We would like to thank the editor for giving us a chance to resubmit the paper, and also thank the reviewers for giving us constructive suggestions which would help us both in English and in depth to improve the quality of the paper. Here we submit a new version of our manuscript with the title “………………………”, which has been modified according to the reviewers’ suggestions. Efforts were also made to correct the mistakes and improve the English of the manuscript. We mark all the changes in red in the revised manuscript.
The following is a point-to-point response to the two reviewers’ comments.
Reviewer #1: The paper presents an interesting experimental investigation to assess the photocatalytic degradation of polyethylene plastic with goethite under UV irradiation. The research work is clearly presented but the conclusions, the introduction and other parts of the paper relate the results obtained with unjustified claims about the impact of the work. In addition, the background information provided in the introduction part needs significant enrichment. In particular:
Answer: Thank you for the comments on the paper. We have revised the manuscript as suggested since we consider that some sentences or descriptions in the Conclusion part are not so accurate based on the results. Page 3, line 46: recycling is not available…
Even though a large amount of agricultural plastic waste in burnt or buried in the fields, some quantities of specific categories of good quality agricultural plastic waste are recycled in several countries while research efforts and projects are in progress to improve the corresponding percentage. The authors should refer to the corresponding recent literature.
Answer:Yes. Your opinions inspired us and we revised the manuscript accordingly. In the revised paper, the sentence “Recycling is not available for economy,” was changed to “In order to reduce costs, the thickness of application agriculture films in some regions in China is less than 0.005 mm result in diffcult to recycle, And because the process of recycling is expensive and time-consuming, only a small percentage of the agricultural plastic waste is currently recycled at the end of cultivation in China ”(Page 3 line 49-52). Page 3, line 76: biodegradable and photodegradable….
There are developments in the area of biodegradable materials that indicate the opposite. Concerning photodegradable materials, they are not considered to represent a solution as they have not been proven to be biodegradable. The authors should refer to the corresponding recent literature.
Answer: Thank you for reminding us the improper description on the study. We have the improper parts revised accordingly and hope that this new manuscript will be convincing ( Page 3 line 52-55). Page 4, line 65: find an eco-friendly….
The best eco-friendly disposal for agricultural plastic waste is recycling and for non-recyclable materials, energy recovery. Degrading materials produced from fossil sources is not an eco-friendly disposal! The authors should refer to the corresponding recent literature.
Answer: Thank the reviewer for the comments. We’ve recognized that some of the descriptions in the previous copy were really not so accurate and a little bit arbitrary due to our poor English level and the study on recent literature. After consulting more references, we therefore revised paper to be more reasonable and convincing. Page 4, line 66: to carbon dioxide and water….
Conversion of fossil oil based materials into carbon dioxide and water is much worse than converting renewable-based materials into carbon dioxide and water
Answer: Thank the reviewer for the comments. We’ve recognized that this description in the previous copy were not accurate, due to our poor study on recent literature. The sentence “it is very important to find an eco-friendly disposal of plastic waste where they degrade to carbon dioxide and water under the sunlight irradiation without producing toxic byproducts.” has been deleted. Page 6, line 112: volatile products….
Define the products.
Answer: We have defined the volatile products in Page 6 line 124-125. Page 9, line 185: eco-friendly disposal….
The claims of the authors that this technique is an eco-friendly one are not justified. The conclusions and other parts of the paper need to be rewritten and limit the scope of the presented research work to the technical objectives without deriving unjustified general conclusions and claims about the impact of this work.
Answer: Thank the reviewer for the comments. We’ve recognized that this description in the previous copy were not accurate. The sentence “The development of this kind of composite polymer can lead to an eco-friendly disposal of polymer wastes.” was changed to “The present paper intends to study goethite as photocatalytst for degradating plastic. Further attention could be focused on the application of the technique.” (Page 9 line 192-194).
/1. Title and abstract should indicate that the work has been done with PE-Goethite composite film.
Answer: Your suggestion is greatly appreciated. We agree and therefore change the title to: Solid-phase photocatalytic degradation of polyethylene–goethite composite film under UV-light irradiation.
/2. Please revise the first paragraph of ‘Introduction’. It is difficult to understand. In general, the language of the paper should be revisited.
Answer: The Introduction part has been rewritten both in contents and in English. We particularly revised some sentences since they are not correct or so confusing.
/3. Materials and methods - Details of the chemicals to be furnished
Answer: The reviewer and editor’s suggestions have been adopted and the details of the chemicals has been shown in Page 4 line 79-83.
/4. Characterization are required for PE (Molecular weight, grade) and Goethite prepared (particle size, BET surface area, SEM-EDS and XRD)
Answer: The reviewer and editor’s suggestions have been adopted and the characterization for PE has been shown in Page 4 line 79. The Goethite prepared (particle size, BET surface area, SEM and XRD) has been reported by Liao et al. (2007), We clarify that in the revised manuscript in Page 5 line 91-93.
/5. A schematic diagram of the experimental set up to be given
Answer: The reviewer and editor’s suggestions have been adopted and a schematic diagram of the experimental has been given in Fig. 1 in the present paper. The original Fig. 1. was changed to Fig. 2 and Fig. 3.
/6. Results - A rate equation should be proposed from the time-weight data
Answer: The reviewer and editor’s suggestions have been adopted and the rate equation a schematic diagram of the experimental has been given in Table. 1in the present paper.
/7. A few data are required to show the influence of process parameters such as goethite loading, intensity of UV radiation.
Answer: Reviewer and editor’s suggestions have been adopted and the influence of goethite loading has been shown in Fig. 2 in the present paper. And the influence of intensity of UV radiation has been shown in Fig. 3 in the present paper. The original Fig. 2 was changed to Fig. 4 and The original Fig. 3 was changed to Fig. 5 in the present paper.
/8. Until other intermediates are isolated, upto Eqn.(7) (line 162) is sufficient.
Answer: Reviewer and editor’s suggestions have been adopted and We changed the Eqns as recommended. Eqs. (8)-(12) are deleted and Eqn.(7) was change to “–(CH2CH2)– + .OH → degradationproducts” (Page 9 line 184).
/9. Figure 3 and 4: 3 pairs are required, namely (i) Only PE film before and after irradiation, (ii) PE-Goethite film (0.4wt %) - before and after irradiation (iii) PE-Goethite film (1.0 wt %) - before and after irradiation.
Answer: Reviewer and editor’s suggestions have been adopted and the original Fig. 3 and 4 was changed to Fig .5 in the present paper.
/10. Point 3 above is also applicable for SEM photographs. Please rearrange and clearly mark the difference between the films before and after irradiation for both SEM and FTIR results.
Answer: Thank the reviewer and editor’s for the comments. During the revision of the paper, we did a supplementary experiment got some new SEM photographs, which has been shown in Fig. 4 in the present paper. And The FTIR results has been rearranged in Fig.5 in the present paper, respectively.
/11. It should be clearly mentioned in the conclusion that the degradation was more when goethite loading and intensity of light both were more
Answer: The reviewer and editor’s suggestions have been adopted and the conclusions has been changed in Page 9 line 192-198.