Adsorption Characteristics of Dodecamethylcyclohexasiloxane and Dodecamethylpentasiloxane from Landfill Leachate by Municipal Solid Waste under the Landfill Circumstance
Round 1
Reviewer 1 Report (Previous Reviewer 1)
Manuscript improved after the revision
Author Response
Thanks for your suggestions!
Reviewer 2 Report (New Reviewer)
1. I would like to see a more detailed description and study of the sorbent used in the article (well, and why, specifically, the authors are in this sorbent, and not in any other)
2. How was the temperature range chosen for the experimental part of the article?
3. there is not enough data for kinetics
4. I was very confused by Figure 2, I would like more explanations for it
5. Have you determined the capacity of the adsorption monolayer and the area of the "landing pad"
6. From my point of view, the English language in the article needs to be improved, as well as the style of presentation.
7. I would expand materials and methods. at the moment, it seems to me, not everything is in the form that is required in the magazine.
8. I would like to expand the list of literary sources
Author Response
- I would like to see a more detailed description and study of the sorbent used in the article (well, and why, specifically, the authors are in this sorbent, and not in any other)
Response: Thank you for your suggestions! In this study, the Adsorption characteristics of dodecamethylcyclohexasiloxane and dodecamethylpentasiloxane by municipal solid waste (MSW) were investigated to understand the releasing behavior of siloxane through leachate during the running of the landfill. Therefore, MSW was used in this study. A more detailed description for the choosing of the sorbent has been provided in the revised manuscript marked in red. (Lines 69-73, Page 4; Line 84-85, Page 5)
- How was the temperature range chosen for the experimental part of the article?
Response: Thank you for your suggestions! The temperature range was chosen according to the temperature variation of the practical landfill sites reported in the previous literatures, which has been explained in the revised manuscript marked in red (Lines 164-171, Pages 8-9)
- There is not enough data for kinetics.
Response: Thank you for your suggestions! Totally 11 groups of data concerning time-adsorption profile are presented in the manuscript, with the time ranging from 1 min to 32 h. Unlike other adsorption studies, time-adsorption test was carried out to find out the equilibrium time of the adsorption. The data may not meet the requirement of the kinetics model study. But the data could help us to find out the equilibrium time. We have modified the illustration of the manuscript with red marks to make it more reasonable. (Lines 191-205, Page 10)
- I was very confused by Figure 2, I would like more explanations for it
Response: Thank you for your suggestions! We have modified the illustration of section 3.1.1 for the better explanation of the result of Figure 2 with red marks. (Lines 191-205, Page 10)
- Have you determined the capacity of the adsorption monolayer and the area of the "landing pad"
Response: Thank you for your suggestions! The capacity of the adsorption monolayer has been determined and provided in the manuscript. As MSW was an assembly of bulk organic matter and inorganic minerals, it is hard to determine the "landing pad". We will focus on the surface characteristic in our future research. (Lines 231, Page 13)
- From my point of view, the English language in the article needs to be improved, as well as the style of presentation.
Response: Thank you for your suggestions! We have improved the language of the manuscript. (The whole manuscript)
- I would expand materials and methods. at the moment, it seems to me, not everything is in the form that is required in the magazine.
Response: Thank you for your suggestions! We have expanded materials and methods with red marks. (Lines 129-131, 135-139, Page 7; Line 164-171, Page 8-9)
- I would like to expand the list of literary sources.
Response: Thank you for your suggestions! The list of literary sources has been expanded. (Lines 402-407, 412-416, 423-426, Page 22-23)
Reviewer 3 Report (New Reviewer)
General comments:
- Minor grammatical errors should be corrected throughout the manuscript.
Specific comments:
1. Section 2.3, line 111: Please add the units for concentrations of L5 and D6.
2. Section 2.3, line 115: Why did the contact time have such a large range? Please comment.
3. Section 2.3, lines 129-130: It is stated that “a” is the maximum amount of siloxane per unit weight of MSW. However, there is no “a” in equations 3-5. Please correct.
4. Lines 210-213: Relevant references should be added to support the statements on these lines.
5. Figure 5: Please add the operating conditions to the figure caption.
6. Lines 229-232: Relevant references should be added to support the statements on these lines.
7. Lines 240-241: The accumulation of organic acids is due to the anaerobic processes of acidogenesis and acetogenesis. Please add this information.
8. Lines 270-272: The conclusive remarks on these lines are not supported by experimental results. The results presented in the manuscript were not obtained at various stages of landfill operation. Relevant adsorption results should be collected under various operating conditions of landfill established at various stages. The authors should present relevant experimental results and discuss the results in relation to these statements.
9. Similar comments as above apply to the statements on lines 283-285.
Author Response
- Section 2.3, line 111: Please add the units for concentrations of L5 and D6.
Response: Thank you for your suggestions! The units have been added for concentrations of L5 and D6. (Lines 125, Page 7)
- Section 2.3, line 115: Why did the contact time have such a large range? Please comment.
Response: Thank you for your suggestions! The comment has been added with red marks. (Lines 130-131, Page 7)
- Section 2.3, lines 129-130: It is stated that “a” is the maximum amount of siloxane per unit weight of MSW. However, there is no “a” in equations 3-5. Please correct.
Response: Thank you for your suggestions! It has been corrected. (Lines 153, Page 8)
- Lines 210-213: Relevant references should be added to support the statements on these lines.
Response: Thank you for your suggestions! Relevant reference has been added. (Lines 242-245, Page 14)
- Figure 5: Please add the operating conditions to the figure caption.
Response: Thank you for your suggestions! The operating condition has been added for Figure 5. (Lines 249-250, Page 14)
- Lines 229-232: Relevant references should be added to support the statements on these lines.
Response: Thank you for your suggestions! Relevant reference has been added. (Lines 264-267, Page 15)
- Lines 240-241: The accumulation of organic acids is due to the anaerobic processes of acidogenesis and acetogenesis. Please add this information.
Response: Thank you for your suggestions! The information has been added. (Lines 275-277, Page 16)
- Lines 270-272: The conclusive remarks on these lines are not supported by experimental results. The results presented in the manuscript were not obtained at various stages of landfill operation. Relevant adsorption results should be collected under various operating conditions of landfill established at various stages. The authors should present relevant experimental results and discuss the results in relation to these statements.
Response: Thank you for your suggestions! The have remove the unsupported remarks. Instead, the discussion concerning the possible variation of adsorption behavior was provided. (Lines 310-315, Page 18)
Round 2
Reviewer 3 Report (New Reviewer)
The authors have properly revised the manuscript based on my comments and suggestions. The revised manuscript can be published in the present form.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Summary and general comments
In this study, the authors used municipal solid waste as an adsorbent for the removal of siloxanes from an aqueous solution. The overall work is alright and interesting to read. The chosen methods are suitable and relevant for adsorption studies; however, there are many minor errors. The introduction and methodology should be improved. Please see the specific comment for the details.
Specific comments
1. Change all “percent” to %
2. The introduction is not enough to provide sufficient background. The authors need to describe more about D6 and L5 as these two chemicals are the focus of this study. What are these chemicals exactly, their uses, their origin or source, how do they differ from other siloxanes, etc.
3. Please describe briefly the concept of adsorption and the choice of adsorbent this technique is used in this study. Here are some of my recommendations that authors may find useful.
4. Section 2.1 it is not clear which portion of the solid waste was used as the authors mentioned 24 %ash and 1.8% glass and metal. Are these ash, glass, and metal components included together for the preparation of the adsorbent?
5. Section 2.2. some of the procedures were just mentioned by the method code. Usually, it is recommended the authors briefly describe the experimental method so that the readers do not need to refer to an external source.
6. Qt should be defined as adsorption capacity at time t.
7. Inconsistency of symbols in the equations and the text. In scientific writing, symbols Ct and CT could mean different variables. Do make them all consistent.
8. Sections 2.3.1 and 2.3.2 which are referring to the kinetics and isotherm models. However, the kinetics and isotherm models were not mentioned.
9. Sections 2.3.1 to 2.3.4 can be written more concisely. Please see the references provided above for example. Here is a quick example: The effects of adsorbate concentration (0-200 ppb), pH (3-8), temperature (20-50 oC), and ionic strength (0- 5000 ppm NaCl) were investigated with 10 g MSW and 50 mL adsorbate.
10. Section 3.1.2 qe should be defined as adsorption capacity at equilibrium.
11. Please recheck the axis labels and units in Fig 3. In section 3.1.2, the qe unit is listed as ug g-1, while Ce should ne ug L-1.
12. As isotherm equations are listed in section 3.1.2, there is no need to repeat the equations in Table 1 as this is a duplication of effort.
13. Authors have used “?%” symbol to represent percentage removal. I suggest authors to consistently use the ?% symbol in both the text description and figure. However, in the figures and table, “percentage removal (%) was used instead. And avoided changing to “removal rate (%)” for another figure.
14. Fig 5 x-axis label spelling error “temparature”
15. Section 3.1.5 quoting the sentence” similar chemical structure with the liner siloxane”. Please recheck. Do you mean “linear”?
16. Conclusion: Avoid using “absorption capacity”. Please correct to adsorption capacity.
Reviewer 2 Report
After reading this manuscript, I have several of comments, namely:
The title of the article is written incorrectly. What does it mean adsorption characteristic of dodecamethylcyclohexasiloxane
and dodecamethylpentasiloxane? Can be "characterization of adsorption of dodecamethylcyclohexasiloxane
and dodecamethylpentasiloxane....." Please, write correctly
The purpose of the work is missing in the manuscript!
Authors did not explain why the influence of organic acids and anions on the adsorption process of D6 and L5 was study.
Authors did not explain why exactly D6 and L5 were chosen for study and their concentrations.
To Introduction section should to add the need of explanations!!!!!! It's not clear what is the chemical siloxane.....? Siloxane is a functional group in organosilicon chemistry with the Si−O−Si linkage. The siloxane functional group forms the backbone of silicones, the premier example of which is polydimethylsiloxane. The authors need to add more explanations about these chemicals. The introduction is incomprehensible to the average reader, as it is necessary to use additional professional literature.
Also, the Authors need to write that there are cyclical (D) and linear (L) siloxanes. In this form, the information is completely unclear in the Introduction.
The literature is very old. Very little literature has been used to study the adsorption process of the study chemicals pollutions.
The Methods section needs to be redone. It is not possible to use such an algorithm for conducting experimental research. There is no information about the initial concentrations of D6 and L5, their concentrations for constructing isotherms. If the Authors investigate the adsorption of specific chemical substances, they should also be written in the Methods section. The authors call these substances by the general word Siloxanes.
All formulas should be in the Methods section!
It is not clear how exactly the Authors determined the concentration of each chemical substance!!!!
For kinetic studies, how were prepared solutions of D6 and L5?
With regards
