Detailed Group-Type Characterization of Plastic-Waste Pyrolysis Oils: By Comprehensive Two-Dimensional Gas Chromatography Including Linear, Branched, and Di-Olefins
Round 1
Reviewer 1 Report
The paper of Hang Dao Thi, Marko R. Djokic and Kevin M. Van Geem is very interesting work, regarding on group-type characterization of plastic waste pyrolysis oils by using comprehensive two-dimensional gas-chromatography.
Plastic waste and pyrolysis, as well as the use of GCxGC are an interesting topics, increasingly interesting to scientists. It also may be the portion of the submission of most interest to readers of this journal. I would therefore support publication after revision. English is fairly good but does need some corrections -there are stylistic differences (British vs American) within the text. Please check carefully other mistakes, for example - missing letters (ex. line 285 - Stabi(l)wax, etc.). Please provide figures & tables with better quality (maybe tables with different organisation, for better readability; it's suggestion only).
Author Response
Please find in the attachment our response to your comments.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper by Thi et al reports their research into the development and application of a new method to analyse plastic waste pyrolysis oils by hydrocarbon group and heteroatoms present.
The abstract is appropriate in length and description of the content and results of the article. Furthermore, the introduction is relevant and presents the foundation, background and need for the presented research.
Overall, there is novelty and utility in the presented research - the authors have developed a new method to characterize plastic waste pyrolysis oils and quantify the different classes of olefins and diolefins using two-dimensional gas-chromatography GC × GC. It should be noted that they were unable to separate and analyse aromatic compounds also present by this method. In saying that, before I would recommend acceptance of this manuscript for publication, a number of changes should be made - please see below.
- The title should be revised so "comprehensive" is not repeated.
- Line 106: boiling
- Line 182: the term "blob" should be replaced with something more appropriate
- Extensive reformatting needs to be performed, particularly with regard to the tables in the manuscript - they are of inconsistent style, go over a page break and are cut off.
- Data analysis methods are not described in the manuscript (i.e. graphing, software, replicates, etc).
- Graphs also need to be improved - axis labels are far from the graphs and not well presented
- The results in Tables 3 and 4 should be reported with an associated error and information provided about the number of replicates.
Author Response
Please find in the attachment our response to your comments.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
This is my second review of this paper by Thi.
Firstly, I would like to say that in general I appreciate the efforts by Thi and co-workers to address my comments from my previous review.
I would, however, say that I do not believe a couple of my comments were not appropriately addressed. These comments are those related to the measurements obtained in their method. None of their measurements have any stated errors, which many would argue render them invalid. The authors quote "average" values, but provide no information on how many values were averaged and their standard deviation. The particular values I am most concerned with are those in Table 3 and 4 and the lack of error bars on Figure 2.
I would not be comfortable recommending publication until this was addressed.
Author Response
Please find our response to your comment in the file attached.
Author Response File: Author Response.pdf
