A Mathematical Modeling of the Reverse Osmosis Concentration Process of a Glucose Solution
Round 1
Reviewer 1 Report
Major Revision
The author has presented the mathematical modelling for concentrating glucose by reverse osmosis (RO) process. This is a good topic that may arise some researcher's interests studying mathematical modelling for reverse osmosis. The mathematical models were properly used and an extensive research outputs were provided, however, there are few serious issues that have been mentioned below. The author must answer with more clarity in order to enhance the quality of the research paper:
1. Lot of research works have been already done based on mathematical modelling for reverse osmosis (RO). So, author must highlight the novelty part of this research work as a similar research has already been done. For eg. “Modeling of reverse osmosis flux of aqueous solution containing glucose, Korean J. Chem. Eng., 34(2), 407-412 (2017) DOI: 10.1007/s11814-016-0298-9”. Therefore, the novelty of this study is doubtful.
2. Kindly cite few articles from “Membranes”, “Polymers” and “Water” journals (MDPI) and put following references in introduction section to validate your statements:
1. Chung, T. S., Zhang, S., Wang, K. Y., Su, J., & Ling, M. M. (2012). Forward osmosis processes: yesterday, today and tomorrow. Desalination, 287, 78-81.
2. Jamal, K., Khan, M. A., & Kamil, M. (2004). Mathematical modeling of reverse osmosis systems. Desalination, 160(1), 29-42.
3. Ray, S. S., Chen, S. S., Sangeetha, D., Chang, H. M., Thanh, C. N. D., Le, Q. H., & Ku, H. M. (2018). Developments in forward osmosis and membrane distillation for desalination of waters. Environmental chemistry letters, 1-19.
4. Ray, S. S., Chen, S. S., Nguyen, N. C., Nguyen, H. T., Dan, N. P., & Thanh, B. X. (2018). Exploration of polyelectrolyte incorporated with Triton-X 114 surfactant based osmotic agent for forward osmosis desalination. Journal of environmental management, 209, 346-353.
3. In order to validate the mathematical modeling used in the research paper, the author must show the triplicate experimental values with error bars. (Specifically, in Figure 6 and Figure 7)
4. Typically, Reynold’s number indicates the type of flow, but in this paper the author didn’t mention the significance of calculating Reynold’s number properly. So, the author must discuss it elaborately for better understanding.
5. Next, very importantly, rewrite the significance of each parameters evaluated here in the paper with more scientific discussions to make it more attractive for the readers.
Comments for author File: 
Comments.pdf
Author Response
Manuscript ID: processes-478759
Title: A Mathematical Modeling of Glucose Solution for Reverse Osmosis Concentration Process
Dear Reviewers,
Thank you very much for your valuable opinions and comments on our manuscript (Manuscript ID: processes-478759).
The manuscript has been revised carefully according to the reviewer's comments and suggestions by the corresponding author and co-authors. In order to highlight the changes we have made, the modifications were highlighted in red in the revised version of the manuscript. In addition, the detailed responses to each question from the reviewers are attached as follow.
We deeply appreciate your comments, attention and consideration of our manuscript. If you have any further queries, please don’t hesitate to contact me at the following address. Many thanks.
Yours sincerely
Chenghan Chen
Biomass Energy Technology Research Center, Biogas Institute of Ministry of Agriculture, Chengdu 610041, PR China
Email: [email protected]
Response to Reviewers' comments:
Reviewer 1 (Comments to the Author)
The author has presented the mathematical modelling for concentrating glucose by reverse osmosis (RO) process. This is a good topic that may arise some researcher's interests studying mathematical modelling for reverse osmosis. The mathematical models were properly used and an extensive research outputs were provided, however, there are few serious issues that have been mentioned below. The author must answer with more clarity in order to enhance the quality of the research paper:
Comments:
Point 1: Lot of research works have been already done based on mathematical modelling for reverse osmosis (RO). So, author must highlight the novelty part of this research work as a similar research has already been done. For eg. “Modeling of reverse osmosis flux of aqueous solution containing glucose, Korean J. Chem. Eng., 34(2), 407-412 (2017) DOI: 10.1007/s11814-016-0298-9”. Therefore, the novelty of this study is doubtful.
Response 1: Thanks a lot for the reviewer's comments. In the literature (Modeling of reverse osmosis flux of aqueous solution containing glucose, Korean J. Chem. Eng., 34(2), 407-412 (2017) DOI: 10.1007/s11814-016-0298-9), the model developed by the researchers is mainly for flat RO membranes, and the main focus of this study is the spiral-wound membrane. And the subject solution of this study is different compared to other studies. For this study, the authors want to give the following explanation. The glucose model solutions were selected to carry out RO concentration experiments as a preliminary study. Further research is the RO concentration of straw hydrolyzates, which contains sugar, furfural, acid and other substances. This study is eager to understand the mass transfer of glucose during RO process, in order to investigate how to separate the sugars and furfural and acids in straw hydrolyzates based on their different mass transfer processes. Therefore, the paper studies the mass transfer process of glucose solution in spiral-wound RO membrane.
Point 2: Kindly cite few articles from “Membranes”, “Polymers” and “Water” journals (MDPI) and put following references in introduction section to validate your statements:
1. Chung, T. S., Zhang, S., Wang, K. Y., Su, J., & Ling, M. M. (2012). Forward osmosis processes: yesterday, today and tomorrow. Desalination, 287, 78-81.
2. Jamal, K., Khan, M. A., & Kamil, M. (2004). Mathematical modeling of reverse osmosis systems. Desalination, 160(1), 29-42.
3. Ray, S. S., Chen, S. S., Sangeetha, D., Chang, H. M., Thanh, C. N. D., Le, Q. H., & Ku, H. M. (2018). Developments in forward osmosis and membrane distillation for desalination of waters. Environmental chemistry letters, 1-19.
4. Ray, S. S., Chen, S. S., Nguyen, N. C., Nguyen, H. T., Dan, N. P., & Thanh, B. X. (2018). Exploration of polyelectrolyte incorporated with Triton-X 114 surfactant based osmotic agent for forward osmosis desalination. Journal of environmental management, 209, 346-353.
Response 2: Thanks for the reviewer's suggestion. The authors have updated references based on your suggestion in the revised manuscript, highlighted in red color (page 12,13).
Point 3: In order to validate the mathematical modeling used in the research paper, the author must show the triplicate experimental values with error bars. (Specifically, in Figure 6 and Figure 7)
Response 3: Thanks a lot for the reviewer's suggestion. In the revised manuscript , Figure 6 and Figure 7 have been modified according to your comments, highlighted in red color (page 9,11).
Point 4: Typically, Reynold’s number indicates the type of flow, but in this paper the author didn’t mention the significance of calculating Reynold’s number properly. So, the author must discuss it elaborately for better understanding.
Response 4: Thanks a lot for the reviewer's suggestion. In the revised manuscript, the description of Reynolds number has been added, highlighted in red color (Page 10).
Point 5: Next, very importantly, rewrite the significance of each parameters evaluated here in the paper with more scientific discussions to make it more attractive for the readers.
Response 5: Thanks a lot for the reviewer's suggestion. In the revised manuscript, the parameters involved in this research, including the flux of permeate solution (Jv), RO recovery (y) and the mass transfer coefficient (k), have been introduced and explained, highlighted in red color (Page 3,4,9).
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript developed a mathematical model for glucose separation using RO membranes. The conclusions are supported by experimental and modeling results. My comments are listed below.
In Section 4.1, why the feed flow rate change with trans-membrane pressure? Which condition did the authors control, flow rate or pressure?
Can the authors briefly explain why calculated Jv is higher than the experimental value at low flow rate, but higher at high flow rate?
Author Response
Manuscript ID: processes-478759
Title: A Mathematical Modeling of Glucose Solution for Reverse Osmosis Concentration Process
Dear Reviewers,
Thank you very much for your valuable opinions and comments on our manuscript (Manuscript ID: processes-478759).
The manuscript has been revised carefully according to the reviewer's comments and suggestions by the corresponding author and co-authors. In order to highlight the changes we have made, the modifications were highlighted in red in the revised version of the manuscript. In addition, the detailed responses to each question from the reviewers are attached as follow.
We deeply appreciate your comments, attention and consideration of our manuscript. If you have any further queries, please don’t hesitate to contact me at the following address. Many thanks.
Yours sincerely
Chenghan Chen
Biomass Energy Technology Research Center, Biogas Institute of Ministry of Agriculture, Chengdu 610041, PR China
Email: [email protected]
Response to Reviewers' comments:
Reviewer 2 (Comments to the Author)
This manuscript developed a mathematical model for glucose separation using RO membranes. The conclusions are supported by experimental and modeling results. My comments are listed below.
Comments:
Point 1: In Section 4.1, why the feed flow rate change with trans-membrane pressure? Which condition did the authors control, flow rate or pressure?
Response 1: Thanks a lot for the reviewer's comments. In the present work, the pump used was a vertical multistage centrifugal pump (CDLF1, 50HZ, CNP), and in the experimental design, one of a valves was installed at the outlet of the RO membrane (valve 3, Fig.2). In fact, the feed flow and trans-membrane pressure in the system changed by adjusting the valve 3. The experiment regulated flow by controlling valve 3, in this process, there was a correlation curve between feed flow and trans-membrane pressure (Fig.3). In the revised manuscript, the valves have been labeled (line 131, Fig.2) and some descriptions of the process have been modified (line 149), highlighted in red color.
Point 2: Can the authors briefly explain why calculated Jv is higher than the experimental value at low flow rate, but higher at high flow rate?
Response 2: Thanks a lot for the reviewer's comments. One thing to note is that Fig.6 is drawn based on the original data. Initially, the authors did not consider the specific trend of the values. Now, the author notices this fact with your reminder. One of the possible explanation is that the concentration polarization is more severe at low flow rate during the experiment, and the experimental values were lower. On the other hand, the concentration polarization is relieved under high flow conditions, resulting in high experimental values.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors have responded in proper manner. So I would recommend this article in this present format.
