Nascent Rice Husk as an Adsorbent for Removing Cationic Dyes from Textile Wastewater
, Phyo Phyo Kyi 1, Seung-Hee Hong 2, Chang-Gu Lee 3 and Seong-Jik Park 4,*Round 1
Reviewer 1 Report
Very good research paper. Congratulations
Author Response
Reviewer #1
Very good research paper. Congratulations
Answer: Thanks for your comments
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Applied Sciences
Manuscript ID: applsci-791818
Title: Nascent rice husk as an adsorbent for removing cationic dyes from textile wastewater.
Reviewer comments:
The authors have produced an original and interesting study concerning the use of rice husk as dyes adsorbent for wastewater remediation. The work has been undertaken diligently and the interpretation of the data supports the conclusions. However, some points should be modified. I would suggest publishing it on Applied Sciences after minor revisions.
(1) lines 13-14: this sentence is not necessary.
(2) line 79: I have a curiosity about the raw material used; is there some difference between different typologies of rice available? No data about the rice here used is provided so someone could think that each kind of rice could be used. An explanation is requested.
(3) Figure 1, axis scale: the rice husk was heated at different temperatures, and the authors underline that the first temperature analyzed is 0°C but I mean that the right temperature should be room temperature….is it correct?
Furthermore, the same graph for CV adsorption test should be provided.
(4) About the treatment temperature of rice husk, the authors explain the best temperature is 75°C but looking Figure 1 seems that in the case of low concentration of MB, 300 mg/L, the adsorption capacity is the same at 0, 75 and 100°C. The authors should explain this point.
(5) 3.6. section: about the adsorbent dosage, it is not clear the range of dosage used, is it arbitrary or based on some references (for example real indicators of BM/CV in wastewaters)?
(6) I have a doubt about the real and future application of this new technology; I think that in a real device the rice husk should be used in a container..so the real rice husk adsorption capacity could be different…..
Author Response
Reviewer #2
The authors have produced an original and interesting study concerning the use of rice husk as dyes adsorbent for wastewater remediation. The work has been undertaken diligently and the interpretation of the data supports the conclusions. However, some points should be modified. I would suggest publishing it on Applied Sciences after minor revisions.
On the behalf of my co-authors, I appreciate your dedicated to review this manuscript and give us valuable comments. All your comments are helpful to improve the quality of the manuscript. We tried our best to reflect your comments to the revised manuscript.
(1) lines 13-14: this sentence is not necessary.
Answer: As your comments, the sentence was removed from the revised manuscript.
(2) line 79: I have a curiosity about the raw material used; is there some difference between different typologies of rice available? No data about the rice here used is provided so someone could think that each kind of rice could be used. An explanation is requested.
Answer: The species of rice and the information about the cultivation in paddy were described in the revised manuscript.
(3) Figure 1, axis scale: the rice husk was heated at different temperatures, and the authors underline that the first temperature analyzed is 0°C but I mean that the right temperature should be room temperature….is it correct?
Furthermore, the same graph for CV adsorption test should be provided.
Answer: Yes, room temperature is more suitable for describing the experimental condition performed in this study. It was revised. The adsorption test for CV adsorption test with rice husk thermally treated under different temperatures was not performed in this study.
(4) About the treatment temperature of rice husk, the authors explain the best temperature is 75°C but looking Figure 1 seems that in the case of low concentration of MB, 300 mg/L, the adsorption capacity is the same at 0, 75 and 100 °C. The authors should explain this point.
Answer: It was mentioned in P3 L113-119 that the RH thermally treated at 0, 75 and 100 °C had similar adsorption capacity at 300 mg/L of MB. However, at 500 mg/L of MB, the RH at 75 °C showed highest adsorption capacity of MB.
(5) 3.6. section: about the adsorbent dosage, it is not clear the range of dosage used, is it arbitrary or based on some references (for example real indicators of BM/CV in wastewaters)?
Answer: The purpose of adsorbent dosage experiments was newly described in P14 L279-282.
(6) I have a doubt about the real and future application of this new technology; I think that in a real device the rice husk should be used in a container..so the real rice husk adsorption capacity could be different…..
Answer: In this study, the experimental results were obtained under a well-mixed condition. However, the adsorption amount might not be high when mixing is insufficient and other interference materials are present in real condition.
Author Response File: Author Response.pdf
Reviewer 3 Report
Please find the attachment.
Comments for author File: Comments.pdf
Author Response
Reviewer #3
Title: Nascent Rice Husk as an Adsorbent for Removing Cationic Dyes from Textile Wastewater In this work, authors presented a study on the usage of rice husk as an adsorbent for removal of MB and CV from water. Their work focuses on the kinetics of the adsorption process. The manuscript appears to be interesting and fits within the scope of the journal. However, there are some questions that need to be addressed before considering its suitability for publication in Applied Sciences. Authors are recommended to take care of the below comments and modify the manuscript accordingly. Therefore, another round of revision of the current manuscript is recommended.
On the behalf of my co-authors, I appreciate your dedicated to review this manuscript and give us valuable comments. All your comments are helpful to improve the quality of the manuscript. We tried our best to reflect your comments to the revised manuscript.
Comment 1. Following corrections are needed (See highlighted part)
- selected as adsorbent material – should be “an adsorbent”
Answer: It was revised in P2 L61.
- “…….RH treated at 75 ℃, had superior removal capacity than that at other….”- specify it.- removal capacity in terms of which material?
Answer: The sentences in P16 L299-300 was revised.
- What was the primary basis for study effect of temp. in adsorption prop of RH?
Answer: The reduction of specific surface area and pore diameter of RH by thermal treatment on RH leaded to the reduction RH adsorption.
- Would treated RH work for anionic dyes in anyway? Any comment on that?
Answer: The point zero charge of RH is 2.7 and its surface charge is negative at neutral pH. Therefore, we can expect that it is not suitable for the adsorption of anionic dyes. It was mentioned in P12 L271-272.
- Hypothesis of the study needs to be mentioned clearly.
Answer: We expected that the RH pyrolysis above 300 °C would be helpful for enhancing the removal efficiency of RH for the dyes. However, the result was the opposite of the assumption. It was described in P15-16 L298-299.
Comment 2. How did authors get these surface area and pore size data? Please provide details about it.
- What is the surface area and pore size of RH-70 sample? This sample showed higher performance in MB adsorption capacity. Also, RH-100 showed higher performance (See Fig. 1) similar to RH70; Authors should highlight some comments in this regard.
- Authors are suggested to include the pore size distribution in these samples, if possible.
Answer: The method for the analysis of specific surface area and pore size was described in P3 L123-124. The average size of different rice husks is provided in the manuscript but the distribution of pore size was not obtainable.
Comment 3. “The fast increase in the adsorbed dye amount was ascribed to enough 145 adsorption active sites initially, caused by diffusion of micro pores ..” - Are these thermally treated RH microporous or mesoporous in nature? Can authors comment on that in reference to their study.
Answer: As your comments, we have clarified the sentence in P5 L145-146.
Comment 4. Reference section needs modification e.g., following points need to be taken care of -Recent references must be included in some discussion - e.g photocatalytic oxidation;
Photochemical or AOP process. Some recent articles need to be included in the discussion with a brief highlight on key findings in the introduction. Authors can highlight the key benefits of the proposed method compared with others. In this regard, authors can cite the following important articles for improvement-
- ChemCatChem 2018, 10, 3305
- Appl. Sci. 2019, 9(9), 1958
- Water Research, Volume 139, 1 August 2018, Pages 118-131
Answer: We have added the references you have provided to describe the previous studies on photochemical or AOP process.
Comment 5. Authors included too many references (over 100); Authors are recommended to consider those references that are of more relevant with this manuscript. Many references are similar and does not add significant values. Also, authors are suggested to include latest references in their field so that they highlight the progress and challenges present in this field of study.
Answer: We reduced the number of references and added the latest references in this field.
Comment 6. How is the morphology of untreated RH? Authors should include SEM surface morphology of the untreated RH. This would help to understand the changes in morphology due to thermal treatment.
Answer: We have provided the FE-SEM image of RH dried at room temperature in the revised manuscript.
Comment 7. In Fig. 4(a)- y=1.7842x – Can authors justify for the straight line equation based on only 2 data points?
Answer: The two data points were used because the value of the linear regression correlation coefficient R2 was higher as compared to that produced by the three data points. In addition, the two data points represents the initial repaid transportation of MB molecules to the external surface of RH through film diffusion, and therefore cannot be ignored in the application of the IPD model.
- How did authors obtain boundary thickness of 16.401? Please highlight it clearly.
Answer: The sentence was a mistake in our expression. Therefore, we revise the sentence.
Comment 8. What was the ave. size of RH particles before thermal treatment? How did the thermal treatment change the ave. size of the RH. Authors can include those data in the discussion part.
- Adsorption capacity of RH in current work is significantly lower than existing literature. Is there any other benefits of using this material other than presumably low material cost? What’s the main novelty of this work – briefly clarify this in the revised manuscript.
Answer: RH can be easily obtained in developing countries such as Vietnam and Myanmar. And it can be used as it is without heat treatment. In most biomass, the adsorption amount increases when pyrolysis, but the adsorption amount decreases in RH.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Authors took care of majority of the queries. Quality of the manuscript has been significantly improved. The revised manuscript can be considered for publication with the following changes in the final version-
Suggestions-
Authors should include BET experimental details (e.g., sample preparation condition, and instrument details etc.)
- Authors are also encouraged to include BET adsorption isotherm plots of the samples as supplementary information.
Also, please include informational details of the SEM used in this paper.
Author Response
Authors took care of majority of the queries. Quality of the manuscript has been significantly improved. The revised manuscript can be considered for publication with the following changes in the final version-
On behalf of my co-authors, I appreciate you spending your valuable time to review this manuscript.
Suggestions-
Authors should include BET experimental details (e.g., sample preparation condition, and instrument details etc.)
As your comments, we added detail information to analyze specific surface area and pore size in P2 L85-89.
Authors are also encouraged to include BET adsorption isotherm plots of the samples as supplementary information.
The authors also agree with your comments that BET adsorption isotherm plot can provide the pore size distribution of RH. However, we only received information on the result value, but there was no raw data to draw the plot of BET adsorption isotherm.
Also, please include informational details of the SEM used in this paper.
The specifications of FE-SEM used in this study was provided in P2 L84-85.
Author Response File: Author Response.pdf
