Material Recycling of Plastics—A Challenge for Sustainability

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper innovatively addresses the challenges posed by the increasing complexity of plastic polymers and additives on high-quality recycling, particularly focusing on the issue of "legacy additives." It summarizes the difficulties in recycling mixed plastic waste containing regulated or banned additives and recommends avoiding the use of such recyclates in consumer-contact products.

The recycling and disposal of plastic waste have become extremely difficult due to the use of additives, so an overview of this area is extremely important. Some issues need to be improved before publication.

 

1. The abstract should include the most important information from the paper, including the research purpose, key findings, and main conclusions. Ensure there are clear transitions between each section.

2. Introduction should reference more literature, supporting problem statements and research necessity, especially on plastic additives and recycling policies.

3. The Introduction should briefly explain the paper's organization, detailing the content and logical relationships of each section.

4. To distinguish from Section 2.1 "Plastics", can the title of Section 2.2 be changed to Copolymers? Additionally, is the title of the Section 2 appropriate?

5. Recommend adding images or other visual aids to help readers better understand the complexity of plastic recycling, the impact of additives, and the effectiveness of different policies. This will significantly enhance the readability and appeal of the article.

6. Recommend providing a detailed comparison of different types of plastic recycling methods, such as mechanical and chemical recycling. Analyze their respective advantages, disadvantages, and applicability to give readers a comprehensive understanding of the differences between these recycling approaches.

7. The author should further explore the environmental and economic impacts of plastic and additive recycling, especially the economic feasibility of high-quality recycling and its potential contribution to climate policies. Additionally, it is recommended that the author clearly define standards for high-quality recycling, thereby enhancing the depth and practicality of the article.

8. The paper should propose future research directions, identifying current shortcomings and pressing issues that need addressing, particularly in the innovation of plastic recycling technologies and policy improvements. This will provide valuable guidance for researchers in the field.

Author Response

Thank you very much for taking the time to review this manuscript and your constructive comments and valuable hints. Please find the detailed responses below and the corresponding revisions/corrections in track changes in the re-submitted file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is a study that discusses the use of post-consumer plastic materials in the production of new products. In this context, the authors bring an important reflection on the presence of dangerous compounds/additives in post-consumer artifacts and their reuse in products that come into direct contact with the consumer, such as children's toys, plastic packaging, kitchen utensils and textile products. .

The authors also discuss the different types of additives present, concentrations, persistence during recycling cycles, risks in the migration process of these components and the regulation of POPs (Persistent Organic Pollutants). Such discussions bring the reader reflections on the current policies that regulate recycling processes and the risks that involve circularity processes, which are so much talked about today.

An also interesting discussion is about human exposure to Legacy additives, bringing current data already published on the subject and which are worth our reflection.

The authors propose a type of moratorium on the use of post-consumer recycled plastics, that is, non-use of post-consumer materials that could pose a risk to human health in the production of new products that would have direct contact with the consumer. According to the authors, this proposal is based on recent studies that show high levels of dangerous and prohibited additives in recycled materials. The authors also propose high-quality closed-loop recycling as a solution. What I believe, in practice, is quite complicated, since it would initially be necessary to have a detailed characterization of post-consumer materials, which would lead to the need for the actual identification of the components and their levels present in the artifacts, which would imply the purchase of expensive equipment and hiring specialists to evaluate the analysis results, which for a recycler, in its current form, would not be viable.

This work brings a provocative and positive discussion, as it raises already consolidated questions about circularity for debate. In this sense, I believe that this subject deserves to be published so that the scientific community interested in the areas of circular economy, recycling and reuse of solid plastic waste can discuss the subject.

To improve the manuscript, authors must make clear, both in the abstract and in the introduction, the objective of the work and its innovation.

Authors should amend the "Materials and Methods" chapter. For the work context, it does not apply.

Author Response

Thank you very much for taking the time to review this manuscript and your constructive comments and valuable hints. Please find the detailed responses below and the corresponding revisions/corrections in track changes in the re-submitted file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised manuscript is suggestted to be acceptted in the present form.