A hollow mesoporous carbon from metal-organic framework for robust adsorbability of ibuprofen drug in water

Herein, we described a tunable method for synthesis of novel hollow mesoporous carbon (MPC) via direct pyrolysis (800oC) of MIL-53 (Fe) as a self-sacrificed template. The structural characterization revealed a hollow, amorphous, defective and mesoporous MPC along with high surface area (approx. 200 m2 g−1). For the experiments of ibuprofen adsorption onto MPC, effects of contact time, MPC dosage, ionic strength, concentration and temperature were systematically investigated. The optimal conditions consisted of pH = 3, concentration 10 mg l−1 and dose of 0.1 g l−1 for the highest ibuprofen removal efficiency up to 88.3% after 4 h. Moreover, adsorption behaviour, whereby chemisorption and monolayer controlled the uptake of ibuprofen over MPC, were assumed. Adsorption mechanisms including H-bonding, π–π interaction, metal–oxygen, electrostatic attraction were rigorously proposed. In comparison to several studies, the MPC nanocomposite in this work obtained the outstanding maximum adsorption capacity (206.5 mg g−1) and good reusability (5 cycles); thus, it can be used as a feasible alternative for decontamination of ibuprofen anti-inflammatory drug from water.


Recommendation?
Major revision is needed (please make suggestions in comments)

Comments to the Author(s)
It this work, a mesoporous carbon from MIL-53(Fe) is synthetized for the elimination of IBU from water.
Title: -is it aDsorbability or aBsorbability? May be it need to me modified as the adsorbent is a porous material.
Introduction: -"Pharmaceutically bioactive compounds (PBCs) are widely consumed over the world because of their crucial role playing in protecting human's health from the attack of bacteria species". Are the PBCs only used to protect from the attack of bacteria species? what about pain? inflammation? or other diseases? -The authors mentioned that "With their excellent tailorability and versatile functionalities, the MOFs are applicable as promising catalysts, adsorbents, drug delivery systems 20-24." However, in this references there are no articles related with the drug delivery. They need to complete this information.
-What is the concentration of IBU in wastewater? is it similar to the one used in this study? What is the pH of this wastewater? Why is important to eliminate IBU from water better than other pharmaceutic contaminants? Experimental -The authors measured the IBU concentration by UV-vis but at which wavelength?? -Is there any work in bibliography were the elimination of IBU in waterwaste is studied? What it the % of eliminated IBU? For example: "Ultrasonic treatment of water contaminated with ibuprofen". Water Research 42 (16) Title: A hollow mesoporous carbon from metal-organic framework for robust absorbability of ibuprofen drug in water Manuscript ID: RSOS-190058 Thank you for your submission to Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry.
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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. ********************************************** RSC Associate Editor: Comments to the Author: (There are no comments.) RSC Subject Editor: Comments to the Author: (There are no comments.) **********************************************  RSOS-190058 To author General comments: The manuscript entitled "A hollow mesoporous carbon from metal-organic framework for robust absorbability of ibuprofen drug in water" has been reviewed. The authors presented an interesting work about the remediation of ibuprofen by adsorption from a metal-organic framework MIL-53 (Fe). The resulting material was fully characterised using FTIR, XRD, XPS, BET, SEM and TEM. The adsorption experiments were also applied to kinetic and isotherm models to determine the mechanism of adsorption. Recyclability of the material was tested and gave good results. The paper also makes a good contribution to this field of study and presents a suitable material that can be considered for the removal of ibuprofen. However the paper has variety of errors which must be corrected before further consideration for acceptance. Here below are some examples of errors which demand reconsideration: Specific comments: 1. Some improvements can be made with regard to including instrumentation used, conditions of analysis and any sample preparations carried out -these should be included in the experimental. 2. The novelity of work should be clarified. 3. The PXRD and FT-IR spectra ( Fig. 1. a, b) should be indexed, and Zeta potential of samples ( Fig. 1. d) at different pHs should be presented. 4. In the section "3.3. Recyclability study", the author said "ibuprofen-MPC complex", the description seems vague. I suggest this text should be better replaced with "ibuprofen-loaded MPC". 5. In the section "3.2.6. Effect of temperature", the thermodynamic study was conducted and Gibbs free energies (∆G) have been clarified with negative values. Why don't you conclude that the adsorption is a spontaneous process? 6. Several statements need more references, for example "Porous carbon coatings may also increase the surface area and improve functionalized surface chemistry, facilitating the contact between adsorbents and adsorbates" in the background; "733 cm¬-1 and 550 cm-1 (Fe¬-O) on the MPC" in FT-IR analysis section, etc. 7. Why don't the authors study the effect of ibuprofen concentration at higher levels instead of 5-20 mg/L? Please provide more analysis about the effct of contact time in the section "3.2.4. Adsorption kinetics" 8. Many English grammar and spelling errors need to be advoided to ensure that the paper flows and reads well for readers. Some minor comments: The authors should also pay attention to the English of the paper to ensure that it flows and reads well. For example: Page 3, Line 15, 'presented' should be 'presenting' Page 4, Line 18. I think your presented application is insufficient and I am not very convinced about study objectives. I suggest you to exemplify additional interesting applications of nano Fe-MOF to raise the need for your paper. If possible, give some shortcomings of reviewed papers and state which will be overcome by your study. Page 5, Line 44. should be 'against' Page 6, Line 28. 'which' should be 'in which' Page 6, Line 39. Please rewrite this sentence Page 7, Line 12. Please remove 'was' Page 8, Line 44. I suggested to revise the phrase after '…proportional to…' Page 9 Line 24. I suggest to rewrite as '…due to competition between cations and active site seizure of inorganic cations'. Page 9, Line 29. Should be 'reduces' Page 10, Line 28. Should be 'are protected'. Also, please rewrite the phrase after the comma Page 10, Line 43. Should be 'playing' Page 10, Line 46, Should be 'in which' instead of 'which' Page 10, Line 57, Should be 'was obtained' Page 11, Line 38. Please write the whole sentence starting from 'moreover,……'. I suggest splitting it into two separate sentences. Page 12, Line 21. Should be 'briefly' Reviewer: 2 Comments to the Author(s) It this work, a mesoporous carbon from MIL-53(Fe) is synthetized for the elimination of IBU from water.
Title: -is it aDsorbability or aBsorbability? May be it need to me modified as the adsorbent is a porous material.
Introduction: -"Pharmaceutically bioactive compounds (PBCs) are widely consumed over the world because of their crucial role playing in protecting human's health from the attack of bacteria species". Are the PBCs only used to protect from the attack of bacteria species? what about pain? inflammation? or other diseases? -The authors mentioned that "With their excellent tailorability and versatile functionalities, the MOFs are applicable as promising catalysts, adsorbents, drug delivery systems 20-24." However, in this references there are no articles related with the drug delivery. They need to complete this information.
-What is the concentration of IBU in wastewater? is it similar to the one used in this study? What is the pH of this wastewater? Why is important to eliminate IBU from water better than other pharmaceutic contaminants? Experimental -The authors measured the IBU concentration by UV-vis but at which wavelength?? -Is there any work in bibliography were the elimination of IBU in waterwaste is studied? What it the % of eliminated IBU?

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)
The authors have successfully respond to all issues indicated in the review report. It is a pleasure to accept your manuscript in its current form for publication in Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry.
The comments of the reviewer(s) who reviewed your manuscript are included at the end of this email. We would like to express our gratitude for the Editor and Reviewer's efforts to improve the quality of our manuscript. We believe that our manuscript as a qualified paper in Royal Society Open Science. We have tried our best to respond to all issues indicated in the review report fully. In the revised version, we have highlighted the changes to our manuscript using various colors. Here, we would like to address the reviewer's concerns as follows:

Reviewer #1:
The manuscript entitled "A hollow mesoporous carbon from metal-organic framework for robust absorbability of ibuprofen drug in water" has been reviewed. The authors presented an interesting work about the remediation of ibuprofen by adsorption from a metal-organic framework MIL-53 (Fe).
The resulting material was fully characterised using FTIR, XRD, XPS, BET, SEM and TEM. The adsorption experiments were also applied to kinetic and isotherm models to determine the mechanism of adsorption. Recyclability of the material was tested and gave good results. The paper also makes a good contribution to this field of study and presents a suitable material that can be Appendix A

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considered for the removal of ibuprofen. However, the paper has variety of errors which must be corrected before further consideration for acceptance. Here below are some examples of errors which demand reconsideration: Specific comments: 1. Some improvements can be made with regard to including instrumentation used, conditions of analysis and any sample preparations carried out -these should be included in the experimental.
We are very thankful for the reviewer's evaluation and suggestion to improve the quality of the manuscript. As mentioned, we clarified this instrumentation, conditions of analysis and sample preparations included in the supporting information (SI) document, as follows: "All chemicals including ibuprofen, 1,4-benzendicarboxylic acid, iron chloride and potassium chloride were commercially purchased from Merck. The D8 Advance Bruker powder diffractometer was used to record the X-ray powder diffraction (XRD) profiles using Cu-Kα beams as excitation sources. The S4800 instrument (Japan) was implemented to capture the scanning electron microscope (SEM) images with the magnification of 7000 using an accelerating voltage source (15 kV). The JEOL JEM 1400 instrument was used to study the transmission electron microscopy (TEM). The characteristics of surface chemistry was investigated by the FT-IR spectra on the Nicolet 6700 spectrophotometer.
The N2 adsorption/desorption isotherm and pore size distribution data were recorded on the Micromeritics 2020 volumetric adsorption analyzer system. The UV-Vis spectrophotometer was used to determine the ibuprofen concentration at 222 nm. The photoelectron spectrometer Kratos Axis-Ultra was used to recorded the signals of the X-ray photoelectron spectra (XPS) using a monochromatic X-ray source of Al Kα and Casa XPS software was utilized to analyze the XPS spectra. All XPS spectra were calibrated using the C 1s peak (284.8 eV) with a subtraction by Shirley background. Gupta and Sen (GS) multiplets was used to fit the high-spin Fe 3+ states".
To help the readers follow easily, we inserted these related items in "Section 2. Experimental" (Page 4), and "section 2.1. Chemicals and instruments" which you can track them with bright green color as follows: "Chemicals and instruments for the synthesis and characterization of MIL-53 (Fe) and MPC materials were described in supplementary information (SI) material. In addition, adsorption kinetic, isotherm equations, and mathematical formula were addressed."

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2. The novelty of work should be clarified.
The authors highly appreciate the reviewer's comment to emerge the novelty of paper. Herein, we clarify the novelty of paper as follows:  For the first time, the magnetically and hierarchically mesoporous carbon (MPC) from metalorganic framework MIL-53 (Fe) was adopted for the treatment of ibuprofen drug.
 Compared with several studies, outstanding adsorption capacity (206.5 mg/g), high stability, and good reusability (up to 5 cycles) were reached using MIL-53 (Fe)-based mesoporous carbon.
With points mentioned above, therefore, we are pleased to clarify the novelty in the manuscript as the following texts: In the abstract, page 2 (lines 11-12), we added: "effects of contact time, MPC dosage, ionic strength, concentration and temperature were systematically investigated".
In the abstract, page 2 (lines 21-24), we modified: "In comparison to several studies, the MPC nanocomposite in this work obtained the outstanding maximum adsorption capacity (206.5 mg/g) and good reusability (5 cycles), thus it can be utilized as a feasible alternative for decontamination of ibuprofen anti-inflammatory drug from water." In the introduction, page 4 (line 28-30), we added: "To our best knowledge, this is the first time that the magnetically and hierarchically mesoporous carbon from metal-organic framework MIL-

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3. The PXRD and FT-IR spectra ( Fig. 1. a, b) should be indexed, and Zeta potential of samples ( Fig. 1. d) at different pHs should be presented.
We highly appreciate the reviewer's comment to make the figure more obvious. According to the suggestion from reviewer, PXRD and FT-IR spectra ( Fig. 1. a, b) have been indexed, and Zeta potential of samples ( Fig. 1. d) at different pHs has been be presented.
In pages 18, we inserted a new version with minor detailed modification as follows: We highly appreciate the reviewer's comment to make the text more obvious. According to the suggestion from reviewer, the authors have adjusted the text "ibuprofen-MPC complex" into "ibuprofen-loaded MPC" under a bright green color in page 13.

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5. In the section "3.2.6. Effect of temperature", the thermodynamic study was conducted and Gibbs free energies (∆G) have been clarified with negative values. Why don't you conclude that the adsorption is a spontaneous process?
We highly appreciate the reviewer's comment. In section 3.2.6. Effect of temperature, we found that the adsorption of ibuprofen onto MPC was an exothermic (negative ∆H) and spontaneous (negative Gibbs free energies ∆G) process. According to the suggestion from reviewer, the authors have had a conclusion about this process.
In page 12, section 3.2.6, we modified a new text under bright green color for more analysis, as follows: "The negative values of Gibbs free energy from -50.609 to -53.443 kJ/mol (Table 5) indicated that the adsorption of ibuprofen over MPC was a spontaneous process".
On the other hand, we adjusted the decimal number of energies in Table 5.
In page 12, line 35, we also adjusted the decimal number of energies "-50.6 to -53.4". We highly appreciate the reviewer's comment to improve the quality of this manuscript. According to the reviewer's suggestion, we modified more literatures to support the statements "Porous carbon coatings may also increase the surface area and improve functionalized surface chemistry, facilitating the contact between adsorbents and adsorbates" in the background; and "733 cm -1 and This is the list of references, which was mentioned in the manuscript revision and appeared under bright green color.
We highly appreciate the reviewer's comment to improve the quality of this manuscript. In this study, we conducted the experiments by selecting the appropriate range of ibuprofen concentration from 5-20 mg/L. Performing the adsorption at higher ibuprofen concentration is not referred because the solubility of ibuprofen in water at 25 o C is found at approximately 21 mg/L [1]. Sung et at. also R7 reported that ibuprofen concentration in their work limited to 21 mg/L due to low solubility of ibuprofen [2]. To obtain the higher concentration, it may be under the use of surfactants such as polyvinyl pyrrolidone (PVP), sodium lauryl sulphate (SLS) or other methods according to recent studies [3][4][5]. However, we solely carried out the experiments in water without surfactants, therefore, it is reported to be 5 -20 mg/L for ibuprofen concentration.
For more analysis about the effect of contact time in the section "3.2.4. Adsorption kinetics", the authors modified the new text bright green color.
In page 11, a paragraph has been inserted as follows: 8. Many English grammar and spelling errors need to be avoided to ensure that the paper flows and reads well for readers.

Some minor comments:
The authors should also pay attention to the English of the paper to ensure that it flows and reads well. For example: The authors fully appreciate the reviewer's detection to improve the quality of paper. For the right definition, it should be "adsorbability" instead of "absorbability". According to the reviewer' suggestion, we are pleased to provide the misleading definition, and replacing with new one.
Therefore, we adjusted the title as follows: "A hollow mesoporous carbon from metal-organic framework for robust adsorbability of ibuprofen drug in water".
Again, we are very thankful for your detection. The authors fully appreciate the reviewer's questions to improve the quality of paper. For these concerns, it is true that PBCs include many roles and effects, not only used to protect from the attack of bacteria species. Therefore, we added more information about the role of PBCs according to the reviewer.
In page 3 (lines 4-7), we rewrote the first sentence of the background section under the turquoise color as follows: "Pharmaceutically bioactive compounds (PBCs) are widely consumed over the world because of their crucial role playing in protecting human's health from the attack of bacteria R11 species, as well as exhibiting a wide range of biological activities (e.g. antifungal, anticancer, antitumor, anti-inflammatory, antioxidant, etc.)" -The authors mentioned that "With their excellent tailorability and versatile functionalities, the MOFs are applicable as promising catalysts, adsorbents, drug delivery systems 20-24." However, in this references there are no articles related with the drug delivery. They need to complete this information.
The authors fully appreciate the reviewer's detection to improve the quality of paper. For these concerns, we modified a recent review discussing on the application of MOFs in the drug delivery field.
In page 3 (lines 40-42), there are six articles provided to mention about these concerns: The authors fully appreciate the reviewer's detection to improve the quality of paper. For these concerns, we are pleased to respond according to our best knowledge as follows. For concentration of IBU in wastewater, Miege et al. reported a database to quantitatively assess the occurrence and removal efficiency of pharmaceuticals and personal care products (PPCPs) in wastewater treatment processes (WWTPs) from many scientific publications, which IBP concentrations in the effluents leaving several sewage-treatment plants were found to be between 0.17 and 59.2 ug/L [9]. Moreover,

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ibuprofen concentration reported in effluents in France and Sweden were 7.11, and 85 ug/L, respectively [10]. The IBU concentration varies and depends on the geographically polluted regions, and contaminated environment (stream, river, etc.). For example, the water column of Lake Greifensee (Switzerland) was mean 1.3 μg/L for ibuprofen [11], while this number in in the Höje River, Sweden was from 0.12 to 2.2 μg/L [12].
It is extensively used as non-prescription medicine, with an annual consumption of several hundreds of tons in developed countries. For example, in France, UK, and Spain, it was reported that the volume of pharmaceutically active compounds sold in different countries was great, for ibuprofen, at more than 240, 330, and 276 tons only in 2004 [10]. Moreover, excretion rate of ibuprofen is high (up to 8%) with an incomplete metabolite, likely leading to the penetration of ibuprofen into soil, aquatic media, even human's food source, therefore, it is important to eliminate IBU from water better than other pharmaceutic contaminants [10].
In this study, we conducted the experiments in the range of ibuprofen concentration from 5-20 mg/L, which is so far higher than the fate and occurrence of ibuprofen in geographically polluted regions, and contaminated environment (stream, river, etc.). This concentration range is reported in many works. For example, Sung et at. also reported that the adsorption of ibuprofen at the concentration 5-20 mg/L. However, it is unnecessary to employ at higher such concentration due to low solubility of ibuprofen (21 mg/L) [2]. To obtain the higher concentration, it may be under the use of surfactants such as polyvinyl pyrrolidone (PVP), sodium lauryl sulphate (SLS) or other methods according to recent studies [3][4][5]. However, we solely carried out the experiments in water without surfactants, therefore, it is reported to be 5-20 mg/L for ibuprofen concentration.
The pH values of ibuprofen-contaminated wastewater can vary in wide range [13]. In this study, however, we investigated the effect of pH on the ibuprofen adsorption and to obtain the highest removal efficiency. Therefore, based on the investigation of adsorption of ibuprofen by MPC, the experiments need to be performed at the optimal pH condition (at pH 3) to reach the maximum adsorption capacity (206.5 mg/g).
With analysis mentioned above, we inserted two passages along with the respective references as follows: In the introduction, pages 3 (starting from line 25) with a yellow highlight:

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"For concentration of IBU in wastewater, Miege et al. reported a database to quantitatively assess the occurrence and removal efficiency of pharmaceuticals and personal care products (PPCPs) in wastewater treatment processes (WWTPs) from many scientific publications, which IBP concentrations in the effluents leaving several sewage-treatment plants were found to be between 0.17 and 59.2 ug/L [9]. Moreover, ibuprofen concentration reported in effluents in France and Sweden were 7.11, and 85 ug/L, respectively [10]. The IBU concentration varies and depends on the geographically polluted regions, and contaminated environment (stream, river, etc.). For example, the water column of Lake Greifensee (Switzerland) was mean 1.3 μg/L for ibuprofen [11], while this number in in the Höje River, Sweden was from 0.12 to 2.2 μg/L [12].
It is extensively used as non-prescription medicine, with an annual consumption of several hundreds of tons in developed countries. For example, in France, UK, and Spain, it was reported that the volume of pharmaceutically active compounds sold in different countries was great, for ibuprofen, at more than 240, 330, and 276 tons only in 2004 [10]. Moreover, excretion rate of ibuprofen is high (up to 8%) with an incomplete metabolite, likely leading to the penetration of ibuprofen into soil, aquatic media, even human's food source, therefore, it is important to eliminate IBU from water better than other pharmaceutic contaminants [10]." Experimental -The authors measured the IBU concentration by UV-vis but at which wavelength??
The authors fully appreciate the reviewer's detection to improve the quality of paper. We added the wavelength at 222 nm for ibuprofen determination by UV-Vis spectroscopy.
In page 5, line 5, a modification text was inserted under the turquoise color. For the previous studies on the elimination of IBU in wastewater, we agree with the reviewer that there is a lack of review about previous studies on the elimination of IBU in wastewater. We therefore attempted to refer to two references that the reviewer provided. We also hope that these documents help the readers found a useful source. The authors are very thankful for your comments, and we think that these concerns are very intriguing. Based on our best knowledge, we are pleased to respond as follows: Chemisorption is characterized by the interaction of chemical groups between adsorbent and adsorbate. It is understandable that the more chemical functional groups (acidic, laconic, phenolic, basic groups) exist on the surface of MPC, the better the adsorption of ibuprofen is facilitated to occur. Therefore, we determined the quality and quantity of functional groups on the surface of MIL-53 (Fe) and MPC via Boehm titration. According to Table 1, it is revealed that the number of functional groups including total oxygenated (2.2 mmol/g) and basic (0.85 mmol/g) groups for MPC.
Above functional groups may contribute to enhancing the adsorbability of MPC towards ibuprofen.
These results are again supported by the kinetic studies, which the pseudo-second-order model was found to be the most suitable, demonstrated by the extremely high coefficient of determination (R 2 = 0.9994) of the linear plot (Table 2). This model assumes that adsorption of ibuprofen over MPC can be chemisorption via electrostatic attraction between adsorbent and adsorbate [14]. Moreover, there are many works proved the adsorption of ibuprofen and other drugs onto MOFs-derived MPC

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was the chemisorption process with the crucial role of functional groups [2,[15][16][17][18]. Therefore, we argue that the chemisorption may be a dominance of ibuprofen adsorption in this study.
With analysis menioned above, confirming chemisorption was incorporated into the manuscript as follows: In page 11, starting from line 25, we inserted new passage with a yellow highlight: "Note that chemisorption is characterized by the interaction of chemical groups between adsorbent and adsorbate. It is understandable that the more chemical functional groups (acidic, laconic, phenolic, basic groups) exist on the surface of MPC, the better the adsorption of ibuprofen is facilitated to occur. In fact, we determined the quality and quantity of functional groups on the surface of MIL-53 (Fe) and MPC via Boehm titration. According to Table 1, it is revealed that the number of functional groups including total oxygenated (2.2 mmol/g) and basic (0.85 mmol/g) groups for MPC. Above functional groups may contribute to enhancing the adsorbability of MPC towards ibuprofen. Tung et al. also demonstrated that surface functional groups are a key factor for adsorption of ibuprofen [19]. Moreover, there are many works proved the adsorption of ibuprofen and other drugs onto MOFs-derived MPC was the chemisorption process with the crucial role of functional groups [2,[15][16][17][18]. Consequently, we argue that the chemisorption may be a dominance of ibuprofen adsorption in this study." Moreover, to confirm the high stability of MPC materials, the XRD spectra of the pristine and ibuprofen-loaded MPC were used. As can be observed from Fig. 1, the main peak at 44.5 o of ibuprofen-loaded MPC still maintained, and existed at the similar position as pristine MPC, proving that the structure of MPC is stable beneath ibuprofen adsorption conditions in aqueous media. The authors highly appreciate the reviewer's comment to improve the quality of the manuscript.
According to the reviewer's suggestion, we inserted new figures (Pages 22, 23) with error bars.
In pages 22, 23, we replaced the old with new figures, as follows: