Removal of Fluoroquinolone Antibiotics by Chitosan–Magnetite from Aqueous: Single and Binary Adsorption
, Tung Q. Vu 1, Xuan T. Vuong 1, Vinh D. Nguyen 1, Linh T. N. Nguyen 1, Ha T. Le 2, Hoa T. H. Nguyen 1 and Van Phuoc Nguyen 3,4,*Round 1
Reviewer 1 Report
Chitosan-magnetite composites were synthesized and their applications for antibiotics removal from aqueous and industrial solutions were also studied. Various analytical approaches were used to characterize the adsorbents and the removal efficiency. The study provides promising industrial applications. However, I have some comments and hope the authors can address them before being considered for publication.
The removal of ciprofloxacin (CFX) and levofloxacin (LFX) by the composites was achieved by chitosan. It is not clear how magnetite affects the removal. I suggest a control experiment on how chitosan removes CFX and LFX.
The authors claimed that the adsorption isotherms follow Langmuir AND Freundlich models. I believe an isotherm should only follow one model. This issue was caused by the low concentration of CFX and LFX. In Figure 11, the concentrations of antibiotics are too low that there are only 4 data points that can be fitted by either Langmuir or Freundlich model. Consider adding more data points at higher antibiotic concentrations.
Which controls the pzc of the composites, chitosan or magnetite particles? Provide pzc values of both and discuss how the two components contribute to antibiotics removal. For example, some studies show that the pzc of magnesite is 6.55 (e.g., https://doi.org/10.1016/0021-9797(72)90016-1), which is close to the value in the current study. Does that mean the pzc of the composites was mainly controlled by magnesite, while the authors explained the adsorption mechanisms as interactions between antibiotics and chitosan?
Minor comments:
English language check. E.g., L40-41. Add period in L67. L302, “Error! …”, etc.
Table 1, consider separating “Effect of time/ initial concentration”. It is not clear how the experiments were conducted.
Figure 1, consider adding standard PDF card of magnetite and adding wavelength of X-ray. “XRD patterns” not “XRD”.
Figure 2, “spectro”.
Figure 3, label the shoulder around 700 eV.
Figure 4, SEM would be better to see the interactions between chitosan and magnetite particles.
L221, numbering is inconsistent. Check numbering for all sections.
L249, Figure ?.
Figure 10, change the two lines to solid and dashed lines for better comparison.
L302, “Error! …”
L344-345, the maximum adsorption capacities may not be true because of the low concentrations used.
L402, “Error! …”.
L415, “Error! …”
L457, “… Washed with 0.5 N NaOH solution” is inconsistent with L156.
Check the grammar of the manuscript.
Author Response
Dear Editor and reviewers,
We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of our manuscript. We have tried our best to respond to all issues indicated in the review report sufficiently. In the revised version, we have highlighted the changes to our manuscript using the red color. The answers to the questions you raised are detailed here.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This article deals with an important topic howto hinder antibiotics ciprofloxacin (CFX) and levofloxacin(LFX) from getting out in our environement as the have harmful effects on both human and aquatic ecosystems. The methods and mathematical models for adsorption kinetics can be used for design of removal of these antibiotics from wastewater systems.
i find this article interesting, easy to read and dealing with an revelant topic and giving a solution to a current problem. the authors describe their methods, experimental work and models in a clear way
i found just few mistakes in the pdf listed her below, please check
page 11 line 302 Table 3 , there is some extra text on the line "Error! No text of specified style in document." please check
same thig page 15 line 402 " Table Error! No text of specified style in document."
Author Response
Dear Editor and reviewers,
We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of our manuscript. We have tried our best to respond to all issues indicated in the review report sufficiently. In the revised version, we have highlighted the changes to our manuscript using the red color. The answers to the questions you raised are detailed here.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments in the attachment.
Comments for author File: Comments.pdf
Author Response
Dear Editor and reviewers,
We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of our manuscript. We have tried our best to respond to all issues indicated in the review report sufficiently. In the revised version, we have highlighted the changes to our manuscript using the red color. The answers to the questions you raised are detailed here.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I am pleased that the authors addressed my comments and added more data, which makes the manuscript publishable.
