Removal of Model Aromatic Hydrocarbons from Aqueous Media with a Ferric Sulfate–Lime Softening Coagulant System
Round 1
Reviewer 1 Report
“Removal of model aromatic hydrocarbons from aqueous media with a ferric sulfate-lime softening coagulant system” by Venegas-Garcia et al studied the PNP and naphthalene removal efficiency with a ferric sulfate and a lime softening coagulant system. This work is important in municipal water treatment as it provides a method to optimize the coagulation process. The experiments were designed properly and the results reflect different adsorption mechanism for different chemicals. I recommend that it be accepted after the minor revisions noted below.
1. Page 3 Line 120-121. It is more clear to define Y with only one terminology rather than three.
2. It is hard to read the figures，especially fig3, fig4 and fig6 with samll fonts. It's better to use higher resolution figures.
3. Along with the Table 4, it would be helpful if R^2 are also indicated in Figure 5 next to the curves.
Author Response
Authors’ Response to the Reviewer Reports on MS-ID: surfaces-1921078
Please note that the Authors’ responses are in blue font. All corresponding changes were made to the manuscript in red font in the markup version of the manuscript.
Reviewer #1
“Removal of model aromatic hydrocarbons from aqueous media with a ferric sulfate-lime softening coagulant system” by Venegas-Garcia et al studied the PNP and naphthalene removal efficiency with a ferric sulfate and a lime softening coagulant system. This work is important in municipal water treatment as it provides a method to optimize the coagulation process. The experiments were designed properly and the results reflect different adsorption mechanism for different chemicals. I recommend that it be accepted after the minor revisions noted below.
- Page 3 Line 120-121. It is more clear to define Y with only one terminology rather than three.
Response: Y is defined as the pollutant removal efficiency acting as the response surface function in the BBD. A clarification was made in the revised markup version manuscript.
- It is hard to read the figures especially fig3, fig4 and fig6 with small fonts. It's better to use higher resolution figures.
Response: Thanks for your constructive comment. Figures 3, 4 and 5 were modified accordingly to address the reviewer comment.
- Along with the Table 4, it would be helpful if R^2 are also indicated in Figure 5 next to the curves.
Response: Figure 5 was modified to have a better resolution but also R2 value was included.
The authors appreciate the insightful and constructive comments provided by Reviewer #1, which are reflected in the revised version of the manuscript. The manuscript was further edited for language and clarity throughout to meet the high standards of the journal Surfaces.
Author Response File: 
Author Response.docx
Reviewer 2 Report
General comments:
- It lacks novelty and the results are poorly presented.
- English and sentence structure need extensive improvements.
- ANOVA results are incomplete.
Abstract:
- Why was this study conducted? Justify in one sentence.
- What ranges of parameters were selected for BBD of RSM?
- What are the optimal conditions obtained in this research?
Introduction:
- Line 48, is it the only benefit of using coagulation?
- Literature review on the coagulants used for such applications is missing.
- The justification for the need of this study is missing.
Materials and Methods:
- Where is the RSM design?
- Follow the proper sequence of methods
- Where are the isotherm model equations?
Results and Discussion
- 3.1 Calibration curves; move the methodology portion of this section into Materials and Methods and only describe results and discussion in results and discussion. The thickness of the spectral lines in Figure 1 must be increased.
- Table 1 must be in Materials and Methods. Table 1: Increase the length of spectral lines and increase the font size of the text.
- Table 2 must be moved to Materials and Methods.
- Table 3, where are other ANOVA results such as R2, lack of fit, pure error, adequate precision, and coefficient of variance.
- Figures 3 & 4, the font size is very small and unreadable.
- 3.3 Adsorption Isotherms, why the model descriptions and equations are in this section? This section is only for results and discussion on results.
- Figure 6 b & c, increase the line thickness of spectra.
- Figure 7, where is the Optical Microscopy method in materials and methods?
Conclusions:
Be precise and only describe conclusions obtained related to the objectives.
Comments for author File: 
Comments.pdf
Author Response
Authors’ Response to the Reviewer Reports on MS-ID: surfaces-1921078
Please note that the Authors’ responses are in blue font. All corresponding changes were made to the manuscript in red font in the markup version of the manuscript.
Reviewer #2
Comments and Suggestions for Authors
General comments:
- It lacks novelty and the results are poorly presented.
- English and sentence structure need extensive improvements.
- ANOVA results are incomplete.
Abstract:
- Why was this study conducted? Justify in one sentence.
Response: The removal of model hydrocarbon oil systems (4-nitrophenol (PNP) and naphthalene) from laboratory water was evaluated using a ferric sulfate and a lime-softening coagulant system. This study addresses the knowledge gap in the open scientific literature for the removal of BTEX model compounds using ferric sulfate coagulant system in alkaline media. The reviewer is referred to markup version of the MS for respective changes that were carried out.
- What ranges of parameters were selected for BBD of RSM?
Response: Three independent variables were considered: coagulant dosage (10 – 100 mg/L (PNP) and 30 – 100 mg/L (naphthalene)), lime dosage (50 – 200 %) and initial pollutant concentration (1-35 mg/L (PNP) and 1-25 mg/L (naphthalene)). The reviewer is referred to markup version of the MS for respective changes that were carried out.
- What are the optimal conditions obtained in this research?
Response: The response optimization showed a 28% PNP removal achieved at optimal conditions (74.5 mg/L of ferric sulfate, 136 % lime dosage at an initial PNP concentration of 2 mg/L). Optimal conditions for naphthalene removal were found at 42 mg/L ferric sulfate, 50% lime dosage and 16.3 mg/L as initial concentration, where 90% removal could be achieved for naphthalene. The reviewer is referred to markup version of the MS for respective changes that were carried out.
Introduction:
- Line 48, is it the only benefit of using coagulation?
Response: Among these, coagulation process is an economical method that has been extensively applied due to its low-cost, simple operation with basic infrastructure requirements, and overall effectiveness in pollutant removal. The reviewer is referred to markup version of the MS for respective changes that were carried out.
- Literature review on the coagulants used for such applications is missing.
Response: For each one of the coagulants presented a reference was cited, showing that these coagulants can act effectively against hydrocarbon oil pollutants. The reviewer is referred to markup version of the MS for respective changes that were carried out.
- The justification for the need of this study is missing.
Response: The revised MS was updated to provide further clarity on the justification for this research study.
Materials and Methods:
- Where is the RSM design?
Response: Appendix A (Supplementary Material) was created and the RMS design was outlined in Table A1.
- Follow the proper sequence of methods
Response: The revised manuscript was updated to address the reviewer query.
- Where are the isotherm model equations?
Response: This section on models and equations was moved to the Materials and methods part in Section 2.
Results and Discussion
- 3.1 Calibration curves; move the methodology portion of this section into Materials and Methods and only describe results and discussion in results and discussion. The thickness of the spectral lines in Figure 1 must be increased.
Response: This section outlined above was moved to the Materials and methods part in Section 2. Figure 1 was replaced with a better resolution image to address the reviewer comment.
- Table 1 must be in Materials and Methods.
Response: Table 1 was moved to the Materials and methods part in Section 2.
- Table 2 must be moved to Materials and Methods.
Response: Table 2 was moved to the Materials and methods part in Section 2.
- Table 3, where are other ANOVA results such as R2, lack of fit, pure error, adequate precision, and coefficient of variance.
Response: Appendix A (supplementary material) was created and the ANOVA results were included in Table A2 (PNP) and A3 (naphthalene).
- Figures 3 & 4, the font size is very small and unreadable.
Response: The figures were replaced with better resolution images.
- 3.3 Adsorption Isotherms, why the model descriptions and equations are in this section? This section is only for results and discussion on results.
Response: This section was moved to the Materials and methods part in Section 2.
- Figure 6 b & c, increase the line thickness of spectra.
Response: The corresponding Figure was updated with better resolution images.
- Figure 7, where is the Optical Microscopy method in materials and methods?
Response: The methodology for the optical microscopy was added to the Materials and methods part in Section 2.
Conclusions:
Be precise and only describe conclusions obtained related to the objectives
Response: The conclusion section was updated to address the reviewer comment.
The authors appreciate the insightful and constructive comments provided by Reviewer #2, which are reflected in the revised version of the manuscript. The manuscript was further edited for language and clarity throughout to meet the high standards of the journal Surfaces.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors have addressed all my concerns and I do not have any further comments.
