Preparation of aminated chitosan microspheres by one-pot method and their adsorption properties for dye wastewater

Polyamine chelating adsorbents have a good removal effect on dye wastewater. In this study, small molecule triethylenetetramine and macromolecular poly(ethylene imine) were selected as aminated reagent, and two kinds of aminated chitosan microspheres, TETA-CTSms and PEI-CTSms, were obtained by emulsion cross-linking method. The microspheres were fully characterized by FTIR, SEM, XRD, EDS and TGA. EDS results showed that the N content of the PEI-CTSms and TETA-CTSms microspheres increased significantly after the cross-linking reaction and can reach 5.7 wt% and 7.3 wt%, respectively. Adsorption experiments confirmed that TETA-CTSms and PEI-CTSms showed greater adsorption characteristics for anionic dye reactive yellow (RY) in aqueous solutions compared with CTSms, and the adsorption capacity per unit area was increased by 39.11% and 88.56%, respectively. The adsorption capacity of aminated microspheres for RY decreased with the increase of pH. The adsorption kinetics conformed to the pseudo-second-order model, and the adsorption process was in accordance with the Langmuir isotherm model. The negative value of ΔG confirmed that the adsorption process was spontaneous, and the dye adsorption was a multiple process dominated by chemical chelating and physical adsorption.

2. Summary of the section on the conclusion is also presented in the abstract 3. In the introduction section used more literature. The following references should be cited in this section for upgrading the quality of the manuscript: 3.1. Removal of reactive blue 29 dye by adsorption on modified chitosan in the presence of hydrogen peroxide, Environment Protection Engineering, 42(1), pp. 149-168. 3.2. Synthesis of nanochitosan for the removal of fluoride from aqueous solutions: A study of isotherms, kinetics, and thermodynamics, Fluoride, 50(2), pp. 256-268. 3.3. Synthesis and performance evaluation of chitosan prepared from Persian gulf shrimp shell in removal of reactive blue 29 dye from aqueous solution (Isotherm, thermodynamic and kinetic study), Iranian Journal of Chemistry and Chemical Engineering, 36(3), pp. 25-36. 3.4. Optimization of humic acid removal by adsorption onto bentonite and montmorillonite nanoparticles. Journal of Molecular Liquids, 259, pp. 76-81 3.5. Investigation of equilibrium, kinetics and thermodynamics of extracted chitin from shrimp shell in reactive blue 29 (RB-29) removal from aqueous solutions. Desalination and Water Treatment,70,. Equilibrium and kinetics study of reactive dyes removal from aqueous solutions by bentonite nanoparticles. Desalination and Water Treatment,97, 4. For characterization of adsorbents, because the process was adsorption, so the analysis BET must be made to determine the surface area of the particles. 5. Formulas related to calculation of kinetics and thermodynamics in the section of experimental expressed not in the results section. 6. The conclusion is poorly written and must be rewritten.

11-Dec-2018
Dear Mr Yu: Manuscript ID: RSOS-181923 Title: "Preparation of aminated chitosan microspheres by one-pot method and their adsorption properties for dye wasterwater" Thank you for submitting the above manuscript to Royal Society Open Science. Your paper was sent to reviewers and their comments are included at the bottom of this letter.
In view of the concerns raised by the reviewers, the manuscript has been rejected in its current form. However, a new manuscript may be submitted which takes into consideration these comments.
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Once you have revised your manuscript, go to https://mc.manuscriptcentral.com/rsos and login to your Author Center. Click on "Manuscripts with Decisions," and then click on "Create a Reviewer: 2 Comments to the Author(s) In the research the authors were studied the preparation of aminated chitosan microspheres by one-pot method and their adsorption properties for dye wastewater. They investigated Characterization of chitosan microspheres with the analysis such as FT-IR, XRD, SEM, TG and EDS, and they also investigated adsorption kinetic constants for chitosan microspheres, thermodynamics parameters and the effects of parameters such as pH on the adsorption process. 1. More quantitative measurements be mentioned in the abstract 2. Summary of the section on the conclusion is also presented in the abstract 3. In the introduction section used more literature. The following references should be cited in this section for upgrading the quality of the manuscript: 3.1. Removal of reactive blue 29 dye by adsorption on modified chitosan in the presence of hydrogen peroxide, Environment Protection Engineering, 42 (1) 4. For characterization of adsorbents, because the process was adsorption, so the analysis BET must be made to determine the surface area of the particles. 5. Formulas related to calculation of kinetics and thermodynamics in the section of experimental expressed not in the results section. 6. The conclusion is poorly written and must be rewritten.

Author's Response to Decision Letter for (RSOS-181923.R0)
See Appendix A.

Is the language acceptable? Yes
Is it clear how to access all supporting data? Not Applicable

Do you have any ethical concerns with this paper? No
Have you any concerns about statistical analyses in this paper? No

Recommendation?
Major revision is needed (please make suggestions in comments)  Fig 4 show those MSs were seriously agglomerated as they been produced. The agglomerated adsorbents present perfect dye remove performance. The conclusion is seemed contradictory." Author's reply: During the preparation of the aminated microspheres, due to the addition of the polyamine-based substances TETA and PEI, the degree of cross-linking between the molecular chains was increased, causing aggregation. But the amino group content on the same surface area was significantly increased, which in turn leaded to a higher adsorption amount.
Thus, please provide evidence data about "the amino group content on the same surface area was significantly increased". This claimed conclusion should be proved by Solid data, not description.

Review form: Reviewer 2
Is the manuscript scientifically sound in its present form? Yes

Recommendation? Accept as is
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• Ethics statement Please clarify whether you received ethical approval from a local ethics committee to carry out your study. If so please include details of this, including the name of the committee that gave consent in a Research Ethics section after your main text. Please also clarify whether you received informed consent for the participants to participate in the study and state this in your Research Ethics section. *OR* Please clarify whether you obtained the necessary licences and approvals from your institutional animal ethics committee before conducting your research. Please provide details of these licences and approvals in an Animal Ethics section after your main text. *OR* Please clarify whether you obtained the appropriate permissions and licences to conduct the fieldwork detailed in your study. Please provide details of these in your methods section. ********************************************** RSC Associate Editor Comments to the Author: (There are no comments.) **********************************************  Fig 4 show those MSs were seriously agglomerated as they been produced. The agglomerated adsorbents present perfect dye remove performance. The conclusion is seemed contradictory." Author's reply: During the preparation of the aminated microspheres, due to the addition of the polyamine-based substances TETA and PEI, the degree of cross-linking between the molecular chains was increased, causing aggregation. But the amino group content on the same surface area was significantly increased, which in turn leaded to a higher adsorption amount.
Thus, please provide evidence data about "the amino group content on the same surface area was significantly increased". This claimed conclusion should be proved by Solid data, not description.