TiO2 and Active Coated Glass Photodegradation of Ibuprofen
, Sabino A. Bufo 2, Rafik Karaman 2,3 and Laura Scrano 4Round 1
Reviewer 1 Report
Review of the paper: “TiO2 and active coated glass photodegradation of ibuprofen”.
The authors reported photocatalytic degradation of ibuprofen using TiO2 as a dispersed powder and TiO2 immobilized on the glass. In my opinion the topic of research is interesting and needed due to the increasing environmental pollution, especially in the field of pharmaceuticals. However, some corrections and explanations should be done.
(i) Did the authors repeat the adsorption and photolysis experiments? Or did they do only one time?
(ii) How long the reaction was carried out in the dark when the authors did the adsorption experiments? According to the line 233 it was 60 min. Next, the photocatalytic experiments were carried out for 24 hours. Did the authors check if the adsorption is changing after 60 min?
(iii) Sometimes the axis captions or figures captions are missing. Figures 7 and 8 seems to be the same.
(iv) We can read on the Evonik Industries website about P25: “Titanium dioxide is a light-sensitive semiconductor, and absorbs electromagnetic radiation in the near UV region. The energy difference between the valence and the conductivity bands in the solid state is 3.05 eV for rutile and 3.29 eV for anatase, corresponding to an absorption band at <415 nm for rutile and <385 nm for anatase”. The authors of “TiO2 and active coated glass photodegradation of ibuprofen” wrote in the line 295: “However, in the presence of TiO2 a complete removal of this NSAID was obtained although a xenon lamp with low UV energy was used for irradiation aiming at the simulation of sunlight effect”. Therefore, it is surprising that pure P25 (unmodified) was able to degrade such a complicated, ring compound as ibuprofen in 100%. Did the authors check the results more than one time?
(v) There are a few small things that do not diminish the value of work but need to be improved.
According to the lines 72 and 82 the authors wrote the word photocatalysis together or separately (photocatalysis or photo-catalysis). Please unify that. According to Zaleska-Medynska et al., Metal Oxide-Based Photocatalysis: Fundamentals and Prospects for Application, Elsevier 2018, ISBN: 9780128116340 the word photocatalysis should be written together. In the line 85 the authors wrote that semiconductor particles absorb large fractions of the UV spectrum. However, some pristine semiconductors are able to absorb the visible irradiation (e.g. WO3, Fe2O3 and CuO).Author Response
Dear Editor and Reviewer,
We have carefully studied your comments on our manuscript, and replenished our manuscript
Accordingly. The requested modifications in our manuscript are presented in the revised version.
Detailed responses to Reviewer’s comments are listed as below:
Comment 1:
Did the authors repeat the adsorption and photolysis experiments? Or did they do only one time?
Response:
Yes they are repeated and three experiments were performed in triplicate for adsorption, direct photolysis and photocatalysis reactions; and results values reported are the means of three replicates.
Comment 2:
How long the reaction was carried out in the dark when the authors did the adsorption experiments? According to the line 233 it was 60 min. Next, the photocatalytic experiments were carried out for 24 hours. Did the authors check if the adsorption is changing after 60 min?
Response:
The reaction was carried out in the dark for 24 hr, but the adsorption concentration did not change after 60 min and adsorption equilibrium has been achieved, that why we were satisfied with a show 60 min.
Comment 3:
Sometimes the axis captions or figures captions are missing. Figures 7 and 8 seems to be the same.
Response:
The axis captions have been added in the modified version; regarding to the figures 7 and 8 the mistake was corrected by adding figure 8 since figure 7 was repeated by mistake in the previous submitted manuscript.
Comment 4:
We can read on the Evonik Industries website about P25: “Titanium dioxide is a light-sensitive semiconductor, and absorbs electromagnetic radiation in the near UV region. The energy difference between the valence and the conductivity bands in the solid state is 3.05 eV for rutile and 3.29 eV for anatase, corresponding to an absorption band at <415 nm for rutile and <385 nm for anatase”. The authors of “TiO2and active coated glass photodegradation of ibuprofen” wrote in the line 295: “However, in the presence of TiO2 a complete removal of this NSAID was obtained although a xenon lamp with low UV energy was used for irradiation aiming at the simulation of sunlight effect”. Therefore, it is surprising that pure P25 (unmodified) was able to degrade such a complicated, ring compound as ibuprofen in 100%. Did the authors check the results more than one time?
Response:
Yes, The experiment was done in triplicate, and almost the same results were obtained. also studies showed that the degradation of the IBP and the results indicated that the photocatalytic treatment with titania catalyst leads to rapid mineralization of ibuprofen.
Choina J, Kosslick H, Fischer C, Flechsig GU, Frunza L, Schulz A (2013) Photocatalytic decomposition of pharmaceutical ibuprofen pollutions in water over titania catalyst. Appl Cataly B 129:589–598
Comment 5:
There are a few small things that do not diminish the value of work but need to be improved.
According to the lines 72 and 82 the authors wrote the word photocatalysis together or separately (photocatalysis or photo-catalysis). Please unify that. According to Zaleska-Medynska et al., Metal Oxide-Based Photocatalysis: Fundamentals and Prospects for Application, Elsevier 2018, ISBN: 9780128116340 the word photocatalysis should be written together. In the line 85 the authors wrote that semiconductor particles absorb large fractions of the UV spectrum. However, some pristine semiconductors are able to absorb the visible irradiation (e.g. WO3, Fe2O3 and CuO).
Response:
Regarding to the first part of comment; all were unified as photocatalysis. For the second part yes we agree with the reviewer that there are other semiconductors that able to absorb the visible irradiation, but here we are try to describe the mechanism that the TiO2 photo-excited accordingly.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The catalysts-719468 manuscript describes an interesting and well-organized work concerning the photocatalytic degradation of ibuprofen. TiO2 (P25) powder and anatase coated glass were used as photocatalysts. The work worths publication after major revision.
Major comments
Figure 8A and 8B are duplication of Figure 7A and 7B. Please, provide the correct figures.
Lines 422-424: The phrase “The adsorption…//… catalyst [34]. should be omitted. It is not correct.
Lines 428-430: The phrase “For some pollutants, which are weakly acidic in nature such as IBP, negatively charged in basic pHs and neutral at pH less than 3, the rate of photocatalytic oxidation increases at lower pH due to an increase in the extent of adsorption under acidic conditions [31].” should be modified as follows
As IBP is weakly acidic in nature, it is expected to be negatively charged at pH higher than 3 [31], while the TiO2 surface to be positively charged at pH less than 6.9 [34]. Therefore, at pH=4.5 where the photocatalytic experiment has taken place the adsorption of IBP and consequently its photocatalytic oxidation are favored.
Minor comments
Line 47: “Figure 1” --->Figure 1,
Line 51: “in efficient” ---> inefficient
Line 78: “, oxidation” should be omitted
Lines 157-158: The phrase should be moved to 2.2 section (Line 170).
Line 231: “IBU” ---> IBP
Line 338: “powder.” ---> powder and TiO2 coated active glass.
Lines 438-441: Some spaces are missing
Author Response
Dear Editor and Reviewer,
We have carefully studied your comments on our manuscript, and replenished our manuscript
Accordingly. The requested modifications in our manuscript are presented in the revised version.
Detailed responses to Reviewer’s comments are listed as below:
Comment 1:
Figure 8A and 8B are duplication of Figure 7A and 7B. Please, provide the correct figures.
Response:
Regarding to the figures 7 and 8 the mistake was corrected by adding figure 8 since figure 7 was repeated by mistake in the previous submitted manuscript.
Comment 2:
Lines 422-424: The phrase “The adsorption…//… catalyst [34]. should be omitted. It is not correct.
Response:
Done in the modified version.
Comment 3:
Lines 428-430: The phrase “For some pollutants, which are weakly acidic in nature such as IBP, negatively charged in basic pHs and neutral at pH less than 3, the rate of photocatalytic oxidation increases at lower pH due to an increase in the extent of adsorption under acidic conditions [31].” should be modified as follows
As IBP is weakly acidic in nature, it is expected to be negatively charged at pH higher than 3 [31], while the TiO2 surface to be positively charged at pH less than 6.9 [34]. Therefore, at pH=4.5 where the photocatalytic experiment has taken place the adsorption of IBP and consequently its photocatalytic oxidation are favored.
Response:
Done in the modified version.
Minor comments
Line 47: “Figure 1” --->Figure 1,
Line 51: “in efficient” ---> inefficient
Line 78: “, oxidation” should be omitted
Lines 157-158: The phrase should be moved to 2.2 section (Line 170).
Line 231: “IBU” ---> IBP
Line 338: “powder.” ---> powder and TiO2 coated active glass.
Lines 438-441: Some spaces are missing
Response:
All are done in the modified version.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
I believe the manuscript has been significantly improved and now warrants publication in Catalysts.
