Enhanced Photocatalytic Degradation of Rhodamine-B under Led Light Using CuZnAl Hydrotalcite Synthesized by Co-Precipitation Technique

Round 1

Reviewer 1 Report

Recommendation: This paper is publishable subject to major revisions noted

Ms. Ref. No.: inorganics-1735191

Title: Enhance the efficiency of rhodamine-B degradation under led light using the CuZnAl hydrotalcites as photocatalyst

Comments to Author:

Overview and general recommendation:

In this study, the authors report Cu-modified ZnAl-hydrotalcite materials by co-precipitation. They varied the Cu molar ratio from 0-3.5 and studied the photocatalytic degradation of a dye rhodamine-B (Rh-B). They performed XRD, SEM -, TEM -, EDX, BET - and UV-Vis analyses to characterize the structural, morphological, compositional, and optical properties of the synthesized samples. The synthesize Colloidal particles with three diameters were prepared by semi-continuous emulsion polymerization, which responded to UV radiation CIS. The morphology of the particles was determined by TEM, the diameter of the particles by DLS, and the optical properties by UV-Vis and fluorescence spectroscopy.

I found that some critical points were inadequate or missing altogether. I have very little confidence in the analysis and have too many questions to recommend this work for publication in its current form. Therefore, I recommend that the manuscript is not suitable for publication in its present form. I explain my concerns in more detail below.

Major Compulsory Revision:

1. I suggest the authors modify the title. For example, Enhanced photocatalytic degradation of rhodamine-B under led light using CuZnAl hydrotalcite synthesized by co-precipitation technique.
2. The introduction is not well structured and the problem is not clearly stated. The introduction can be changed to put more emphasis on the synthesis method and the limitations of different methods to synthesize CuZnAl hydrotalcite. The introduction does not clearly outline the research question. I suggest the authors provide a literature review of previous studies and their limitations and how their method is better.
3. I suggest that the authors divide the introduction into several paragraphs, with the last paragraph highlighting the main points of their research and what to expect from this article.
4. I suggest that the authors provide a table with all parameters such as "a", "d", average grain size, etc. for all samples for clarity.
5. The reproduction of materials and experiments is very important for the dissemination of scientific knowledge. I suggest that the authors provide the methods/tools for characterization and also the details of the absorption, PL, and reflection measurements. For example, in Figure 2, the absorption and PL measurements were made with visible light immediately after UV light irradiation for 120 s, or how? How was the reflectance measurement performed at different angles? The sample is quite large (4 × 4 cm), at how many points were the measurements performed? What was the size of the measurement spot, etc.
6. Figure 2, please provide the SEM and TEM for all prepared samples shown in Figure 1. For clarity, label the SEM /TEM images with the name of the sample for easy reference.
7. Page 4, using EDX spectrum the authors claim that “It was possible to attach the H material with the composition Zn4Al2CO3(OH)12.3H2O, which is a component of the mineral Zaccagnaite.” However, the authors did not draw any conclusions about the exact composition of the synthesized material from the XRD and EDX spectra. The authors should provide conclusive evidence and arguments for the present phase of the material.
8. Table 2, What is the reason for the decrease in the total porous diameter of H- CuH3.0. and why does the porous diameter increase from CuH1.0 to CuH3.0?
9. I suggest the authors should also present a scheme of the bandgap representing the degradation process.
10. Figure 6 and Figure 7 show that the 30 ppm Rh-B in sample ChH3.0 degrades to 20% of its initial concentration in about 90 minutes (Figure 6), while it took only 30 minutes (Figure 7) in the second figure. Why? How many times was the experiment repeated? I suggest that the authors also include the SD in the data plots [Figures 6-9 and 10(a)] along with the number of observations for each sample.
11. Authors should also provide the purity of the chemicals used in the methods section.

Minor Revisions:

12. The paper contains a lot of grammatical and typographical errors. This frequency is not simply an oversight, and it is appropriate to ask the authors to hire a professional editing service to revise the language of the manuscript.
13. The number of figures (11) and tables (3) is very high. I suggest the authors either combine them or move some of them to the ESI to reduce the number.

These issues must be resolved before the work can be published.

Author Response

Dear Editor and reviewers,

We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of our manuscript. We have tried our best to respond to all issues indicated in the review report sufficiently. In the revised version, we have highlighted the changes to our manuscript using the yellow color. The answers to the questions you raised are detailed here.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Manuscript by Thi Ha Thanh Pham et  al. describes a standard test for photocatalytic dye oxidation. In addition to the dubious scientific novelty of the study, a large number of questions arise regarding the implementation of the experiment and the quality of the work design.

1. English language and punctuation should be improved throughout the text.

2. It is not clear from the experimental part which wavelength was used for illumination, and this is a fundamental question. Authors only write about 30 W LED.

3. Total organic carbon should be measured during the experiment.

4. TiO2 Evonik (Degussa) P25 should used as a benchmark.

5. Table 2. Too many significant digits.

6. Figures 6-10. The error of measurements should be shown.

7.  The biggest question is the rationale for choosing a photocatalyst. The introduction should clearly explain why this particular material was chosen.

The manuscript may only be re-reviewed after making all of these changes.

Author Response

Dear Editor and reviewers,

We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of our manuscript. We have tried our best to respond to all issues indicated in the review report sufficiently. In the revised version, we have highlighted the changes to our manuscript using the yellow color. The answers to the questions you raised are detailed here.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have made significant changes in several parts of the paper to reflect the previous major revisions. I recommend the manuscript for publication after a minor grammatical review.

Author Response

Dear Editor and reviewers,

Thank you for your favorable response to our manuscript.

We appreciate the expenditure of your time and effort in considering our manuscript and we look forward to hearing from you soon.

Author Response File: Author Response.docx

Reviewer 2 Report

I'm satisfied with the review.

Author Response

Dear Editor and reviewers,

Thank you for your favorable response to our manuscript.

We appreciate the expenditure of your time and effort in considering our manuscript and we look forward to hearing from you soon.

Author Response File: Author Response.docx