5.Line 67 : Tube furnace was used to heat samples.

Based on your suggestions we have changed

A certain amount of corn straw liquefaction product was weighed and placed in a corundum crucible, the crucible was pushed to the center of the tube furnace and nitrogen was introduced for 0.5 h to ensure that the reaction was in an inert gas environment.(line116-118)

 

6.All parts of 2.3 are written in present tense, while the rest of the manuscript is in past tense. It should be corrected for the sake of consistency.

Based on your suggestions we have changed

 

 

2.3.1. CS liquefied process

10.0 grams of CS were weighed and placed into an autoclave (500ml, PTFE lining, Shanghai Rock Levy, Shanghai). Subsequently, a polyol liquefaction agent, consisting of a mixture of PEG200 and glycerol at a mass ratio of 7:3, was added to the autoclave, along with 0.3 grams of hydroxyethylene diphosphoric acid catalyst. The autoclave was then subjected to a vacuum drying environment for the purpose of liquefaction reaction. The reaction temperature was set at 140 ℃. Following a predetermined temperature, the constant temperature was maintained for a duration of 5.0 hours, resulting in the production of liquefied products.

2.3.2. Preparation of graphitized carbon

A certain amount of corn straw liquefaction product was weighed and placed in a corundum crucible, The crucible was pushed to the center of the tube furnace and nitrogen was introduced for 0.5 h to ensure that the reaction was in an inert gas environment. The carbonization reaction is conducted at a temperature of 600℃, with a heating rate of 5℃ per minute, and the temperature is maintained constant for a period of 1.0 hours. Once the reaction is complete and the temperature has decreased to 25℃, immerse the carbonized product in a solution of 20 wt% absolute ethanol and subsequently perform suction filtration. Finally, the carbon product was obtained by drying at 80℃ for 12.0 h.1.0 g of carbonized product was weighed and mixed with 7.0 mmol/g of ferric acetylacetonate catalyst. The reaction temperature was raised to 850℃ and stored for 1.0 h. After reducing the reaction to 25℃, the crucible was removed, sonicated for 1.0 h, filtered, and dried for 80℃ for 12.0 h to obtain CSBGC(Fig.1). Calculation formula of graphitized carbon yield (1)（line107-128）

 

7.Line 100 and wrap carbon particles, Llayered between carbon...

 

Based on your suggestions we have changed. We have deleted this sentence.

 

8.Line 252 (bibliography, Ref.2) : Journal title is repeated.

 

Based on your suggestions we have changed. We have deleted this sentence.

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript is focused on the preparation of corn straw-based graphitized carbons by using ferric acetylacetonate as catalyst. Different process parameters have been explored for the identification of those allowing for the preparation of the material with the better structural properties. Unfortunately, the produced materials, after a conventional structural characterization, have not been tested for specific applications. It is hard to understand the novelty of the proposed approach. The manuscript seems a laboratory report.

The manuscript is not easy to follow, some parts are written in a confused way and important experimental details are missing. Major revisions are needed. In the following more details on the issues to be addressed during the revision phase are reported.

Entire manuscript

-              Grammar and linguistic checks of the entire manuscript are kindly suggested. Many sentences need to be changed or rewritten.

-              There is a mixed use of the words "corn stover" and "corn straw". Please choose only one of the two options and use it consistently throughout the text.

Abstract

-          Too short and not very informative. Improvements are needed.

-          "Corn straw is rich in carbon sources". This sentence is trivial and not correct, I suggest to improve it.

Introduction

-          Report the experience of other authors in corn straw or similar biomass types liquefaction procedure

-          Sentences at lines 32-40: This part is quite confusing, and its collocation in the introduction does not sound appropriate. I suggest that this part of the text be revised.

Experimental section

-          Section 2.2: Add all the details regarding of how each instrument was operated. Details about thermogravimetry are missing. Remove the details about the tube furnace and move them into the section dedicated to the carbonization process reporting also its dimensions and constituent material.

-          Section 2.3: Use past tense.

-          Section 2.3.1: Add details about the autoclave (volume, material, brand) used for liquefaction process

-          Section 2.3.2: Use the word "quantity" instead of "quality". Specify why ethanol soaking was performed after carbonization process. Use the adjective "carbonized" instead of "calcined" because the calcination is a process performed in air, while the carbonization one is performed under inert atmosphere.

-          2.3.3: Which is the final content of iron in the graphitized carbon? How did Authors check the complete removal of the catalyst and its derivatives? Did Authors perform only one washing of the produced material?

-          Section 2.3.4: I suggest to deeply modify or eliminate this section. The Figure 1 has to be improved. I suggest to fuse this section with the previous ones.

Results and discussion section

-          Section 2.1: Add a brief summary of what will be reported in this section

-          Section 3.1.1: this section is very confusing and a mix of improper information is reported. Please revise it. Probably this section should be reported after sections 3.1.2 and 3.1.3

-          Compositional details of the obtained materials have to be reported. In particular, C, H, O, N and metallic species contents of the materials produced at the different stages of the process have to be reported.

-          Section 3.2.1: the authors underlined the presence of ether bonds in the produced materials. Please explain why ether bonds are present in the samples and why their presence is so relevant.

-          Caption Figure 4: Clearly specify which panels are SEM images and which panels are TEM images.

-          Section 3.2.6: Details about the conditions applied to perform the TG analyses have to be reported in section 2. Thermogravimetry is a powerful tool to predict the behavior of a sample during a thermoconversion process, but here it is not clear the meaning of this kind of analysis. Did the Authors simulate by TG the graphitization process? If yes, are the experimental conditions applied during TG analysis comparable to those of the carbonization process? The discussion of the obtained results should be improved. The sentence at lines 212-213 is completely wrong: during liquefaction the conversion of cellulose and hemicellulose into "oligosaccharides" occurs, not into "polysaccharides". This section needs a complete revision and improvements.

-          Figure 8: Revise the graphics specifying the quantities reported on the axes.

-          I suggest to make a comparison with the structural properties of other carbon-rich materials produced from corn straw and described by the open literature

-          I suggest to add some attempts in the use of the graphitized materials for specific applications

Conclusions

-          Please cite some possible applications for the produced materials.

The manuscript is not easy to follow. Many parts are confusing and need to be rewritten.

Author Response

Dear editor and Reviewers

I am the writer of the article "Preparation and Characterization of Corn Straw-based Graphitized Carbon with Ferric Acetylacetonate as Catalyst" (ID:2552218). I am grateful to the editors and reviewers for their suggestions for the revision of this article, and according to the suggestions careful modifications have been made. We will now report to you the status of the revision of this article.

For language, we have invited professionals to make modifications.

 

1.There is a mixed use of the words "corn stover" and "corn straw". Please choose only one of the two options and use it consistently throughout the text.

 

At your suggestion we have standardized the nomenclature of corn straw.

 

2.Too short and not very informative. Improvements are needed

 

We've rewritten Abstract based on your suggestion.

 

3."Corn straw is rich in carbon sources". This sentence is trivial and not correct, I suggest to improve it.

 

We have removed this sentence at your suggestion.

 

4.Report the experience of other authors in corn straw or similar biomass types liquefaction procedure

 

Based on your suggestion we have added the corresponding literature on liquefaction procedures for corn stover or similar biomass types.

Weisheng Chen et al., using polyethylene glycol 400 (PEG400) and glycerol as liquefaction solvents, and liquefaction with sulfuric acid as a catalyst. The liquefaction conditions were optimized at 95.39% liquefaction yield under the reaction conditions of 150 ℃ and 120 min. Sabzoi Nizamuddin et al., using ethanol as a solvent, which showed that the thermal stability of biochar improved after the solvation liquefaction process(line50-55).

 

5.Sentences at lines 32-40: This part is quite confusing, and its collocation in the introduction does not sound appropriate. I suggest that this part of the text be revised

 

We have rewritten the above sentence based on your suggestion.

 

6.Section 2.2: Add all the details regarding of how each instrument was operated. Details about thermogravimetry are missing. Remove the details about the tube furnace and move them into the section dedicated to the carbonization process reporting also its dimensions and constituent material.

 

In response to your suggestions, we have added details on how to use each of our instruments, as well as details on the TG.

Several residues were analyzed by using a Fourier transform infrared (FTIR) spectrometer. IR spectra were recorded on a Fuji FIRIS-25 Fourier transform spectrometer. Transmittance measurements were conducted using the KBr pellet method. Raman Spectra were measured with a 532 nm excitation laser (Lab RAM HR evolution, Horiba Jobin Yvon SA, France) and recorded to study the properties of D and G bands over the range 3500~1000 cm^-1. Nitrogen sorption measurements were carried out on a Micromeritics TriStar II 3020 analyzer, the sample was degassed and dehydrated at 180 °C for 12 h. The Brunauer-Emmett-Teller surface area  of CSBGC was calculated by Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) methods, respectively. Scanning electron microscopy (SEM) was performed with a Philips XL30 FEG FE-SEM instrument at an accelerating voltage of 25 kV. Transmission electron microscopy (TEM) was performed with a JEOL JEM-2100F. X-ray powder diffraction (XRD) measurements were performed on a SmartLab X-ray diffractometer in the range of 10~70° 2θ at room temperature. Cu-Kα radiation (λ = 0.15406 nm) was used with an X-ray tube operating at 40 kV and 30 mA. All analyses and fitting of the peaks were conducted on MDI Jade version 9 software (Materials Data Inc, Liverpool, CA). Thermogravimetric (TG) analysis, differential thermogravimetric (DTG) analysis were conducted on a thermal analyzer, Netzsch409PC. About 3.0 mg of sample was used in the TG/DTG. Pyrolysis was initiated at room temperature and ended at 900 ℃ with a heating rate of 10 ℃/min under a flow of 50 mL/min of nitrogen.(line88-105)

 

7.Section 2.3.1: Add details about the autoclave (volume, material, brand) used for liquefaction process

 

We've rewritten it based on your suggestions

autoclave (500ml, PTFE lining, Shanghai Rock Levy, Shanghai)(line108-109)

 

8.Section 2.3.2: Use the word "quantity" instead of "quality". Specify why ethanol soaking was performed after carbonization process. Use the adjective "carbonized" instead of "calcined" because the calcination is a process performed in air, while the carbonization one is performed under inert atmosphere

 

As per your suggestion, we have made the replacement.

 

9: Which is the final content of iron in the graphitized carbon? How did Authors check the complete removal of the catalyst and its derivatives? Did Authors perform only one washing of the produced material?

 

As you said that the Fe content in the graphitized carbon is more than 1%, we have to admit the shortcomings of our work, for which we have carried out 3 cleanings and new XRD, and ICP characterizations, as shown in the XRD characterization on page 6, picture V.

 

 

10.Section 2.3.4: I suggest to deeply modify or eliminate this section. The Figure 1 has to be improved. I suggest to fuse this section with the previous ones.

 

We have rewritten it according to your suggestions.

2.3.2. Preparation of graphitized carbon

A certain amount of corn straw liquefaction product was weighed and placed in a corundum crucible, The crucible was pushed to the center of the tube furnace and nitrogen was introduced for 0.5 h to ensure that the reaction was in an inert gas environment. The carbonization reaction is conducted at a temperature of 600℃, with a heating rate of 5℃ per minute, and the temperature is maintained constant for a period of 1.0 hours. Once the reaction is complete and the temperature has decreased to 25℃, immerse the carbonized product in a solution of 20 wt% absolute ethanol and subsequently perform suction filtration. Finally, the carbon product was obtained by drying at 80℃ for 12.0 h.1.0 g of carbonized product was weighed and mixed with 7.0 mmol/g of ferric acetylacetonate catalyst. The reaction temperature was raised to 850℃ and stored for 1.0 h. After reducing the reaction to 25℃, the crucible was removed, sonicated for 1.0 h, filtered, and dried for 80℃ for 12.0 h to obtain CSBGC(Fig.1). Calculation formula of graphitized carbon yield(line115-128)

 

11.Section 2.1: Add a brief summary of what will be reported in this section

 

We have rewritten it according to your suggestions.

The optimal parameters for the carbonization and graphitization process were determined through single factor experiments. These parameters include a solid-liquid ratio of 1:2 as the carbonization raw material, a carbonization temperature of 600 ℃, a graphitization temperature of 850 ℃, the graphitization catalyst is Fe(acac)₃ and the amount is 7.0 mg / g carbonization product, a product ID/IG ratio of 0.8272, and a 2θ value of 26.38°. When these conditions are applied, the resulting material exhibits superior graphitization, a microscopic sheet structure, and fewer defects compared to the direct graphitization of corn straw.(line133-139)

 

12.Section 3.1.1: this section is very confusing and a mix of improper information is reported. Please revise it. Probably this section should be reported after sections 3.1.2 and 3.1.3

 

We have rewritten it according to your suggestions.

3.1.1.Graphitization Temperature

It was found that the temperature had a significant influence on the degree of graphitization of corn straw by experiments in Fig. 2(b). It was shown that the yield of CSBGC increased significantly, during the graphitization temperature of 750 ℃-850 ℃, and within 850 ℃-900 ℃, the yield of graphitized carbon did not change significantly. Considering the experimental cost, process conditions, and other factors, the graphitization temperature of CS was 850 ℃.

2.3.2. Preparation of graphitized carbon

A certain amount of corn straw liquefaction product was weighed and placed in a corundum crucible, The crucible was pushed to the center of the tube furnace and nitrogen was introduced for 0.5 h to ensure that the reaction was in an inert gas environment. The carbonization reaction is conducted at a temperature of 600℃, with a heating rate of 5℃ per minute, and the temperature is maintained constant for a period of 1.0 hours. Once the reaction is complete and the temperature has decreased to 25℃, immerse the carbonized product in a solution of 20 wt% absolute ethanol and subsequently perform suction filtration. Finally, the carbon product was obtained by drying at 80℃ for 12.0 h.1.0 g of carbonized product was weighed and mixed with 7.0 mmol/g of ferric acetylacetonate catalyst. The reaction temperature was raised to 850℃ and stored for 1.0 h. After reducing the reaction to 25℃, the crucible was removed, sonicated for 1.0 h, filtered, and dried for 80℃ for 12.0 h to obtain CSBGC(Fig.1). Calculation formula of graphitized carbon yield(line141-159).

 

13.Compositional details of the obtained materials have to be reported. In particular, C, H, O, N and metallic species contents of the materials produced at the different stages of the process have to be reported

 

In accordance with your suggestion, we performed an ash test on the graphitized carbon obtained in this experiment, which contained less than 1%, and supplemented it with an ICP test with the following results

Table 1 The Fe content results of CSBGC.

Sample	Test 1	Test 2	Test 3	Average
	(wt%)	(wt%)	(wt%)	(wt%)
CSBGC (by ICP-OES)	0.022	0.011	0.013	0.015

 

14.Section 3.2.1: the authors underlined the presence of ether bonds in the produced materials. Please explain why ether bonds are present in the samples and why their presence is so relevant.

 

Corn stover and polyethylene glycol 200 were added during the liquefaction process, which contains a large number of ether bonds, leading to findings in the infrared spectrograms.

 

15.Caption Figure 4: Clearly specify which panels are SEM images and which panels are TEM images.

 

We've rewritten and corrected it based on your suggestions.

 

Figure 4. SEM and TEM CSBGC after pickling with various magnification SEM SEM(a)CSBGC wrapped by annealed and cooled before ferric element removal SEM(b) CSBGC directly prepared from CS SEM(c) CSBGC TEM(d)(line202-205)

 

16.Section 3.2.6: Details about the conditions applied to perform the TG analyses have to be reported in section 2. Thermogravimetry is a powerful tool to predict the behavior of a sample during a thermoconversion process, but here it is not clear the meaning of this kind of analysis. Did the Authors simulate by TG the graphitization process? If yes, are the experimental conditions applied during TG analysis comparable to those of the carbonization process? The discussion of the obtained results should be improved. The sentence at lines 212-213 is completely wrong: during liquefaction the conversion of cellulose and hemicellulose into "oligosaccharides" occurs, not into "polysaccharides". This section needs a complete revision and improvements.

 

We have rewritten the TG analysis based on your suggestions.

TG and DTG diagrams of liquefied products and liquefied products with Fe(acac)₃ catalysts of CS were shown in Fig.8(a) and (b). According to that figure, the thermogravimetry of liquefied products includes three stages. Stage 1, is mainly caused by the removal of water and volatiles from the liquefied CS before 120℃[19]. The weight loss in the second stage mainly occurs at 120℃-400℃, which is the main stage of pyrolysis. In this stage, the conversion of cellulose and hemicellulose to oligosaccharides during liquefaction occurs, meanwhile, oligosaccharides thermal decomposition reaction is violent. Therefore, the mass loss is more significant. The third stage is 400 ℃-800℃. This stage is mainly a partial pyrolysis of lignin, which undergoes contraction of the carbon network, structural reformation, and formation of the carbon skeleton. At this stage, oligosaccharides and lignin are pyrolyzed through chemical bond breakage and rearrangement, and carbon is formed while pyrolysis gases such as CO₂ and CO, along with liquid products such as methanol and wood tar are released[20]. Comparing (Fig. 8(a)) when Fe(acac)3 (Fig. 8(b)) catalyst is added, thermal decomposition occurs at 170°C, complete thermal decomposition at 640°C, (Fig. 8(b)) has a solid weight plateau at 600°C, probably caused by the decomposition of the enol in the Fe(acac)₃, which tends to plateau when the temperature continues to increase (Fig. 8(a)) (Fig. 8(b)) does not change, and the CSBGC has a Thermal stability also applies to our study. before(Fig.8(a)) and after(Fig.8(b)) the addition of Fe(acac)3 catalyst, the yield of graphitized carbon was significantly increased after the addition of Fe(acac)3 catalyst.(line238-256)

 

17.Figure 8: Revise the graphics specifying the quantities reported on the axes

 

We have changed the information in the picture according to your suggestion.

 

 

18.suggest to make a comparison with the structural properties of other carbon-rich materials produced from corn straw and described by the open literature

 

Based on your suggestions we will compare the appropriate biomass materials in our future work.

 

19.I suggest to add some attempts in the use of the graphitized materials for specific applicationsConclusions

 

Based on your suggestions, we will use this product in our future work.

 

20.Please cite some possible applications for the produced materials.

 

In accordance with your suggestions, we have concluded with examples of corresponding graphitized carbon applications.

including electrochemical energy storage, electrolyte conductance, electrodes, etc.(line271-271)

 

 

 

Author Response File: Author Response.pdf

Reviewer 3 Report

This research focuses on the preparation and characterization of corn straw-based graphitized carbon (CSBGC) using ferric acetylacetonate as a catalyst. The study highlights the use of corn straw as a rich carbon source and the authors claiming a novel method for synthesizing graphitized carbon from it. Unfortunately, similar study can be found out: https://doi.org/10.1039/D2RA07352H.

This study presents similar output results with published paper: graphitization temperature 850 °C, and the catalyst was ferric acetylacetonate at a concentration of 7.0 mmol g−1. The corn straw-based graphitized carbon yield reached 22.20%. Moreover, XRD, FTIR and SEM data also exhibits similar results. Because this paper does not contain sufficient novelty in the design and affecting parameters to justify. Thus, this manuscript should be rejected.

The authors should find out some new points and maybe focus some, but not listing everything.

1.     Abstract should be more focused and concise on the study's findings.

2.     The author should be improved the language of the manuscript.

3.     In the manuscript, abbreviations must be clearly defined before usage

4.     Throughout the manuscript, there are many typos and spelling mistakes, should be revised.

5.     Provide explanation regarding many crystalline peak around 40-50o.

6.     Compare your results with the literature ones. Provide a tabular form of the literature performance results with the present work.

The author should be improved the language of the manuscript.

Author Response

Dear editor and Reviewers

I am the writer of the article "Preparation and Characterization of Corn Straw-based Graphitized Carbon with Ferric Acetylacetonate as Catalyst" (ID:2552218). I am grateful to the editors and reviewers for their suggestions for the revision of this article, and according to the suggestions careful modifications have been made. We will now report to you the status of the revision of this article.

For language, we have invited professionals to make modifications.

 

1.Abstract should be more focused and concise on the study's findings.

 

We've rewritten Abstract based on your suggestion.

Abstract: Carbon graphitization exhibits exceptional thermal stability, electrical conductivity, corrosion resistance, and various intricate physical and chemical properties. Consequently, it has found extensive applications in diverse fields such as electrodes, refractory materials, nuclear reactors, and supercapacitors. However, natural graphite is a limited non-renewable resource, so it is important to find other materials, explore reliable graphitization methods, and achieve efficient green graphite production as an important trend in the future. In this paper with corn straw liquefied product (CSLP) (corn straw (CS)as raw material, ethylene glycol (PEG200) compound glycerol mass ratio of 7:3 mixed solution as a liquefaction agent, 0.3g hydroxy dib fork phosphoric acid as catalyst, CS and liquefaction agent solid-liquid ratio of 1:2) as raw material, ferric acetone catalyst, through carbonization, catalytic graphitization preparation of corn straw based graphitic carbon (CSBGC). When the graphitization temperature was 850 °C and the amount of ferric acetylpropionate (Fe(acac)₃) was 7.0 mmol/g, the graphitized carbon showed better graphitization, microfragmentation structure, and smaller defects, which effectively reduced the graphitization temperature, and the graphitic carbon rate of corn straw reached 25.2%. This study not only presents a highly efficient approach for the synthesis of superior biomass-derived graphite carbon but also introduces usable perspectives on the utilization of corn straw.(line8-22)

 

2.The author should be improved the language of the manuscript.

 

For language, we have invited professionals to make modifications.

 

3.In the manuscript, abbreviations must be clearly defined before usage

 

In response to your suggestion, we have standardized the abbreviations, not the definitions.

 

4.Throughout the manuscript, there are many typos and spelling mistakes, should be revised.

 

For language, we have invited professionals to make modifications.

 

5.Provide explanation regarding many crystalline peak around 40-50°.

 

Iron was not completely removed in the previous period due to the inadequacy of our experiments. We have now completely removed the iron and performed XRD characterization.

 

 

6. Compare your results with the literature ones. Provide a tabular form of the literature performance results with the present work.

 

Carbon materials with considerable pore structure and graphitization at the same time are not common.The point of our study is to encapsulate both of these properties, In the future, we will take your suggestions and try to maximize both features.

Author Response File: Author Response.pdf

Reviewer 4 Report

In this paper, author had converted the corn straw to graphite material using carbonization and catalytic-graphitization methods. The physiochemical properties of graphite products were detected and analyzed, Then the morphology was observed using SEM and TEM techniques. However, the amount of experiment in this work was not enough, and the level of statement was not specific. Therefore, major revision is recommended, and comments are followed.

1.       The format of this manuscript should be adjusted according the request of journal.

2.       It is noted that your manuscript needs careful editing by someone with expertise in technical English editing paying particular attention to English grammar, spelling, and sentence structure so that the goals and results of the study are clear to the reader.

3.       Whether the author should determine the feasibility of this work by basic economic benefit evaluation or life cycle evaluation.

4.       In which aspects the straw foundation graphite prepared in this work had better application performance, please reflect its value.

5.       Should experiment instruments be placed behind material preparation?

6.       Please refer to the format of other papers in this journal to see if the graphs in this article could be more standardized.

7.       Why did the authors not compare the physical and chemical properties of graphite materials prepared under different conditions, but only compare the yield?

8.       Should the title of 3.1 single factor be more complete?

9.       Graphite materials will also have pore properties, it is recommended to supplement its related tests.

10.    In addition, the list of references is not in our style. It is close but not completely correct.

 It is noted that your manuscript needs careful editing by someone with expertise in technical English editing paying particular attention to English grammar, spelling, and sentence structure so that the goals and results of the study are clear to the reader.

Author Response

Dear editor and Reviewers

I am the writer of the article "Preparation and Characterization of Corn Straw-based Graphitized Carbon with Ferric Acetylacetonate as Catalyst" (ID:2552218). I am grateful to the editors and reviewers for their suggestions for the revision of this article, and according to the suggestions careful modifications have been made. We will now report to you the status of the revision of this article.

For language, we have invited professionals to make modifications.

 

1.The format of this manuscript should be adjusted according the request of journal.

 

As per your suggestion, the issue has been resolved.

 

2. It is noted that your manuscript needs careful editing by someone with expertise in technical English editing paying particular attention to English grammar, spelling, and sentence structure so that the goals and results of the study are clear to the reader.

 

For language, we have invited professionals to make modifications.

 

3.Whether the author should determine the feasibility of this work by basic economic benefit evaluation or life cycle evaluation.

 

The product is currently a transitional stage of graphene preparation. The product has some economic value.

 

4.In which aspects the straw foundation graphite prepared in this work had better application performance, please reflect its value.

 

The material can be used in different applications in different fields, including electrochemical energy storage, electrolyte conductivity, electrodes and so on.

 

5.Should experiment instruments be placed behind material preparation?

 

As per your suggestion, the issue has been resolved.

 

6 Please refer to the format of other papers in this journal to see if the graphs in this article could be more standardized.

 

As per your suggestion, the issue has been resolved.

 

7.Why did the authors not compare the physical and chemical properties of graphite materials prepared under different conditions, but only compare the yield?

 

Biomass-based graphitic carbon with hierarchical pore structure is significant.We will continue to explore the suggestions you have provided in our future research!

 

8.Should the title of 3.1 single factor be more complete?

 

We have rewritten it according to your suggestions.

Figure 2. Effect of a single factor on CSBGC yields:(a) Solid-liquid ratio;(b) Graphitization Temperature;(c) Catalyst concentration.(line162-163)

 

9.Graphite materials will also have pore properties, it is recommended to supplement its related tests.

 

Based on your comments we have made additions to the BET test.

 

10.In addition, the list of references is not in our style. It is close but not completely correct.

As per your suggestion, the issue has been resolved.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors improved a lot the manuscript and most of my advises have been addressed, anyway in my opinion the manuscript is still not ready for publication. Major revisions are still needed.

-          There are a lot of typos (many spaces, commas, points are missing). Please revise the entire manuscript from the editing point of view;

-          Abstract: change “Carbon graphitization” into “graphitized carbon”;

-          Abstract: revise the text at lines 13-17;

-          Acronyms have to be introduced at the first appearance in the text and also even if they have been introduced in the abstract section. Please clarify the meaning of the all acronyms like CS, CSS, CSLP, CSCS, CSBGC, etc;

-          Introduction: The aim of the work is not clear, please rewrite it;

-          As already asked during the first round of revision, it is important to report compositional details (C, H, N, O) of all the materials under analysis (starting feedstock included) since the H/C and O/C ratio values can be correlated with the graphitization degree;

-          Section 2.3.2: it contains only experimental details and no discussion of the results. Please revise it accordingly, moving the experimental details to section 2 and adding discussion about the data in Figure 2;

-          Lines 219-220: remove “from Fe(acac)3 catalyst”;

-           Lines 242-248: the text is confusing. Please rewrite.

The Authors improved the quality of the manuscript, but some sentences are confusing and need a revision. A linguistic check of the entire manuscript is still necessary.

Author Response

Dear editor and Reviewers：

I am the writer of the article "Preparation and Characterization of Corn Straw-based Graphitized Carbon with Ferric Acetylacetonate as Catalyst" (ID:2552218). I am grateful to the editors and reviewers for their suggestions for the revision of this article, and according to the suggestions careful modifications have been made. We will now report to you the status of the revision of this article.

For language, we have invited professionals to make modifications.

We hope that the revision is acceptable, and I look forward to hearing from you soon.

Yours sincerely,

LiMu

We would like to express our sincere thanks to the reviewers for their constructive and positive comments. As I have re-edited the language and structure, the overall structure of the article has changed a little and the line numbers are different from before. For your convenience, I will mark the line numbers that have changed after each change.

Replies to Reviewer 2：

1. There are a lot of typos (many spaces, commas, points are missing). Please revise the entire manuscript from the editing point of view;

According to your suggestion, for the language issue, we have invited professionals to make changes.

2. Abstract: change “Carbon graphitization” into “graphitized carbon”;

We have made changes in the article based on your suggestions.

Graphitized carbon exhibits exceptional thermal stability, electrical conductivity, corrosion resistance, and various intricate physical and chemical properties.（line8）

3. Abstract: revise the text at lines 13-17;

Based on your suggestions we have removed the inappropriate parts of the Abstract.

In this paper, with corn straw liquefied product (CSLP) as raw material, ferric acetone catalyst, through carbonization, catalytic graphitization preparation of corn straw based graphitic carbon (CSBGC). When the graphitization temperature was 850 °C and the amount of ferric acetylpropionate (Fe(acac)₃) was 7.0 mmol/g, the graphitized carbon showed better graphitization, micro fragmentation structure, and more minor defects, which effectively reduced the graphitization temperature, and the graphitic carbon rate of corn straw (CS) reached 25.2%.(line13-18)

4. Acronyms have to be introduced at the first appearance in the text and also even if they have been introduced in the abstract section. Please clarify the meaning of the all acronyms like CS, CSS, CSLP, CSCS, CSBGC, etc;

Based on your suggestion we have made a clear definition in the article.

Corn straw liquefied product (CSLP)

Corn straw based graphitic carbon (CSBGC)

Corn straw (CS)

5. Introduction: The aim of the work is not clear, please rewrite it;

We have rewritten the Introduction section based on your suggestions and clarified the purpose of the study.

In this study, an existing combined liquefaction-carbonization-graphitization technique was employed. CSBGC was obtained at the graphitization stage using Fe(acac)₃ as a catalyst. The optimum process conditions for CSBGC were determined by single factor experiments (The successful preparation of CSBGC was achieved by utilizing a dosage ratio of 1:2 for CS to liquefying agent, a graphitization temperature of 850 °C, and a catalyst concentration of 7.0 mmol/g of Fe(acac)₃.). Using a Fourier transform infrared spectrometer (FTIR), an elemental analyzer (EA), an X-ray diffractometer (XRD), a Raman spectrometer (Raman), a scanning electron microscope (SEM), a transmission electron microscope (TEM), Thermal Gravimetric Analyzer (TGA), Brunauer Emmett Teller (BET), Inductive Coupled Plasma Emission Spectrometer (ICP) and so on. The structural evolution during graphitization was analyzed. The inexpensive CS was used to prepare graphitized carbon materials to generate the basic materials for obtaining graphene with high performance.(line70-81)

6. As already asked during the first round of revision, it is important to report compositional details (C, H, N, O) of all the materials under analysis (starting feedstock included) since the H/C and O/C ratio values can be correlated with the graphitization degree;

Following your suggestion we have added the corresponding characterization analyses in articles 3.2.7 and 3.2.8.

3.2.7. Elemental Analysis

EA obtained the changes in the chemical composition of corn straw during graphitization. As presented in Fig. 9, CS initial elemental calculations C, 45.36; H, 7.146; O, 33.7; N, 4.00.CSLP initial elemental calculations C, 40.44; H, 9.30; O, 36.87; N, 3.50. liquefied products with Fe(acac)₃ catalyst initial elemental calculations C, 49.49; H, 5.94; O, 27.87; N,6.80. The pristine CS's atomic content was close to that calculated from its molecular formula. Graphitization pyrolysis products include CO₂, CO, H₂O, NO, NO₂, HCN, and NH₃. These gases are the products of the decomposition of the CS functional groups. In the initial stage of carbonization, the gaseous by-product CO₂ is dominant. With further carbonization, CO escapes and begins to be emitted along with other gaseous products. As the temperature increases, the oxygen, nitrogen, and hydrogen content decreases while the carbon content increases. The carbon content in the graphitization process of carbonization has two stages of rapid increase at 120 °C and 400 °C, while the oxygen content decreases in the following four stages: a sudden decrease from 120 °C to 400 °C, a slight fluctuation until 550 °C, a sharp decrease from 550 °C to 640 °C, and a complete disappearance at 800 °C.On the other hand, the nitrogen and hydrogen contents gradually decrease above 50 °C. This changing carbon and oxygen content behavior is attributed to the conversion of carbonyl groups (C-O) in polyethylene glycol and Fe(acac)₃ to CO or CO₂. Gases such as H₂O, NO, NO₂, NH₃, and HCN precipitate due to the gradual release of nitrogen and hydrogen atoms until gas precipitation is complete at 600 °C. The carbonation process is also characterized by a gradual decrease in nitrogen and hydrogen content from 550 to 640 °C. During the carbonization process, the carbon content of liquefied products with Fe(acac)₃ catalyzes is slightly higher than that of CSLP. This is due to the higher content of carbon atoms and lower content of oxygen atoms in liquefied products with Fe(acac)₃ catalyzes molecules. It is worth noting that the high oxygen content of CS implies that a large amount of CO and CO₂ is released during the carbonization process, thus leading to a low carbon yield. As H/C and O/C decrease, the degree of graphitized carbon gradually increases, and the degree of defects decreases.

Figure 9. Change of atomic contents of CS and CSLP and CSLP with catalysis graphitization temperature.

3.2.8. Inductively Coupled Plasma Optical Emission Spectrometer.

Tabular 1. The Fe content results of CSBGC.

Sample	Test 1	Test 2	Test 3	Average
	(What%)	(What%)	(What%)	(What%)
CSBGC (by ICP-OES)	0.022	0.011	0.013	0.015

 

 

 

 

Since CSLP with Fe(acac)₃ contains Fe element, which will affect the purity of CSBGC, the CSBGC made by adding an excess of 0.1 mol/L hydrochloric acid solution followed by three repetitive washes, repeated rinsing using anhydrous ethanol to remove the excess hydrochloric acid, and finally rinsing with deionized water to adjust the pH neutrality of the graphitized carbon were subjected to AE Elemental analysis was performed. The high percentage of element C in CSBGC confirmed the high purity of CSBGC. At the same time, an ICP-OES test was conducted, and the results are shown in Table I. The average iron content of CSBGC is 0.015%, which indicates that the products produced in this experiment have high purity and can be used to obtain the basic materials with high-performance graphene.(line269-313)

7. Section 2.3.2: it contains only experimental details and no discussion of the results. Please revise it accordingly, moving the experimental details to section 2 and adding discussion about the data in Figure 2;

We have rewritten the Single factor experiment section based on your suggestions and added the appropriate analyses.

3.1.1.Catalyst concentration

Liquefaction products with a 1:2 solid-liquid ratio were prepared according to 2.3.1, and graphitized carbon was prepared by the process of 2.3.2 (Fig. 2(c)). It can be seen that when the graphitization temperature was 850 °C, 1.0 mmol/g-7. 0 mmol/g catalyst dosage had a significant upward trend in the CSBGC yield, and there was no significant upward change in 7.0 mmol/g-9. 0 mmol/g catalyst dosage. Therefore, the yield of the sample was 22.2% at a ferric acetoacetate catalyst concentration of 7.0 mmol/g.

3.1.2. Solid-liquid ratio of liquefied products

Liquefaction products with different solid-liquid ratios were prepared according to 2.3.1, and graphitized carbon was prepared by the process of 2.3.2. (Fig. 2(a)) The results showed that the liquefaction rate increased when the solid-liquid ratio was in the range of 1:0-1:2 at a catalyst dosage of 7.0 mmol/g of Fe(acac)₃ and a graphitization temperature of 850 °C. As the solid-liquid ratio continued to increase to 1:4, the change in liquefaction rate slowly decreased. The trend of graphitized carbon shows that the change in CSBGC yield is not significant as the solid-liquid ratio is in the range of 1:0 -1:4. Therefore, the ratio is determined by the liquefaction rate. The liquefaction rate of corn straw was 15.2% at a ratio of 1:2, at which time the CSBGC yield obtained was 22.2%.

3.1.3.Graphitization Temperature

The liquefaction product with a 1:2 solid-liquid ratio was prepared according to 2.3.1, when the catalyst dosage was 7.0 mmol/g of Fe(acac)₃, and graphitized carbon was prepared by the process of 2.3.2. I was using (Fig. 2(b)). The experiments found that the temperature had a significant effect on the degree of graphitization of corn straw. The results showed that at the graphitization temperature, the yield of CSBGC was significantly increased in the range of 750°C-850°C, whereas there was no significant change in the yield of graphitized carbon in the range of 850°C-900°C. Considering the experimental cost, process conditions, and other factors, the graphitization temperature of CS was 850 °C.(line149-175)

 

8. Lines 219-220: remove “from Fe(acac)3 catalyst”;

As per your suggestion, the issue has been resolved.

It shows the isotherms and pore size distribution curves for the adsorption and desorption of CSBGC in Fig. 7. The Curve (a) is consistent with the type IV adsorption isotherm curve, with capillary aggregation in the high-pressure region, while the curves do not overlap, which reflected that there exist some mesopores.(line237)

9.Lines 242-248: the text is confusing. Please rewrite.

In response to your suggestion, we have rewritten that portion of the text.

The weight loss in the second stage mainly occurs at 120℃-400℃, which is the main stage of pyrolysis. In this stage, biomass polysaccharides are converted to oligosaccharides in the liquefaction process. The mass loss is more significant due to oligosaccharides' poor thermal stability, and oligosaccharides' thermal decomposition reaction is intense at 200°C-400°C in Fig.8(a) and (b). The third stage is 400°C-800°C. This stage may be Fe(acac)₃ pyrolysis, which undergoes contraction of the carbon network, structural reorganization, and formation of the carbon skeleton.(line2500-256)

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Still requires much improvement.

Minor corrections. Still many typo errors.

Author Response

Dear editor and Reviewers：

I am the writer of the article "Preparation and Characterization of Corn Straw-based Graphitized Carbon with Ferric Acetylacetonate as Catalyst" (ID:2552218). I am grateful to the editors and reviewers for their suggestions for the revision of this article, and according to the suggestions careful modifications have been made. We will now report to you the status of the revision of this article.

For language, we have invited professionals to make modifications.

We hope that the revision is acceptable, and I look forward to hearing from you soon.

Yours sincerely,

LiMu

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

The Authors improved the manuscript accordingly with my last indications. The manuscript is now more complete and readable and can be accepted for publication.

Anyway, before the publication I suggest to revise Table 1 following the following indications:

-change “Tabular” with “table”

- change “what%” with “wt.%”, because it is a mass concentration (wt.% means weight percentage)

- specify in the caption of the table the type of measurement (by ICP OES) and remove such a specification from the name of the sample

The Authors improved a lot the quality of the language, anyway there are still some sentences not clear (verbs are sometimes missing)

Author Response

Dear editor and Reviewers：

I am the writer of the article "Preparation and Characterization of Corn Straw-based Graphitized Carbon with Ferric Acetylacetonate as Catalyst" (ID:2552218). I am grateful to the editors and reviewers for their suggestions for the revision of this article, and according to the suggestions careful modifications have been made. We will now report to you the status of the revision of this article.

For language, we have invited professionals to make modifications.

We hope that the revision is acceptable, and I look forward to hearing from you soon.

Yours sincerely,

LiMu

We would like to express our sincere thanks to the reviewers for their constructive and positive comments. As I have re-edited the language and structure, the overall structure of the article has changed a little and the line numbers are different from before. For your convenience, I will mark the line numbers that have changed after each change.

Replies to Reviewer 2：

1. change “Tabular” with “table”

According to your suggestion, the problem has been modified.

 

2. change “what%” with “wt.%”, because it is a mass concentration (wt.% means weight percentage)

According to your suggestion, the problem has been modified.

3. specify in the caption of the table the type of measurement (by ICP OES) and remove such a specification from the name of the sample

According to your suggestion, the problem has been modified.

 

Author Response File: Author Response.pdf