Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing

Round 1

Reviewer 1 Report

The manuscript can consider for publication in the present form

Author Response

To Processes Editors and Reviewers,

Thank you for your letter regarding our manuscript “Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing” (Processes-1507420). We are grateful for the constructive feedback you have provided. We have carefully reviewed your feedback and have made changes to the manuscript item by item to address all your comments.  Please find the proposed corrections attached.

Reviewer 2 Report

The authors presented an interesting manuscript for electronic waste recycling, based on a polymer processing approach. The paper is well written in a clear manner. English is overall accurate requiring only some minor editing.

The authors selected a good number of references for their document. However, it seems that the field of polymer in electronic waste is wider and needs upgrade. Please, look if the DOI suggestions are appropriate:

• 1007/s10965-021-02678-9
• 3390/pr8010053
• 1007/s002160000392
• 3144/expresspolymlett.2012.95
• 1016/j.eurpolymj.2005.04.001
• 4322/polimeros.2014.004
• 1021/acsomega.0c01884
• 1177/0734242X10391528
• 1007/s13762-021-03285-3
• 1007/s11783-017-0991-x

The proposition deals with the mechanical separation of polymers prior to their chemical separation and physical recovery. How disruptive is that in comparison with other methods to process the non-metallic fraction in e-waste? A research statement with a clear novelty presentation would be appropriate on that manner.

Based on that, pyrolysis, gasification, and combustion are widely adopted for polymeric removal from e-waste. It is true that the polymers cannot be reused and are mostly transformed focused on oil production or only on metal recovery. However, it is not clear how the authors compare their process footprint in comparison to the thermochemical alternative that is mentioned critically in Introduction. Their emissions and halogen fate should be compared (mass-balance is an option) as well as the environmental restrictions associated with each solvent studied addressed to assess the process applicability based on that point-of-view.

In terms of process economical viability, the value on metals is much higher than those on polymers. How the introduction of such process in the typical flowchart for metal recovery could contribute for an operation revenue as lucrative co-product? How such alternative could be competitive on that context in comparison with full polymer transformation and removal from metallurgical recovery route?

Non-metallic fraction encompasses ceramic and polymeric substances. The former is basically fiberglass. The fate of ceramics is not clear on the proposed process. How ceramics behave in that process?

The materials characterization is not well presented. Some techniques are listed in Materials and Methods but it could not be observed which one was used in the results presented in Figures 2 to 6. Moreover, the method to calculate the results in Figure 7 is not presented in detail. ESR is only characterized by means of polymeric materials. However, the authors mentioned that the received material was processed by means of hand-sorting and magnetic separation. How effective were these unit operations? How can the authors guarantee that non-magnetic metals such as fine wires of copper, mostly shredded, do not report to any of the obtained products? Why did the authors do not evaluate ESR and the recovered streams by means of SEM/EDS, XRF and XRD?

Author Response

To Processes Editors and Reviewers,

Thank you for your letter regarding our manuscript “Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing” (Processes-1507420). We are grateful for the constructive feedback you have provided. We have carefully reviewed your feedback and have made changes to the manuscript item by item to address all your comments.  Please find the proposed corrections attached.

Author Response File: Author Response.docx

Reviewer 3 Report

Dear Editor,

In the manuscript presented, the authors tried to find a method to dissolve electronic shredder residue (ESR) using various solvents such as : DCM, tetrahydrofuran (THF), toluene, and acetone.

Analyzing the data obtained by the authors, I would have some questions:

-firstly, how they chose these solvents and and secondly whether they thought of mixing them 

-did they try to increase the temperature in solvents to see if the solvents have better effect?

-at page 4 row 160 if possible please put in evidence that you use each solvent separately.

-please add in suplimentary the TG,  DSC and FTIR figures

 

Author Response

To Processes Editors and Reviewers,

Thank you for your letter regarding our manuscript “Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing” (Processes-1507420). We are grateful for the constructive feedback you have provided. We have carefully reviewed your feedback and have made changes to the manuscript item by item to address all your comments.  Please find the proposed corrections attached.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I am satisfied with the progress that authors implemented on their manuscript. Some minor spell checking is required as well as text formatting, but these could be taken into effect after acceptance.