Upgrading Waste Activated Carbon by Equipping Micro-/Mesopore-Dominant Microstructures from the Perspective of Circular Economy

Round 1

Reviewer 1 Report

Comment:

This manuscript reports a general strategy for upgrading waste regenerated activated carbon by surfactant or gel modification. The authors investigate the pore distribution of the RACs produced by different modifications and find that the micropores are favored in surfactant-modified RACs and meso- and macropores are more dominant in gel-modified RACs. However, there are several remaining questions on surface functional groups and pore size distributions. Also, the discussion of the pore formation/transformation mechanism is at a preliminary stage in this manuscript. Thus, I think a major revision is needed for this manuscript before it published on Processes at this stage.

 

Specific comments:

1. The authors characterize the RAC with different surface modifications by XRD, IR but only provide ‘representative’ spectra. Is there any difference among different surfactants? Also, will the surface modification change (1) surface functional group (2) element doping (N, S, P) of the RACs?

 

2. The authors find that, in general, the micropores are favored in surfactant-modified RACs and meso- and macropores are more dominant in gel-modified RACs. However, the classification of micro-, meso-, and macropores are still too vague to compare the effect of different surfactants and gels. Pore size distribution with more details (average radius, curvature, etc.) is needed for a comprehensive study.

 

3. The authors use some low-grade and low-cost surfactants with a poor purity even < 30%. The effect of the modification may come from the other chemicals in the poor purity surfactants. The contents of those chemicals are needed to improve the reproducibility of this work.

Author Response

please refer to the attached file

Author Response File: Author Response.docx

Reviewer 2 Report

The submitted article, “Upgrading waste activated carbon by equipping with micro-/mesopore dominant

microstructure from the perspective of circular economy” is interesting, original and within the scope of the journal but some changes should be addressed:

 

1.      At lines 3 and 4 please give some examples of purification and separation applications where is used the activated carbon and add more references (please see https://doi.org/10.3390/app11157139).

2.      At lines 21, 148, 294, 296, 299 and 368 please insert the numbers of references according to journal instructions, for example [6, 7] instead of [6][7].

3.      Please describe how the samples were prepared for SEM analysis.

4.      Please provide the information regarding the origin country of the equipments used in experimental section.

5.      I recommend to use the same size and font for axes titles in figures.

6.      At line 265 please use "it can not be concluded.." instead of "we are unable to make a clear conclusion…". Also, at line 449, please reformulate "We thus would not..".

7.      Please try to extend the conclusion section.

Author Response

please refer to the attached file

Author Response File: Author Response.pdf

Reviewer 3 Report

Authors have successfully managed to show the ability of the activated carbon (RAC) regeneration by carbonizing associated carbon precursors such as commercially available low-cost surfactants and the gel containing surfactant and methyl cellulose. The modified RAC showed predominantly micropore structure accompany by meso-/macropore structure. It appends that the meso-/macropores could be efficiently transformed by carbonized surfactants, leading to the micropore rich RAC. On the other head, the carbonized gel would block micropores and thus give rise to the meso-/macroporous RAC.

Various methods have been used in order to characterize obtained RAC. Results are presented with sound explanations.

Applied surfactant/gel modifications were found to be insensitive to the properties of surfactant. That this can provide a new alternative for waste/low-grade surfactant cocktails disposal.

The English language has to be improved; I have observed grammar or mistype errors.

This study has a high potential to be cited. 

 

Therefore, I recommend that the Editorial office consider this manuscript for publication, but after minor revision. 

Author Response

please refer to the attached file

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have done a thorough job of addressing the concerns of myself and other reviewers. Therefore, I recommend publishing the manuscript as is.