Pt Modified Heterogeneous Catalysts Combined with Ozonation for the Removal of Diclofenac from Aqueous Solutions and the Fate of by-Products
, Narendra Kumar 1,*, Kari Eränen 1, Jyri-Pekka Mikkola 1,3, Leif Kronberg 2, Patrik Eklund 2, Atte Aho 1, Heikki Palonen 4, Markus Perula 5, Andrey Shchukarev 3 and Tapio Salmi 1,*Round 1
Reviewer 1 Report
The manuscript by Saeid et al., titled “Pt modified heterogeneous catalysts combined with ozonation for the removal of Diclofenac from aqueous solutions and the fate of by-products” reports on degradation of the pharmaceutical diclofenac in aqueous solution by ozonation combined with the use of heterogeneous catalysts. Different catalysts were synthetized by loading Pt on zeolites or alumina in various amounts. The new catalysts were fully characterized by several techniques (SEM, TEM, XPS, etc.) and employed for the degradation of diclofenac with ozonation. The presence of the Pt supported catalyst slightly increases the rate of degradation compared to non-catalytic ozonation. In fact, in the absence of catalyst the diclofenac degradation is almost quantitative in 10 minutes, while in the presence of the catalyst it is complete after 4 minutes. However, the degradation products are different when using the Pt catalyst compared to the non-catalytic test. The major drawback of the catalytic process is the never negligible leaching of Al and Pt into aqueous medium, which limits the practical use. However, the reported results could be of interest for the readers of Catalysts. I would recommend publishing the paper after major revision.
- Recyclability test should be done at least on the best catalyst, in order to quantify the impact of metal leaching on the catalytic activity.
- The authors cover always the reactor vessel with an aluminium foil in order to prevent photodegradation. The catalytic and non-catalytic tests should be carried out also under sunlight to check for differences with respect to the results obtained in the dark.
- In addition, it would be interesting to repeat the ozonation experiments under UV-B irradiation, which dissociates ozone into more reactive species.
English needs to be polished.
Author Response
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript entitled "Pt modified heterogeneous catalysts combined with ozonation for the removal of Diclofenac from aqueous solutions and the fate of by-products" reports a study on the characterization of six catalysts. These have been designed to be used in the degradation of DCF (Diclofenac) present in waste water, through a Pt modified heterogeneous catalysis method and combined with the ozonation process.
The work appears interesting and coherent with the thematic lines of the journal. An important first part was devoted to the characterization of the catalysts using different techniques. In the second part the degradation processes of the DCF were studied. The results obtained are interesting.
The work, however, has some parts that should be improved before we can consider it for its publication. Here are some tips for authors.
(Line129). The text reports "The measured XRD patterns of the MCM-22-100 samples are shown in Fig. 2a and 3b." but in figure 3b are reported TEM images.
Figure 2. What difference is there between figure 2a and 2b. No indication is given in the legend, in the captions and in the manuscript.
Table 2. What does "crystal size" refer to?
Paragraph 2.1 This part is often unclear. For example, "crystal size" or "Pt particles size" or "particles size" is used. It is necessary to clearly indicate in the manuscript and in the graphics.
(Line 190-192). The following statement is not very comprehensive: "The explanation to very small nanoparticles of Pt in 5% wt.Pt-MCM-22-100-EIM appears to 1% wt.Pt-MCM-22-100-EIM can be attributed to very high dispersion of Pt in H-MCM-22-100 catalyst ". What is meant by "... to very high dispersion of Pt in H-MCM-22-100 catalyst".
Table 4. Average crystal size is in nm? How were the Pt concentration data obtained? How many times have the analyzes been repeated?
Line 453 Paragraph 2.2.5 instead of 2.2.3
What are the degradation products of 4'-OH-DCF and 5-OH-DCF? Have further studies been done? This is an aspect that should be explored.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript from Prof. Kumar and co-workers reported heterogeneous Pt-based catalyst combined with ozonation for the removal of Diclofenac. I should note that this manuscript clearly described and summarized to support the authors’ assertions. Finally, I recommend acceptance of the manuscript after minor revision based on the following comments:
- Lines 28: suggest to use ‘Mesoporous Molecular Sieves MCM ‘to replace ‘catalyst MCM’
- Line 30: suggest to add (EIM)
- Line 414: grammatical error, no ’an’
- Pt is a precious metal. It might be good that the reaction catalyst can be replaced by some other inexpensive metal such iron.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors of this paper have adequately responded to all reviewers' comments and concerns and have made appropriate changes.
I find the revised manuscript as presented, acceptable for publication.
