Iron-Loaded Pomegranate Peel as a Bio-Adsorbent for Phosphate Removal

Round 1

Reviewer 1 Report

I recommend small corrections/improvements only in fig. 1a:

1. Please, introduce your abbreviation IS for ionic strength already in the captions of figure. In the legend of fig. 1a you see in brackets 3x (IS = 10). Here, I recommended to explain the meaning of this abbreviation IS (e.g.: IS - ionic strength) even in the captions of figure for a better reading alone from the image. 
2. Please, correct the legend "PP in NACL" into ... NaCl.  In the second legend of this figure (central) is to read "PP in NaCL" (L for NaCl in capital). 

Author Response

Response to Reviewer 1

 

We would like to thank the reviewer for the time and the effort he has dedicated for the revision of our manuscript which has helped to improve its quality. Our response follows the reviewer’s comments. The changes made in the revised manuscript are tracked.

 

Reviewer: I recommend small corrections/improvements only in fig. 1a:

1. Please, introduce your abbreviation IS for ionic strength already in the captions of figure. In the legend of fig. 1a you see in brackets 3x (IS = 10). Here, I recommended to explain the meaning of this abbreviation IS (e.g.: IS - ionic strength) even in the captions of figure for a better reading alone from the image. 
2. Please, correct the legend "PP in NACL" into ... NaCl.  In the second legend of this figure (central) is to read "PP in NaCL" (L for NaCl in capital). 

 

Authors: We thank the reviewer for these recommendations and corrections. We have introduced the abbreviation IS for ionic strength in the captions of fig. 1a and we have corrected the legend.

Reviewer 2 Report

Overview:

Presented manuscript draft "Iron-loaded pomegranate peel as a bio-adsorbent for phosphate removal." has been reviewed. The authors provided a precise evaluation of pomegranate peels loaded by iron efficiency for the phosphate removal from an aqueous solution. The authors provided a characterization of crucial factors which drive the phosphate removal, like pH, Temperature, equilibrium time, and their relationships, helping to understand the adsorption mechanisms. Also, kinetics and isotherms characterization of studied phosphate removal processes are very impressive for potential readers. All obtained data were adequately discussed in the Results and Discussion section. The overall quality of English is good, and all graphs and tables are of acceptable quality.

Overall, the manuscript is good quality and can be considered for possible publication in the Water after minor revision.

Comments:

 

Line 83: Recommended title: Preparation and activation of PP

Lines 96-97: Delete the sentence. It is not needed. The concentrations included in the text are covering the fact that all solutions were prepared that way.

Line 100: This sentence should be moved to the introduction.

Line 114 -119: Please, include the FTIR technique used for infrared data collecting. FTI

Line 117: Replace word “wavenumber” with “middle infrared (MIR).”

 

Questions:

Why did the authors include the FTIR method in this study? 

What information does FTIR provide?

Author Response

Response to Reviewer 2

 

Reviewer: Presented manuscript draft "Iron-loaded pomegranate peel as a bio-adsorbent for phosphate removal." has been reviewed. The authors provided a precise evaluation of pomegranate peels loaded by iron efficiency for the phosphate removal from an aqueous solution. The authors provided a characterization of crucial factors which drive the phosphate removal, like pH, Temperature, equilibrium time, and their relationships, helping to understand the adsorption mechanisms. Also, kinetics and isotherms characterization of studied phosphate removal processes are very impressive for potential readers. All obtained data were adequately discussed in the Results and Discussion section. The overall quality of English is good, and all graphs and tables are of acceptable quality.

Overall, the manuscript is good quality and can be considered for possible publication in the Water after minor revision.

 

Authors: We are very grateful for the encouraging comment of the reviewer and for the time and effort he has dedicated to provide valuable feedback and insightful comments on our manuscript which has helped to improve its quality. Our response follows the reviewer’s comments and questions. The changes made in the revised manuscript are tracked.

Comments:

Reviewer: Line 83: Recommended title: Preparation and activation of PP

Authors: Thanks and done!

Reviewer: Lines 96-97: Delete the sentence. It is not needed. The concentrations included in the text are covering the fact that all solutions were prepared that way.

Authors: Thanks and done!

Reviewer: Line 100: This sentence should be moved to the introduction.

Authors: We have deleted this sentence.

Reviewer: Line 114 -119: Please, include the FTIR technique used for infrared data collecting.

Authors: We have included the FTIR technique used for infrared data collecting in section “2.3 characterization of IL-PP” as follow:

“Fourier transform infrared (FTIR) spectra of PP and IL-PP were used to observe the functional groups present on their surface and assess the occurred changes after the activation of PP and the adsorption of phosphate (PO₄³⁻) by IL-PP. The spectra were recorded with a BIO-RAD Digilab Division FTS-65A/896 FTIR spectrophotometer having a 4 cm−1 resolution in the middle infrared range of 4000–400 cm−1. Each spectrum was scanned 256 times. Besides the spectra of each sample, single-reflection diamond attenuated total reflection accessory measurements were taken using diffuse reflection technique and an angle of incidence of 45°.The software Omnic 7.3 was used for FTIR data collection.”

Reviewer: Line 117: Replace word “wavenumber” with “middle infrared (MIR).”

Authors: Done!

Questions:

Reviewer: Why did the authors include the FTIR method in this study? 

Authors: The FTIR was used to identify the characteristics functional groups present on the surface of PP and IL-PP, which are instrumental in PP activation and PO₄^3- adsorption by IL-PP, and therefore helps to identify possible interactions mechanisms. We have emphasized this issue in material and method section “2.3 characterization of IL-PP” as follow:

“Fourier transform infrared (FTIR) spectra of PP and IL-PP were used to observe the functional groups present on their surface and assess the occurred changes after the activation of PP and the adsorption of phosphate (PO₄³⁻) by IL-PP.”

Reviewer: What information does FTIR provide?

 

Authors: FTIR allowed a qualitative and preliminary analysis of the main functional groups on the surface of PP that may be responsible for the incorporation of Fe(III), Which can be verified through a comparison between the FTIR spectrum of PP and IL-PP. Similarly FTIR analysis of IL-PP after PO₄^3- adsorption help to determine active sites responsible for PO₄^3- uptake and thus help to understand possible interactions between the surface of  IL-PP and PO₄^3-. We have clarified d this issue in section “3.1.3. FTIR analysis” as follow:

 

“Figure 3 shows the FTIR spectra of PP and IL-PP before and after PO₄³⁻ adsorption. Table 2 presents the results of the analysis carried out to identify the functional groups present on their surfaces and understand the possible interactions responsible for the incorporation of Fe³⁺ onto the surface of PP and for the adsorption of PO₄³⁻ by IL-PP.”

Reviewer 3 Report

Dear Author's,

the conclusions could be improved with further comparisons with the results of other similar studies. The mention of some study limitations not mentioned is also to be missing.

Author Response

Response to Reviewer 3

 

We would like to thank the reviewer for his careful and thorough reading, thoughtful comments, and constructive suggestions, which have helped to improve the quality of this manuscript. Our response follows the reviewer’s comments. The changes made in the revised manuscript are tracked.

 

Reviewer:

Dear Author's,

The conclusions could be improved with further comparisons with the results of other similar studies. The mention of some study limitations not mentioned is also to be missing.

Authors:

We thank the reviewer for these comments and suggestions. We have added a new section “3.3.3. Comparison of IL-PP with other iron-loaded bio-adsorbents” where we compare IL-PP with the most relevant bio-adsorbent activated using the iron-loading method.

We have also mentioned some limitations of the used approach in the conclusion as follow:

“This study evaluated the efficiency of IL-PP at removing PO₄³⁻ from an aqueous solution. The results indicated that IL-PP is an efficient bio-adsorbent that can be optimized as a green technology for wastewater treatment, waste biomass management, and phosphate recovery. However, a more detailed study on the performance of IL-PP at removing PO₄³⁻ from real wastewater under real operating conditions is required to check the effect of interfering ions. The successful regeneration and application of phosphate-loaded IL-PP as fertilizer must also be investigated to make this approach more sustainable and attractive especially in regions known by the huge cultivation of pomegranate fruit.”

 

Author Response File: Author Response.pdf