Physicochemical and Sorption Characteristics of Carbon Biochars Based on Lignin and Industrial Waste Magnetic Iron Dust

Round 1

Reviewer 1 Report

In this paper, the author prepared magnetosensitive biochars using lignin and blast furnace dust. The prepared sample was characterized well with different techniques. The ability of the prepared biochar for dye removal from water was investigated. Considering some innovations of this work, it can be considered for publication after minor revision.

 

1-    It has been shown recently, that the classical form of the Langmuir equation is not valid for modeling of adsorption equilibrium data of the liquid phase (Chemical Physics, 2018, 513, 99-104). So it is necessary to re-fit the adsorption equilibrium data with the modified Langmuir instead of the Langmuir equation.

2-    A comparison of the obtained data in the present work with the literature data is recommended.

Author Response

Reviewer  I

 

In this paper, the author prepared magnetosensitive biochars using lignin and blast furnace dust. The prepared sample was characterized well with different techniques. The ability of the prepared biochar for dye removal from water was investigated. Considering some innovations of this work, it can be considered for publication after minor revision.

 

1. It has been shown recently, that the classical form of the Langmuir equation is not valid for modeling of adsorption equilibrium data of the liquid phase (Chemical Physics, 2018, 513, 99-104). So it is necessary to re-fit the adsorption equilibrium data with the modified Langmuir instead of the Langmuir equation.

 

Thank you for your advice. The adsorption isotherms were refitted using the modified Langmuir equation.

 

2. A comparison of the obtained data in the present work with the literature data is recommended.

 

Thank you for your comment. The adsorption values were compared with the literature data. It should be marked that the type of lignin as well as the microstructure of char yield depends on the source of biomass and the amount of cellulose and lignin. Lignin-derived biochars are characterized by differentiated porosity and S_BET, and adsorption properties depending on the initial raw materials.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript presented the characterization of carbon bio-chars based on two different materials. However, there is no relevant background on why these materials combined to produce bio-chars. Limited explanation related to the topic gap to introduce this kind of bio-chars make the weak novelty of the manuscript. Therefore, the background needs to be improved.

An additional comparison is needed to enrich the discussion by comparing the present results to the pure lignin and industrial waste from the published papers. For example, the specific surface area in the range of 290−330 m2/g; is it small or large size compared to other materials?

In the Thermal Analysis section, heating the bio-chars will affect the characteristics of bio-chars, it could be relevant to the physical activation process. However, in the manuscript, the discussion only focuses on weight loss.

It is concluded that the best adsorption properties are for the sample with the highest filler content and the highest share of mesopores in the pore structure. However, if we observed in Fig. 2 and Fig. 6, even the samples with a small distribution of mesopores structure can perform to remove the methylene blue.

Author Response

Reviewer II

 

1. The manuscript presented the characterization of carbon bio-chars based on two different materials. However, there is no relevant background on why these materials combined to produce bio-chars. Limited explanation related to the topic gap to introduce this kind of bio-chars make the weak novelty of the manuscript. Therefore, the background needs to be improved.

 

Thank you for your comment. A detailed description of the initial components and justification for the selection of lignin and metallurgical dust as raw materials for carbons synthesis was added in the INTRODUCTION sections. The aspect of novelty the obtained indulin-iron dust biochars was better exposed.

 

2. An additional comparison is needed to enrich the discussion by comparing the present results to the pure lignin and industrial waste from the published papers. For example, the specific surface area in the range of 290−330 m²/g; is it small or large size compared to other materials?

 

Thank you for your comment.

We could agree. The S_BET is not very high and may be inferior to the values described in the literature, but our strategy is based on the use of iron dust as a filler, which plays the role of a graphitization catalyst, as well as a porosity activator, and at the same time allows obtaining magneto-sensitive carbon sorbent systems. The advantage of such adsorbents is that in the contact purification of solutions, the use of magnetic sorbents greatly simplifies the separation of the sorbent by magnetic separation and the completeness of its processing. Besides, numerous described in the literature biochars are characterized by specific surface areas below 100 m²/g. Taking into account biochars, other aspects are also important (reduction of production costs, reusing of wastes). Overall, the sentence was rewritten according to the suggestion.

 

3. In the Thermal Analysis section, heating the bio-chars will affect the characteristics of bio-chars, it could be relevant to the physical activation process. However, in the manuscript, the discussion only focuses on weight loss.

 

Thank you for your comment. The Thermal Analysis Section was improved. The main purpose of the thermal measurements was to determine the differences in the thermal stability of materials with a change in the initial ratios of the components, which seems very important in the aspect of their practical application (recovery/disposal/activation). Due to the difficulties associated with the characteristics of individual stages due to the lack of analysis of gaseous products, we focused mainly on the quantitative aspect of this process. In this version of the manuscript, we improved the thermal analysis description and added the most important aspects.

 

4. It is concluded that the best adsorption properties are for the sample with the highest filler content and the highest share of mesopores in the pore structure. However, if we observed in Fig. 2 and Fig. 6, even the samples with a small distribution of mesopores structure can perform to remove the methylene blue.

 

Thank you for your comment. The text was corrected.

Author Response File: Author Response.docx

Reviewer 3 Report

This work explored the potential utilization of abundant lignin and industrial magnetic dust as the precursors of magnetosensitive carbon systems. This manuscript is well written and can be published after the following revisions.

1.       Which is the main role of physical adsorption or chemical adsorption? What is their contribution to adsorption?

2.       It is recommended to compare the adsorption effect with industrial adsorbents.

3.       What is the rationale for choosing pH=2, 4, 7, 10 as the experimental condition?

4.       The following literature may be helpful in improving the quality of the manuscript. (Journal of Hazardous Materials, 2022, 426: 128062. Applied Clay Science, 2019, 169: 40-47.)

5.       There are grammatical errors in the manuscript, and I advise the author to revise them carefully.

Author Response

Reviewer III

This work explored the potential utilization of abundant lignin and industrial magnetic dust as the precursors of magnetosensitive carbon systems. This manuscript is well written and can be published after the following revisions.

1. Which is the main role of physical adsorption or chemical adsorption? What is their contribution to adsorption?

Thank you for your comment. In the case of studied systems the physical adsorption dominates. Discussion was widened taking into account different interactions between adsorbate and adsorbents. The scheme presenting the synthesis procedure and possible adsorption mechanisms was added.

2. It is recommended to compare the adsorption effect with industrial adsorbents.

Thank you for your comment. The data were compared with other biochars and also industrial adsobents (Table 6). In general, it can be stated that we obtained the MB adsorption results comparable to other studies. They show weaker adsorption properties than commercially available activated carbons, but their advantage is that they are characterized by a lower cost of production, and wastes reuse (environment friendliness).

Industrial adsorbents can have much higher adsorption capacity, however, in our case, sorbents were obtained on the base of industrial wastes and they were compared with carbonized unmodified lignin. The positive effect of the filler on the adsorption properties was shown. In addition, our approach makes it possible to obtain magneto-sensitive composites that are easily removed from the solution under the action of an external magnet.

3. What is the rationale for choosing pH=2, 4, 7, 10 as the experimental condition?

Thank you for your comment. In the adsorption experiment the influence pH was examined to check the effectiveness of obtained adsorbents in various conditions (change from acidic to basic conditions for wastes). Moreover, the effect of contact time was examined.

4. The following literature may be helpful in improving the quality of the manuscript. (Journal of Hazardous Materials, 2022, 426: 128062. Applied Clay Science, 2019, 169: 40-47.)

Thank you for your recommendation. The mentioned literature was used to improve the quality of the manuscript.

5. There are grammatical errors in the manuscript, and I advise the author to revise them carefully.

Thank you for your comment. The possible grammar errors were corrected.

Author Response File: Author Response.docx

Reviewer 4 Report

 

This paper studied the Physicochemical and Sorption Characteristics of Carbon Biochars Based On Lignin and Industrial Waste Magnetic Iron Dust. There are some problems, which must be solved before it is considered for publication

 

1.    The innovation of this study is not well described in "INTRODUCTION" section. Recheck it. The "Introduction" section needs a major rewrite. The following references are useful to cover this gap : https://doi.org/10.1080/01496395.2019.1676785, https://doi.org/10.1080/01496395.2016.1178289, https://www.deswater.com/DWT_abstracts/vol_172/172_2019_86.pdf, https://doi.org/10.3390/app12157587.

2. The novelty needs to refinement and should be highlighted in the introduction part.
3. Authors need to spell English language throughout the manuscript. English is good, but some phrases are written with wrong word order.
4. Why did the authors use the Methylene Blue Dye?
5. Authors have to detrmine the pH0 first?
6. Page 06 line 218 equation 03, a is not the amount adsorption but the amount adsorption at the equilibrium am is the maximum amounte note the adsorption capacity, the unit of V is what even the unit of m please check
7. Page 06 line 222The Freundlich constant n is the heterogeneity factor
8. Authors need to calculate RL which can
9. The authors should add the probal mechan
10. Page 06, line 230-234, authors mention that they have carried out the kinetic study, but in the section results and discution nothing is indicated
11. In the conclusion, line …. authors mention that the .materials show good adsorption but in contrast the am, the maximum capacity was very low (tabl05) please check.

12. The conclusion is also not targeted to the important aspects described in the manuscript; please rephrase it.

 

Author Response

Reviewer IV

This paper studied the Physicochemical and Sorption Characteristics of Carbon Biochars Based On Lignin and Industrial Waste Magnetic Iron Dust. There are some problems, which must be solved before it is considered for publication

1. The innovation of this study is not well described in "INTRODUCTION" section. Recheck it. The "Introduction" section needs a major rewrite. The following references are useful to cover this gap : https://doi.org/10.1080/01496395.2019.1676785, https://doi.org/10.1080/01496395.2016.1178289, https://www.deswater.com/DWT_abstracts/vol_172/172_2019_86.pdf, https://doi.org/10.3390/app12157587.

Thank you for recommending interesting literature. The introduction was rewritten according to the Reviewer’s suggestions. The references were added to the Introduction.

2. The novelty needs to refinement and should be highlighted in the introduction.

Thank you for your comment. The novelty of the prepared and investigated materials is better exposed in the Introduction.

3. Authors need to spell English language throughout the manuscript. English is good, but some phrases are written with wrong word order.

Thank you for your comment. The manuscript was checked in terms of English grammar or spelling mistakes.

4. Why did the authors use the Methylene Blue Dye?

Thank you for your comment. Dyes are compounds widely used in the cosmetics, printing, plastics or textile industries to colour products, resulting also in the colouration of industrial wastewater. Methylene blue is an organic (thiazine) dye widely used in the textile industry to colour textiles blue but is dangerous to the environment due to its toxicity and resistance to natural degradation, therefore its removal is of great importance.

5. Authors have to determine the pH first?

Thank you for your comment. We performed experiments of contact time and pH before the adsorption studies. Thus, the effectiveness of obtained adsorbents in various conditions (change from acidic to basic conditions for wastes) was analysed.

6. Page 06 line 218 equation 03, a is not the amount adsorption but the amount adsorption at the equilibrium, am is the maximum amount note the adsorption capacity, the unit of V is what even the unit of m please check

Thank you for your comment. The equation was checked and the description was corrected.

7. Page 06 line 222The Freundlich constant n is the heterogeneity factor

Thank you for your comment. The equation descriptions were corrected.

8. Authors need to calculate RL which can.

Thank you for your comment. The obtained R_L values for the individual materials were in the ranges of: 0.18-0.82 (STInd-1); 0.21-0.84 (STInd-2); 0.24-0.86 (STInd-3); 0.17 -0.82 (STInd-4); 0.002-0.004 (Indulin/Carbon). The values in the range of 0<R_L<1 mean the favourable process of the investigated systems. In the corrected manuscript the modified Langmuir equation was used according to Reviewer I recommendations and this sentence was finally removed.

9. The authors should add the probable mechanism.

Thank you for your comment. The probable mechanism of MB adsorption on the investigated biochars was added (the scheme presenting the synthesis procedure and possible adsorption mechanisms).

10. Page 06, line 230-234, authors mention that they have carried out the kinetic study, but in the section results and discussion nothing is indicated

Thank you for your comment. In this work, only equilibrium adsorption studies were performed. Before the experiments, the effect of contact time was checked but generally kinetic studies were not performed.

11. In the conclusion, line …. authors mention that the .materials show good adsorption but in contrast the am, the maximum capacity was very low (tabl05) please check.

Thank you for your comment. This statement was improved.

12. The conclusion is also not targeted to the important aspects described in the manuscript; please rephrase it.

Thank you for your comment. We improved the conclusions and added the most important aspects.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The manuscript has been improved to show the novelty. Relevant background on why these materials combined to produce bio-chars has been added. An additional discussion has also been developed to increase the present work's clear presentation. However, some minor revisions should be made to the citation of the references.

Reviewer 4 Report

Accepted in the present form