Catalytic Degradation of Chitosan by Supported Heteropoly Acids in Heterogeneous Systems
Round 1
Reviewer 1 Report
Introduction
- …’’Low molecular weight chitosan has higher solubility, and easy to be absorbed.’’…
The sentence should be completed. Absorbed where?
- …’’The studies show that the chitosan molecules were easy to in homogeneous system…’’ the sentence should be corrected.
The authors should clarify more which are the current needs for chitosan decomposition.
Materials
The properties of chitosan studied should be reported. In addition, the physicochemical properties of activated carbon sued should be also reported.
PTA was not reported in the materials-reagents.
Paragraph 2.2.
‘’Then, the solution was filtered.’’ The type of filters and the porosity should be mentioned.
‘’W0 - quality of activated carbon, g; ‘’ Please correct : quantity instead of quality. The same for W1. The same for paragraph 2.3.
Paragraph 2.3.
2000 g ? 2 Kg in a conical flask? Please correct.
Paragraph 2.4
Calibration curves for glucosamine and chitosan should be provided.
General: The experimental part should be written more carefully with more details and information.
Paragraph 2.5.
‘’The single factor experiment was carried out by controlling the variable method’’ The sentence has no meaning.
‘’…the ratio of hydrogen peroxide to hydrogen peroxide was R=2,…’’ The manuscript was written in a pell-mell way.
Paragraph 2.7.
LWCS is not defined previously.
Paragraph 2.8.
‘’…to measure the pore size of PTA with different loading samples ranging from 0 to 420,000
nm.’’ The sentence should be corrected. The methodology (instrument parameters) should be better described.
Results and Discussion
The PTA loaded on the activated carbon was not easy to be lost. The experimental results showed a different trend. There is no such evidence.
‘’According to the Box-Behnken central composite design principle, four factors, such as catalyst load (A), hydrogen peroxide amount (B), catalyst amount (C) and temperature (D), were selected to…..’’ According to the Box-Behnken central composite design principle, four factors, such as catalyst load (A), hydrogen peroxide amount (B), catalyst amount (C) and temperature (D), were selected to….’’
In Table 2 a different matching to the experimental factors is provided e.g. Hydrogen peroxide dosage (A), etc.
The quadratic equation can be simplified based on the significance of the factors effect.
Response surface plots are not discussed. The observed response should be explained.
Which is the reason of specific area increase after certain catalyst loading.
Fig. 11 is meaningless.
The discussion of the results is lacking. The characterization of the materials is incomplete.
Author Response
Thank you very much for your comments. I have revised them one by one according to your requirements. Looking forward to hearing from you again
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work by Song et all report the oxidative degradation of chitosan with supported phosphotungstic acid as catalyst. The paper is a valuable contribution to the study of the oxidation and degradation of high molecular weight chitosan.
I recommend acceptance. However, the authors should establish a comparative that clearly justifies the conclusion: “The efficiency of the supported PTA catalyst was significantly higher than that of a non-supported catalyst.
Author Response
Thank you very much for your comments. I have revised them one by one according to your requirements. Looking forward to hearing from you again.
Reviewer 3 Report
This manuscript presents activated carbon-supported PTA(phosphotungstic acid) as catalyst for degradation of chitosan. The property of obtained chitosan by the difference in preparation condition of activated carbon-supported PTA is examined. The results are reasonable. However, it should be revised because some mentions errors are found.
Comments:
- The deacetylation degree of chitosan greatly has an influence on the properties of it. Therefore, please show the deacetylation degree of the chitosan before degradation and after degradation.
- Page 4, line 11-12 “catalyst loading (A) ・・・　reaction time (D)”: They do not match notation of Tabel 1.
- Page 6, line 4-5 from the bottom “such as catalyst load (A) ・・・　catalyst amount (C)”: They do not match notation of Tabel 2.
Please confirm.
(1) Abstract line 1 “phosphotungsticacid” :　→ “phosphotungstic acid ”　 ?
(2) Page 3, line 5 “W1g”: → “W1 g”　 ?
Insert half size space before a unit. Please confirm it through the whole manuscript. e.g. Page 2, line 1 from the bottom “2mol/L”: → “2 mol/L”
Page 3, line 3 “75Hz”: → “75 Hz”
　　　Page 3, line 4 “2s” “4s” “3min”: → “2 s” “4 s” “3 min”
Page 3, line 12 “2000g”: → “2000 g”
A lot of others.
(3) Please express the numerical formula so that it is interpreted exactly.
e.g. Page 3, line 8 “Catalyst loading%=W1-W0/W1×100%”:
→ “Catalyst loading%=(W1-W0)/W1×100% ” ?
Page 3, line 7 from the bottom “Mn=Csample×Vsample/Cbaseline×Vbaseline ×Mbaseline”:
→ “Mn=(Csample×Vsample/Cbaseline×Vbaseline) ×Mbaseline ” ?
(4) Page4, line 17 from the bottom “LWCS”: The abbreviation should be defined when it appeared first.
(5) Figure 11. VI “Loading 42.51% of active carbon” → “Loading 41.51% of active carbon” ?
Comments for author File: Comments.pdf
Author Response
Thank you very much for your comments. I have carefully revised according to your suggestions and hope to receive your reply.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Although that some of the queries have been successfully addressed some key questions have not been revised with appropriate completions and additions of data.
As an example, I asked to provide characterization and physicochemical properties for activated carbon used in the study and the authors have responded that the properties appeared in the introduction part providing the general characteristics of every activated carbon material such as a black powder with high specific surface area, etc
As a result, I remain negative for the publication of the study.
Author Response
Dear Professor,
First of all, thank you very much for your valuable comments on this article. For the content of "physicochemical properties of activated carbon", the measurement experiment of pore structure of activated carbon is given in the section of "2.8 mercury infiltration porosity (MIP)" and the results of physicochemical properties of activated carbon are given in "3.4 point structure analysis of supported PTA catalyst".
If there are still problems in the article, I hope to get your further guidance.
I'm looking forward to your reply.
Best wishes,
Hang Zhang
Round 3
Reviewer 1 Report
When I referred on the characterization of activated carbon, its not only the surface area and porosity measurements but other techniques too such as SEM, elemental analysis, surface groups, etc.
In any case, the manuscript is improved and can be published according to the editor decision.
