Efficient Adsorption of Lead Ions from Synthetic Wastewater Using Agrowaste-Based Mixed Biomass (Potato Peels and Banana Peels)

Round 1

Reviewer 1 Report

This is an interesting and worthwhile submission.  The authors study the removal of lead(II) ions via biomass, biochar, and nanoparticles.

I think there might be a number of errors on the part of the authors:

1. Line 44 lists "Cr2+"...perhaps the authors meant Cr6+?
2. Line 44 also mentions As2+.  I think the intent was to list As3+.
3. Lines 81-82 have a list of ions, but Cr(VI) is mentioned twice.
4. Line 113, TiO2 needs to have the 2 as a subscript.
5. Line 124 has the wrong formula for lead(II) nitrate--it should be Pb(NO3)2.
6. Figure 2 has both of the last micrographs labeled as e.  The final one should be labeled f.
7. Beginning in Line 180, there is mention made of Figure 4.4x.  There is no Figure 4.4x anywhere, as far as I can tell.  It supposedly refers to FTIR spectra, but there are none showing what the authors are referring to there.  The reference occurs again at Line 190.
8. Additionally, though Figures in the manuscript are labeled as Figure 1, Figure 2, etc., there is a consistent reference to figures as Figure 4.X.  This inconsistency should be corrected.
9. Line 269, the words "contact time" are in a larger font than the rest of that heading.
10. Beginning in Section 6.1 and continuing through the end of the article, it would be very helpful to have the equations and variables have subscripts when appropriate.  Not having them at present makes it a much more difficult read.
11. Line 348 mentions adsorption by chromium.  This is the first mention of chromium as part of this study.  I think this might be an error by the authors?
12. Line 434 mentions psidium guajava for the first time, but not the banana or potato peels.  Again, this seems to be an error.
13. Line 440 again mentions the removal of chromium.  Again, it's probably an error

There are a number of places where the sentence or sentences are confusing or not comprehensible.  I guess this is an English language issue, not a scientific issue.  These occur at:

1. Lines 88-90.
2. Lines 288-291.
3. Lines 375-376.

I think that rewording these sentences and rewriting the English would help these sentences to make sense to the reader.  As they are currently written, they are not comprehensible to the English reader.

Author Response

 "Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript presented for review is interesting. However, I have some comments. My suggestions are as follows:

• Chapter 3 lists the methods used to characterize the tested adsorbents. The apparatus on which the measurements were made should be completed.
• It is advisable to complete the research: measurement of low-temperature nitrogen adsorption isotherms and determination of the parameters of the porous structure: specific surface area, total pore volume, the volume of micro and mesopores, pore size, etc.
• Punctuation marks (periods) are omitted in the manuscript, eg: page 3, lines 127, 132. Please check the punctuation throughout the manuscript. Also subscripts (page 3, line113) and superscripts - for units (page 3, line 133, page 5, line 182, page 6, line 188 etc.). Please correct the subscripts where required in all equations. A lot of editorial errors appeared throughout the work. I recommend checking and correcting these errors.
• Figures are not numbered in accordance with the numbers in the text. Please correct. For example:

Figure 1. FTIR spectra,  Figure 4.4 in the text, etc.

• Page 4, line 163, the last picture is "e", correct it with "f".
• Page 7, line 269, correct the font size.
• The results obtained in the work should be compared with the results presented in the literature. The tested adsorbents (maximum removal efficiency) should be compared with other adsorbents from the literature. List the data in the table.
• All references should be adjusted to the Water rules. This applies to the references in both the text and the References section.

Author Response

 "Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper deals with a very important issue, which is lead sorption on selected adsorbents. The importance is related to the almost universal presence of lead in wastewater from many cities and regions. However, the article is written without attention to detail, so it should be corrected before being published. Detailed comments are provided below.

1. The article organization is not correct. The Materials and Methods section should be separated from the Results section. Currently, in Chapters 4-7, methodology elements are mixed with results. There is no clear separation of Results.
2. Fig. 4. - colors of points, methods of their description and lines of functions should be standardized.
3. Where are figures 4.4a, 4.4.b etc.? Lines 148, 180, 189 etc.
4. Fig. 4 and the titles of subsections 5.1, 5.2, 5.3. and 5.4. The word "Effect" means nothing. In this case it is "Lead Adsorption Effect". Should be improved.
5. Line 321-322. Where are tables 4.8 and 4.9 and figure 4.9?
6. Line 334 - it's q(mg/g), and it should be qt(mg/g)
7. Last sentence - lines 443-445. Which results are the basis of this conclusion? R2 for the Freundlich isotherm are higher than R2 for the Langmuir isotherm.
8. Chapters 6 and 7 - there are no characteristic data that should be read and calculated from graphs 5 and 6. that is k1, k2, qe, Xm, n and Kf..
9. A period is missing from the end of many sentences.

 

Author Response

 "Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

I accept the correction. However, with such a large number of deletions and changes, I hope that the editors will handle it.