Solar Light-Induced Photocatalytic Degradation of Sulfamethoxazole by Cobalt Phosphide-Promoted Bismuth Vanadate

Round 1

Reviewer 1 Report

Review

Manuscript Number: water-2298932

Title:  Solar light‐induced photocatalytic degradation of sulfamethoxazole
by cobalt phosphide promoted BiVO4

In this paper, the authors have synthesized and studied a series of cobalt phosphide (CoP, 0.125-1.00 wt.%) promoted bismuth vanadate (BiVO4) photocatalysts used for sulfamethoxazole (SMX) destruction in ultrapure water (UPW) under simulated solar light irradiation. They were also characterized by means of X-Ray diffraction (XRD), nitrogen isotherm absorption (BET) diffuse-reflectance spectroscopy (DRS) and high-resolution transmission electron microscopy (HRTEM). It was found that the examined system was able to remove >99% of 300 μg/L SMX in deionized water utilizing 80 kJ/L of solar irradiation.

 

There are some questions and remarks to be answered:

1.    The authors should perform a proof reading of the text (some mistakes, typos, greek letters, improve the indexes in the tested parameters, etc.).

2.    There is a lack of graphical abstract.

3.    There is no information on the applied reagents (chemical purity).

4.    There is no diagram or picture of the pilot-scale demonstrator used.

5.    In the equation no. 1 there is no description of the parameters along with the units.

6.    There is a lack of information, concerning the applied method of error analysis, method accuracy and reproducibility, for instance, in Figure 4-8.

7.    How were the optimal conditions for carrying out the process on a pilot scale determined?

8.    In the Conclusions, the authors should explain why the proposed method is better than the existing ones, give its advantages and compare the obtained results with previous literature results.

9.    The Conclusions should be supplemented with the obtained results.

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

 I have reviewed your manuscript titled "Solar light‐induced photocatalytic degradation of sulfamethoxazole by cobalt phosphide promoted BiVO4" and would like to offer some suggestions for improvement.

 

## Overall Comments:

The paper has potential, but there are some weaknesses that need to be addressed. The paper's presentation should be improved to enhance the readers' understanding of the research's significance and findings. The authors have used limited characterization, and the results need to be better explained. In addition, the preparation section also needs to be improved for the reproducibility of work. Therefore, I recommend a careful "Major Revision."

 ##Comments on the title, Abstract, and References:

 The title needs to be revised to include the full name of the compound. Please write bismuth vanadate instead of BiVO4 on the title. The authors should avoid abbreviations in the Abstract. Furthermore, please cite some papers from this journal for better circulation of this paper.

 ##Comments on Introduction:

 The authors should avoid repeating the use of abbreviations and formulas. The authors should discuss the removal of pharmaceutical components from wastewater in more detail. Also, the statement on line 105, "In the present study, cobalt phosphide (CoP) was for the first time deposited on BiVO4 surface to enhance its photocatalytic performance," may not be accurate; please check https://doi.org/10.1016/j.ijhydene.2021.02.094. Additionally, more details are needed about the effects of Sulfamethoxazole, sources in water, concentration in water, and permissible level in the water.

##Comments on Experiments:

 Please add the CAS No. of chemicals and the company details with city and country. Some chemicals were used in the experiment, but they are not listed. Please include everything in the materials section. Also, please provide details on the amount of chemicals used, time, pH, temperature, and the color of the products for the synthesis of CoP and BiVO4. Cited references are not representing the preparation of the same compounds. Furthermore, please rewrite the preparation of CoP/BiVO4 and discuss the solvent's role of DMF, hexane, Ethanol, and Toluene. How did the authors remove these solvents from products? Please provide details on how the authors chose the amount of 125 mg/L for 0.50COO/BiO4. Is it the same amount used for other compounds? Please provide details.

Materials characterization should be provided in detail, such as sample amount, Instrumental analysis conditions.

 ##Comments on Results and Discussion:

 The authors should discuss each characterization result elaborately. More characterization data is needed to explain the formation of CoP/BiVO4. Please provide XPS data and SAED, EDS mapping, or EDS spectra of CoP, BiVO4, and CoP/BiVO4. Please include a zoomed view of Fig. 4 A, especially Ads: 0.125, 0.25, 0.5, and 1.0 CoP/BiVO4. Also, please clarify how inorganic species, such as bicarbonates and chlorides, decrease significantly SMX degradation (line 297). Additionally, please move some sentences from lines 317-332 to the Experimental section.

Please include a separate section, "Limitations of this study." Please also include the regeneration study of the catalyst and how the authors confirm that the treated water is free from this catalyst. Please report any results.

 ##Comments on Conclusion:

Please include the results, limitations, regeneration, and utility in the conclusion section.

Overall, please carefully address the comments provided to improve the paper's quality and clarity. I look forward to seeing the revised

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

This study presents a promising approach to developing efficient and low-cost photocatalysts for the removal of sulfamethoxazole (SMX) from water. By synthesizing cobalt phosphide (CoP) promoted bismuth vanadate (BiVO4) photocatalysts and characterizing them using various techniques, the researchers found that the deposition of small amounts of CoP on BiVO4 significantly enhances SMX degradation under simulated solar light irradiation. The efficiency of the photocatalyst was further investigated in real and synthetic matrices, and in a pilot plant configuration, where it was able to remove >99% of 300 μg/L SMX in deionized water utilizing 80 kJ/L of solar irradiation. These results offer a promising avenue for the development of effective and environmentally friendly methods for removing SMX from water. However, there are some technical issues followed here:

1. Avoid the use of short forms in the title of the manuscript. Give full form of BiVO4.

2. Remove the spaces in the text and maintain consistency. For example, Line 270, section 3.4 title has more space between the words, avoid it.

3. Add errorbars to all photocatalytic application graphs in order to understand the reproducibility of results.

4. Discuss the prepared material's environmental, cost-effectiveness, and application feasibility by comparing the existing similar types of materials, in inorder to justify the low-cost of this material, which the authors mentioned.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All comments were properly taken into account by the authors.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

The authors have done a good job with the revised manuscript. Thank you for it. However, I have some minor comments that need to be addressed for clarity. I recommend the publication of the manuscript after a minor revision. Please review the following points:

1. Line 121: Please include the unit (ng-μg/L) along with the value.

2. Could you please provide the weight of purified BiVO4? Kindly add it to line 170.

3. Line 175: Please mention the exact amount of CoP that was dispersed in hexane, and the amount of hexane used.

4. The authors have not addressed the role of various solvents such as DMF, hexane, EtOH, and Toluene. Please include this information in lines 171-186.

5. Figure S1 requires a detailed description.

 

6. Figure 3c is not meaningful. The authors should provide SEM micrographs and EDS mapping images separately for each element (Co, P, Bi, V, O), and then an overlay image like Fig. 3c. The reviewer also recommends including an EDS spectrum and a table of Atomic weight%. Figure 3 requires careful improvement and explanations of the findings.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx