A Sustainable Amine Magnetic Biocomposite Based on Rice Husk–Sugarcane Bagasse Fiber for Lead and Contaminant Adsorption in Aqueous Solution
, Chairul Irawan 1, Meilana Dharma Putra 1, Hesti Wijayanti 1, Yuniza Shentya Dewi 1 and Yenny Meliana 3
Round 1
Reviewer 1 Report
The authors investigated amine magnetic biocomposite based on rice husk-sugarcane bagasse fiber (B-MNH2) as novel adsorption for heavy metal, COD and TOD removal. The characterization and removal performance of B-MNH2 were confirmed. In general, authors have done a detailed and hard work. However, it seems to me that the articles need some corrections before the final publication.
1. Double check writing to eliminate syntax errors, English writing throughout the manuscript should be improved.
2. The adsorption isotherm of adsorbent toward lead should be provided.
3. The comparison between B-MNH2 and other adsorbents should be listed.
4. The grade/purity of chemicals used in the study should be given in 2.1 Materials.
5. For the Introduction, please detailledly explain the reason for your choosing the Fe3O4. How about other the spinel (e.g., MnFe2O4), which was more stable.
6. The leasing of Fe should be determined, which influences the magnetism.
7. Please identify the function of Fe3O4 in the adsorption process, especially for the Pb. The XPS spectra before and after utization should be presented.
8. The function of -NH2 should be explored for mechnism investigation (e.g. hydrogen-bond interaction).
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article addresses the separation of Pb(II) ions and other contaminants from industrial wastewater. For this, the authors use magnetic biocomponents modified with amine groups. The topic is important and interesting, but the manuscript needs some revisions. My detailed suggestions are listed below.
Section 2.1
Symbols and acronyms (e.g. TSS, COD – lines 71-72) should be explained where they are used for the first time.
Some organic formulas used in this section are written as molecular formulas (number of carbon atoms, then hydrogen, then other atoms in alphabetical order), but ethanol is written with a separate OH group. It should be standardized.
Also, some additional information on the type and concentration of dye in textile wastewater would be useful.
Section 2.4.
Line 100 - the unit ppm is used, but in the following text it is used rather mg L-1. This should be standardized.
Line 103 - this "a certain amount of biocomposite" should be more specifically defined.
Line 106 - the word "filtrate" seems inappropriate - there was no filtration of samples after adsorption.
Section 2.5.
Line 124 - Volt and ampere units should be written using capital (not lowercase) letters (V, A).
Section 2.6.
Equation (3) - why was a coefficient of 5 used in the equation? In the cited work [20], 5 mL of supernatant, taken from 25 mL of the total solution, was titrated - so the coefficient of 5 is adequate. In this work, 20 mL, taken from 50 mL, was titrated, so the factor should be changed.
Line 146 – it should be a lowercase n in KMnO4.
Equation (4) - the formulas of KMnO4 and H2C2O2, written after the C symbol as a subscript, would be more readable.
Line 155 - what does "water sample" analyzed for TSS mean? Was it textile wastewater? Before or after the addition of the Pb solution?
As I mentioned earlier, the authors should characterize the dye present in the wastewater. Dyes can vary significantly, comparing their different types or functional groups in their molecules. This section does not even specify the wavelength at which spectrophotometric measurements were made.
Section 3.1.
Line 235 - the letter g is missing in 580 k/m3.
Lines 309-310 – the sentence “The B-MNH2 thermograms shows more stable than B-M at 100-200 oC, the B-MNH2 309 only weight loss about 4% and 7% for B-M.” is unclear in my opinion and should be reworded.
Section 3.2.
Line 329 – the word “adsorbed” seems to be in the wrong place in this sentence.
Figure 3 – some reaction conditions are listed in the Figure caption, but other important parameters are omitted (Pb concentration, adsorbent mass).
Line 362 and 383 - in -NH3+, 3 should be written as a subscript.
Lines 371 and 375 - a decimal point (not a comma) should be used in Qe values (also line 488).
Lines 378 – 379 – what do the authors mean by “liquid membrane diffusion”?
Section 3.3.
Equation 8 - I propose the notation Pb2+ on the left side of the reaction (instead of Pb(II)) so that the signs on both sides of the reaction are equal.
Equation 9 - in PbOH+ the + sign should be a superscript.
Lines 402 – 404 – the explanation given by the authors is unclear to me: “The increasing of Pb(II) ion adsorbed occurs at pH 5, in this condition the H+ ion will reduces and the equilibrium shifts to the right reaction, so the PbOH+ equilibrium increases.” The adsorption of Pb(II) at pH 5 increases compared with pH 7 or pH 9, but the concentration of H+ is higher (not reduced) at pH 5 compared with pH 7 or 9. The statement "in this condition the H+ ion will reduce" indicates that the authors compare pH 5 to the lower pH values, which were not investigated.
Figure 6, 7, and 8 captions – what dose of adsorbents were used?
Section 5 – "5. Conclusions" should be 4. Conclusions
Lines 483,485 - typo errors: “dan” – should be and, “wate water” – should be wastewater.
Line 486 – the value of pH is missing.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The authors presented an original method for the production of magnetic biocomposites. The structure and absorption properties of the obtained samples were investigated. The article was prepared according to the requirements of the journal and contains new results. However, there are a number of remarks:
It is necessary to describe in more detail the mechanism of separation by a magnetic field.
Authors' statement in lines 182, 183 "The amine magnetic biocomposite (Fig. 2b) have smaller size (±50 nm) than biocomposite 182 prepared without amine (Fig. 2a)." is controversial, since these figures show only a fragment of the biocomposite.
Lines 250,251, the authors probably meant “magnetic particles”, and not “magnetic”
The main remark to the work is the lack of comparison of the effectiveness of the obtained biocomposites with known adsorbents, including those of plant origin. The indicated data must be placed in the work under graphs 6-8. The findings are reflected in the conclusion.
After these minor changes, the article can be published.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors complemented enough work and discussion on the previous version with regard to reviewers' comments. All the issues raised by the reviewers have been addressed well. This paper can be accepted for publication in Magnetochemistry.
