Degradation of 2-Chlorophenol in Aqueous Solutions Using Persulfate Activated by Biochar Supported Sulfide-Modified Nanoscale Zero-Valent Iron: Performance and Mechanisms

Round 1

Reviewer 1 Report

 

1.       Lines 27-34: Some references should be cited.

2.       The typical concentration of 2-CP in aquatic environment, especially in groundwater, should be supplemented.

3.       Other important AOPs, such as activated peracetic acid process (10.1016/j.seppur.2022.120716, 10.1016/j.seppur.2023.124083 and 10.1016/j.cej.2022.138588) should be cited in lines 38-40.

4.       The writing style of radicals should be corrected according to the following reference: “Koppenol, W. (2000). "Names for inorganic radicals (IUPAC Recommendations 2000)." Pure and Applied Chemistry 72(3): 437-446.”

5.       Lines 157-163: Pls provide the radical trapping agents used in ESR.

6.       It’s very strange to make figures using reaction kinetics while mentioned removal efficiencies in manuscript (Figures 2-6), pls clarify.

7.       Section 3.3.1: the result of effects of different initial 2-CP concentrations is very strange, pls explain in depth.

8.       Lines 261-268: The activation energy can be calculated according to the Arrhenius equation model.

9.       References style should be revised.

Author Response

We provide a point-by-point response to the reviewer’s comments and upload it as a Word file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Herein, I submit my comments for initial submission of the manuscript entitled: “Degradation of 2-chlorophenol in aqueous solutions using Persulfate activated by Biochar Supported Sulfide-modified Nanoscale Zero-valent Iron: performance and mechanisms”.

Comments for author File: Comments.pdf

Author Response

We provide a point-by-point response to the reviewer’s comments and upload it as a Word file.

Author Response File: Author Response.pdf

Reviewer 3 Report

This study investigated the degradation of 2-chlorophenol using persulfate with biochar supported Sulfide-modified zero-valent iron. The results look good, but there are some comments that need to be addressed before publication.

Specific comments:

1.       The data presentation in figures to express the degradation efficiency of 2-chlorophenol. It is hard to read the percentage unless the readers do the calculations. And why did the authors use ln(C/C0) vs reaction time and add the linear trend lines in the figures? I recommend using the  remove efficiency of 2-CP or C/C0 vs reaction time to present the data.

2.       Do the authors propose that the degradation reaction is the first-order reaction? I did not see the discussion in the manuscript. In some cases, they fit the first-order reaction, but in other cases, they did not fit, especially pH=9 and pH=11 in figure 5(a), 2-CP=100 mg/L in figure 4. Please explain why.

3.       Did the author see any intermediate degradation products during the reaction time? In the Methods part, GC-FID was used to determine 2-CP concentration, are any other peaks showed up in the chromatographs?

4.       In section 3.4, how do the authors weigh the contributions rate for each chemical factor? Only the intensity of DMPO-•OH and DMPO-SO4•- were measured by ERS. How about the contribution of “oxidation of PS” and “function of BC@S-nZVI”? If possible, please provide the degradation pathway of 2-CP in this reaction system.

5.       In figure 6(b), ln(C/C0) was not close to 0 at the beginning of time point, why? Does that mean nitrate can enhance the absorption of 2-CP to the surface of catalyst? This is very interesting. The authors should mention this in the manuscript and add some discussion.

6.       In figure 4, why did the removal efficiency of CP increase and then decrease when the initial concentration of 2-CP increases from 20 to 100 mg/L?

7.       In Line 321, please add more references for the adsorption and reductive de-chlorination of 2-CP with nZVI.

8.       Line 121, please remove milliliters.

9.       Line 142, please use BC@S-nZVI to replace “biochar supported sulfide-modified nanoscale zero-valent iron”.

10.   Line 366-367, please delete the last sentence since the relatively low temperature will limit the application of BC@S-nZVI/PS system in ISCO of groundwater showed in Line 266-268.

Showed in comments above.

Author Response

We provide a point-by-point response to the reviewer’s comments and upload it as a Word file.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The article was improved by the authors, nevertheless, I still consider things are still missing. I submit my comments for the second revision round of the manuscript entitled: “Degradation of 2-chlorophenol in aqueous solutions using Persulfate activated by Biochar Supported Sulfide-modified Nanoscale Zero-valent Iron: performance and mechanisms”. 

Comment 1: The selection of soybean as raw material for the synthesis of the biochar should be related to the cultivation areas reserved for this product, as well as the percentage of residues generated from it. Please add these numbers.

Comment 2: In my previous review, I was asking for the temperature range, nevertheless, reviewing the title of figures 2-9 it seems like the evaluated temperature was 30 °C, not different reaction temperatures as the authors claim. Please explain.

Comment 3: Regarding the SEM images, the same: magnification should be stated in the legend of Figure 1.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Thanks for your revision. The quality of this manuscript improved a lot. However, there are several comments before publication.

1.       For the comments 1, I still recommend using the  remove efficiency of 2-CP or C/C0 vs reaction time to present the data. Because in the manuscript, the data of removal rate was shown, but if the logarithmic form of the ratio was used in the figure, it is hard to get the removal rate directly.

2.       For comment 4, please add some of those response to the manuscript to describe how to calculate the contributions.

3.       For comment 6, I looked close to Figure 4, and the data point for the case with the concentration of 2-CP at 100 mg/L were very close to those at 50 mg/L except the last time point (48 h). Could you please add the explanation for this? Is there diffusion-limit step during the reaction?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf