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Open AccessArticle
Peer-Review Record

Adsorption of Chloramphenicol on Commercial and Modified Activated Carbons

Water 2019, 11(6), 1141; https://doi.org/10.3390/w11061141
Reviewer 1: Tran Hai
Reviewer 2: Anonymous
Water 2019, 11(6), 1141; https://doi.org/10.3390/w11061141
Received: 23 April 2019 / Revised: 24 May 2019 / Accepted: 25 May 2019 / Published: 30 May 2019
(This article belongs to the Special Issue Wastewater Treatment: Review, Key Challenges, and New Perspectives)

Round 1

Reviewer 1 Report

The author reported “adsorption of chloramphenicol on commercial and modified activated carbons”. Although the data and idea are interesting, too many mistakes and problems were found. I hope that the author can improve the quality of the revised manuscript. My comments are as follows:

1. Abstract should be revised carefully, and more important results need to be added.

2. Introduction needs to be revised to confirm why this work should be published in this journal.

3. Table 1. pKa of chloramphenicol is 5.5 ????????????

4. Section 2.5. Please revise the content as formal writing.  

5. It was assumed that the time to the achievement of the adsorption equilibrium occurs when the change in concentration during 2 h is less than 0.5%???????????? Impossible.

6. In case of the pseudo-second-order kinetics equation, qmax was more similar to the results of the  experiment compared to the pseudo-first-order kinetics model??????????????? qmax or qe ????????? please also revise in Tables 2 and 5.

7. This may indicate the presence of various interactions (not only physical adsorption) during the adsorption of chloramphenicol. These include  the effects of the van der Waals forces, the electron-donor-acceptor interaction (EDA), or hydrogen  bonds [35, 49, 50].?????????????? Why did the authors know? Only based on the adsorption isotherm to withdraw this conclusion?

8. Figure 2. Kinetics of adsorption of chloramphenicol on commercial activated carbons. The authors should be present the result as qt (mg/g) vs time (min) rather than Co (mg/L) vs time (min).

9. Figure 3. This Isotherms of chloramphenicol adsorption on commercial activated carbon. Clearly, the adsorption process did not reach equilibrium, please add data of adsorption of chloramphenicol at a higher initial chloramphenicol concentration and re-calculate the parameters of all used models. A similar mistake was found in Figure 7.

10. The presentation of RL in Table 6 is not correct (Tran et al., 2017a; Kumar, 2006)

11. Other mechanisms responsible for the  adsorption of chloramphenicol can be the n-π interactions between the benzene rings of  chloramphenicol and carboxyl groups on the surface of activated carbon and the π-π interactions between the aromatic rings of chloramphenicol and activated carbon????????????????? Please read the paper (Tran et al., 2017b) and revise carefully.

12. The authors ignore the important role of pore filling mechanism. Please read the papers (Tran et al., 2017c; Tran et al., 2017d).

13. The discussion on the effect of temperature is not enough convincing. Please add the adsorption isotherms at different temperatures rather than, only experiments at only initial adsorbate concentration (Lima et al., 2019). The other option is the removal of Figure 6.

14. In the 21th century, I do not think that the linear method is suitable to calculate the parameters of used models (i.e., pseudo-first-order and Langmuir) (Tran et al., 2017a). Please use the non-linear method to re-calculate the parameters of all used models.

15. Discussion is too weak. Please revise the discussion thoroughly.

16. Too many unimportant discussion, information, and data are presented and discussed. This problem will decrease the quality of the manuscript. The author should consider and move some unimportant data into supporting information. A similar suggestion for discussion. Please only give important discussion and explanation, the other less important information and discussion should be deleted.

17. The organization of this study is very difficult to follow. Please revise carefully.

18. Please carefully use the comma and semicolon when the author present data, such as 0.182 mmol/g, not 0,182 mmol/g (Table 9). Please check and revise a similar mistake.

19 Table 9, it is impossible to get the extremely high values of basic groups/sites, such as up to 467 mmol/g???????????????

20. Please proved the excel files of raw data of all adsorption experiments when the authors submit the revised manuscript.

21. English should be improved.


References

Tran, H.N., You, S.-J., Hosseini-Bandegharaei, A. and Chao, H.-P., 2017a. Mistakes and inconsistencies regarding adsorption of contaminants from aqueous solutions: A critical review. Water Research 120, 88.

Kumar, K.V., 2006. Comments on “Adsorption of acid dye onto organobentonite”. Journal of Hazardous Materials 137(1), 638.

Tran, H.N., You, S.-J. and Chao, H.-P., 2017b. Fast and efficient adsorption of methylene green 5 on activated carbon prepared from new chemical activation method. Journal of Environmental Management 188, 322.

Tran, H.N., Wang, Y.-F., You, S.-J. and Chao, H.-P., 2017c. Insights into the mechanism of cationic dye adsorption on activated charcoal: The importance of π–π interactions. Process Safety and Environmental Protection 107, 168.

Tran, H.N., Wang, Y., You, S. and Chao, H., 2017d. Sustainable biochar derived from agricultural wastes for removal of methylene green 5 from aqueous solution: Adsorption kinetics, isotherms, thermodynamics, and mechanism analysis. Air, Gas, and Water Pollution Control Using Industrial and Agricultural Solid Wastes Adsorbents (1st Edition). Boca Raton: CRC Press., 255.

Lima, E.C., Hosseini-Bandegharaei, A., Moreno-Piraján, J.C. and Anastopoulos, I., 2019. A critical review of the estimation of the thermodynamic parameters on adsorption equilibria. Wrong use of equilibrium constant in the Van't Hoof equation for calculation of thermodynamic parameters of adsorption. Journal of Molecular Liquids 273, 425.

 


Author Response

Reply for the Reviewer

I would like to thank you for your valuable comments contained in the review. I am grateful for your factual and editorial remarks concerning the text, which will undoubtedly help me improve the paper.  Having read the proposed studies, I have corrected many mistakes which I repeated based on other papers. I would like to thank you for your valuable literature items, which allowed me to broaden my knowledge. 

I agree with all the comments contained in the review and have included them in the revised manuscript. I hope that the current discussion meets the requirement of your journal. 

Thank you for proposing articles that allowed me to better interpret the research results I obtained.

Abstract should be revised carefully, and more important results need to be added.

Improved

Introduction needs to be revised to confirm why this work should be published in this journal.

Supplemented

Table 1. pKa of chloramphenicol is 5.5 ????????????

Corrected. He is referring to the correct source of literature.

Section 2.5. Please revise the content as formal writing.

Reworded  

It was assumed that the time to the achievement of the adsorption equilibrium occurs when the change in concentration during 2 h is less than 0.5%???????????? Impossible.

The 0.5% value refers to the initial concentration. Supplemented in the article.

In case of the pseudo-second-order kinetics equation, qmax was more similar to the results of the  experiment compared to the pseudo-first-order kinetics model??????????????? qmax or qe ????????? please also revise in Tables 2 and 5.

Corrected

This may indicate the presence of various interactions (not only physical adsorption) during the adsorption of chloramphenicol. These include  the effects of the van der Waals forces, the electron-donor-acceptor interaction (EDA), or hydrogen  bonds [35, 49, 50].?????????????? Why did the authors know? Only based on the adsorption isotherm to withdraw this conclusion?

This conclusion has been removed

Figure 2. Kinetics of adsorption of chloramphenicol on commercial activated carbons. The authors should be present the result as qt (mg/g) vs time (min) rather than Co (mg/L) vs time (min).

Corrected

 

Figure 3. This Isotherms of chloramphenicol adsorption on commercial activated carbon. Clearly, the adsorption process did not reach equilibrium, please add data of adsorption of chloramphenicol at a higher initial chloramphenicol concentration and re-calculate the parameters of all used models. A similar mistake was found in Figure 7.

Additional measurements were made and isotherms were corrected

 

The presentation of RL in Table 6 is not correct (Tran et al., 2017a; Kumar, 2006)

Corrected. He is referring to the correct source of literature.

11. Other mechanisms responsible for the  adsorption of chloramphenicol can be the n-π interactions between the benzene rings of  chloramphenicol and carboxyl groups on the surface of activated carbon and the π-π interactions between the aromatic rings of chloramphenicol and activated carbon????????????????? Please read the paper (Tran et al., 2017b) and revise carefully.

Text has been corrected.

 

The authors ignore the important role of pore filling mechanism. Please read the papers (Tran et al., 2017c; Tran et al., 2017d).

Dziękuję za zaproponowanie artykułów dzięki którym mogłam lepiej zinterpretować otrzymane wyniki badań.

The discussion on the effect of temperature is not enough convincing. Please add the adsorption isotherms at different temperatures rather than, only experiments at only initial adsorbate concentration (Lima et al., 2019). The other option is the removal of Figure 6.

I have removed information on the effect of temperature on adsorption

 

In the 21th century, I do not think that the linear method is suitable to calculate the parameters of used models (i.e., pseudo-first-order and Langmuir) (Tran et al., 2017a). Please use the non-linear method to re-calculate the parameters of all used models.

Model coefficients of adsorption kinetics and adaorption isotherms were calculated from non-linear forms.

Discussion is too weak. Please revise the discussion thoroughly.

The discussion has been improved

Too many unimportant discussion, information, and data are presented and discussed. This problem will decrease the quality of the manuscript. The author should consider and move some unimportant data into supporting information. A similar suggestion for discussion. Please only give important discussion and explanation, the other less important information and discussion should be deleted.

The discussion has been improved. Part of the text was removed and some results were transferred to the supporting information.

The organization of this study is very difficult to follow. Please revise carefully.

The research methodology has been supplemented and revised

Please carefully use the comma and semicolon when the author present data, such as 0.182 mmol/g, not 0,182 mmol/g (Table 9). Please check and revise a similar mistake.

Corrected

 Table 9, it is impossible to get the extremely high values of basic groups/sites, such as up to 467 mmol/g???????????????

Corrected. The value was incorrectly given in µmol/g

 

Please proved the excel files of raw data of all adsorption experiments when the authors submit the revised manuscript.

Attached

English should be improved.

Improved

 

Author Response File: Author Response.docx

Reviewer 2 Report

Major Comments:

Because of the size of the antibiotic studied, I would suspect that pore size would be an important factor in the adsorption. The pore size was explored, but was not properly discussed in the background or presented in the description of the carbon characteristics in table 4. 

The literature review should develop the theoretical foundation to support the modifications performed on the carbon. 

Section 2.5 seems incomplete. It does not align with the style of the remainder of the paper.

The authors fail to adequately compare their results to the results of Liao, Fan, and others regarding kinetic and adsorption models as well as adsorption capacity. A table comparing these research findings would be useful. This also helps establish a case for the importance of the work, if it outperforms previous carbons explored for chloramphenical adsorption. An attempt was made to do so in the paragraph starting on line 330. 

The authors suggested they would explore the DR adosprtion model but did not. This is an important oversight because previously reported carbons fit this model for adsorption of chloramphenical. 

What is the error for the Boehm titration results reported in Table 9? 

The abstract states "The temperature and pH value of the solution have little effect on sorrption efficiency." This is contradicted starting on line 334. Also, this paragraph should be converted from bullet points to sentence format for consistency with the document. Then again, line 356 refers to an insignificant effect but then discusses how pH influenced the adsorption. 

Overall, I feel this work has significance. However, the authors fail to properly communicate the significance of their work beyond an effective adsorption experiment. Why is this carbon better than for chloramphenical adsorption than others reported in the literature? What other contributions does this work make? Did other studies establish the influence of pH?   

Minor Comments: 

a. Throughout, this manuscript should be reviewed for proper spelling, grammar, and syntax. 

b. Line 44, you repeat "high biological activity"

c. Line 44, you cite [4]. This article discusses advanced WWT for removal of antibiotic-resistant genes. You should cite the primary source for the facts you present in this sentence. 

d. Line 48 needs a citation. 

e. Line 57, data never proves a fact, only supports it.  


Author Response

Reply for the Reviewer

I would like to thank you for your valuable comments contained in the review.  I agree with all the comments and have included them in the revised manuscript. These comments will also allow me to improve my future papers.  I hope that the current version of the manuscript is suitable for publication in your journal. 

 

Because of the size of the antibiotic studied, I would suspect that pore size would be an important factor in the adsorption. The pore size was explored, but was not properly discussed in the background or presented in the description of the carbon characteristics in table 4. 

Table size 4 has been supplemented. The discussion was complemented.

 

The literature review should develop the theoretical foundation to support the modifications performed on the carbon. 

The research methodology explains why this modification was chosen.

Section 2.5 seems incomplete. It does not align with the style of the remainder of the paper.

Reworded

The authors fail to adequately compare their results to the results of Liao, Fan, and others regarding kinetic and adsorption models as well as adsorption capacity. A table comparing these research findings would be useful. This also helps establish a case for the importance of the work, if it outperforms previous carbons explored for chloramphenical adsorption. An attempt was made to do so in the paragraph starting on line 330.

A table was inserted comparing the results of different researchers.

The authors suggested they would explore the DR adosprtion model but did not. This is an important oversight because previously reported carbons fit this model for adsorption of chloramphenical. 

The D-R model has been supplemented.

What is the error for the Boehm titration results reported in Table 9? 

Corrected. The value was incorrectly given in µmol/g.

The abstract states "The temperature and pH value of the solution have little effect on sorrption efficiency." This is contradicted starting on line 334. Also, this paragraph should be converted from bullet points to sentence format for consistency with the document. Then again, line 356 refers to an insignificant effect but then discusses how pH influenced the adsorption. 

Improved

Overall, I feel this work has significance. However, the authors fail to properly communicate the significance of their work beyond an effective adsorption experiment. Why is this carbon better than for chloramphenical adsorption than others reported in the literature? What other contributions does this work make? Did other studies establish the influence of pH?   

Improved

Minor Comments: 

Throughout, this manuscript should be reviewed for proper spelling, grammar, and syntax. 

Improved

Line 44, you repeat "high biological activity"

Corrected

Line 44, you cite [4]. This article discusses advanced WWT for removal of antibiotic-resistant genes. You should cite the primary source for the facts you present in this sentence.

Corrected

Line 48 needs a citation. 

Supplemented

Line 57, data never proves a fact, only supports it. 

 Corrected

 

 

Round 2

Reviewer 1 Report

Dear the author:


May thanks for your great efforts in revising the manuscript.

Clearly, the quality of the revised manuscript has been significantly improved. Therefore, it should be accepted and published in this journal.

There are still some slight grammar errors, the author should do some relevant corrections in the proof. 

Author Response

Thank you for all the comments that made the article better. The text has been improved by a native speaker.

Reviewer 2 Report

The authors have adequately addressed my concerns from the first submission. They have put a significant effort into improving their manuscript. 

Author Response

Thank you for all the comments that made the article better. The text has been improved by a native speaker.

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