Wastewater Treatment by Coupling Adsorption and Photocatalytic Oxidation: A Review of the Removal of Phenolic Compounds in the Oil Industry
, Paola Andrea Acevedo 1, Luis Roberto Hernández-Angulo 2, Daniel Tobón-Vélez 3, AnamarÃa Franco-Leyva 1 and MarÃa Margarita Sierra-Carrillo 1,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe article “Wastewater treatment by coupling adsorption and photocatalytic oxidation: Application of 2,4-dimethylphenol present in oil effluents” needs major corrections, due to the following considerations.
In principle, the article looks like a research article, but, it is a review of what, according to the authors, it didn’t studied yet. However, neither in the title nor in the abstract, the authors make clear that is a review. All the references related to Thesis must be changed to an article.
In the abstract, the authors stated that the paper explores recent advancements in a novel treatment process. However, it is unclear what aspects of the process are truly novel.
In topic 2.1
The reference 23 is about heterogeneous catalysis and the authors utilized it to define two terms about adsorption. What is the reason? It is evident that heterogeneous catalysis involves adsorption but, in general, is associated with supported metal particles.
To discuss the very short time to reach the equilibrium in physisorption, the author must discuss the influence of the mass in the adsorption process.
In line 83 the author points out that what determines the usage of the adsorbent is the pore size and specific surface area, however, this is not true considering organic pollutants. Properties like functional groups in the surface, zero charge potential, and which bonds are formed are also important. See https://doi.org/10.1007/s11157-021-09585-x and https://doi.org/10.1007/s11157-021-09585-x. This discussion must be improved.
What is the reason for utilizing reference 25 to corroborate the UIPAC definition instead of the article of UIPAC (https://doi.org/10.1515/pac-2014-1117)?
The BET method to determine the surface area does not preconize the multilayer formation. Review the information.
The authors utilized the reference 46 to discuss the accessibility of the adsorbate to adsorbent but not discuss the diffusion and its implications. It is as if only surface area is important to the detriment of the concentration, system agitation, and hydrokinetic diameter of the molecule.
In topic 2.2
What is the reason to present only two models for isotherm adsorption? This topic must be expanded.
To induce the linearization of the models is unacceptable. See https://doi.org/10.1080/15422119.2021.1951757, https://doi.org/10.1016/j.clema.2022.100100, and other articles.
The authors affirm that kinetics adsorption is employed to assess the diffusion of adsorbate into the pores, but, not all the models applied to adjust the data mean it. Please, review the means of each model.
In topic 2.3
Please, bring references for the raw materials utilized to produce activated carbon.
The author postulated that physical activation involves the production of charcoal followed by activation. There are many references in the literature which makes the process in one step.
How is possible to make the chemical activation in one step? Some authors react the raw material with acid/base/solution followed by physical activation and others make the inverse. Chemical activation needs to be made separately.
In topic 2.4
Consider that the decrease in the adsorption rate with the reduction of free spaces on the surface and in the pores of the solid does not consider the possibility of multilayer formation. So, if this information is true, only the Langmuir model will adjust for all isothermal data. Please, review the phrase.
Why the authors do not cite https://doi.org/10.1016/j.chemosphere.2004.09.067
In topic 2.5
Bring a reference (preferably from EPA) for the toxicity for environmental and human health.
The reference https://doi.org/10.3390%2Fpolym16030443 seems to be interesting.
It is not because Methyl Orange and Acid Fuchsin possess benzene rings that can be compared to 2,4-DMP. In that case, would be better to compare with phenolic acid compounds (3,4,5-TMB; 3,4-DMB; 4-HB; 3,4-DHB) or other phenolics.
The discussion about the possibility of 2,4-DMP adsorbs on ACF is weak. Comparison with MO indicating that 2,4-DMP is a small molecule did not consider how the MO is adsorbing. For example, if MO adsorbs through SO3 leaving the N group free, will be vertical adsorption. The authors must bring FTIR data that corroborate the mechanism of MO adsorption to extrapolate to 2,4-DMP.
In topic 3.1
The mechanism of Fenton process must be revised considering the regeneration of Fe2+. If don’t, consider the mechanism of like-Fenton reaction.
In topic 3.2
There are no references to the photocatalysis of 2,4-DMP. A simple search in Google brings the https://doi.org/10.1016/j.apcatb.2004.11.023. Please, address this issue.
In topic 4.2
The Table 1 must be discussed in more detail.
There is a reference 46 in the text which is not presented in Table 1. Why?
In topic 4.3
Which is the mechanism to improve the removal of pollutants due to the couple photocatalysis? Discuss in more detail.
Based on this mechanism, how 2,4-DMP follow the same tendency of degradation? The reference 57 discusses the mechanism for phenol but, doesn’t consider the substitutes in the aromatic ring.
In Conclusion
Must be rewritten to avoid reader bias in considering the paper as effectively studying or reviewing the 2,4-DMP degradation.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for Authorseng
Wastewater treatment by coupling adsorption and photocatalytic oxidation: Application of 2,4-dimethylphenol present in 3 oil effluents
Manuscript Number: DES-D-23-01402
This is an interesting study. The paper has to be strengthened based on the following MAJOR corrections
1. Abstract: the abstract needs to be improved by incorporating the methodology used in this research and the most important findings of this research. The novelty of this research is not clear in the abstract
2. Introduction: line 39 page 1, please cite another reference instead of [1]
3. Introduction: I have just noticed that this paper is a review study which is not clearly stated in the main title and abstract. Please refine the title to reflect this word (Review) and improve the abstract to do so
4. still the introduction has not clearly stated the novelty of this paper and its significance. The authors are invited to mention the most relevant studies (review studies) that encountered with similar topic to pave the way towards the importance of this review
5. Please cite the sentence in lines 188-189 in page 4.
6. The authors stated that the review would cover the associated studies that encountered with the coupling of adsorption and photocata-2 lytic oxidation methods based on the removal of 2,4-dimethylphenol present in oil effluents. However, most of the heart of the manuscript have focused on some other organic compounds such as Phenol, Methylene blue, Formalde-hyde, etc. It is only my opinion to edit the main title to suit the removal of phenolic compounds
7. Line 359, it is not preferable to use the pronoun (We)
It is also recommended to include the specific comparison (in a summary table) to introduce the removal efficiency of some other industrial wastewater treatment processes such as Reverse Osmosis process and advanced oxidation process such as Trickle bed reactor and the hybrid system of these processes. Several studies can be found in the open literature. Please see for example (https://doi.org/10.1061/(ASCE)EE.1943-7870.0001284); (https://doi.org/10.1016/j.desal.2011.07.053 ); (https://doi.org/10.1016/B978-0-444-63965-3.50454-2); (https://doi.org/10.1002/ep.12078); (https://doi.org/10.22079/jmsr.2017.23344); (https://doi.org/10.1515/cppm-2020-0025); (https://doi.org/10.3390/membranes11080595). Please note, it is not compulsory to cite these papers. These are only examples that might reflect your attention and many other papers can be found in the open literature
8. Conclusions: please provide the statistical data related to the maximum removal of the studied pollutant
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors made the requeried corrections
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors perfectly responded to the raised comments.
