Modified Nanocellulose-Based Adsorbent from Sago Waste for Diclofenac Removal
Round 1
Reviewer 1 Report
In this manuscript, the authors present good work on “Modification of Nanocellulose from Sago Waste for Diclofenac Removal” . The manuscript is well written. I also recommended the manuscript for publication in Sustainability.
Comments:
It would be better if author could include the ChemDraw structures (schematic diagram) of synthesis of materials and removal of Diclofenac (DCF) from waste water in the materials and methods section.
What is R-H in equation 7?
The plots in figure 2 should be arranged in ascending or descending order
What is MNP? in figure 4, should explain
Figure 5 needs to be explained in detail: Explain all four images and label them properly (a? and b?)
Is there any correlation or difference between the NC/Fe3O4 130°C plots shown in figures 2 and 3.
What is the reason/limitation of removal only 82.4% of Diclofenac (DCF)? Has the optimization of reaction conditions been done?
The future aspect of the study should include
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Reviewer 2 Report
The authors contribute a Fe3O4/TiO2 modified nanocellulose adsorbent through hydrothermal process and its application as a photocatalytic adsorbent for diclofenac removing in industrial wastewater. Techniques like XRD, FTIR, FESEM and BET were used for material characterization, it likely shows the modification of TiO2/Fe3O4 particles on nanocellulose substrate. Modified with TiO2/Fe3O4 on the surfaces, those materials give out better performance forward photocatalytic removing of diclofenac from industrial wastewater of 57.5 % with adding 200 µL of TiO2 and up to 82.4 % with 800 µL and the maximum removal capacity is 13.3mg/g, fitting well with pseudo-first order model. The results are somehow interesting particularly combining a recyclable cellulose with photocatalysis. However, this manuscript cannot be recommended for publication with current shape. Here are some suggestions for authors to be considered for the improvement needed.
1) For sample preparation. What’s the interaction between magnetite and nanocellulose? Is it physical absorption?
Authors should put more details about the synthesis process.
2) For the crystallinity index (CrI) calculation, why not using peak located at around 15° for amorphous deduction, since both sample have this peak. Also, why here is extra peak for raw sago sample at around 35°, while that is not obvious for nanocellulose?
3) For XRD characterization. Since well-crystallized TiO2 and Fe3O4 with clear peak were observed from XRD patterns, what about the crystal size? It should be able to be calculated from Scherrer equation. Are they comparable to the size from electron microscopy analysis? If not, what may be the reason?
4) The corresponding element mapping should be provided for samples shown in Figure 5. Otherwise, it not meaning for at all.
5) The authors should be carefully giving out the conclusion about photocatalysis with different loading of TiO2 amount. Why the DCF removal percent is almost same for 200 and 400μL?
6) Couple of writings lack background/evidence over the manuscript.
Page 10, “This shows that more •OH radical form upon TiO2 activation that could have aided to almost complete removal of diclofenac. How the photocatalysts developed? How did they work for DCF removal process?
Page 9. “This represent that 800 µl TiO2 is the best amount to promote the maximum UV light absorption and transfers the charge carriers to the surface for photocatalytic treatment.“ How the charge transfer process happened? Will here be charge carriers recombination?
7) The authors should take seriously to organize all data and figure captions. Like IR, XRD, SEM images, they are not readable.
Author Response
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Reviewer 3 Report
In this paper, the authors have developed a NC/Fe3O4/TiO2 photocatalytic adsorbent via hydrothermal process, which was able to remove diclofenac from industrial wastewater. The authors have used and compared three mathematical models to quantitatively predict and correlate adsorption capacities/strengths and to design adsorptive processes. This work is interesting, but the novelty and significance of the work is not evident. It is difficult to tell what makes the proposed NC/Fe3O4/TiO2 photocatalytic adsorbent different from other adsorbents that have been previously reported. The authors might want to clarify/improve their uniqueness/novelty argument of this work vs. existing publications. Furthermore, before publication in Sustainability, the following issues need to be addressed:
1. In this paper, Figure 6 shows that the percentage of diclofenac removal display no significant changes for 200μl and 400μl TiO2, but the percentage of diclofenac removal becomes much higher when the loading of TiO2 is increased to 800μl. Could the authors briefly explain this transition? Furthermore, the authors claimed that 800μl TiO2 is the best amount to promote the absorption. The authors may need to provide data of TiO2 larger than 800μl in order to prove that 800μl TiO2 has the highest percentage of diclofenac removal.
2. In this paper, Figure 10 shows that the experiment data display no significant change for 200μl and 400μl TiO2. But the calculated data shows difference between 200μl and 400μl TiO2. Could the authors briefly explain this difference between experiment data and calculated data?
Author Response
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Reviewer 4 Report
Summary and general comments
In this study, the authors infused magnetite and TiO2 into nanocellulose derived from sago bark and investigated its adsorptive and photocatalytic performance in the removal of the antihistamine “Diclofenac” from the aqueous solution.
The study is scientifically sound, and the chosen methods are suitable for these studies. The manuscript is also interesting, and English is easy to read and understand. However, the manuscript can be further improved. Please refer to the specific comments for detail.
Specific Comments
1. The title should be rewritten to reflect that both adsorption and photodegradation processes are involved.
2. The keyword is useful for enhancing the discovery of the article and for future impact. I suggest that the authors include diclofenac as a keyword.
3. Abstract. Recheck line 25 ‘the pseudo-first order PSO model”
4. Abstract. Terms that appear only once do not require abbreviation
5. Abstract. When the authors mention the performance using % removal, I suggest that the authors also include the initial adsorbate concentration.
6. Introduction. Because this study involved both photocatalysis and adsorption. The authors focus only on the photocatalysis and did not mention much about the adsorption. Here are some of the recommendations that authors can use to describe the adsorption part. doi.org/10.5004/dwt.2018.21775
doi.org/10.1016/j.jtice.2021.11.001
7. Section 2. Describe how the DFC was prepared. Mention the manufacturer, reagent grade, and purity.
8. Section 2.4. The sputtering information prior to SEM should be briefly mentioned. FTIR is not mentioned. Specify if it is the conventional FTIR or ATR.
9. The symbols used in this manuscript need to be unified. Qt and qt are both used in the manuscript and figures.
10. There a be should description on what insight the authors can obtain when using the Langmuir Hinshelwood model.
11. Figure captions should be informative and standalone.
12. Error bars should be added to the figure wherever applicable
13. Figs. 1, 2 and 3 can be merged
14. Important peaks should be labelled in Fig. 4.
15. Table 2. The authors should remove “200” and “400” from the adsorbent column.
16. Line 276-288. When mentioning the removal efficiency (%), the authors should at least mention the initial concentration of diclofenac.
17. Line 283: error “irradiion”.
18. Table 3. The level of significant should be consistent and applied to the number.
19. Table 4. There is no need for the word maximum. It is known that qe means adsorption capacity at equilibrium.
20. Table 4. The parameter column is not required. This information can be included in the text in the methodology section.
Author Response
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Reviewer 5 Report
This manuscript focuses on the catalytic applications of Nanocellulose support derived from Sago Waste to photocatalytic degradation of diclofenac using Fe3O4 and TiO2. The catalyst characterization was relatively well performed, while the novelty of this study needs to be thoroughly discussed, and the results and discussion sections need more explanation and discussion. For these reasons, this study is incomplete, and, unfortunately, I cannot recommend the publication of this manuscript in its present form.
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Round 2
Reviewer 2 Report
After this sufficient improvement, it should be able to publish in Sustainability.
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Reviewer 3 Report
The authors have addressed my concerns in this revision.
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Reviewer 4 Report
After the revision, the manuscript is of acceptable quality
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Reviewer 5 Report
Moderate corrections were made.
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