Depolymerization to Decontamination: Transforming PET Waste into Tailored MOFs for Advanced Pollutant Adsorption

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Sure, this is hot topic, and are worth to be reviewed accordingly. This review summarizes metal-organic frameworks ynthesis from terephthalic acid and ethylene glycol—essential MOF precursors through depolymerized polyethylene terephthalate waste for wastewater treatment. Therefore, I do recommend it acceptance for publication after careful revisions and improvements.

Table 5 lists environmental application of MOF from waste plastics. Please add discussion and comments on detailed mechanistic insights and performances for each case, for instance, how Ni-MOF works as efficient CO2 photoreduction on the basis of MOF structure and working mechanism.

most Chemcial equations in Table 1 summarizing depolymerization methods, are vague. In particular, alkaline hydrolysis appears wrong.

 

Author Response

Author Response to Reviewer and Editor Comments

Manuscript ID: physchem-3691715
Type of manuscript: Review
Title: Depolymerization to Decontamination: Transforming PET waste into
tailored MOFs for advanced pollutant adsorption
Authors: Asma Nouira , Imene Bekri Abbes
Received: 25 May 2025

 

We would like to express our sincere thanks to the reviewers for their thoughtful and constructive comments, and to the editor for the careful and professional handling of our manuscript. The feedback provided has been highly valuable in helping us improve the clarity, accuracy, and overall quality of our work. All suggested corrections have been carefully addressed, and the corresponding changes are marked in red in the revised manuscript

 

 

Review 1

Table 5 lists environmental application of MOF from waste plastics. Please add discussion and comments on detailed mechanistic insights and performances for each case, for instance, how Ni-MOF works as efficient CO2 photoreductionon the basis of MOF structure and working mechanism.

We sincerely appreciate the reviewer’s constructive feedback. As suggested, we have enhanced Table 4 (table 5 in the first version) (page 19) and text (page 18-19) by incorporating detailed discussions on mechanistic insights and performance metrics for each case of waste-derived MOFs in environmental applications.

2-mostChemcial equations in Table 1 summarizing depolymerization methods, are vague. In particular, alkaline hydrolysis appears wrong

Thank you very much for your valuable comment regarding Table 1 and the chemical equations summarizing the depolymerization methods. We greatly appreciate your careful observation and constructive feedback. In response, we have revised Table 1 to correct and clarify the chemical equations (page 6). Additionally, due to the limited space within the table columns, it was difficult to insert a clear image directly into the table. Therefore, we have replaced the previous image with a detailed mechanisms to enhance clarity and eliminate any ambiguity. Corrections are in red in the text (page 6).

 

Reviewer 2 Report

Comments and Suggestions for Authors

The review is devoted to the transformation of PET polymer waste into Metal-Organic Frameworks and to the applications of PET-derived MOFs for pollutant adsorption. So, the review covers three areas: PET recycling by different methods, synthesis of MOFs from the compounds issued from PET waste, applications of these MOFs. Authors’ intention is valuable, but such large covering leads to several drawbacks on the presence of some important information, not optimal text structure for easy understanding. After revision, the review can be reconsidered for publishing. Some points and issues are presented below.

1. The manuscript is not always well structured. Why to separate the sections 3.1, 3.2 , 3.3 and 3.4. by this manner? Why not to start with main methods, then to present all the results classified by method and summarized in one or two tables?
2. The drawbacks of different PET treatment methods should be better presented.
3. It is quite strange that the requirement of high-pressure expensive reactors is given as the main drawback of neutral hydrolysis (section 2.3.3), whereas for other methods the pressures and temperatures are similar or even higher than for neutral hydrolysis.
4. The problematics of MOF synthesis from waste PET is not sufficiently discussed. In some examples there is some discussion on impurities, but in general it is not well presented. It is not clear from the manuscript why not to purify the obtained BDC, then to use it in common MOF synthesis.
5. The quality of MOFs obtained from PET waste merits a separate general discussion, even if it is mentioned in the description of some works.
6. In the section 2.3.3, the part on acid hydrolysis is presented before alkaline hydrolysis, whereas it refers several time to the last one. Why to not change the order?
7. Section 2.3. PET aminolysis is mentioned, but never presented. Possibly, this is not an optimal method for waste PET-derived MOF synthesis, but this should be mentioned.
8. The same page, section 2.2.3. Table 2 caption from another article is mentioned.
9. The Figure 1 is not well done (no a). b). c).; application and synthesis quite basic and not well presented and badly referenced in the text), its utility is not evident in present form. Schematic of MOF synthesis is primitive, organic linkers seem to be presented as carbon chains, whereas for MOFs they are generally rigid aromatic molecules.
10. Table 1 is quite strange and not well presented. Why not to unite all the synthesis of MOFs from PET waste together? Why to present unsuccessful methods in spite of discussion of synthesis strategy in the text of this section? A column on synthesis drawbacks is welcome. The synthesis procedures are not always clearly described.
11. The conclusions are poor, the discussion on the problematics of MOF synthesis the quality of obtained materials is not sufficient.

Comments on the Quality of English Language

The manuscript should be read one more time after revision to correct some misprints and unclear sentences present in current version. 

Author Response

Author Response to Reviewer and Editor Comments

Manuscript ID: physchem-3691715
Type of manuscript: Review
Title: Depolymerization to Decontamination: Transforming PET waste into
tailored MOFs for advanced pollutant adsorption
Authors: Asma Nouira , Imene Bekri Abbes
Received: 25 May 2025

 

We would like to express our sincere thanks to the reviewers for their thoughtful and constructive comments, and to the editor for the careful and professional handling of our manuscript. The feedback provided has been highly valuable in helping us improve the clarity, accuracy, and overall quality of our work. All suggested corrections have been carefully addressed, and the corresponding changes are marked in red in the revised manuscript

 

 

Review 2

1-The manuscript is not always well structured. Why to separate the sections 3.1, 3.2 ,
3.3 and 3.4. by this manner? Why not to start with main methods, then to present all the
results classified by method and summarized in one or two tables?
We appreciate the reviewer’s constructive feedback regarding the organization of Sections
3.1–3.4. Our structuring aligns with the logical progression of PET-derived MOF
development:
1. Section 3.1 (Early Development) provides historical context, highlighting foundational
challenges and successes in PET-to-MOF synthesis, which informs later
methodological advancements.
2. Section 3.2 (Preparation Methods) distinguishes between direct and indirect synthesis
routes, emphasizing their unique advantages and limitations (summarized in Table 2).
3. Section 3.3 (Techniques of sythesis) delves into specific synthetic methodologies (e.g.,
solvothermal, mechanochemical), as their optimization is critical for addressing
impurities and defects noted in Section 3.1.
4. Section 3.4 (Ligand Variants) explores alternative PET-derived linkers (e.g., BHET,
DST), showcasing how monomer selection influences MOF properties.
This separation ensures clarity in tracing the evolution of PET-derived MOFs—from early
proof-of-concept to advanced applications—while Tables 2, 4, and 5 consolidate key data for
cross-referencing.
Additionally, to minimize the number of tables in the manuscript ,the table summarizing
ligands is now presented in a figure ( Figure 4, page 17)

2-The drawbacks of different PET treatment methods should be better presented.

We have comprehensively addressed the reviewer's request for clearer presentation of
advantages and drawbacks in PET recycling methods through significant revisions to our
analysis. The updated comparative table now features dedicated columns highlighting both
benefits and limitations of each technique. The table 1 is in red  (page 6)

3-Table 1 is quite strange and not well presented. Why not to unite all the synthesis of
MOFs from PET waste together? Why to present unsuccessful methods in spite of
discussion of synthesis strategy in the text of this section? A column on synthesis
drawbacks is welcome.

We sincerely appreciate the reviewer’s valuable feedback regarding the presentation of MOF
synthesis methods from PET waste. In response to your concerns, we have made the
following revisions to improve clarity, organization, and relevance:
1. Reorganization of Synthesis Methods:
o We have restructured the section to provide a clearer and more logical flow,
beginning with the early developments in PET-derived MOFs (Section 3.1),
followed by a detailed discussion of direct vs. indirect synthesis
approaches (Section 3.2), and concluding with  techniques of synthesis
(conventional and non conventional)(Section 3.3).
o This reorganization ensures a progressive narrative, from foundational research
to advanced methodologies, while maintaining focus on successful strategies.

2. Removal of Unsuccessful Methods from Tables:
o As suggested, we have omitted unsuccessful synthesis attempts from the tables
to prioritize clarity and relevance. Instead, these are now discussed in the text
(Section 3.1) to provide context for challenges and optimizations.
o A new Table 3 (page 17) summarizes recent advances (2024–2025) in PET-
derived MOF synthesis. This table serves as a quick reference for readers for
new works.

3. Addition of Synthesis Drawbacks:
o A dedicated column in Table 2 (page 12) (Direct vs. Indirect Methods) now
outlines key limitations (e.g., purity control, energy consumption, scalability)
for each approach.

4. New Paragraph on Recent Advances (2024–2025):
o A new subsection (3.4, page 15) synthesizes cutting-edge studies, emphasizing
trends like microwave-assisted synthesis, waste-metal integration, and
bimetallic MOFs.

Key modifications are highlighted in red in the revised manuscript for ease of review.
4-The problematics of MOF synthesis from waste PET is not sufficiently discussed. In
some examples there is some discussion on impurities, but in general it is not well
presented. It is not clear from the manuscript why not to purify the obtained BDC, then
to use it in common MOF synthesis
We sincerely appreciate the reviewer’s insightful critique regarding the need for deeper
discussion on the challenges of MOF synthesis from PET waste, particularly concerning
impurities and purification strategies. In response, we have significantly expanded our
analysis with a New Added a comprehensive subsection titled "3.7 General Considerations
on the Quality of PET-Derived MOFs " (highlighted in red, page 20) that systematically
addresses:
Sources of impurities: Residual additives (plasticizers, dyes), oligomers from incomplete
depolymerization, and metal contaminants from waste sources.
Impact on MOF properties: How impurities affect crystallinity (e.g., XRD peak
broadening), porosity (reduced surface area), and adsorption performance (site blocking).
Comparative analysis: PET-derived vs. commercial-terephthalate MOFs, emphasizing trade-
offs between sustainability and material quality.

5-The quality of MOFs obtained from PET waste merits a separate general discussion,
even if it is mentioned in the description of some works.

We sincerely appreciate the reviewer’s astute observation regarding the need for a dedicated
discussion on the quality of PET-derived MOFs. In response, we have Added comprehensive
subsection titled "General Considerations on the Quality of PET-Derived MOFs" (highlighted
in red, page 20)
6-In the section 2.3.3, the part on acid hydrolysis is presented before alkaline hydrolysis,
whereas it refers several time to the last one. Why to not change the order?

We thank the reviewer for this relevant observation. We agree that presenting alkaline
hydrolysis first improves the logical flow of the section, especially since acid hydrolysis
refers to it multiple times. Accordingly, we have revised the order in Section 2.3., placing
alkaline hydrolysis before acid hydrolysis.
7-Section 2.3. PET aminolysisis mentioned, but never presented. Possibly, this is not an
optimal method for waste PET-derived MOF synthesis, but this should be mentioned.

We thank the reviewer for this pertinent remark. PET aminolysis is indeed briefly mentioned
but was not elaborated upon in the original manuscript. As suggested, we have now added a
paragraph in Section 2.3.4 discussing aminolysis and is marked in red at page 8 ,

8-The same page, section 2.2.3. Table 2 caption from another article is mentioned.
We appreciate you pointing out the error in Table 2's caption in Section 2.2.3. We've
corrected this oversight.

9-The Figure 1 is not well done (no a). b). c).; application and synthesis quite basic and
not well presented and badly referenced in the text), its utility is not evident in present
form. Schematic of MOF synthesis is primitive, organic linkers seem to be presented as
carbon chains, whereas for MOFs they are generally rigid aromatic molecules.

We sincerely appreciate the reviewer's valuable feedback regarding the visual presentation of
MOF synthesis and applications. In response to these concerns, The previous schematic has
been removed and replaced with a new, more technically accurate Figure 2 (page 8)

Table 1 is quite strange and not well presented. Why not to unite all the synthesis of
MOFs from PET waste together? Why to present unsuccessful methods in spite of
discussion of synthesis strategy in the text of this section? A column on synthesis
drawbacks is welcome. The synthesis procedures are not always clearly described.
We sincerely appreciate the reviewer's constructive feedback regarding the presentation of
MOF synthesis methods from PET waste. In response to your valuable suggestions, we have
implemented the following significant improvements by table Elimination and
Reorganization: The original Table 1 has been removed entirely to address the concerns
about unclear presentation and inclusion of unsuccessful methods and in
Section 3.1 (page 10) (Early Development of PET Waste-Derived MOFs): we Provides
historical context and foundational synthesis approaches.

The conclusions are poor, the discussion on the problematics of MOF synthesis the
quality of obtained materials is not sufficient
We appreciate your valuable remark regarding the conclusion. We've taken your feedback
into careful consideration and have revised the conclusion accordingly to address your points
(in red,page 28-29).

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have successfully addressed my concerns. I am satisfied with sufficient changes, thus suggest acceptance it for publication in the current form.