Mechanistic Insight into Degradation of Cetirizine under UV/Chlorine Treatment: Experimental and Quantum Chemical Studies

Round 1

Reviewer 1 Report

The main objective of the paper is to study the degradation of a representative antihistamine using UV radiation and Chlorine.

The authors describe the strong problem generated for the presence of PPCPs species in water and wastewater. However, the content and results of the paper should be much clearer about the future used of these results. The conclusions are scarce to consider as the contribution for "the state of the art".

The approach of the paper is phenomenological at all. In this sense it will be mention of some aspects that should be considered:

1) There is not data about the optical properties of the reaction systems. This is crucial when reactions with the participation of radiation occurs in a participative and reactive media.

2) How that the authors calculate the ""light intensity" of the lamp?

3) The emission of the lamp is monochromatic at 254 nm? If exist another peak, how can affect the reaction rate?

4) The authors used any statistical methods to analyse the data?

5) Which represents the sentence "observed degradation rate"? Is a pseudo first order constant?

6) The authors should be considering the probably screen effects of the different compounds present (e.g., DOM)

7) Considering the whole data of figures 6 and 7, the obtained conclusions are scarce.

8) About the experimental setup, it is important to include:

i) a figure of the experimental reactor,

ii) the absorption spectral of the species

iii) the spectral emission of the lamp

iv) the total volume of the reactor

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have investigated the degradation of an organic contaminant by UV/chlorine and an underlying reaction mechanism has been proposed by combining the methods of experiment and quantum chemical calculation. Both methods have been well studied. However, quantum chemical calculations are not determinants, by themselves, of the reaction mechanism. It is necessary to corroborate the presence of CTZ degradation products experimentally, by means of HPLC-MS or extraction and LC-MS.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The author's answers are complete and the modification in the text are in accordance with the improve required.

Reviewer 2 Report

The authors have correctly justified the non-inclusion of the proposed analysis. Therefore, I consider that the article can be published in Water.