Quaternary Ammonium-Based Ionosilica Hydrogels as Draw Solutes in Forward Osmosis
, Philippe Trens 1 and Peter Hesemann 1,*Round 1
Reviewer 1 Report
This manuscript reports a Quaternary ammonium based ionosilica hydrogels as draw solutes in forward osmosis. Furthermore, the author studied the regeneration of the hydrogels via ultrafiltration (UF), allowing the development of a closed FO-UF process. The language of this article is well organized and the experimental data is comprehensive. Their finding is interesting and deserves to be published if the authors can address the following issues.
1-A table of comparing the performance of the present matrix with previously reported composites should be given.
2-The cost effective should be considered specially the authors have used several steps in preparing the quaternary ammonium based ionosilica hydrogels.
3-I recommend to carefully check the full text again to avoid some errors in details. Such as, it in the introduction section, sometimes using acronym for Forward Osmosis and draw solute and sometimes not.
Author Response
1-A table of comparing the performance of the present matrix with previously reported composites should be given.
We did not introduce a comparative study as huge literature exist on this topic. We therefore believe that a detailed comparison of the performance of the ionosilica matrix with previously reported systems would be beyond the scope of our manuscript. Instead, we added a paragraph that compares the ionosilica hydrogels with other types of organic polyelectrolytes such as poly(N-isopropylacrylamide) (PNIPAM) or poly(sodiumacrylate) (PSA) . We added the following paragraph to the manuscript (page 8, last paragraph), and we introduced the new reference 34:
‘These results indicate that the water fluxes generated by ionosilica hydrogels are twice as high as those generated by hydrogels based on organic polymers such as poly(N-isopropylacrylamide) (PNIPAM) or poly(sodiumacrylate) (PSA). Furthermore, these latter systems show a more pronounced decrease over time of the generated water flux compared to ionosilica hydrogels [34].’
2-The cost effective should be considered specially the authors have used several steps in preparing the quaternary ammonium based ionosilica hydrogels.
We added a paragraph on page 2 focusing on the costs of ionosilica syntheses:
‘Indeed, ionosilicas are relatively inexpensive materials that can be obtained in a kilogram scale from standard chemicals such as (3-chloropropyl)trimethoxysilane and (3-aminopropyl)trimethoxysilane. The availability of ionosilicas in large quantities allows applications of these phases on a pilot scale in chromatography, anion exchange and thermochemical heat storage [28]. Ionosilicas are therefore not only laboratory curiosities, but easily accessible and highly polyvalent materials with a broad application spectrum.’
3-I recommend to carefully check the full text again to avoid some errors in details. Such as, it in the introduction section, sometimes using acronym for Forward Osmosis and draw solute and sometimes not.
We carefully checked the manuscript and replaced ‘forward osmosis’ by ‘FO’ for example in line 36.
Reviewer 2 Report
I've made some minor editorial suggestions to the manuscript. Please refer to the uploaded file. The finding of your research would be of interest to the scientific community, policy makers and environmentalists as well as a contribution to the body of scientific literature.
Congratulations!
Comments for author File: 
Comments.pdf
Author Response
Molecules 1044558 Peer Review
Please note that my comments are highlighted in red in the text below for ease of conveying my feedback to the authors.
Title: “Quaternary ammonium based ionosilica hydrogels as draw solutes in forward osmosis”
Reviewer’s suggestions:
Line 49: nanoparticles, dissolved gases or volatiles or switchable polar solvents have been investigated (I would suggest that the authors insert some reference at the end of the sentence).
We inserted three references at this place dealing with various kinds of draw solutes:
- Klaysom, C.; Cath, T. Y.; Depuydt, T.; Vankelecom, I. F. J., Forward and pressure retarded osmosis: potential solutions for global challenges in energy and water supply. Chem. Soc. Rev. 2013, 42, (16), 6959-6989, 10.1039/c3cs60051c.
- Alejo, T.; Arruebo, M.; Carcelen, V.; Monsalvo, V. M.; Sebastian, V., Advances in draw solutes for forward osmosis: Hybrid organic-inorganic nanoparticles and conventional solutes. Chem. Eng. J. 2017, 309, 738-752, 10.1016/j.cej.2016.10.079.
- Long, Q.; Jia, Y.; Li, J.; Yang, J.; Liu, F.; Zheng, J.; Yu, B., Recent Advance on Draw Solutes Development in Forward Osmosis. Processes 2018, 6, (9), 10.3390/pr6090165.
The references 11 and 12 are new.
Line 142: The reaction sequence for the formation of the ionosilica hydrogels is illustrated in scheme (It should be “Scheme” to be consistent with the rest of the text i.e., Scheme 1 b Line 195).
We capitalized the word ‘Scheme’.
Line 239: In a second time, (I would suggest replacing the word “time” with the word “iteration”)
We replaced ‘time’ to ‘iteration’
Line 379: This The finding of this study is therefore of fundamental….(As indicated in the conclusions of the article, the fact that “Ionosilica hydrogels could easily be obtained from quaternized trisilylated ammonium 369 precursor” is a key highlight.
We changed ‘This’ by ‘The finding of this study’ as requested by the reviewer.
