Preparation of Magnetic Dummy Molecularly Imprinted Meso-Porous Silica Nanoparticles Using a Semi-Covalent Imprinting Approach for the Rapid and Selective Removal of Bisphenols from Environmental Water Samples
Round 1
Reviewer 1 Report
In this article the authors have demonstrated the use of magnetic dummy molecularly imprinted mesoporous silica nanoparticles (m-DMI-MSNPs) based on the Fe3O4@SiO2@mSiO2 structure, for the adsorption of Bisphenol (BP) pollutant from water samples. These materials have been previously studied (doi.org/10.1021/nn1035697) as a means for separating bisphenol A (10.1039/C1JM14139B; doi.org/10.1039/C8NJ06027D) in prior studies. In this study the authors have separated BP from tap water, mineral water and sewage water samples using the aforementioned nanoparticle constructs. The paper is well written, and the motivation is clear. The data presented in within the scope of the Journal. The manuscript can be improved upon based on comments below:
1. The first sentence and the second sentence in the abstract needs to be linked properly. The authors need to justify the requirement for this study based on the premise of BP pollutants.
2. Please provide full terminologies for the acronyms in the abstract.
3. In Figure 1 schematic, please add details for “remove template” step. Please add reaction details such as temperature etc. for each step. If the authors have studied the formation of particles at each step, each step can also be accompanied with a TEM image showing the formation at various stages. Such as schematic will be very informative to readers. Increase font size for legibility.
4. In supplementary document, please provide appropriate references (DOI) for methods or experimentation based on published literature.
5. In Experimental section please provide methods for statistical analysis and provide details for t-tests or ANOVA conducted.
6. Please provide error bars and statistical analysis (p-values) for the datapoints in Figure 2A and 2B. Please provide “n” replicate number-count for the data collected and analyzed per group.
7. Would recommend the authors to add a library of TEM images for each particle at various stages in addition to images shown in Manuscript, to the supplementary file. The images should have low and high magnifications (2/1 um, 500 nm and 100 nm scale) in order to study particle uniformity, colloidal properties such as clustering etc. Please provide the kV values in methods and a size distribution histogram for the final particulate.
8. The authors are recommended to add EDX element-peaks for particle core-shell structure using TEM.
9. Please correct Figure numbers in section 3.1.2 and check the rest of the manuscript. The error shown is Figure 5 instead of 3. Please label the core and shell with respective distances (nm) within the TEM image using yellow highlights. Please provide spacing between all four images.
10. Have the authors studied the hydrodynamic size in solvent by DLS and surface charge of nanoparticles. DLS data and zeta values should be added to the characterization section.
11. Would recommend the authors to add a stability study (size/turbidity measurements varying with time) for the nanoparticles in colloidal form within suitable testing solvents and pH ranges. Such a result will further bolster the applicability of these particles for real world use.
12. In the FT-IR characterization section please provide references for attribution for O-H, C=O and C-O peaks.
13. Would recommend the authors to state the power of the external magnetic field tested for particle separation in results section.
14. The authors should add TEM images of particle after adsorption and regeneration to supplementary if possible.
15. Please provide statistical analysis (p-values) for the datapoints in Figure 6. Please provide “n” replicate number-count for the data collected and analyzed per group.
16. Please provide error values for removal efficiency in Table 1.
17. Please provide more details on the collection characteristics of the water samples.
18. Can the authors comment whether the pH or salt concentration of solvent affect the adsorption kinetics?
19. Does particle size affect adsorption kinetics?
Author Response
Response to Reviewer 1 Comments
We are very grateful to the reviewer for reviewing the paper so carefully. Each suggested revision and comment, brought forward by the reviewer was considered. We have carefully considered the suggestion of the reviewer and made some changes. Below the comments of the reviewers is response point by point.
- The first sentence and the second sentence in the abstract needs to be linked properly. The authors need to justify the requirement for this study based on the premise of BP pollutants.
Response 1: Thanks for rtheeviewer‘s comment. We have revised the manuscript according to the reviewers' comments: Bisphenol compounds (BPs) are a severe threat to humans and creatures, hence it is critical to develop a quick and simple approach for removing trace BPs from water. (line 8-9)
- Please provide full terminologies for the acronyms in the abstract.
Response 2: Thanks for the reviewer‘s comment. We have provided the full terminologies for the acronyms in the abstract as reviewer‘s comment.
- In Figure 1 schematic, please add details for “remove template” step. Please add reaction details such as temperature etc. for each step. If the authors have studied the formation of particles at each step, each step can also be accompanied with a TEM image showing the formation at various stages. Such as schematic will be very informative to readers. Increase font size for legibility.
Response 3: Thanks for the reviewer‘s comment. We have revised the schematic as reviewers' comments
- In supplementary document, please provide appropriate references (DOI) for methods or experimentation based on published literature.
Response 4: Thanks for the reviewer‘s comment. We have added the DOI in the supplementary document.
- In Experimental section please provide methods for statistical analysis and provide details for t-tests or ANOVA conducted.
Response 5: Thanks the for reviewer‘s comment. The data in the figures in this paper are the results of multiple parallel determinations, and we refer to the data expressions in the relevant literature in this field (10.1016/j.cej.2018.09.080, 10.1021/acsami.9b06953,10.1016/j.cej.2018.09.080), and the data in the figures are expressed as mean value ± standard deviation. Such a data treatment represents the precision of the method without statistical significance, and therefore cannot be subjected to ANOVA or t-test.
- Please provide error bars and statistical analysis (p-values) for the datapoints in Figure 2A and 2B. Please provide “n” replicate number-count for the data collected and analyzed per group.
Response 6: Thanks the for reviewer‘s comment. We have revised the manuscript according to the reviewers' comments. The bars represent the mean value ± standard deviation (n = 3).
- Would recommend the authors to add a library of TEM images for each particle at various stages in addition to images shown in Manuscript, to the supplementary file. The images should have low and high magnifications (2/1 um, 500 nm and 100 nm scale) in order to study particle uniformity, colloidal properties such as clustering etc. Please provide the kV values in methods and a size distribution histogram for the final particulate.
Response 7: Thanks the for reviewer‘s comment. We have added TEM images at different magnifications in the manuscript, supplemented the operating voltage of TEM, and provided histograms of its particle size distribution in the supplemental file.
- The authors are recommended to add EDX element-peaks for particle core-shell structure using TEM.
Response 8: Thanks the for reviewer‘s comment. We have revised the manuscript according to the reviewers' comments and add EXD element-peaks in supplementary material.
- Please correct Figure numbers in section 3.1.2 and check the rest of the manuscript. The error shown is Figure 5 instead of 3. Please label the core and shell with respective distances (nm) within the TEM image using yellow highlights. Please provide spacing between all four images.
Response 9: Thanks the for reviewer‘s comment. We are very sorry for our careless mistake and it was rectified as Figure 3. And we have revised the TEM image according to the reviewers' comments.
- Have the authors studied the hydrodynamic size in solvent by DLS and surface charge of nanoparticles. DLS data and zeta values should be added to the characterization section.
Response 10: Thanks the for reviewer‘s comment. We all agree that hydrated particle size and surface charge are critical features of nanoparticles. However, the m-DMI-MSNPs synthesized in this research have high density, facile sedimentation, strong magnetic characteristics, and easy agglomeration, among other traits. We are now unable to undertake DLS investigations due to existing experimental conditions and time constraints. When the experimental conditions are mature, we will further carry out such studies in future experiments.
- Would recommend the authors to add a stability study (size/turbidity measurements varying with time) for the nanoparticles in colloidal form within suitable testing solvents and pH ranges. Such a result will further bolster the applicability of these particles for real world use.
Response 11: Thanks the for reviewer‘s comment. We strongly agree that the stability of colloids is important for practical applications, but limited by time and experimental equipments we were unable to carry out a study of the change in particle size of m-DMI-MSNPs with time. However, we supplemented the study of the effect of pH on the adsorption of m-DMI-MSNPs to illustrate its potential application to real samples from another perspective and added the results to the supplement. According to visual observation, the particle size of m-DMI-MSNPs in aqueous solutions with different pH did not change significantly for at least 24 h.
- In the FT-IR characterization section please provide references for attribution for O-H, C=O and C-O peaks.
Response 12: Thanks the for reviewer‘s comment. We have added references in manuscript.
- Would recommend the authors to state the power of the external magnetic field tested for particle separation in results section.
Response 13: Thanks the for reviewer‘s comment. The external magnetic field we used during the experiments was provided by NdFeB, which we have further described in the corresponding position in the manuscript.
- The authors should add TEM images of particle after adsorption and regeneration to supplementary if possible.
Response 14: Thanks the for reviewer‘s comment. We have added the TEM images of particle after adsorption and regeneration to supplementary.
- Please provide statistical analysis (p-values) for the datapoints in Figure 6. Please provide “n” replicate number-count for the data collected and analyzed per group.
Response 15: Thanks the for reviewer‘s comment. We have revised the manuscript according to the reviewers' comments. The bars represent the mean value ± standard deviation (n = 3).
- Please provide error values for removal efficiency in Table 1.
Response 16: Thanks the for reviewer‘s comment. We have added the error values for removal efficiency in Table 1 as reviewer‘s comment.
- Please provide more details on the collection characteristics of the water samples.
Response 17: Thanks the for reviewer‘s comment. We have added the details on the collection characteristics of the water samples.
- Can the authors comment whether the pH or salt concentration of solvent affect the adsorption kinetics?
Response 18: Thanks the for reviewer‘s comment. As suggested by the reviewer, we investigated at the effect of pH and salt concentration on adsorption. The investigations revealed that the adsorption capacity varied with pH (the results are provided in Figure S5), but the impact on adsorption kinetics was extremely minimal. However, both adsorption kinetics and capacity were essentially unaffected by salt concentration.
- Does particle size affect adsorption kinetics?
Response 19: Thanks the for reviewer‘s comment. The number of surface active sites is the key influencing factor because, theoretically, the particle size has an effect on the specific surface area of the particles. The m-DMI-MSNPs generated in this experiment primarily depend on the combination of surface imprinting sites and BPs for adsorption. When the particle size was within a specified range, the mesoporous silica coating efficiently enhanced the specific surface area of the adsorbent, meaning there would be no impact on the adsorption kinetics.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
BPs represent a serious threat to the human reproductive system, and many stuides foucesed on the removal of these pollutants. In this study, Magnetic dummy molecularly imprinted mesoporous silica nanoparti- 70 cles (m-DMI-MSNPs) based on the Fe3O4@SiO2@mSiO2 structure were successfully syn- 71 thesized employing PP-ICPTES as a dummy template, and their binding capabilities and adsorption performance on BPs were investigated. The paper is well written, and the conclusions are of great scientific value. There are only a few minor problems in the text，which might require a reconsideration.
1. Line 32, BPA，this English abbreviation appears for the first time and is not given in full;
2. Line 416, as shown in Table 1, m-DMI-MSPNs have good selective adsorption ability on BPF, BPE, and BPA from tap water, mineral water, and sewage turn, respectively. How about the removal rate, stability, and the removal potential？
3. Line 421, Table 3 was not found.
Author Response
We are very grateful to the reviewer for reviewing the paper so carefully. Each suggested revision and comment, brought forward by the reviewer was considered. We have carefully considered the suggestion of the reviewer and made some changes. Below the comments of the reviewers is response point by point.
- Line 32, BPA，this English abbreviation appears for the first time and is not given in full;
Response 1: Thanks for reviewer‘s comment. We have added the English abbreviation to the manuscript accordingly as requested by the reviewers.
- Line 416, as shown in Table 1, m-DMI-MSPNs have good selective adsorption ability on BPF, BPE, and BPA from tap water, mineral water, and sewage turn, respectively. How about the removal rate, stability, and the removal potential？
Response 2: Thanks for reviewer‘s comment. The m-DMI-MSPNs prepared in this study have the same rapid bonding rate and good stability as BPE and BPF. Since BPA is the most widely used BPs, we chose the BPA results as a representative for the discussion in this work.
- Line 421, Table 3 was not found.
Response 3: Thanks for reviewer‘s comment, We are very sorry for our careless mistake and it was rectified at Line 432.
Author Response File: Author Response.pdf
