Dye Adsorbent Materials Based on Porous Ceramics from Glass Fiber-Reinforced Plastic and Clay
Round 1
Reviewer 1 Report
- heating rate in K
- crushing an milling the composite, which final fiber length is in the composite
- particle size distribution by siveing through mesh is not adequate, please use a grain size measuring technique for complete grain size distribution
- how is the chemical composition determined?
- figure 2 : the fibers can't be seen at this low magnification, beside the coor change there is no use to have this picture
- information on load cell is missing
- Mercury intrusion is not the best way to determine pore size distribution, in fact it's the worst one, because it uses a cylindrical pore shape approach, which will not fit.Please look instead after adsorption techniques and add more sem images which show the pores
- it's not clear, are all samples washed to remove the fine ceramic particles (size is missing) before preforming further experiments? If yes, how are they dried?
- how does the dissolving of the clay and composites effects the results? in fact the pH change will
- a dissolving structure may not be appropiate for a filtering application
- how is the turbity determined?
- how is the carbon content determined?
- there is no proof at all for plastic carbide
- the explanation why a pH change by MB adsorption is caused isn't proofed at all.
Author Response
Dear reviewer,
Thank you for inviting us to submit a revised draft of our manuscript (applsci-450467) entitled“Dye adsorbent material based on porous ceramics from glass fiber-reinforced plastic and clay” to Applied Sciences.
We would submit the revised manuscript.
We sincerely apologize for the delay in submitting the revised manuscript.
To answer the reviewers' questions and comments, we added the experimental data on oxidatively fired 20% GFRP/clay and 40% GFRP/clay ceramics. Furthermore, we measured the pore size distributions of granular ceramic samples by using the nitrogen gas adsorption method.
We think that we could investigate the MB dye adsorptivity of the oxidatively and reductively fired GFRP/clay ceramics in more detail.
Again, thank you for giving us the opportunity to strengthen our manuscript with your valuable comments and queries.
Sincerely yours,
Hiroyuki Kinoshita
University of Miyazaki, Japan
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors have been dealing with such porous materials (originating from a fired mixture of GFRP and clay) and their potential applications for a numbe of years (e.g. [4-8]).
Issues:
(1) Table I. Last column. The CaO/SiO2 is too high for glass (e.g. E glass, S glass, plain glass etc)- please explain the significance of the listed values
(2) Oxidatively fired 60 % GFRP and Reductively fired 60% GFRP show comparable porosities but the specific surface area of the latter is almost 4 times larger; the authors attribute this difference to the much larger fraction of sub-0.1 micron pores in the latter case. The suggested explanation is the expected one but it is not clear at all that this is actually so on the basis of the corresponding Fig. 6 plots; if nothing else the sub-0.1 micron part of the distribtion in both cases appears to be extremely small (e.g. cmpared to the pure clay case) and at least the specific surface area of the reductively fired 60% sample should be interpreted in a convincing data-based manner.
(3) The authors show that as regards dye adsorption th Reductively fired 60% GFRP performs better than either the Oxidatively fired 60 % GFRP or the plain clay and this an interesting finding attributed to the combination of high porosity/high surface area and residual carbide. The question is what the results might be if one uses a simpler fired mixture, namely one of clay and [waste] polymer. Why do the authors preclude such a material from measurements? (please discuss this point /potentia; material competitor).
(4) The origin of porosity (and its variation as a function of composition and processing) should be discussed in some more detail
Author Response
Dear reviewer,
Thank you for inviting us to submit a revised draft of our manuscript (applsci-450467) entitled“Dye adsorbent material based on porous ceramics from glass fiber-reinforced plastic and clay” to Applied Sciences.
We would submit the revised manuscript.
We sincerely apologize for the delay in submitting the revised manuscript.
To answer the reviewers' questions and comments, we added the experimental data on oxidatively fired 20% GFRP/clay and 40% GFRP/clay ceramics. Furthermore, we measured the pore size distributions of granular ceramic samples by using the nitrogen gas adsorption method.
We think that we could investigate the MB dye adsorptivity of the oxidatively and reductively fired GFRP/clay ceramics in more detail.
Again, thank you for giving us the opportunity to strengthen our manuscript with your valuable comments and queries.
Sincerely yours,
Hiroyuki Kinoshita
University of Miyazaki, Japan
Author Response File: Author Response.pdf
Reviewer 3 Report
I have read with interest this research concerning the use of waste glass fiber-reinforced plastic to remove dye from industrial wastewater. I was impressed by the recycling point of view as well as by the positive outcomes concerning removing dye from wastewater. The paper sounds well. The state of art is clearly presented, the experimental is carefully drawn and the results discussed with competence. I believe this is a good paper in the area of recycling and environment.
Author Response
Dear reviewer,
Thank you for inviting us to submit a revised draft of our manuscript (applsci-450467) entitled“Dye adsorbent material based on porous ceramics from glass fiber-reinforced plastic and clay” to Applied Sciences.
We would submit the revised manuscript.
We sincerely apologize for the delay in submitting the revised manuscript.
To answer the reviewers' questions and comments, we added the experimental data on oxidatively fired 20% GFRP/clay and 40% GFRP/clay ceramics. Furthermore, we measured the pore size distributions of granular ceramic samples by using the nitrogen gas adsorption method.
We think that we could investigate the MB dye adsorptivity of the oxidatively and reductively fired GFRP/clay ceramics in more detail.
Again, thank you for giving us the opportunity to strengthen our manuscript with your valuable comments and queries.
Sincerely yours,
Hiroyuki Kinoshita
University of Miyazaki, Japan
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
- some improvements were done, but there are still three major issues
a) mechanical load testing: using a 50 kN load cell, the minimum precise detectable load is 500 N. Comparing sample size and results I have to assume, that the results are in particular for the 40 and 60% composite not right measure
b) grain size distribution, the authores sifted and used an optical approach. But from the 50 samples every diameter has to be recognized. There are other possibitlities. This needs more improvement
c) pore size distribution: the adsorption showed, that the results from mecury intrusion are wrong. Hg-intrusion has a magnitude lower values 0.001 which is 1 nm (!) and gas adsorption is only 0.01 (=10 nm) up to pore sizes of 100 µm . They haven't specified the adsorption method. This is mandantory to evaluate, if the maximum of 100µm is right.
Author Response
Dear reviewer,
Subject: Submission of revised paper “applsci-450467”
We wish to express our strong appreciation to you for careful reading our manuscript again. The following is a point-by-point response to the comments.
Comments
Some improvements were done, but there are still three major issues.
(1) Mechanical load testing: using a 50 kN load cell, the minimum precise detectable load is 500 N. Comparing sample size and results I have to assume, that the results are in particular for the 40 and 60% composite not right measure.
Answer
The following figure and table show photographs and specifications of the universal testing machine used in the experiment.
Load cell capacity of the machine was 50 kN. The precision of the test force was within ± 1% of displayed test force for 1/1 to 1/1000 of the load cell capacity. The minimum precise detectable load is not 500 N but 50 N.
We revised the following sentences.
Page 5, 216 line;
Figure 4 lists the compressive strengths of the GFRP/clay ceramics. Here, cylindrical specimens, with a diameter of 14 mm and length of approximately 30 mm, were used for the compressive tests. Cylindrical specimens were compressed using a universal testing machine (AG-X50kN, Shimadzu Corporation, Kyoto, Japan) with a crosshead speed of 0.5 mm min−1. Load cell capacity of the machine was 50 kN, and the precision of the test force was within ± 1% of displayed test force for 1/1 to 1/1000 of the load cell capacity, conforms to JIS B7721 Class 1 and ISO 7500-1 Class 1. Compressive strength was determined by dividing the measured maximum compressive load by the specimen cross-sectional area. The data points are the average compressive strengths calculated from measurements of the four specimens.
(2) Grain size distribution, the authors sifted and used an optical approach. But from the 50 samples every diameter has to be recognized. There are other possibilities. This needs more improvement.
Answer
As a method to measure the particle size distribution of the specimen, there is a laser diffraction scattering method. For the specimens sifted with ~0.5 mm mesh screens, we have already measured the particle size distributions with the laser diffraction type of particle size distribution measuring device (SALD-2100, Shimadzu Corporation, Kyoto, Japan). The following figure shows the particle size distributions of specimens, which were measured with the apparatus. (But we did not show the figure in our manuscript.)
However, the measurable particle size by the apparatus was within 1 mm. Thus, we measured the particle size distributions using an optical approach for the specimens sifted with 1.0 mm or more mesh screens.
(3) Pore size distribution: the adsorption showed, that the results from mercury intrusion are wrong. Hg-intrusion has a magnitude lower values 0.001 which is 1 nm (!) and gas adsorption is only 0.01 (=10 nm) up to pore sizes of 100 µm. They haven't specified the adsorption method. This is mandatory to evaluate, if the maximum of 100µm is right.
Answer
In the text on the measurement of the pore size distributions of specimens, I have made a great mistake. I have confused you.
Correctly, the figure on the left shows the pore size distribution measured by a gas adsorption method, and the figure on the right shows the distribution measured by a mercury intrusion method. Although the layout of the figures is correct, the positions of “a gas adsorption method” and “a mercury intrusion technique” in the text were incorrect.
I sincerely apologize.
We revised the following sentences, and wrote “Measurement by a gas adsorption method” and “Measurement by a mercury intrusion technique” into each graph in Figure 7.
Page 10, line 396;
Figure 7 shows the pore size distributions of the GFRP/clay ceramics. Here, in the two figures on each ceramic, the pore size distribution which is shown in the figure on the left, was measured by using a gas adsorption method, and that in the figure on the right was measured by using a mercury intrusion technique. For the oxidatively fired GFRP/clay ceramics, the nano-sized pores in the structure decreased as the GFRP mixing ratio was increased, and 60%GFRP/clay ceramic few had them. We presume that the clay and glass fibers or regions between glass fibers sintered, so that nano-sized pores disappeared. The specific surface areas of the ceramics also decreased as the GFRP mixing ratio was increased, as shown in Table 4.
(4) Other
We have had the manuscript rewritten by an experienced scientific editor, who has improved the grammar and stylistic expression of the paper.
Thank you very much.
Sincerely yours,
Hiroyuki Kinoshita
University of Miyazaki Japan
Author Response File: Author Response.pdf
Reviewer 2 Report
As regards my question No1 while the new data are substantially different from the old ones, still the CaO/SiO2 ratio is somewhat high for a glass; it might be correct within large error bars for certain glass fibers (e.g. E glass or ECR glass), while it is way too high for other glass fibers . Either the composition-determination method of the authors is not a very safe one (and this might be so as this is a method allowing for 0.82 ratio in the first version and a 0.49 ratio in the second version) and in addition the glass is say E glass or there is somewhere an additional source of calcium (e.g. a CaCO3 filler in the polymer?).
The fastest thing that can be done at this stage is an inclusion, in the manuscript, of the following comment
‘The type of incorporated glass fibers is not specified by the manufacturer but the pertinent composition determined by us is compatible, within broad error bars, with glass fibers of the E glass type family; on the other hand, for some other types of glass fibers the found CaO content is too high and might include a contribution from another source (e.g. a CaCO3 polymer filler)’.
Additional issues (mentioned in my first review)
The authors have tried hard to provide satisfactory answers (/pertinent information) to all other points of mine. I would have asked at this point for a second round of changes (pertinent to the same issues) but given the [essentially] 'yes or no' scheme of this Journal and the minor character of remaining points I choose the 'accept' option.
[In order to facilitate the process of review and publication I will not ask to see again the manuscript for the requested addition pertinent to the CaO/SiO2 ratio]
Author Response
Dear reviewer,
Subject: Submission of revised paper “applsci-450467”
We wish to express our strong appreciation to you for careful reading our manuscript again.
Comments
(1) As regards my question No1 while the new data are substantially different from the old ones, still the CaO/SiO2 ratio is somewhat high for a glass; it might be correct within large error bars for certain glass fibers (e.g. E glass or ECR glass), while it is way too high for other glass fibers. Either the composition-determination method of the authors is not a very safe one (and this might be so as this is a method allowing for 0.82 ratio in the first version and a 0.49 ratio in the second version) and in addition the glass is say E glass or there is somewhere an additional source of calcium (e.g. a CaCO3 filler in the polymer?).
The fastest thing that can be done at this stage is an inclusion, in the manuscript, of the following comment.
‘The type of incorporated glass fibers is not specified by the manufacturer but the pertinent composition determined by us is compatible, within broad error bars, with glass fibers of the E glass type family; on the other hand, for some other types of glass fibers the found CaO content is too high and might include a contribution from another source (e.g. a CaCO3 polymer filler)’.
Additional issues (mentioned in my first review).
The authors have tried hard to provide satisfactory answers (/pertinent information) to all other points of mine. I would have asked at this point for a second round of changes (pertinent to the same issues) but given the [essentially] 'yes or no' scheme of this Journal and the minor character of remaining points, I choose the 'accept' option.
[In order to facilitate the process of review and publication I will not ask to see again the manuscript for the requested addition pertinent to the CaO/SiO2 ratio.]
Answer
We added the following sentence.
Page 2, line 74;
Table 1 shows the inorganic chemical compositions of the GFRP and clay after firing at 1,073 K. The inorganic chemical compositions were measured with an energy dispersive X-ray analyzer (EDX-720, Shimadzu Corporation, Kyoto, Japan) by using a fundamental parameter method. The type of the glass fibers included in GFRP is compatible with E glass type family within broad error bars. But the glass fibers might include a contribution from another source (e.g. a CaCO3 polymer filler) because CaO content is too high.
(2) Other
We have had the manuscript rewritten by an experienced scientific editor, who has improved the grammar and stylistic expression of the paper.
Thank you very much.
Sincerely yours,
Hiroyuki Kinoshita
University of Miyazaki Japan
Author Response File: Author Response.pdf
