Degradation of Benzene Using Dielectric Barrier Discharge Plasma Combined with Transition Metal Oxide Catalyst in Air
and Dezheng Yang 1,2,3,*Round 1
Reviewer 1 Report
Dear Authors:
Congratulations on your work, it elucidates the advantages of the dielectric barrier discharge plasma, combined with the use of transition metal oxide catalyst, during the degradation of a model molecule, benzene. So far, the manuscript should be accepted, and the following aspects should be considered now or in future work:
(1) Regarding the methodology, it should be presented before the results to have a better perspective of the results. To be honest, It would be very helpful for the reader.
(2) Experimental error should be presented, mainly for the degradation results.
(3) Regarding the degradation, a carbon balance should be presented for every run to evaluate the mineralization percentage of benzene.
(4) Regarding the catalytic materials, they should be characterized by physicochemical and electrochemical techniques to relate their properties with the grade of degradation observed.
(5) Reaction mechanism should be more explicit showing the formation of intermediates till obtaining CO2. A discussion with the literature should be presented.
(6) If possible it would be interesting to observe degradation reaction rates, conversion and selectivities as a function of time. These results should be compared with conventional technologies to elucidate the importance of your contribution.
(7) Typos should be corrected throughout the whole manuscript.
With kind regards.
The Reviewer.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript investigates the improvement of benzene degradation using the synergistic effect of dielectric barrier discharge and transition metal oxide catalyst. The investigation is timely and of potential interest to ‘Catalysts’ readers. The Introduction part explained the research background well and the Results and Discussion part provided good information for researchers conducting related research through detailed explanations. In my opinion, however, the manuscript needs some revisions before publication.
1.
Line 354-356: In “ZnO, CuO, and Fe3O4 are chosen as catalysts with 1-3 mm particle size which are packed in the DBD discharge region.”, In which form are the metal oxide catalysts present on the quartz glass tube? Is it in the form of a film with a constant thickness? What does “pack” mean? Do you mean completely filling the discharge area? Or do you mean deposit the layer?
2.
You claimed that CuO had the best performance on the benzene conversion. Why do the authors show the data when applying ZnO in most experiments in the manuscript (Figures 2, 4, 5, 7 and 8)? Wouldn't it be correct to show the experimental data for the best performing CuO and describe the case of CuO?
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The paper summarizes new information on a uniform and stable dielectric barrier discharge plasma is present for the 13 degradation of benzene combined with transition metal oxide catalyst. The discharge images, 14 waveforms of discharge current and optical emission spectra are measured to investigate the plasma 15 characteristics. The effects of catalyst types, applied voltage, driving frequency, and initial VOCs 16 concentration on the degradation efficiency of benzene are studied. It is found that the addition of 17 the packed dielectric materials can effectively improve the uniformity of the discharge and enhance 18 the intensity of the discharge, thus promote the degradation of benzene. With the applied voltage 19 of 22 kV, the degradation efficiency of dielectric barrier discharge plasma packed with CuO, ZnO 20 and Fe3O4 are 93.6%, 93.2% and 76.2%, respectively. When packing with ZnO, the degradation 21 efficiency of dielectric barrier discharge plasma is improved from 86.8% to 94.9% as the applied 22 voltage from 16 kV to 24 kV. The synergistic mechanism and the property of the catalyst are 23 responsible for benzene degradation in plasma-catalysis system. In addition, the main 24 physiochemical processes and possible degradation mechanism of benzene are discussed. The experimental results are interesting and informative, but some data were not well presented. Details are listed below.
1) The authors measured the electrochemistry of ZnO, CuO, and Fe3O4. However, XRD data must be added to confirm the correct crystallinity of this sample.
2) The author explained the degradation reaction of benzene by electrochemical reaction. However, there are no experimental data to explain the mechanism of benzene in this paper. Therefore, experimental data that can prove the mechanism should be added.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The manuscript can be published in the present form.
Reviewer 3 Report
I accept this paper as your revision is well written
