Manganese Adsorption onto Permanganate-Modified Bamboo Biochars from Groundwater
Round 1
Reviewer 1 Report
Removing manganese (Mn) from sources of drinking water is of considerable interest and great significance for health and sustainable development of human beings. The authors designed a potassium permanganate-modified bamboo biochar (MBB) as an adsorbent. Compared to bamboo biochar (BB), manganese greensand and activated carbon, MBB exhibited a maximum Mn adsorption capacity of 4.70 mg g-1 at a pH of 6.7 ± 0.1. Besides, the adsorption isotherm of MBB was investigated through the Langmuir model. The research of this manuscript is interesting and results are reliable. However, major revision is required and the comments are given below.
1. In the sentence of “this study aimed to investigate the removal efficiencies of manganese bamboo biochar (BB) and potassium permanganate-modified bamboo biochar (MBB) (line 81)”, “for” might be missed between “manganese” and “bamboo biochar”.
2. Biochar has shown promising application in metal ion removal. Some typical references are suggested to be cited to enrich the background, e.g. Journal of Bioresources and Bioproducts 2021, 6 (4), 292-322; Journal of Bioresources and Bioproducts 2022, 7 (2), 109-115.
3. “MnSO4.H2O (line 90)”, “SO42- and NO3- (Table 1)” should be revised. The authors should double-check the whole text to eliminate similar errors.
4. In the sentence of “The pores of BB and AC range from micro- to macropore sizes (10-100 μm) (line 216)”, the authors should reinvestigate the definition of micropore, mesopore and macropore.
5. Scale bars are suggested to be added in the Figure 1a-d.
6. In Figure 3, after 24h, Mn adsorption for MnG is has decreased. Please explain this result.
7. Can MBB be recycled and reused? How about Mn adsorption capacity for MBB after several times of recycles?
8. Please unified format of “Figure and Figure.” in the manuscript. For example, “Figure 1. and 4. (line 223, 390)”as well as “Figure 2 and 3 (line 274, 319)”.
9. In Figure 2b, text should not intersect with pictures.
10. The “biochar” in the keywords is suggested to be replaced with “bamboo biochar”.
11. Please pay attention to the placement of text references ([5, line 43]).
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript titled "Manganese adsorption onto and fractions in permanganate modified bamboo biochars from groundwater" by Anawat Pinisakul prepared bamboo biochar, potassium permanganate-modified bamboo biochar and compared these removal perfoamcnes with activated carbon and manganese greensand. Some problems should be addressed.
1. Fig.1. The scale bar should be clearly shown.
2. Fig.2. (a) and (b) should be written in the two sub-graphs.
3. The XRD and XPS may characterize manganese dioxide details, which is necessary.
4. Why did the red line go up first and then down?
5. Fig. 4. The words in the sub-graphs were covered.
6. Real groundwater should be used to test the effect of natural organic matter on the adsorption of manganese.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
This study aims to investigate Mn bamboo biochar (BB) removal efficiencies and potassium permanganate-modified bamboo biochar (MBB). The removal efficiencies (RE, %) were not explicitly mentioned, and adsorption capacity (mg g-1) was used. To compare the Mn removal % from groundwater samples and compare to WHO and local limits, it is necessary to add removal efficiencies (RE, %). The recommended formula can be found in the paper https://doi.org/10.3390/ijms21051563The author must highlight in the conclusion if the suggested MBB removal efficiency meets the WHO and local limits of 0.08 and 0.3 mg/L, respectively.
Consider changing the title to “Manganese adsorption onto permanganate-modified bamboo biochars from simulated groundwater. “
Is there any risk of leaching of Mn from modifying BB with MnO4- to MBB onto the groundwater? How can the author support this experimentally?
The similarity is relatively high 30% paraphrasing, and proper citing is needed. For example, line 351, page 11, and the table title is copied from Fan Yang and wan not cited https://doi.org/10.3390/app12073368
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
The paper presents an interesting research work. In general, the paper is properly organized. However, some of description needs to be explained more in detail. I think that the current paper could be accepted after major revision.
1. Some typo and grammar errors can be found in the manuscript, and the authors should check the whole manuscript very carefully to avoid any mistakes.
2. Please mention the novelty of this manuscript?
3. The authors should include the novelty of the work in terms of cost, reliability and performance.
4. Provide a complete list of chemical and reagents with purity in material and method section.
5. In the introduction section, It is strongly recommended to add a recent literature survey and the novelty of the present study. Furthermore, analysis techniques and wastewater technologies along with their applications for a sustainable environment should be cited. Research gaps should be highlighted more clearly, and future applications of this study should be added. The information provided needs to be well organized for a better understanding of the reader. Authors can get help from the following recent literature. Authors can get help from the following recent literature to improve the section:
https://doi.org/10.1007/s10924-022-02464-8
- The authors' should also apply Dubinin–Radushkevich isotherm model, which evaluates the adsorption energetically, to the concentration data. So author can have an idea whether the adsorption process is physical or chemical.
https://doi.org/10.1007/s10967-023-08820-9
7. Contact time effect on Mn removal should be studied. In my opinion, the intra particle diffusion models should be analyzed to get better understanding on process of adsorption kinetics.
8. Authors are recommended to perform FT-IR and SEM-EDX analysis after Mn removal. Because it will be evidence of removal.
9. Why did the authors not investigate the effect of temperature on removal? In order to better understand the adsorption process, In my opinion, the effect of temperature on adsorption should be studied and thermodynamic parameters (enthalpy, entropy, free gibbs energy) should be analyzed. It is recommended to the authors to evaluate the adsorption in terms of thermodynamics by investigating the effect of temperature on adsorption and drawing the lnk-1/T graph. The authors should derive the thermodynamic parameters (ΔG, ΔS, ΔH).
https://doi.org/10.1007/s13399-023-03781-1
10. Are the adsorbent used in this study a better adsorbents for the removal of Mn than other adsorbents in the literature? It would be interesting to compare the adsorption capacity of the “MBB” adsorbent with literature data.
11. Please add future aspect of this study in view of current results.
12. Conclusions should be rewritten. The authors are only repeating the results.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
Accept in present form
