Efficient Degradation of Rhodamine B Dye through Hand Warmer Heterogeneous Activation of Persulfate
, Cong Li 1 and Haoyu Luo 2Round 1
Reviewer 1 Report
The manuscript title “Efficient rhodamine B dye degradation using hand warmer 1 activation of persulfate: the formation of micro-batteries” is written well, but lacks information about the synthesis of a catalyst and some characterization.
1. Please provide details on the synthesis of a catalyst in the experimental section, including the reusability test of the catalyst.
2. Indicate the molecular mass in g/mol for each chemical used, e.g. use the molecular weight of Rhodamine B as 479.02g/mol instead of writing 479.02 only.
3. As indicated in the EDS, it shows the presence of Fe, C, O, and Si. I wonder where the peak of Si and C comes from. Also, if the sample contains Fe and O, is it possible that the Fe exists in the form of an oxide such as FeO or Fe2O3 or Fe3O4 in a sample?
4. In the XPS survey scan of a sample, Fig. 3a, where do the peaks of Mg, Na, Ca, Al, and Si arise from?
5. In the XPS of Fe 2p provided in Figs 3b and 3d, the authors mention iron oxides, which form of iron oxides is present in the sample, and how to prove it.
6. What is the difference between the normal pH (pH = 4.5±0.2) on line 128, page 6, and the pH (pH = 4.5±0.2) on line 215, page 11?
Author Response
19-Aug-2023
Response to Reviewer 1 Comments
Dear reviewer,
Re: Manuscript ID: sustainability-2547505 and Title: Efficient degradation of rhodamine B dye by hand warmer heterogeneous activation of persulfate
Thank you for your precious comments and advice concerning our manuscript entitled “Efficient degradation of rhodamine B dye by hand warmer heterogeneous activation of persulfate” (ID: sustainability-2547505). Those comments are valuable and very helpful. We have read through the comments carefully and have made corrections. Based on the instructions provided in your report, we uploaded the revised manuscript. Revisions in the text are shown using red highlight. The responses to the reviewer's comments are marked in red and presented following.
We would love to thank you for allowing us to resubmit a revised copy of the manuscript and we highly appreciate your time and consideration.
Sincerely.
Jianqiang Zhang
South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, Guangdong 510655, PR China.
The responses to the reviewer's comments
Reviewers' comments:
The manuscript title “Efficient rhodamine B dye degradation using hand warmer activation of persulfate: the formation of micro-batteries” is written well, but lacks information about the synthesis of a catalyst and some characterization.
Point 1: Please provide details on the synthesis of a catalyst in the experimental section, including the reusability test of the catalyst.
Response 1: Thanks for your nice comments on our article. The production of the hand warmer is simple. 75% iron powder, 15% vermiculite, 7% activated carbon, and 3% NaCl were added and mixed with stirring at room temperature. The mixtures were stored in a vacuum for further experiments. But in this paper, the catalyst of the hand warmer was purchased from Alibaba (Shanghai, China). And we added the reusability test of the catalyst in the paper.
The reusability test was initiated immediately by adding 0.02 g recycled catalyst, 100 mL 100 mg/L RhB (pH = 4.5± 0.2), and 3 mM PS.
Point 2: Indicate the molecular mass in g/mol for each chemical used, e.g. use the molecular weight of Rhodamine B as 479.02g/mol instead of writing 479.02 only.
Response 2: Yes, we agree with your suggestion. We revised the molecular mass in g/mol for each chemical used. For example, The Rhodamine B (RhB, C28H31ClN2O3, 479.02 g/mol) and potassium persulfate (K2S2O8, 270.32 g/mol) were provided by Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).
Point 3: As indicated in the EDS, it shows the presence of Fe, C, O, and Si. I wonder where the peak of Si and C comes from. Also, if the sample contains Fe and O, is it possible that the Fe exists in the form of an oxide such as FeO or Fe2O3 or Fe3O4 in a sample?
Response 3: Thank you for your comments. The catalyst of the hand warmer contains about 15% of vermiculite, which contains Si, C, and O. The oxygen in the catalyst mainly comes from vermiculite. Additionally, the catalyst is prone to oxidation, and Fig 3 XPS shows that the surface of the catalyst is an oxide of iron. Therefore, Fe exists in the form of an oxide on the surface of the catalyst due to the oxidation of Fe. But the formation of iron oxides does not affect the catalyst activation in this study.
Point 4: In the XPS survey scan of a sample, Fig. 3a, where do the peaks of Mg, Na, Ca, Al, and Si arise from?
Response 4: Thanks for your comments. Because the catalyst of hand warmer contains vermiculite and NaCl. The Mg, Ca, Al, and Si arise from vermiculite, and Na arises from NaCl.
Point 5: In the XPS of Fe 2p provided in Figs 3b and 3d, the authors mention iron oxides, which form of iron oxides is present in the sample, and how to prove it.
Response 5: Thank you for pointing this out. The main active component in the catalyst is Fe0 or Fe2+, and the catalytic effect of iron oxides (like Fe2O3 and Fe3O4) is not ideal. Therefore, there is no point in proving which form of iron oxides is present in the sample. In the XPS of Fe 2p provided in Figs 3b and 3d, there was no Fe0 on the surface of the hand warmer, since the Fe0 was easily oxidized. As exhibited in Fig. S9 (a), compared to the hand warmer, the Fe 2p spectra of the recycled hand warmer consisted of Fe3+ 2p3/2, Fe3+ 2p1/2, and satellite Fe3+ peaks. Moreover, a satellite Fe2+ peak located at 714.6 eV emerged which confirmed the existence of Fe2+ species on the surface of the recycled material. Thus, the presence of the Fe2+ gives the recycled hand warmer capability to activate PS.
Fig. S9 XPS profiles of the surface of recycled hand warmer. (a) Fe 2p spectra.
Point 6: What is the difference between the normal pH (pH = 4.5±0.2) on line 128, page 6, and the pH (pH = 4.5±0.2) on line 215, page 11?
Response 6: We feel great thanks for your professional review work on our article. There is no difference between the normal pH (pH = 4.5±0.2) on line 128, page 6, and the pH (pH = 4.5±0.2) on line 215, page 11. The pH (pH = 4.5±0.2) on line 215 was just used to emphasize the reaction conditions of the solution. In order to avoid misunderstandings, we deleted the “normal” on line 128, page 6.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript (sustainability-2547505) was well written, but it needs to revise carefully.
My comments are as follows:
1. English grammar needs to revise carefully; the present form is not good.
2. The title, abstract, and conclusions need to rewrite and revised carefully.
3. What problems in this work were solved?
4. The importance of present work needs to identify
5. What is the importance of this work in real industries?
6. Please compare your work with the old works, and show the advantages of this work
This manuscript (sustainability-2547505) was well written, but it needs to revise carefully.
My comments are as follows:
1. English grammar needs to revise carefully; the present form is not good.
2. The title, abstract, and conclusions need to rewrite and revised carefully.
3. What problems in this work were solved?
4. The importance of present work needs to identify
5. What is the importance of this work in real industries?
6. Please compare your work with the old works, and show the advantages of this work
Author Response
19-Aug-2023
Response to Reviewer 2 Comments
Dear reviewer,
Re: Manuscript ID: sustainability-2547505 and Title: Efficient degradation of rhodamine B dye by hand warmer heterogeneous activation of persulfate
Thank you for your precious comments and advice concerning our manuscript entitled “Efficient degradation of rhodamine B dye by hand warmer heterogeneous activation of persulfate” (ID: sustainability-2547505). Those comments are valuable and very helpful. We have read through the comments carefully and have made corrections. Based on the instructions provided in your report, we uploaded the revised manuscript. Revisions in the text are shown using red highlight. The responses to the reviewer's comments are marked in red and presented following.
We would love to thank you for allowing us to resubmit a revised copy of the manuscript and we highly appreciate your time and consideration.
Sincerely.
Jianqiang Zhang
South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, Guangdong 510655, PR China.
The responses to the reviewer's comments
Reviewers' comments:
This manuscript (sustainability-2547505) was well written, but it needs to revise carefully. My comments are as follows:
Point 1: 1. English grammar needs to revise carefully; the present form is not good.
Response 1: Thank you for your helpful comments. We have tried our best to revise the English grammar and hope that the correction will meet with approval. Here, we did not list the changes but marked them in red in the revised manuscript.
Point 2: The title, abstract, and conclusions need to rewrite and revised carefully.
Response 2: Thanks for your recommendation. We revised the title, abstract, and conclusions, as shown below.
Title: Efficient degradation of rhodamine B dye by hand warmer heterogeneous activation of persulfate
Abstract
In this study, an innovative method for RhB (Rhodamine B) degradation in the persulfate (PS) and hand warmer heterogeneous activation system was investigated. The hand warmer shows better catalytic performance and excellent reusability in PS activation. The reaction rate constants of RhB removal in the hand warmer/PS process (0.354 min−1) were much faster than that in other PS and Fe-related processes (0.010-0.233 min−1) at pH 7. The iron in the hand warmer is the main active ingredient to catalyze PS, and activated carbon, salt, and H+/OH- accelerate the activated reaction due to the formation of micro-batteries in the solution. Moreover, the catalyst of the hand warmer showed excellent stability and reusability with a low level of iron leaching. This new, effective, inexpensive, repeatable, and environmentally friendly catalyst combined with PS has promising prospects for the removal of dyes from industrial wastewater.
Conclusions
A novel method for RhB degradation in a heterogeneous activation system of PS and hand warmer was investigated. The results showed that the degradation efficiencies of RhB were maintained above 90% in 30 min by using 0.1 ~ 0.4 g/L hand warmer to activate 3 mM PS. The heterogeneous process was suitable for wide pH (pH 3.0-9.0) conditions in solution. The iron in the hand warmer is the main active ingredient to catalyze PS, and the formation of micro-batteries with iron, activated carbon, salt, and H+/OH- accelerates the activation reaction in solution. Based on the quenching experiments and EPR results, the HO• and SO4•– were the two main reactive oxygen species in the hand warmer/PS process. The generated HO• and SO4•– destructed the conjugated structure of RhB, and decomposed RhB to several intermediates. Moreover, the hand warmer could be reused several times to activate PS. Therefore, this study gives an in-depth insight into further reusable mechanisms studies of hand warmer. This work exhibited a promising hand warmer catalyst for efficient RhB removal and provided new insights into the activation mechanism of PS by hand warmer.
Point 3: What problems in this work were solved?
Response 3: We innovatively investigated the use of hand warmer/PS system to degrade RhB. The hand warmer/PS system exhibited advantages over other processes to remove RhB in terms of contaminant removal, working pH range, and chemical dose. Moreover, the catalyst of hand warmer showed excellent stability and reusability with a low level of iron leaching. Further, this article studied the mechanisms for the reason of the excellent performance of catalysts in RhB degradation. The findings of this work demonstrate a new pathway for the activation of PS, which could effectively degrade organic pollutants and provide some new insights into PS remediation of contaminated water.
Point 4: The importance of present work needs to identify
Response 4: Thanks for your criticism. We have revised the abstract, and the importance of present work is identified in abstract. “We innovatively investigated the use of hand warmer/PS system to degrade RhB. The hand warmer/PS system exhibited advantages over other processes to remove RhB in terms of contaminant removal, working pH range and chemical dose. Moreover, the catalyst of hand warmer showed excellent stability and reusability with a low level of iron leaching. Further, this article studied the mechanisms for the reason of the excellent performance of catalyst in the RhB degradation. The findings of this work demonstrate a new pathway for activation of PS, which could effectively degrade organic pollutants and provide some new insights into PS remediation of contaminated water.”
Point 5: What is the importance of this work in real industries?
Response 5: This new, effective, inexpensive, repeatable, and environmentally friendly catalyst combined with PS possibly has promising prospects for the removal of dyes from industrial wastewater.
Point 6: Please compare your work with the old works, and show the advantages of this work
Response 6: Thanks for your recommendation. We added the following content to the article.
3.6 Compare the degradation of RhB by different processes
As shown in Table 1, we compared the degradation of RhB in the PS process with different catalysts. When the dosage of PS is only 3mM in our hand warmer/PS process while the PS dosage of other catalysts is above 8mM, the reaction rate constants of RhB removal in these processes (0.010–0.233 min−1) were much lower than that in the hand warmer/PS process (0.354 min−1) at high concentration of RhB and pH 7. If the dosage of PS increases, the reaction rate would be faster. The reason for the faster reaction rate of hand warmer may be the formation of many tiny micro-electrolysis, the micro-electrolysis could bring about the electrical environment to promote the reaction rate of PS activation in RhB degradation at pH 7. In addition, our hand warmer/PS process presented a high pH working range even at pH 9 (28.74 min−1). Generally, catalysts such as Fe0, Fe2+, and pre-Fe0 will dissolve into the solution during oxidation and cannot be reused. Nevertheless, the hand warmer is easily removed from the reactor at the end of each oxidation process and then can be repetitively used. Therefore, the hand warmer/PS process showed the advantage over other PS-based processes for the degradation of RhB.
Table1 Compare the degradation of RhB by different processes
|
Type of Process |
Catalyst (g L−1) |
PS (mM) |
RhB (mg L−1) |
pH |
Reaction rate constant (min −1) |
Reusability of catalyst |
Ref. |
|
Pyrite/PS |
1 |
8 |
20 |
3 |
0.031 |
No |
[44] |
|
Fe3O4/PS |
10 |
12 |
76 |
3.5 |
0.01 |
Yes |
[28] |
|
Fe0/PS |
0.224 |
8 |
100 |
7 |
0.094 |
No |
[34] |
|
Fe2+/PS |
0.224 |
8 |
100 |
7 |
0.142 |
No |
[34] |
|
Pre-Fe0/PS |
0.224 |
8 |
100 |
7 |
0.233 |
No |
[34] |
|
hand warmer/PS |
0.2 |
3 |
100 |
7 |
0.354 |
Yes |
This study |
Author Response File: Author Response.docx
Reviewer 3 Report
1. The abstract is too long I suggest the authors reduce it and put the essentials in this section.
2. In the EDS pattern of the catalyst, the Atom% and Weight% of elements should be added.
3. All references should be checked carefully. The authors should use a uniform format for references.
4. The manuscript contains some English syntax and grammar errors that require thorough revision and correction.
5. References should be updated by citing recently reported references. Particularly during the years 2021-2023.
6. The novelty of this work should be highlighted.
7. A comparison of this work to other works in literature should be added.
The manuscript contains some English syntax and grammar errors that require thorough revision and correction.
Author Response
19-Aug-2023
Response to Reviewer 3 Comments
Dear reviewer,
Re: Manuscript ID: sustainability-2547505 and Title: Efficient degradation of rhodamine B dye by hand warmer heterogeneous activation of persulfate
Thank you for your precious comments and advice concerning our manuscript entitled “Efficient degradation of rhodamine B dye by hand warmer heterogeneous activation of persulfate” (ID: sustainability-2547505). Those comments are valuable and very helpful. We have read through the comments carefully and have made corrections. Based on the instructions provided in your report, we uploaded the file of the revised manuscript. Revisions in the text are shown using red highlight. The responses to the reviewer's comments are marked in red and presented following.
We would love to thank you for allowing us to resubmit a revised copy of the manuscript and we highly appreciate your time and consideration.
Sincerely.
Jianqiang Zhang
South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, Guangdong 510655, PR China.
The responses to the reviewer's comments
Reviewers' comments:
Point 1: The abstract is too long. I suggest the authors reduce it and put the essentials in this section.
Response 1: Thanks for your recommendation. We have revised the abstract.
Abstract
In this study, an innovative method for RhB (Rhodamine B) degradation in the persulfate (PS) and hand warmer heterogeneous activation system was investigated. The hand warmer shows better catalytic performance and excellent reusability in PS activation. The reaction rate constants of RhB removal in the hand warmer/PS process (0.354 min−1) were much faster than that in other PS and Fe-related processes (0.010-0.233 min−1) at pH 7. The iron in the hand warmer is the main active ingredient to catalyze PS, and activated carbon, salt, and H+/OH- accelerate the activated reaction due to the formation of micro-batteries in the solution. Moreover, the catalyst of the hand warmer showed excellent stability and reusability with a low level of iron leaching. This new, effective, inexpensive, repeatable, and environmentally friendly catalyst combined with PS has promising prospects for the removal of dyes from industrial wastewater.
Point 2: In the EDS pattern of the catalyst, the Atom% and Weight% of elements should be added.
Response 2: Thanks for your suggestion. We added the Atom% and Weight% of elements in the EDS pattern of the catalyst as shown in Fig.1.
Point 3: All references should be checked carefully. The authors should use a uniform format for references.
Response 3: Thanks for your criticism. We unified the citation format for references.
Point 4: The manuscript contains some English syntax and grammar errors that require thorough revision and correction.
Response 4: We were very sorry for our careless mistakes. Thank you for your reminder. We have tried our best to revise the English grammar and hope that the correction will meet with approval. Here, we did not list the changes but marked them in red in the revised manuscript.
Point 5: References should be updated by citing recently reported references. Particularly during the years 2021-2023.
Response 5: Thanks for your helpful suggestion. We cited literature during the years 2021-2023, such as “Y. Gao, J. Luo, T. Song, X. Yu, Research progress on nano-Fe0/PS system for degradation of refractory organics in aqueous solution, Journal of Environmental Chemical Engineering, 9 (2021) 105345.”, “Y. Zhang, Z. Ma, X. Xie, D. Wu, X. Peng, J. Li, Mechanochemically synthesized silicotungsten acidified ZVI composite for persulfate activation: Enhancement of the electron transfer and Fe slowly release mechanism, Chemosphere, 336 (2023) 139254.”,” X. Wang, Y. Zhou, S. Ndayiragije, N. Wang, H. Tang, L. Zhu, Advanced oxidative degradation of sulfamethoxazole by using bowl-like FeCuS@Cu(2)S@Fe(0) catalyst to efficiently activate peroxymonosulfate, J Environ Sci (China), 126 (2023) 348-364.”, and so on.
Point 6: The novelty of this work should be highlighted.
Response 6: The novelty of this work has been highlighted in the abstract. There were few reports about the use of hand warmer/PS system to degrade RhB. The hand warmer/PS system exhibited advantages over other processes to remove RhB in terms of contaminant removal, working pH range, and chemical dose. Moreover, the catalyst of hand warmer showed excellent stability and reusability with a low level of iron leaching. Further, this article studied the mechanisms for the reason of the excellent performance of catalyst in the RhB degradation. The findings of this work demonstrate a new pathway for activation of PS, which could effectively degrade organic pollutants and provide some new insights into PS remediation of contaminated water.
Point 7: A comparison of this work to other works in literature should be added.
Response 7: Thanks for your useful recommendation. We have added the following content to the article.
3.6 Compare the degradation of RhB by different processes
As shown in Table 1, we compared the degradation of RhB in the PS process with different catalysts. When the dosage of PS is only 3mM in our hand warmer/PS process while the PS dosage of other catalysts is above 8mM, the reaction rate constants of RhB removal in these processes (0.010–0.233 min−1) were much lower than that in the hand warmer/PS process (0.354 min−1) at high concentration of RhB and pH 7. If the dosage of PS increases, the reaction rate would be faster. The reason for the faster reaction rate of hand warmer may be the formation of many tiny micro-electrolysis, the micro-electrolysis could bring about the electrical environment to promote the reaction rate of PS activation in RhB degradation at pH 7. In addition, our hand warmer/PS process presented a high pH working range even at pH 9 (28.74 min−1). Generally, catalysts such as Fe0, Fe2+, and pre-Fe0 will dissolve into the solution during oxidation and cannot be reused. Nevertheless, the hand warmer is easily removed from the reactor at the end of each oxidation process and then can be repetitively used. Therefore, the hand warmer/PS process showed the advantage over other PS-based processes for the degradation of RhB.
Table1 Compare the degradation of RhB by different processes
|
Type of Process |
Catalyst (g L−1) |
PS (mM) |
RhB (mg L−1) |
pH |
Reaction rate constant (min −1) |
Reusability of catalyst |
Ref. |
|
Pyrite/PS |
1 |
8 |
20 |
3 |
0.031 |
No |
[44] |
|
Fe3O4/PS |
10 |
12 |
76 |
3.5 |
0.01 |
Yes |
[28] |
|
Fe0/PS |
0.224 |
8 |
100 |
7 |
0.094 |
No |
[34] |
|
Fe2+/PS |
0.224 |
8 |
100 |
7 |
0.142 |
No |
[34] |
|
Pre-Fe0/PS |
0.224 |
8 |
100 |
7 |
0.233 |
No |
[34] |
|
hand warmer/PS |
0.2 |
3 |
100 |
7 |
0.354 |
Yes |
This study |
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear Authors, Thanks for submitting a revised version of your manuscript. I am impressed that you were able to address all my comments and suggestions. All explanations are logical and relevant to the study.
Reviewer 3 Report
This manuscript can be published in Sustainability.
