Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
Halloysite nanotube-based electrospun ceramic nanofibre
mat: a novel support for zeolite membranes
Zhuwen Chen, Jiaying Zeng, Dong Lv, Jinqiang Gao, Jian Zhang, Shan Bai, Ruili Li, Mei
Hong and Jingshen Wu
Article citation details
R. Soc. open sci. 3: 160552.
http://dx.doi.org/10.1098/rsos.160552
Review timeline
Original submission:
Revised submission:
Final acceptance:
27 July 2016
21 October 2016
17 November 2016
Note: Reports are unedited and appear as
submitted by the referee. The review history
appears in chronological order.
Review History
RSOS-160552.R0 (Original submission)
Review form: Reviewer 1
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
No
Is it clear how to access all supporting data?
All the data required to understand the paper is provided.
Do you have any ethical concerns with this paper?
No
© 2016 The Authors. Published by the Royal Society under the terms of the Creative Commons
Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use,
provided the original author and source are credited
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
2
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Major revision is needed (please make suggestions in comments)
Comments to the Author(s)
------Overall feedback
------The authors have successfully produced via a electrospinning method a halloysite nanotube
based nanofiber mat. As evidenced in Figure 2 the mats are shown to have relatively uniform
pore sizes and the pore size can be controlled by the pressure applied before sintering. The mats
out performs the commercial equivalent in terms of permeability.
The mats were then used as supports for zeolite seed where is was demonstrated using
ultrasonication and SEM that the various seeds adhere well to the surface, an improvement over
the commercial FNJ supports.
Side on SEM was used to determine the thickness of the layers and EDX line profiles of the layers
determined no leaching occurred when using the HMN support. In Figure 7 (a) this could be
improved by discarding the line profile data from before the edge of the film. The X-rays detected
are not generated in the same plane (lower planes) as once you are on the sample. This doesn't
alter the conclusion that leaching is not occurring. Line mapping shows Al leaching is occurring
clearly.
The data supports the conclusions made.
There are a great deal of errors in the language that are listed below. This manuscript should
have had a through proof read before submission and the reviewers should not have to list this
many corrections. I didn't record all the errors in the final pages are it was taking a long time and
is beyond the role of a reviewer.
The largest holes are in the experimental where it is currently not possible to reproduce the
experiment as a number of quantities, concentrations and volumes are absent as listed below. In
addition, some of the language in the discussion is inappropriate for scientific literature, e.g. "To
our delight...". Some of the figure captions are not detailed enough and a few changes to figures is
recommended in the comments below.
Due to the quantity of corrections I have recommended major corrections to the manuscript.
--------Deatiled comments
--------Errors that need addressing
L=line number
Page 3
L7 Ratio poorly described. A single number is not a ratio "1 to infinity"
L12 Poor English replace with "attract more attention"
L14 Poor English replace with "applications"
L14 Poor English replace with "less than twenty"
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3
L17 Poor English replace with "The low quality"
L31 "a larger increase in flux"? Leap doesn't suggest the direction of change.
L33 Please clarify "support quality". Which property of the support?
L41 Replace "Support qualities" with "Features of the support"
L53 Add Kwang et al. Adv. Mater. 2000, 12, 1114 as a reference after [25]
Page 4
L9 Replace "Unfortunately, very few" with "Very few"
L12 Add space after "Fibrous"
L21 Halloysite nanotubes sentence doesn't make sense. Please fix.
L24 Not sure of the use of the word lapped. Do you mean interwoven?
L27 Add space after "be"
Section 2.1 Use ≤99% instead of 99+% to described purities
Page 5
Remove section headings 2.2.1, 2.2.2 and 2.2.3. They should all be under 2.2 as it is all brief.
L9 Replace "mixed solvent" with "mixture"
L9 What is the ratio of ethanol and water in the mixture?
L9 How long was it sonicated for?
L9 Replace "ultrasonic assistance" with "by ultrasonication"
L10 How much PVP was added?
L25 Replace "by" with "using a"
The steal mold dimensions and pressure applied are not stated. Please state.
The ratios are described in a strange and confusing way in pages 5 and 6. For instance on L36
1Al2O3:2SiO2:2Na2O:120H2O should be " the Al2O3:SiO2:Na2O:H2O ratio was 1:2:2:120". The
same is true for all ratios throughout the paper.
L37 Delete "clear".
L37 & L38 How much sodium hydroxide was added and what was the concentration and volume
of the aluminate solution. Can't reproduce the experiment without this information.
L41 Delete "in a three neck bottle"
L42 Was the reaction quenched by washing with water or was it quenched and then washed? If
so, how was it quenched?
L47 After "mat" add "(HNM)" and delete "(denoted as HNM).
L48 Delete "with gloved fingers"
L53 Provide details on the washing step, e.g. how much water and how many times was it
washed?
Page 6
L4 Delete "A clear synthesis solution was obtained by slowly adding"
L5 How much TEOS was added?
L5 What was the concentration and volume of the TPAOH solution?
L7 Replace "solution" with "reaction mixture"
L8 For the washing how much water was used and how many times was it washed?
L9 Delete "solution containing silicalite-1 seeds and 50% ethanol solution" and replace with "a
50:50 mixture of the silicalite-1 seeds suspension in water and ethanol"
L15 I don't understand which solution is "the synthesis solution".
L16 Delete "for only one time" and "water".
L16 Add after "washed" add "with water applied".
L33 Delete "The gel was prepared as follows:"
L33 Provide concentration and volume of phosphoric acid solution used.
L34 Provide concentration and volume of aluminium isopropoxide solution used.
L39 Replace "into a same" with "into the same"
L44 Delete "with temperature programmer"
L48 Provide a citation for the 1966-1996 method.
L52 Replace "KV" with "kV".
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4
L55 Provide model number of the Oxford EDS analyzer.
Page 7
L4 Provide the manufacturer of the DSA30
L5 Fiberlite F21s-8x50y is the model of the rotor for the centrifuge. Please also provide the model
of the centrifuge.
L17 Use of the word lapped again. I think interwoven is a better description.
L27 Replace "probably due to" with "as a possible consequence of"
Figure 1 Do you have the same magnification for the (b), (c) and (d)? This would make
comparision by eye easier.
L29 After "magnification" add "before heating"
L29 After "membrane" add "after heating at 1100 C under N2"
L29 After "HNMs" add "after sintering in air at 1200 C"
L55 After "At" add "a transmembrane pressure of".
L55 Delete "transmembrane pressure drop"
L56 Which porosity did you use for the flux experiment? Please state as you have demonstrated
that you can make different porosity mats.
Page 9
Figure 2 Increase font size on all parts of the figure. I can barely read most of it.
Figure 2 Adjust y axis to start at 40 and finish at 90.
L24 Delete "for guiding the eyes"
L24 replace "results" with "patterns"
L32 Replace "mdarcy" with "mD".
I have stopped correcting typos at this stage and recommend the authors check the rest of the
document. This is the job of the authors prior to submission and not the reviewer.
Figure 4 caption is confusing. Please rewrite.
Figure 5 The peak labels (squares and circles) are difficult to distinguish. Use dots and crosses for
clarity.
Page 12
L4 The Si:Al in Figure6a is 0.9:1 and not 1:1 as stated. State in the text it is 0.9:1 which is close to
the expected composition and explain the slight difference.
L16 The XRD pattern in Figure 5 f shows two patterns although only one is identified in the text.
L21 The EDX ratio of Si:O is 1.1:2. Again a deviation from the expected value. Explain and state
the correct value. Oxygen is difficult to quantify via EDX as it is a common containment in SEM
samples although your sample is O deficient. Can you add how the SEM samples were prepared
in the SI.
L57 The caption contains very little information. Please explain the sample in all parts.
Figure 5 Inset SEM images need scale bars.
Page 13
Figure 6. SEM images need scale bars.
L24 The X-rays escaping when doing a surface measurement will only be from about 500 nm
deep. The SEM in figure 5 suggests the film is approx 3.5 microns thick. The EDX values from the
surface only tell you that the leaching has not made its way to the surface. I'd change or remove
the sentence starting "One interesting..."
Page 14
Figure 7. (a) I don't think the EDX line map is meaningful once you have gone beyond the edge of
the sample. The beam is focused above the sample and the X-rays generated will be generated
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
5
when the unfocussed beam hits the sample. I recommend removing the data from before the edge
of the sample and shortening the arrow accordingly.
L51 Delete "In our lab"
L51 Delete entire sentence "To our delight when we screened another..." Replace with something
like "When using aluminophosphate AlPO4-5 a continious intergrown member was obtained... "
The original reads like a personal diary an not scientific writing.
Page 15
L4 Add "The" before "XRD pattern"
Review form: Reviewer 2 (Jianhua Yang)
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
There is no supporting materials for this work.
Do you have any ethical concerns with this paper?
No
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Accept with minor revision (please list in comments)
Comments to the Author(s)
Zeolite membranes have been industriallized for dehydration of organics in many areas,
currently intensive efforts are being foused on lowering the cost therefore for wider application.
It is reproted that the normal Al2O3 tube support accounts for 70% cost of the zeolite membrane.
Therefore it is of signifcance to develop new type of the support with larger posity and narrow
pore size distribution. In the present manuscript, the halloysite nanotube-based mats show higher
porosity and narrower pore size distribution which is favourable for high flux of the resulting
zeolite membrane. Before the publication, the following concerns are suggested to address.
1. One of the highlight of the work is use of halloysite nanotube as the support strcuture units
instead of powder particles, therefore the literatures on nanotube materias as the support units
should be briefly addressed.
2. The work on the NaA zeolite membrane supported on macroporous mullite and Al2O3 tube
repesctively should be cited (Sep. Purif. Technol. 25 (2001) 251-260 AIChE, 59 (2013) 936-946,
Journal of membrane Science 444 (2013)513-522 because these work are of great importance in
terms of the coarse macroporous support for the zeolite membranes.
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
6
Decision letter (RSOS-160552)
30-Sep-2016
Dear Professor Hong,
Thank you for your submission to Royal Society Open Science. The editors assigned to your
paper ("Halloysite Nanotube-Based Electrospun Ceramic Nanofiber Mat: a Novel Support for
Zeolite Membranes") have now received comments from reviewers. We would like you to revise
your paper in accordance with the referee and Editor suggestions which can be found below.
Please note this decision does not guarantee eventual acceptance.
Please submit a copy of your revised paper within three weeks (i.e. by the 22-Oct-2016). If we do
not hear from you within this time then it will be assumed that the paper has been withdrawn. In
exceptional circumstances, extensions may be possible if agreed with the Editorial Office in
advance.We do not allow multiple rounds of revision so we urge you to make every effort to
fully address all of the comments at this stage. If deemed necessary by the Editors, your
manuscript will be sent back to one or more of the original reviewers for assessment. If the
original reviewers are not available we may invite new reviewers.
To revise your manuscript, log into http://mc.manuscriptcentral.com/rsos and enter your
Author Centre, where you will find your manuscript title listed under "Manuscripts with
Decisions." Under "Actions," click on "Create a Revision." Your manuscript number has been
appended to denote a revision. Revise your manuscript and upload a new version through your
Author Centre.
When submitting your revised manuscript, you must respond to the comments made by the
referees and upload a file "Response to Referees" in "Section 6 - File Upload". Please use this to
document how you have responded to the comments, and the adjustments you have made. In
order to expedite the processing of the revised manuscript, please be as specific as possible in
your response.
Once again, thank you for submitting your manuscript to Royal Society Open Science and I look
forward to receiving your revision. If you have any questions at all, please do not hesitate to get
in touch.
Yours sincerely,
Liisa Niitsoo
Publishing Editor, Journals
Royal Society Open Science
Royal Society of Chemistry
Tel +44 (0) 1223 432167
[email protected]
Comments to Author:
Associate Editor's comments:
RSC Associate Editor: Hazel Cox
Comments to the Author:
(There are no comments.)
RSC Subject Editor: Anthony Stace
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
7
Comments to the Author:
As you will see, one of the referees has recommended that quite major revisions are required
before the paper is suitable for publication. Please check the recommendations carefully and
make the necessary changes. If there are recommendations that you do not consider appropriate,
please comment on those in a covering letter.
Reviewers' Comments to Author:
Reviewer: 1
Comments to the Author(s)
------Overall feedback
------The authors have successfully produced via a electrospinning method a halloysite nanotube
based nanofiber mat. As evidenced in Figure 2 the mats are shown to have relatively uniform
pore sizes and the pore size can be controlled by the pressure applied before sintering. The mats
out performs the commercial equivalent in terms of permeability.
The mats were then used as supports for zeolite seed where is was demonstrated using
ultrasonication and SEM that the various seeds adhere well to the surface, an improvement over
the commercial FNJ supports.
Side on SEM was used to determine the thickness of the layers and EDX line profiles of the layers
determined no leaching occurred when using the HMN support. In Figure 7 (a) this could be
improved by discarding the line profile data from before the edge of the film. The X-rays detected
are not generated in the same plane (lower planes) as once you are on the sample. This doesn't
alter the conclusion that leaching is not occurring. Line mapping shows Al leaching is occurring
clearly.
The data supports the conclusions made.
There are a great deal of errors in the language that are listed below. This manuscript should
have had a through proof read before submission and the reviewers should not have to list this
many corrections. I didn't record all the errors in the final pages are it was taking a long time and
is beyond the role of a reviewer.
The largest holes are in the experimental where it is currently not possible to reproduce the
experiment as a number of quantities, concentrations and volumes are absent as listed below. In
addition, some of the language in the discussion is inappropriate for scientific literature, e.g. "To
our delight...". Some of the figure captions are not detailed enough and a few changes to figures is
recommended in the comments below.
Due to the quantity of corrections I have recommended major corrections to the manuscript.
--------Deatiled comments
--------Errors that need addressing
L=line number
Page 3
L7 Ratio poorly described. A single number is not a ratio "1 to infinity"
L12 Poor English replace with "attract more attention"
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
8
L14 Poor English replace with "applications"
L14 Poor English replace with "less than twenty"
L17 Poor English replace with "The low quality"
L31 "a larger increase in flux"? Leap doesn't suggest the direction of change.
L33 Please clarify "support quality". Which property of the support?
L41 Replace "Support qualities" with "Features of the support"
L53 Add Kwang et al. Adv. Mater. 2000, 12, 1114 as a reference after [25]
Page 4
L9 Replace "Unfortunately, very few" with "Very few"
L12 Add space after "Fibrous"
L21 Halloysite nanotubes sentence doesn't make sense. Please fix.
L24 Not sure of the use of the word lapped. Do you mean interwoven?
L27 Add space after "be"
Section 2.1 Use ≤99% instead of 99+% to described purities
Page 5
Remove section headings 2.2.1, 2.2.2 and 2.2.3. They should all be under 2.2 as it is all brief.
L9 Replace "mixed solvent" with "mixture"
L9 What is the ratio of ethanol and water in the mixture?
L9 How long was it sonicated for?
L9 Replace "ultrasonic assistance" with "by ultrasonication"
L10 How much PVP was added?
L25 Replace "by" with "using a"
The steal mold dimensions and pressure applied are not stated. Please state.
The ratios are described in a strange and confusing way in pages 5 and 6. For instance on L36
1Al2O3:2SiO2:2Na2O:120H2O should be " the Al2O3:SiO2:Na2O:H2O ratio was 1:2:2:120". The
same is true for all ratios throughout the paper.
L37 Delete "clear".
L37 & L38 How much sodium hydroxide was added and what was the concentration and volume
of the aluminate solution. Can't reproduce the experiment without this information.
L41 Delete "in a three neck bottle"
L42 Was the reaction quenched by washing with water or was it quenched and then washed? If
so, how was it quenched?
L47 After "mat" add "(HNM)" and delete "(denoted as HNM).
L48 Delete "with gloved fingers"
L53 Provide details on the washing step, e.g. how much water and how many times was it
washed?
Page 6
L4 Delete "A clear synthesis solution was obtained by slowly adding"
L5 How much TEOS was added?
L5 What was the concentration and volume of the TPAOH solution?
L7 Replace "solution" with "reaction mixture"
L8 For the washing how much water was used and how many times was it washed?
L9 Delete "solution containing silicalite-1 seeds and 50% ethanol solution" and replace with "a
50:50 mixture of the silicalite-1 seeds suspension in water and ethanol"
L15 I don't understand which solution is "the synthesis solution".
L16 Delete "for only one time" and "water".
L16 Add after "washed" add "with water applied".
L33 Delete "The gel was prepared as follows:"
L33 Provide concentration and volume of phosphoric acid solution used.
L34 Provide concentration and volume of aluminium isopropoxide solution used.
L39 Replace "into a same" with "into the same"
L44 Delete "with temperature programmer"
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
9
L48 Provide a citation for the 1966-1996 method.
L52 Replace "KV" with "kV".
L55 Provide model number of the Oxford EDS analyzer.
Page 7
L4 Provide the manufacturer of the DSA30
L5 Fiberlite F21s-8x50y is the model of the rotor for the centrifuge. Please also provide the model
of the centrifuge.
L17 Use of the word lapped again. I think interwoven is a better description.
L27 Replace "probably due to" with "as a possible consequence of"
Figure 1 Do you have the same magnification for the (b), (c) and (d)? This would make
comparision by eye easier.
L29 After "magnification" add "before heating"
L29 After "membrane" add "after heating at 1100 C under N2"
L29 After "HNMs" add "after sintering in air at 1200 C"
L55 After "At" add "a transmembrane pressure of".
L55 Delete "transmembrane pressure drop"
L56 Which porosity did you use for the flux experiment? Please state as you have demonstrated
that you can make different porosity mats.
Page 9
Figure 2 Increase font size on all parts of the figure. I can barely read most of it.
Figure 2 Adjust y axis to start at 40 and finish at 90.
L24 Delete "for guiding the eyes"
L24 replace "results" with "patterns"
L32 Replace "mdarcy" with "mD".
I have stopped correcting typos at this stage and recommend the authors check the rest of the
document. This is the job of the authors prior to submission and not the reviewer.
Figure 4 caption is confusing. Please rewrite.
Figure 5 The peak labels (squares and circles) are difficult to distinguish. Use dots and crosses for
clarity.
Page 12
L4 The Si:Al in Figure6a is 0.9:1 and not 1:1 as stated. State in the text it is 0.9:1 which is close to
the expected composition and explain the slight difference.
L16 The XRD pattern in Figure 5 f shows two patterns although only one is identified in the text.
L21 The EDX ratio of Si:O is 1.1:2. Again a deviation from the expected value. Explain and state
the correct value. Oxygen is difficult to quantify via EDX as it is a common containment in SEM
samples although your sample is O deficient. Can you add how the SEM samples were prepared
in the SI.
L57 The caption contains very little information. Please explain the sample in all parts.
Figure 5 Inset SEM images need scale bars.
Page 13
Figure 6. SEM images need scale bars.
L24 The X-rays escaping when doing a surface measurement will only be from about 500 nm
deep. The SEM in figure 5 suggests the film is approx 3.5 microns thick. The EDX values from the
surface only tell you that the leaching has not made its way to the surface. I'd change or remove
the sentence starting "One interesting..."
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
10
Page 14
Figure 7. (a) I don't think the EDX line map is meaningful once you have gone beyond the edge of
the sample. The beam is focused above the sample and the X-rays generated will be generated
when the unfocussed beam hits the sample. I recommend removing the data from before the edge
of the sample and shortening the arrow accordingly.
L51 Delete "In our lab"
L51 Delete entire sentence "To our delight when we screened another..." Replace with something
like "When using aluminophosphate AlPO4-5 a continious intergrown member was obtained... "
The original reads like a personal diary an not scientific writing.
Page 15
L4 Add "The" before "XRD pattern"
Reviewer: 2
Comments to the Author(s)
Zeolite membranes have been industriallized for dehydration of organics in many areas,
currently intensive efforts are being foused on lowering the cost therefore for wider application.
It is reproted that the normal Al2O3 tube support accounts for 70% cost of the zeolite membrane.
Therefore it is of signifcance to develop new type of the support with larger posity and narrow
pore size distribution. In the present manuscript, the halloysite nanotube-based mats show higher
porosity and narrower pore size distribution which is favourable for high flux of the resulting
zeolite membrane. Before the publication, the following concerns are suggested to address.
1. One of the highlight of the work is use of halloysite nanotube as the support strcuture units
instead of powder particles, therefore the literatures on nanotube materias as the support units
should be briefly addressed.
2. The work on the NaA zeolite membrane supported on macroporous mullite and Al2O3 tube
repesctively should be cited (Sep. Purif. Technol. 25 (2001) 251-260 AIChE, 59 (2013) 936-946,
Journal of membrane Science 444 (2013)513-522 because these work are of great importance in
terms of the coarse macroporous support for the zeolite membranes.
Author's Response to Decision Letter for (RSOS-160552)
See Appendix A.
RSOS-160552.R1 (Revision)
Review form: Reviewer 1 (Paul McNaughter)
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
Yes
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
11
Do you have any ethical concerns with this paper?
No
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Accept as is
Comments to the Author(s)
Thank you for making the changes.
Decision letter (RSOS-160552.R1)
17-Nov-2016
Dear Professor Hong,
I am pleased to inform you that your manuscript entitled "Halloysite Nanotube-Based
Electrospun Ceramic Nanofiber Mat: a Novel Support for Zeolite Membranes" is now accepted
for publication in Royal Society Open Science.
You can expect to receive a proof of your article in the near future. Please contact the editorial
office ([email protected] and [email protected]) to let us know if
you are likely to be away from e-mail contact. Due to rapid publication and an extremely tight
schedule, if comments are not received, your paper may experience a delay in publication.
Royal Society Open Science operates under a continuous publication model
(http://bit.ly/cpFAQ). Your article will be published straight into the next open issue and this
will be the final version of the paper. As such, it can be cited immediately by other researchers.
As the issue version of your paper will be the only version to be published I would advise you to
check your proofs thoroughly as changes cannot be made once the paper is published.
In order to raise the profile of your paper once it is published, we can send through a PDF of your
paper to selected colleagues. If you wish to take advantage of this, please reply to this email with
the name and email addresses of up to 10 people who you feel would wish to read your article.
On behalf of the Editors of Royal Society Open Science, we look forward to your continued
contributions to the Journal.
Best wishes,
Liisa Niitsoo
Publishing Editor, Journals
Royal Society Open Science
Royal Society of Chemistry
Tel +44 (0) 1223 432167
[email protected]
Celebrating 175 years of progress and people in the chemical sciences
Join in with our 175th anniversary this year at rsc.li/175
www.rsc.org
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
12
Associate Editor Comments to Author:
RSC Associate Editor: Dr Hazel Cox
Comments to the Author: (There are no comments.)
RSC Associate Editor: Dr Anthony Stace
Comments to the Author:(There are no comments.)
Reviewer's Comments to Author:
Reviewer: 1
Comments to the Author(s)
Thank you for making the changes.
Appendix A
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
Peking University
Guangdong Provincial Key Laboratory
of Nano-Micro Materials Research,
School of Chemical Biology & Biotechnology,
Peking University Shenzhen Graduate School, Shenzhen 518055, China
Fax: +86 755 26033174; Tel: +86 18025383656
E-mail: [email protected]
October 15, 2016
Dr. Liisa Niitsoo
Publishing Editor (Journals)
Royal Society Open Science
Royal Society of Chemistry,
Tel: +44 (0) 1223 432167
Dear Dr. Liisa Niitsoo:
Thank you for considering a revised version of our manuscript, entitled "Halloysite Nanotube-Based
Electrospun Ceramic Nanofiber Mat: a Novel Support for Zeolite Membranes", for publication in Royal
Society Open Science.
We are truly grateful to yours and other reviewers’ critical comments and thoughtful suggestions.
Based on these comments and suggestions, we have made careful modifications on the original
manuscript as highlighted in red color in the track changes version. Detailed experimental conditions such
as reagent amounts, solution concentrations, and procedures have been listed. Relevant references have
been added. Missing scale bars have been added and redundant lines have been discarded in some
figures. All the language errors have been corrected and we have polished the main text considerably in
order to make this revised manuscript more appropriate for scientific literature. In addition to addressing
the requested changes, we have corrected several other errors that we had noticed. We hope the revised
manuscript will meet the standard of Royal Society Open Science. Please see our detailed responses in the
attached pages.
Thank you and Best Regards,
Mei Hong
Associate Professor
Peking University Shenzhen Graduate School
Downloaded from http://rsos.royalsocietypublishing.org/ on June 17, 2017
Detailed Responses to Reviewer’s Comments
Referee 1:
The authors have successfully produced via an electrospinning method and halloysite nanotube based
nanofiber mat. As evidenced in Figure 2 the mats are shown to have relatively uniform pore sizes and the
pore size can be controlled by the pressure applied before sintering. The mats out performs the
commercial equivalent in terms of permeability.
The mats were then used as supports for zeolite seed where is was demonstrated using ultrasonication
and SEM that the various seeds adhere well to the surface, an improvement over the commercial FNJ
supports.
Side on SEM was used to determine the thickness of the layers and EDX line profiles of the layers
determined no leaching occurred when using the HMN support. In Figure 7 (a) this could be improved by
discarding the line profile data from before the edge of the film. The X-rays detected are not generated in
the same plane (lower planes) as once you are on the sample. This doesn't alter the conclusion that
leaching is not occurring. Line mapping shows Al leaching is occurring clearly.
Response:
The line profile data from before the edge of the sample in Figure 7(a) have been removed and the
arrows have been shortened accordingly.
The data supports the conclusions made.
Response:
We would like to thank the referee for the agreeing with our conclusions.
There are a great deal of errors in the language that are listed below. This manuscript should have had a
through proof read before submission and the reviewers should not have to list this many corrections. I
didn't record all the errors in the final pages are it was taking a long time and is beyond the role of a
reviewer.
Response:
The language errors have been corrected as suggested. Besides the pointed errors, we further proof read
the manuscript and corrected some other errors.
The largest holes are in the experimental where it is currently not possible to reproduce the experiment as
a number of quantities, concentrations and volumes are absent as listed below. In addition, some of the
language in the discussion is inappropriate for scientific literature, e.g. "To our delight...". Some of the
figure captions are not detailed enough and a few changes to figures is recommended in the comments
below.
Response:
Detailed experimental conditions such as reagent amounts, solution concentrations, volumes, and
procedures have been listed. The colloquial language inappropriate for scientific literature have been
discarded.
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Page 3
L7 Ratio poorly described. A single number is not a ratio "1 to infinity"
L12 Poor English replace with "attract more attention"
L14 Poor English replace with "applications"
L14 Poor English replace with "less than twenty"
L17 Poor English replace with "The low quality"
L31 "a larger increase in flux"? Leap doesn't suggest the direction of change.
Response:
All these language errors have been corrected as suggested.
L33 Please clarify "support quality". Which property of the support?
Response:
We have changed ''the support quality also has profound effect'' to ''support qualities such as pore
connectivity also have profound effect'' to clarify specific properties of the support that affected zeolite
membrane fabrication.
L41 Replace "Support qualities" with "Features of the support"
Response: "Support qualities" has been replaced by "Features of the support".
L53 Add Kwang et al. Adv. Mater. 2000, 12, 1114 as a reference after [25]
Response: We have added this reference as reference [27] in the revised manuscript to explain previous
efforts on molecular linkers.
Page 4
L9 Replace "Unfortunately, very few" with "Very few"
L12 Add space after "Fibrous"
Response: These language errors have been corrected as suggested.
L21 Halloysite nanotubes sentence doesn't make sense. Please fix.
Response: We have replaced halloysite nanotube sentences of ''In this study, we chose halloysite
nanotubes (HNTs) as the ceramic fiber material for electrospinning. Halloysite nanotubes are cheap
natural clay available in thousands of tons, which are durable with high mechanical strength.'' with
''Nanotube material based membranes have been reported to allow high flux and would be suitable to
act as support. In this study, halloysite nanotubes (HNTs) have been chosen as the ceramic support
material due to its high mechanical strength and abundance in nature compared to other nanotube
materials.''
L24 Not sure of the use of the word lapped. Do you mean interwoven?
Response: Yes, and we have replaced the word ''inter-lapped'' with ''interwoven'' to avoid confusion.
L27 Add space after "be" Section 2.1 Use ≥99% instead of 99+% to described purities
Response: These language errors have been corrected as suggested.
Page 5
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Remove section headings 2.2.1, 2.2.2 and 2.2.3. They should all be under 2.2 as it is all brief.
Response: We agree with the advice and removed section headings 2.2.1, 2.2.2 and 2.2.3.
L9 Replace "mixed solvent" with "mixture"
Response: We have replaced "mixed solvent" with "mixture".
L9 What is the ratio of ethanol and water in the mixture?
L9 How long was it sonicated for?
Response: The weight ratio of ethanol and water in the mixture is 8:1. The mixture of HNTs and
ethanol/water solution was sonicated for one hour. The detailed information have been added in the
revised manuscript.
L9 Replace "ultrasonic assistance" with "by ultrasonication"
Response: We have replaced "ultrasonic assistance" with "by ultrasonication".
L10 How much PVP was added?
Response: 12 wt% PVP was added.
L25 Replace "by" with "using a"
Response: We have replaced "by" with "using a".
The steal mold dimensions and pressure applied are not stated. Please state.
Response: The HNTs/PVP nanofiber membranes were cut using a steel mold with a diameter of 45 mm
and consolidated to be multilayered HNTs/PVP nanofiber membranes by applying compressive pressures
ranging from 4.44 to 16.7 MPa. The detailed information have been added in the revised manuscript.
The ratios are described in a strange and confusing way in pages 5 and 6. For instance on L36
1Al2O3:2SiO2:2Na2O:120H2O should be " the Al2O3:SiO2:Na2O:H2O ratio was 1:2:2:120". The same is
true for all ratios throughout the paper.
Response: We have revised all the descriptions of ratio throughout the paper as suggested.
L37 Delete "clear".
Response: This redundant word has been deleted as suggested.
L37 & L38 How much sodium hydroxide was added and what was the concentration and volume of the
aluminate solution. Can't reproduce the experiment without this information.
Response: Following the reviewer’s suggestion, we have supplemented detailed experimental processes.
As follows:
2.3.1 NaA(LTA) zeolite membrane synthesis
The gel composition used for NaA zeolite seed crystals was Al2O3:SiO2:Na2O:H2O=1:2:2:120. An aluminate
solution was obtained by adding 2 g sodium hydroxide to a solution of 4.1 g sodium aluminate in 25 ml
water and stirred for more than 15 minutes. Then the clear solution was dosed into a silicate solution
including 12 g Ludox and 20 ml water to form an azury gel. The gel was aged for 8 h at 50 °C, followed by
a 3 h hydrothermal synthesis at 100 °C under constant mechanical stirring. After the synthesis, the
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mixture was quenched by washing with deionized water until the pH of supernatant solution was close to
7, then the white solid (named as NaA zeolite seed crystals) was dried at 60 °C. In a seeding procedure,
the seeds were dispersed in a 20% ethanol-water solution before a wet-rubbing operation to implant
seeds on the HNT-based nanofiber mat (HNM) support. The seeded supports were then dried at 60 °C
overnight. The composition of the gel for NaA zeolite membrane secondary growth was
Al2O3:SiO2:Na2O:H2O=1:2:2:150. The solution for zeolite membrane synthesis was obtained by adding 2 g
sodium hydroxide to the mixture of 4.1 g sodium aluminate in 38.5 ml water and stirred for more than 15
minutes. Then the clear solution was dosed into a solution including 12 g Ludox and 20 ml water to form
an azury gel. The gel was aged for 8 h at 50 °C. The secondary growth was performed in an autoclave by
immersing the seeded supports in the gel and then heated to 100 °C for 3.5 h followed by a water
washing step with a wet brush for several times until the pH of solution on membrane surface was close
to 7. The secondary growth procedure was repeated to get a continuous NaA (LTA) membrane.
L41 Delete "in a three neck bottle"
Response: We have deleted this redundant description to make the article more concise.
L42 Was the reaction quenched by washing with water or was it quenched and then washed? If so, how
was it quenched?
Response: Sorry for the confusion. The mixture was quenched by washing with deionized water until the
pH of supernatant solution was close to 7.
L47 After "mat" add "(HNM)" and delete "(denoted as HNM).
Response: This sentence has been corrected as ''to implant seeds on the HNT-based nanofiber mat (HNM)
support''.
L48 Delete "with gloved fingers"
Response: We have deleted this redundant description to make the article more concise.
L53 Provide details on the washing step, e.g. how much water and how many times was it washed?
Response: Thanks a lot for the reviewer’s kind reminder. The experimental process has been described in
detail: “The secondary growth was performed in an autoclave by immersing the seeded supports in the
gel and then heated to 100 °C for 3.5 h followed by a water washing step with a wet brush for several
times until the pH of solution on membrane surface was close to 7.”
Page 6
L4 Delete "A clear synthesis solution was obtained by slowly adding"
Response: We have deleted this redundant description.
L5 How much TEOS was added?
L5 What was the concentration and volume of the TPAOH solution?
Response: Detailed experimental conditions have been added: “5 g TEOS was added to an aqueous
solution of 2.5 g TPAOH and 65 ml water, then was stirred for aging at 50 °C for 8 h.”
L7 Replace "solution" with "reaction mixture"
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Response: The word "solution" has been replaced with "reaction mixture" as suggested.
L8 For the washing how much water was used and how many times was it washed?
Response: The amount of water and the times of washing treatment was dependent on the zeolite
crystals, and the judging criterion for a thorough washing was pH of the supernatant. Therefore, the
zeolite crystals was washed with water for several times until the pH of the supernatant was close to 7.
L9 Delete "solution containing silicalite-1 seeds and 50% ethanol solution" and replace with "a 50:50
mixture of the silicalite-1 seeds suspension in water and ethanol"
Response: This sentence "solution containing silicalite-1 seeds and 50% ethanol solution" has been
replaced with "a 50:50 mixture of the silicalite-1 seeds suspension in water and ethanol".
L15 I don't understand which solution is "the synthesis solution".
Response: We clarified the synthesis solution by adding the sentences of ''The synthesis solution for
silicalite-1 membrane was obtained by slowly adding 6 g TEOS to an aqueous solution of 2.5 g TPAOH and
84 ml water, and aging at 50 °C for 8 h. The seeded support was placed into the synthesis solution and
heated in an autoclave at 180 °C for 9 h.''. So, the synthesis solution was the one used for zeolite
membrane fabrication.
L16 Delete "for only one time" and "water".
L16 Add after "washed" add "with water applied".
L33 Delete "The gel was prepared as follows:"
Response: The inappropriate descriptions have been corrected as suggested.
L33 Provide concentration and volume of phosphoric acid solution used.
L34 Provide concentration and volume of aluminium isopropoxide solution used.
Response: We have added detailed experimental processes: “7.5 g phosphoric acid solution was dosed
into a solution composed of 10.2 g aluminium isopropoxide and 87.0 ml water and stirred at room
temperature for 3 h, then 2.0 g TEA was added and stirred for another 2 days at room temperature to
obtain the synthesis gel with a composition of Al2O3:P2O5:TEA:H2O=1:1.3:1:200. The HNT-based nanofiber
mat supports and commercially available α-Al2O3 supports were placed into the same autoclave filled
with the aforementioned gel and heated at 180 °C for 10 h, then washed with deionized water and dried
at 60 °C overnight. The as-made membranes were calcined in a furnace at 550 °C to remove the organic
template.”
L39 Replace "into a same" with "into the same"
L44 Delete "with temperature programmer"
Response: The redundant descriptions have been deleted as suggested.
L48 Provide a citation for the 1966-1996 method.
Response: The citation for the 1966-1996 method has been provided as reference [40] ''Chinese National
Standard. Test method for apparent porosity and bulk density of porous ceramic. GB/T 1966-1996, 1996.''
L52 Replace "KV" with "kV".
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Response: The unit error has been corrected as suggested.
L55 Provide model number of the Oxford EDS analyzer.
Response: The model number of the Oxford EDS analyzer is XMX1112.
Page 7
L4 Provide the manufacturer of the DSA30
Response: We added the information of DSA30: “Contact angle measurements were carried out in a drop
shape analyzer (DSA30, KRUSS GmbH).”
L5 Fiberlite F21s-8x50y is the model of the rotor for the centrifuge. Please also provide the model of the
centrifuge.
Response: The model of the centrifuge is Thermo Scientific-Sorvall RC 6Plus.
L17 Use of the word lapped again. I think interwoven is a better description.
Response: We have replaced ''lapped'' with ''interwoven''.
L27 Replace "probably due to" with "as a possible consequence of"
Response: We have replaced "probably due to" with "as a possible consequence of".
Figure 1 Do you have the same magnification for the (b), (c) and (d)? This would make comparision by eye
easier.
Response: We have adjusted the magnification for (b), (c) and (d) in Figure 1, and replaced Figure 1 with
the following new one:
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L29 After "magnification" add "before heating"
L29 After "membrane" add "after heating at 1100 C under N2"
L29 After "HNMs" add "after sintering in air at 1200 C"
Response: Following the reviewer’s suggestion, the caption of Figure 1 has been changed to ''Figure 1.
(a,b) SEM images of HNTs/PVP fiber membrane taken under different magnification before heating, (c)
SEM image of HNTs/carbon membrane after heating at 1100 °C under N2, (d) SEM image of HNMs after
sintering in air at 1200 °C, (e,f) Appearance of HNMs.''
L55 After "At" add "a transmembrane pressure of".
L55 Delete "transmembrane pressure drop"
Response: The descriptions have been corrected as suggested and the new sentence is: “At a
transmembrane pressure of 0.98 bar, the water flux for HNM with a porosity of 67% was 2.1 m3/m2/h, 40%
higher than that of 1.5 m3/m2/h for the α-Al2O3 support.”
L56 Which porosity did you use for the flux experiment? Please state as you have demonstrated that you
can make different porosity mats.
Response: The porosity of HNM support we used for the flux experiment is 67%.
Page 9
Figure 2 Increase font size on all parts of the figure. I can barely read most of it.
Figure 2 Adjust y axis to start at 40 and finish at 90.
Response: We have changed to thicker lines, increased font size on all parts of Figure 2 and adjusted y
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axis of Figure 2b as suggested. The following are the modified figures:
L24 Delete "for guiding the eyes"
L24 replace "results" with "patterns"
L32 Replace "mdarcy" with "mD".
Response: All these language corrections have been addressed as suggested.
I have stopped correcting typos at this stage and recommend the authors check the rest of the document.
This is the job of the authors prior to submission and not the reviewer.
Response: We want to express our sincere appreciation for pointing out all these typos. We have carefully
checked the rest of the document and corrected several other errors that we had noticed. For example,
the reference numbers have been placed as close as possible to the positon of citation. The verbs have
been changed to the same tense in some sentences. We polished the main text considerably.
Figure 4 caption is confusing. Please rewrite.
Response: Sorry for the confusion. We have rewrote the caption of Figure 4 as ''Figure 4. SEM images of
(a) a NaA crystal-seeded HNM support before and (b) after a 2-minute ultrasonic treatment; SEM images
of (c) a silicalite-1 crystal-seeded HNM support before and (d) after a 2-minute ultrasonic treatment; SEM
images of (e) a NaY crystal-seeded HNM support before and (f) after a 2-minute ultrasonic treatment.''
Figure 5 The peak labels (squares and circles) are difficult to distinguish. Use dots and crosses for clarity.
Figure 5 Inset SEM images need scale bars.
Response: Thanks a lot for the reviewer’s kind reminder. For better clarity, and we now use red stars＊
and blue crosses＋ which are easier to distinguish than squares and circles. Also, we have added scale
bars for all inset SEM images. The modified Figure 5 is shown below:
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Page 12
L4 The Si:Al in Figure6a is 0.9:1 and not 1:1 as stated. State in the text it is 0.9:1 which is close to the
expected composition and explain the slight difference.
Response: We have explained this in the main text as ''To further verify the purity of LTA zeolite
membrane, a SEM-EDS chemical analysis on the membrane surface (Figure 6a) showed a silicon to
aluminum ratio of 0.98:1 which is close to the standard NaA composition of |Na91.7|[Si96Al96O384], within
the limiting error of the EDS instrument due to membrane surface roughness.''
L16 The XRD pattern in Figure 5 f shows two patterns although only one is identified in the text.
Response: Thanks for pointing out our mistake. We have modified the sentence as ''The XRD pattern
(Figure 5f) of the silicalite-1 membrane showed diffraction peaks that can be indexed to silicalite-1 zeolite
crystalline structure and the HNM support.'' to identify both patterns.
L21 The EDX ratio of Si:O is 1.1:2. Again a deviation from the expected value. Explain and state the correct
value. Oxygen is difficult to quantify via EDX as it is a common containment in SEM samples although your
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sample is O deficient. Can you add how the SEM samples were prepared in the SI.
Response: We have explained this in the main text as ''Although oxygen is difficult to quantify via EDS,
the SEM-EDS chemical analysis of a selected surface of the calcined silicalite-1 membrane showed the
composition ratio of silicon to oxygen 1:1.88 in silicalite-1 zeolite layer, close to the standard O/Si ratio of
2. No Al elements leached from the support (Figure 6b), which confirmed the integrity of these
membranes as well.''. The experimental process for SEM sample preparation was added in section ''2.4
Characterization''.
L57 The caption contains very little information. Please explain the sample in all parts.
Response: Sorry for the confusion. Maybe part of the caption of Figure 5 was neglected because of page
turning. The caption of Figure 5 clearly stated ''Figure 5. (a) SEM top view image and (b) SEM
cross-sectional image, and (c) XRD pattern of the zeolite NaA membrane; (d) SEM top view image and (e)
SEM cross-sectional image, and (f) XRD pattern of the zeolite silicalite-1 membrane; (g) SEM top view
image and (h) SEM cross-sectional image, and (i) XRD pattern of the zeolite NaY membrane. Diffraction
peaks of zeolite phases were marked with stars＊, and diffraction peaks of HNMs were marked with
crosses＋.''
Page 13
Figure 6. SEM images need scale bars.
Response: Scale bars have been inserted for all insert SEM images throughout the paper.
L24 The X-rays escaping when doing a surface measurement will only be from about 500 nm deep. The
SEM in figure 5 suggests the film is approx 3.5 microns thick. The EDX values from the surface only tell you
that the leaching has not made its way to the surface. I'd change or remove the sentence starting "One
interesting..."
Response: The sentence ''One interesting phenomenon is that not a trace amount of Al can be detected
on the surface of a calcined silicalite-1 membrane (Figure 6b), at least up to the detection limit of EDS
mapping.'' has been removed.
Page 14
Figure 7. (a) I don't think the EDX line map is meaningful once you have gone beyond the edge of the
sample. The beam is focused above the sample and the X-rays generated will be generated when the
unfocussed beam hits the sample. I recommend removing the data from before the edge of the sample
and shortening the arrow accordingly.
Response: Following the reviewer’s suggestion, we have removed the data from before the edge of the
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sample in Figure 7(a) and shortened the arrow in SEM image accordingly, in order to make it easier for
observation and understanding.
L51 Delete "In our lab"
L51 Delete entire sentence "To our delight when we screened another..." Replace with something like
"When using aluminophosphate AlPO4-5 a continuous intergrown member was obtained... " The original
reads like a personal diary and not scientific writing.
Response: We have deleted "In our lab" and replaced this sentence "When using aluminophosphate
AlPO4-5 a continuous intergrown member was obtained... " with ''When using aluminophosphate
AlPO4-5 as zeolite layer, a continuous intergrown membrane was obtained.''
Page 15
L4 Add "The" before "XRD pattern"
Response: "The" has been added before "XRD pattern"
Reviewer: 2
Comments to the Author(s)
Zeolite membranes have been industriallized for dehydration of organics in many areas, currently
intensive efforts are being focused on lowering the cost therefore for wider application. It is reported that
the normal Al2O3 tube support accounts for 70% cost of the zeolite membrane. Therefore it is of
significance to develop new type of the support with larger porosity and narrow pore size distribution. In
the present manuscript, the halloysite nanotube-based mats show higher porosity and narrower pore size
distribution which is favourable for high flux of the resulting zeolite membrane. Before the publication, the
following concerns are suggested to address.
One of the highlight of the work is use of halloysite nanotube as the support structure units instead of
powder particles, therefore the literatures on nanotube materials as the support units should be briefly
addressed.
Response: We have added a brief introduction of halloysite nanotube for its suitability as zeolite
membrane support and inserted related references as ''Nanotube material based membranes have been
reported to allow high flux[35,36] and would be suitable to act as support. In this study, halloysite
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nanotubes (HNTs) have been chosen as the ceramic support material due to its high mechanical strength
and abundance in nature[37]compared to other nanotube materials.'' The literatures on the description
of halloysite nanotube materials have also been listed as reference 55, 56.
[35]. Holt, J. K., Park, H. G., Wang, Y., Stadermann, M., Artyukhin, A. B., Grigoropoulos, C. P., Noy, A.,
Bakajin, O. 2006 Fast mass transport through sub-2-nanometer carbon nanotubes. Science. 312,
1034-1037. (10.1126/science.1126298);
[36]. Zhang, H., Zhao, H., Liu, P., Zhang, S., Li, G. 2009 Direct growth of hierarchically structured titanate
nanotube filtration membrane for removal of waterborne pathogens. J. Membr. Sci. 343, 212-218.
(http://dx.doi.org/10.1016/j.memsci.2009.07.030);
[37]. Lu, D., Chen, H., Wu, J., Chan, C. M. 2011 Direct measurements of the Young's Modulus of a single
halloysite nanotube using a transmission electron microscope with a bending stage. J. Nanosci.
Nanotechnol. 11, 7789-7793. (10.1166/jnn.2011.4720)].
[55]. Tully, J., Yendluri, R., Lvov, Y. 2016 Halloysite clay nanotubes for enzyme immobilization.
Biomacromolecules. 17, 615-621. (10.1021/acs.biomac.5b01542);
[56]. Lvov, Y., Abdullayev, E. 2013 Functional polymer–clay nanotube composites with sustained release of
chemical agents. Prog. Polym. Sci. 38, 1690-1719. (10.1016/j.progpolymsci.2013.05.009)
The work on the NaA zeolite membrane supported on macroporous mullite and Al2O3 tube respectively
should be cited (Sep. Purif. Technol. 25 (2001) 251-260 AIChE, 59 (2013) 936-946, Journal of membrane
Science 444 (2013)513-522 because these work are of great importance in terms of the coarse
macroporous support for the zeolite membranes.
Response: These work mentioned are indeed of great importance in terms of the coarse macroporous
support for the zeolite membranes, and we have cited these as references 16, 49, 50 in the main text as
follows:
[16]. Chen, X., Wang, J., Yin, D., Yang, J., Lu, J., Zhang, Y., Chen, Z. 2013 High-performance zeolite T
membrane for dehydration of organics by a new varying temperature hot-dip coating method. AlChE J. 59,
936-947. (10.1002/aic.13851)
[49]. Morigami, Y., Kondo, M., Abe, J., Kita, H., Okamoto, K. 2001 The first large-scale pervaporation plant
using tubular-type module with zeolite NaA membrane. Sep. Purif. Technol. 25, 251-260.
(http://dx.doi.org/10.1016/S1383-5866(01)00109-5)
[50]. Li, H., Wang, J., Xu, J., Meng, X., Xu, B., Yang, J., Li, S., Lu, J., Zhang, Y., He, X., et al. 2013 Synthesis of
zeolite NaA membranes with high performance and high reproducibility on coarse macroporous supports.
J. Membr. Sci. 444, 513-522. (http://dx.doi.org/10.1016/j.memsci.2013.04.030)