The Application of Response Surface Methodology for 2,4,6-Trichlorophenol Removal from Aqueous Solution Using Synthesized Zn²⁺-Al³⁺-Tartrate Layered Double Hydroxides

Round 1

Reviewer 1 Report

Manuscript ID: Processes-1513344

The paper is recommended for publication after major revision.

The manuscript titled: Synthesis of reusable Zn2+-Al3+-C4H4O62--LDHs for the optimization removal of 2,4,6-trichlorophenol by RSM, needs major revision to be accepted for publication in Journal: Processes.

The reviewer judges that it is worth placing this manuscript in the Processes after major revisions/clarifications suggested below.

My comments and questions are as follows:

1. The authors should clarify the 2, 4, 6-TCP initial concentration of 2.0 g/L (2000 PPM) of the present study.
2. The authors should clarify the range of concentrations is using in GC-MS analysis.
3. Authors should represent the GC-MS analysis retention time graph.
4. In section 2.3-line number 120 check this sentence “Simulated water sample with 2,4,6-TCP (2.0000g/L, 50.0 ml)”.
5. Factors of adsorption experimental analysis of the samples do not show the results of the pH system.
6. Authors should present the BET Isotherm data.
7. In line number 221 check this sentence “The smaller P value and the larger F value, the more significant the model is.”
8. In the Abstract section “Under the optimization of RSM, average removal rate of 87.44% was achieved with 2, 4, 6-TCP initial concentration of 2.0g/L at temperature 15.0 ℃ in 2.5 h processing time by 0.1500g adsorbent”.

 

 

Line number-200

After repeated three times of each experiment, the finalized parameters were obtained for 2.0 h of adsorption time, 20.0 ℃ of adsorption temperature and 0.1500g of adsorbent dosage.

Conclusion Section

“the adsorption time is 2.5 hours, the adsorption temperature is 15.0 ℃, and the amount of adsorbent is 0.1500g, the prediction removal rate of 2,4,6-TCP was 94.06%, and the average of practical removal rate was 87.44%.”

The above three statements are different, authors should check and clarify.

9. Authors should present the equilibrium isotherm model data for present studies.
10. There are many mistakes and grammar English corrections are required, so the authors are advised to go carefully through the text.

I suggest the manuscript correct it and submit.

Author Response

1. The authors should clarify the 2, 4, 6-TCP initial concentration of 2.0 g/L (2000 PPM) of the present study.

Reply: Thanks for the reminder, and the initial concentration of 2, 4, 6-TCP was clarified when necessary in manuscript.

2. The authors should clarify the range of concentrations is using in GC-MS analysis.

Reply: The limit detection of 2,4,6-TCP by GC-MS was 0.4 mg/L, and the detailed calculations are compensated in section 2.4.

3. Authors should represent the GC-MS analysis retention time graph.

Reply: the GC-MS analysis retention time graph was represented in figure 2.  

 

4. In section 2.3-line number 120 check this sentence “Simulated water sample with 2,4,6-TCP (2.0000g/L, 50.0 ml)”.

Reply: This sentence was rephrased.

5. Factors of adsorption experimental analysis of the samples do not show the results of the pH system.

Reply: Factor of pH was redesigned in adsorption experimental, please refer to the section of 3.2 and 3.3.

6. Authors should present the BET Isotherm data.

Reply: The BET isotherm data were supplemented.

7. In line number 221 check this sentence “The smaller P value and the larger F value, the more significant the model is.”

Reply: This sentence was rephrased, meanwhile, all the long sentences in the full text were checked and necessary modifications were made.

 

8. In the Abstract section“Under the optimization of RSM, average removal rate of 87.44% was achieved with 2, 4, 6-TCP initial concentration of 2.0g/L at temperature 15.0 ℃ in 2.5 h processing time by 0.1500g adsorbent”.Line number-200: After repeated three times of each experiment, the finalized parameters were obtained for 2.0 h of adsorption time, 20.0 ℃ of adsorption temperature and 0.1500g of adsorbent dosage.Conclusion Section: “the adsorption time is 2.5 hours, the adsorption temperature is 15.0 ℃, and the amount of adsorbent is 0.1500g, the prediction removal rate of 2,4,6-TCP was 94.06%, and the average of practical removal rate was 87.44%.” The above three statements are different, authors should check and clarify.

Reply:According to your suggestion, pH was considered as a factor of adsorption process, and all experiments were redone to obtain the final data group, after the careful checking, each results is consistent with the experiment.

 

9. Authors should present the equilibrium isotherm model data for present studies.

Reply: The equilibrium data were supplemented, and the capacity of adsorbent is 599.6 mg/g.

10. There are many mistakes and grammar English corrections are required, so the authors are advised to go carefully through the text.

Reply: Thanks for your patience. I have made one-to-one corrections and carefully checked the full text to correct grammatical mistakes. I also asked native English speakers to check the whole paper aiming to avoid relevant mistakes.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript has an excellent Introduction and the goals are very clear. Thus, I would like to ask something: Is the synthesis- item 2.2 - totally new or is based in other works? The authors wrote p. 5, line 177: “LDHs were the characteristic diffraction peaks of LDHs” Please, cite a reference. The adsorption models are very known (Hill, CG, 1977, Introduction to Chemical Engineering Kinetics & Reactor Design, Wiley), Langmuir, BET, and so on. Why did you model this with an experimental model? Besides, a correlation equals to 0.9795 (p. 8, line 222) is not high. Spelling and grammar check You would consider an English review. It is not critical, but I found some suggestions when I used the Grammarly, for instance: Abstract P 1 damage of >> damage to p. 1 as potential >> as a potential Introduction p. 1 on health >> on the health p.1 human being >> human beings p. 1 with potentiality >> with the potentiality p. 2 fundamental role to the efficiency >> fundamental role in the efficiency p. 2 hydrotalcite like can be replaced >> hydrotalcite can be replaced Results and discussions p. 4 line 154 and 157: peak at wavenumber >> peak at a wavenumber p. 4, line 163: Excuse me, I can not understand “This section may The morphology of Zn2+-Al3+-C4H4O62--LDHs was observed” p. 6 line 193: factor experiment >> factorial experimente p. 6 line 196: in the figure 5 >> in figure 5 p. 7 line 198: One of parameters >> One of the parameters Conclusions p. 10 line 267: had an obvious line 268 an optimum

Author Response

1. Is the synthesis- item 2.2 - totally new or is based in other works?

Reply: There are studies about that the transition metals and functional anions like Mg/Zn/Al/Ni/Fe/CO₃^2- were employed to prepare LDHs in order to enhance the catalytic performance or used to remove heavy metals of Cu²⁺, Cd²⁺, Pb²⁺ and other pollutant ions of F^-, NO₃^- and so on ^[1-2], with the reason of that the structure and properties of LDHs can be optimized through the variation of chemical composition of host layer and interstitial anions ^[3], we tried to find a procedure which can enable the generation of large-sized of LDHs in order to achieve better adsorption effect of trichlorophenol. A similar literature [4] was cited but there are still many differences in synthesis and application. Therefore, it is an innovation based on previous studies.

• Kameda, S. Saito, and Y. Umetsu,“Mg-Al layered double hydroxide intercalated with ethylene-diaminetetraacetate anion: synthesis and application to the uptake of heavy metal ions from an aqueous solution,” Separation and Purification Technology, vol. 47, no. 1-2, pp. 20–26, 2005.
• Zhao, G. Sheng, J. Hu, C. Chen, and X. Wang, “The adsorption of Pb(II) on Mg2Al layered double hydroxide,”Chemical Engineering Journal, vol. 171, no. 1, pp. 167–174, 2011.

[3]  Liu, Z., Ma, R., Ebina, Y., Iyi, N., Takada, K., Sasaki, T., 2007. General synthesis and delamination of highly crystalline transition-metal-bearing layered double hydroxides. Langmuir 23, 861–867.

[4]  Yasin, Yamin, Maszlin Mohamad, and Faujan BH Ahmad. "The application of response surface methodology for lead ion removal from aqueous solution using intercalated tartrate-Mg-Al layered double hydroxides." International Journal of Chemical Engineering 2013 (2013).

 

2. The authors wrote p. 5, line 177: “LDHs were the characteristic diffraction peaks of LDHs” Please, cite a reference.

Reply: the section of XRD analysis was reorganized, and the references also were cited.

3. The adsorption models are very known (Hill, CG, 1977, Introduction to Chemical Engineering Kinetics & Reactor Design, Wiley), Langmuir, BET, and so on. Why did you model this with an experimental model? Besides, a correlation equals to 0.9795 (p. 8, line 222) is not high.

Reply: Response Surface Methodology (RSM) is an effective statistical technique, which provides an investigative approach towards optimization. In addition, it is a collection of mathematical and statistical techniques used in significance of several affecting factors in an optimum manner, even in the presence of complex interactions [5]. The main reason for implementing RSM is to determine the optimum operational conditions for the process or to determine a region that satisfies the operating specifications[6]. The regression model was redesigned and the correlation equals to 0.990126, which indicated that the stepwise regression model was suitable for the analysis of experimental data in this research. I also referred to another literature [4]. Thank you for your warning and we will pay special attention to this situation when we use the model next time.

[5] K. Ravikumar, S. Krishnan, S. Ramalingam, and K. Balu, “Optimization of process variables by the application of response surface methodology for dye removal using a novel adsorbent,”Dyes and Pigments, vol. 72, no. 1, pp. 66–74, 2007.

[6] R. H. Myers and D. C. Montgomery, Response Surface Methodology, John Wiley and Sons, 2nd edition, 2001.

 

4. Spelling and grammar check You would consider an English review. It is not critical, but I found some suggestions when I used the Grammarly, for instance: Abstract P 1 damage of >> damage to p. 1 as potential >> as a potential Introduction p. 1 on health >> on the health p.1 human being >> human beings p. 1 with potentiality >> with the potentiality p. 2 fundamental role to the efficiency >> fundamental role in the efficiency p. 2 hydrotalcite like can be replaced >> hydrotalcite can be replaced Results and discussions p. 4 line 154 and 157: peak at wavenumber >> peak at a wavenumber p. 4, line 163: Excuse me, I can not understand “This section may The morphology of Zn2+-Al3+-C4H4O62--LDHs was observed” p. 6 line 193: factor experiment >> factorial experimente p. 6 line 196: in the figure 5 >> in figure 5 p. 7 line 198: One of parameters >> One of the parameters Conclusions p. 10 line 267: had an obvious line 268 an optimum

Reply: Thanks for your patience. I have made one-to-one corrections and carefully checked the full text to correct grammatical mistakes. I also asked native English speakers to check the whole paper aiming to avoid relevant mistakes.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper addresses adsorption of trichlorophenols on a new adsorbent based on modified anionic clays.

In general, the topic is of great interest to a broad readership, and of great importance for the environment related research and applications. However, in order to meet the standards of the scientific soundness of MDPI journals it needs some important  improvements so I suggest strong revision before the acceptance.

The main objection is related to poor English and grammar where some of errors do not affect the scientific message (singular/plural, future/present/past tense) but some do.
The main objection related to scientific matter is related to the RSM method. 

I list some comments here and attach the file with the rest of them placed next to highlighted segments.   

It is not clear from the title what is the focus of the paper, is it about the optimization of / optimal / optimized removal of trichlorophenols, or the process of synthesis of the adsorbent is optimized itself.
Line 90 says ... to optimize the process conditions but it should be clear from the beginning

Abstract:
The description of the contribution is not precise. Line 16: "better adsorption performance" than ...? Line 17: greater layer spacing than which ones?
Text in the abstract does not tell what is the starting adsorbent and what is the modification authors elaborate in this paper, so the comparison (better, greater) is confusing.  

Introduction:
There is no literature and comment on the method of optimization. I suggest citing 
Yasin, Yamin, Maszlin Mohamad, and Faujan BH Ahmad. "The application of response surface methodology for lead ion removal from aqueous solution using intercalated tartrate-Mg-Al layered double hydroxides." International Journal of Chemical Engineering 2013 (2013).
and checking if there there are newer references, maybe with another method of optimization (AI, neural networks?)

Materials
2.1 chemicals
There are standardized nomenclatures of chemical compounds and mixtures. I suggest using them along with the formulas.

For the improvement of scientific soundness, rephrase the long sentence, spread in lines 139-141,  into several independent sentences.

3. Results:
Figure 2: there is no y label.
Figure 3: why items start from E,
Lines180-182: rephrase the sentence in order to make it more understandable 

Subsection 3.3 method RSM is not explained, in details that are sufficient to interested reader who intend to replicate the result. For instance which software is used?

Thank you for your work, it will make a nice contribution to Processes.

Seasons greetings, and all the best.

Comments for author File: Comments.pdf

Author Response

1. The main objection is related to poor English and grammar where some of errors do not affect the scientific message (singular/plural, future/present/past tense) but some do.The main objection related to scientific matter is related to the RSM method. I list some comments here and attach the file with the rest of them placed next to highlighted segments.  

Reply:Thanks for your patience, I will continue to improve my English. For this manuscript, I have made one-to-one corrections and carefully checked the full text to correct grammatical mistakes. I also asked native English speakers to check the whole paper aiming to avoid relevant mistakes.

2. It is not clear from the title what is the focus of the paper, is it about the optimization of / optimal / optimized removal of trichlorophenols, or the process of synthesis of the adsorbent is optimized itself.
   Reply: According to your suggestion, the title was changed to “The Application of Response Surface Methodology for2,4,6-trichlorophenol Removal from Aqueous Solution Using Synthesized Zn²⁺-Al³⁺-Tartrate Layered Double Hydroxides”.
3. Line 90 says ... to optimize the process conditions but it should be clear from the beginning

Reply: It has been rewrite.

4. Abstract:The description of the contribution is not precise. Line 16: "better adsorption performance" than ...? Line 17: greater layer spacing than which ones?
   Text in the abstract does not tell what is the starting adsorbent and what is the modification authors elaborate in this paper, so the comparison (better, greater) is confusing.  

Reply: the whole section of abstract was reorganized to make the description clear.

5. Introduction:There is no literature and comment on the method of optimization. I suggest citing 
   Yasin, Yamin, Maszlin Mohamad, and Faujan BH Ahmad. "The application of response surface methodology for lead ion removal from aqueous solution using intercalated tartrate-Mg-Al layered double hydroxides." International Journal of Chemical Engineering 2013 (2013).and checking if there there are newer references, maybe with another method of optimization (AI, neural networks?)

Reply: New references have been added.

5. Materials: 1 chemicals: There are standardized nomenclatures of chemical compounds and mixtures. I suggest using them along with the formulas.

Reply: All the chemical compounds and mixtures were used standardized nomenclatures along with the formulas.

6. For the improvement of scientific soundness, rephrase the long sentence, spread in lines 139-141,  into several independent sentences.

Reply: This sentence was rephrased, meanwhile, all the long sentences in the full text were checked and necessary modifications were made.

7. Results:
   Figure 2: there is no y label.
   Figure 3: why items start from E,
   Lines180-182: rephrase the sentence in order to make it more understandable 

Reply: Thanks for your patience, each question you mentioned has been corrected.

8. Subsection 3.3 method RSM is not explained, in details that are sufficient to interested reader who intend to replicate the result. For instance which software is used?

Reply: The explanation of method RSM was added in manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript has now been accepted for publication in Processes Journal.