Enhancement of Leaching Copper from Printed Circuit Boards of Discarded Mobile Phones Using Ultrasound–Ozone Integrated Approach

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

General comments

 

In this paper a symbiotic effect between ultrasound and ozone was applied for leaching Cu from mobile phone printed circuit boards (MP-PCBs). Also, the influence of key parameters for establishing the optimal conditions for Cu recovery were also investigated from plates of MP-PCBs.

My comments and suggestions are presented below:

1.      The title must be attractive to readers and provide information about efficient recovery or ecological recovery methods, etc.

2.      Improve the abstract and talk about the techniques used for liquid and solid phase analysis.

3.      In the introductory part, talk about the advantages and disadvantages of this synergistic effect.

4.      Highlight the novelty and originality of the paper through the synergistic effect to don’t become just a routine work.

5.      Write the methodology for each parameter studied. Also, in the methodology part, you presented the characterization of the solid phase for the last time, and in the results and discussions, you started with this. Please place an order.

6.      Draw a conclusion for each presented result. Also, please highlight better the explanation of the leaching phenomenon.

7.      Try to indicate some applications of the obtained leachate. After you recover the metals, what do we do with it in the context of the circular economy?

8.      Explain why 3M HCl is the optimal acid concentration for efficient metal leaching and why depending on the acid concentration we have different colors of the leachate.

Author Response

Thank you for handling our manuscript. We have carefully addressed these comments. The point-by-point responses are attached to this letter. Changes made to the manuscript are highlighted in the manuscript. A revised manuscript is resubmitted.

Author Response File: Author Response.pdf

Reviewer 2 Report

I have carefully reviewed this paper on the extraction of copper from printed circuit boards, which referred the leaching combining ultrasound and ozone conditions. Unfortunately, apart from finding the optimal leaching parameters, I have not found any more valuable points. In addition, there are many previous studies on ultrasonic leaching to extract copper, and the author should have provided new insights in ozone leaching and focus more on it. However, apart from the relevant chemical reaction equations, I seem to be unable to find more information. Therefore, I do not recommend publishing this paper in Metals, here are my reasons:

(1) What is the source of ozone? The introduction did not stress this point.

(2) What are the components of the leaching solution? Leaching copper alone is not enough, and it is necessary to separate copper from the leachate. Do other elements, such as iron and aluminum, have an impact on the leaching and separation process of copper?

(3) What are the components of the leach residue? How to utilize other valuable elements besides copper?

(4) The blue-green color of the leaching solution is not sufficient to indicate the problem, as other ions are not colorless, such as ferric ion.

(5) The characterization method is too simple to support the conclusion.

• I am not qualified to evaluate the English language, but the overall is readable.

Author Response

Thank you for handling our manuscript. We have carefully addressed these comments. The point-by-point responses are attached to this letter. Changes made to the manuscript are highlighted in the manuscript. A revised manuscript is resubmitted.

Author Response File: Author Response.pdf

Reviewer 3 Report

Authors have conducted a detailed investigation of Leaching copper from printed circuit boards of discarded mobile phones by ultrasound and ozone. The manuscript highlights the factors influencing the leaching efficiency and the characterization studies. Authors have studied in detail the effects of parameters such as ultrasound, ozone dose, HCl concentration, liquid/solid ratio, temperature, and reaction time on the leaching efficiency and reasons for the variations are explained in detail. 

Authors need to report the activation energy value associated in the reaction.  

Author Response

Thank you for handling our manuscript. We have carefully addressed these comments. The point-by-point responses are attached to this letter. Changes made to the manuscript are highlighted in the manuscript. A revised manuscript is resubmitted.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

 

Dear authors, I have read your answers.

Please, come back to the following aspects.

Please, separate the methodology and add in the article the answer to question no. 8 given for the color of the leachate.

Also, the answer for question no. 8 regarding the influence of acid concentration is not fully explained.

Author Response

Dear Reviewer,

Thank you for your valuable comments. We have made changes accordingly and attached the response letter below. We hope that our answers have fulfilled your comments.

Thank you for your concerns.

Best regards,

Dung Thuy Nguyen Pham.

Author Response File: Author Response.pdf

Reviewer 2 Report

The quality of the manuscript has improved, and according to the suggestions given by other reviewers, the manuscript can be considered for acceptance after completing the revisions.