Immobilization of TiO2 Nanoparticles in Hydrogels Based on Poly(methyl acrylate) and Succinamide Acid for the Photodegradation of Organic Dyes
, Xuelu Wang * and Yefeng Yao *
Round 1
Reviewer 1 Report
This manuscript highlights the use of embedded TiO2nanoparticles into poly(methyl acrylate) and succinimide acid based hydrogels has recyclable photocatalyst for the degradation of organic dyes and photocatalytic H2 evolution.
- If the hydrogel-based TiO2photocatalyst is agitated in the solution by stirring or sonication, will the gel remain intact or disintegrate into smaller pieces? This information could be useful when considering practical applications.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
To authors
General comments
The reviewed article deals with the immobilization of titania nanoparticles in hydrogels based on poly(methyl acrylate) and succinamide acid devised for the photocatalytic removal of organic dyes. I find this work interesting and well elaborated. The general layout of the article is correct. The manuscript was written in good scientific language. The composition of the whole manuscript is coherent and the materials are in-depth characterized using suitable techniques.
The topic of the research is in line with the scope of the Catalysts journal, thus, I suggest the acceptance for its publication in Catalysts after minor revision (in fact, just some minimal changes/explanations are needed). The following clarifications are to be addressed:
1/ As the catalytic activity depends on the number of catalytic sites on the titania surface, it will also be governed by the particle size of TiO2 used for the preparation of the immobilized catalysts. Thus, this parameter should be analyzed (dynamic light scattering measurements, for instance?). The influence of particle size on catalytic performance should also be studied in this regard.
2/ The authors mentioned that they have observed the sediment of titania in the case of the PMA-TiO2 sample. Therefore, what about the stability of the hydrogel-TiO2 system?
3/ The catalytic activity of both hydrogel-titania samples was lower compared to the pure TiO2. I am afraid if it is due to the diffusion limitation (hindered diffusion through the hydrogel matrix)? This issue was not considered.
4/ It is obvious that the decoloration of the dye solutions during the catalytic run is caused either by the adsorption or the catalytic decomposition of the dye molecules. However, it is interesting what are the true products of the photodegradation thereof. Sometimes, despite the decoloration of the dye solution, the products may be even more toxic than the parent dye and they may be retained in the wastewater. Is it possible to check the real products? Maybe total organic carbon measurements should address this issue?
5/ In the case of real industrial wastewater, there may occur different pH, different temperatures, and of course, different components of the spent water. Indeed, this may influence substantially the catalytic activity of the materials. This should also be discussed/studied.
6/ Please provide the information if the catalysts were dried before reuse or not.
Minor issues
1/ The same acronym for acrylamide and acrylic acid (AA) was used.
2/ For clarity, the same scales should be used for plotting H2 evolutions in Fig. 4 a, b, c, as well as Fig. 5 a, b.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
