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  • Khadijah Mohammedsaleh Katubi 1,
  • Fatimah Mohammed Alzahrani 1,* and
  • Mohamed A Tahoon 4,6
  • et al.

Reviewer 1: Anonymous Reviewer 2: Anonymous

Round 1

Reviewer 1 Report

Referee comments on the manuscript Processes-D-21-1191554

 

Partially reduced graphene oxide modified with polyacrylonitrile for the removal of Sm3+ from water

Khadijah Mohammedsaleh Katubi, Fatimah Mohammed Alzahrani, Norah Salem Alsaiari, Abdelfattah Amari, Faouzi Ben Rebah, and Mohamed A. Tahoon

 

This paper describes the preparation of HPAN-PRGO nanocomposite as a novel adsorbent for the removal of samarium ions from water.  Characterization techniques such as SEM, TEM, FT-IR, and XRD have been used. This work is well structured, the techniques used are appropriated, but I think it is necessary to carry out the textural characterization of the adsorbents, that is, the determination of the specific area BET; volume, size and pore size distribution of adsorbents.

The characterization of adsorbents could be improved applying N2 adsorption isotherm, Hg porosimetry, etc. This paper should be improved for its publication in Processes.

Authors should include the performance of the composite preparation process as well as the cost of the preparation process. This is important to know its possible use on an industrial scale. The nanocomposite preparation process is not very detailed. The authors claim that they are compounds based on graphene nanoparticles, but in this work there is no technique that determines the pore size distribution, especially to be able to eliminate Sm3+ from contaminated water.

It is important in this work to know the size of the species to be removed from the water in order to prepare nanocomposites with a certain number and type of nanopores in order to retain said species.

On page 363-364, the authors include the sentence “This indicated that the ions were adsorped over the surface of nanocomposite…….?, It is adsorbed.

The conclusions are too long, they must be short and concise.

Author Response

 

1-This work is well structured, the techniques used are appropriated, but I think it is necessary to carry out the textural characterization of the adsorbents, that is, the determination of the specific area BET; volume, size and pore size distribution of adsorbents.The characterization of adsorbents could be improved applying N2adsorption isotherm, Hg porosimetry, etc. This paper should be improved for its publication in Processes.

We thank the reviewer of this comment. We added the information related to the determination of the surface area using N2 adsorption-desorption isotherm (Lines 243-247)

However, in the present study partial characterisation of the material was conducted and our major objective in this stage was to point out the removal of Sm3+ from water using partially reduced graphene oxide modified with polyacrylonitrile. We are now planning to process further characterisation of the material and we will test its removal efficiency for other pollutants.

2-Authors should include the performance of the composite preparation process as well as the cost of the preparation process. This is important to know its possible use on an industrial scale.

A paragraph was added (Lines 371-380)

3-The nanocomposite preparation process is not very detailed. The authors claim that they are compounds based on graphene nanoparticles, but in this work there is no technique that determines the pore size distribution, especially to be able to eliminate Sm3+from contaminated water. It is important in this work to know the size of the species to be removed from the water in order to prepare nanocomposites with a certain number and type of nanopores in order to retain said species.

Nanocomposite synthesis was conducted as discriped by Marcano et al (2010). This reference was indicated in the muniscript. Therefore, we do not need to detail the methodology.

In the present study, the pore size distribution was not determined, and as mentioned before, we are now planning to process further characterisation of the material. Concerning the size of the species to be removed, in our study, the ionic radius of Sm3+ is of the order of Å (1.08 Å-1.13 Å. However, is very important to indicate here, that the high removal of Sm3+ ions is attributed to the presence of large number of carboxylate and amine groups over the nanocomposite surface.

4-On page 363-364, the authors include the sentence “This indicated that the ions were adsorpedover the surface of nanocomposite…….?, It is adsorbed.

The word " adsorped "was corrected to " adsorbed ".

5-The conclusions are too long, they must be short and concise.

The conclusion was shortened

Reviewer 2 Report

The manuscript describes the ability of polyacrylonitrile nanoparticles @amino-functionalized partially reduced graphene oxide (PAN-PRGO) and hydrolyzed PAN-PRGO to adsorb samarium ions (Sm3+) from water. The topic is interesting and relevant, however, there are some points that the authors should revise before the manuscript be considered for publication:

  • A more detailed description in the materials characterization is needed, such as, how the samples for SEM and TEM analysis were prepared, if the samples needed conductive coating to be analyzed by SEM, acceleration voltage used for TEM, the equipment used for the Raman spectroscopy characterization and the laser used… etc.);
  • The SEM and TEM images should have better resolution;
  • The authors should present some SEM and TEM images of GO and GO-NH2, as they show and discuss some Raman, XRD and FTIR characterization of those nanomaterials. Some EDS analysis would enrich the characterization / discussion of this section.
  • The authors should mention how the distribution of sizes of HPAN and PAN particles is calculated and show the histograms;
  • The discussion of Raman spectroscopy characterization could be improved. The authors should mention how many Raman spectra were acquired per sample to calculate the ID/IG intensity ration and its standard deviation.
  • The XRD discussion could be enriched / improved adding the calculated interlayer spacing for GO, GO-NH2;
  • The typical absorption spectra of the SM3+ in solution could be presented.

Only after the authors revise these topics the manuscript could be considered for publication.

Author Response

 1- A more detailed description in the materials characterization is needed, such as, how the samples for SEM and TEM analysis were prepared, if the samples needed conductive coating to be analyzed by SEM, acceleration voltage used for TEM, the equipment used for the Raman spectroscopy characterization and the laser used… etc.);

 

The most important information related to techniques was added in the methodology (section 2.3. Materials characterization)

 

2-The SEM and TEM images should have better resolution;

The provided images are originals. Images were arranged were rearranged slightly.

 

3-The authors should present some SEM and TEM images of GO and GO-NH2, as they show and discuss some Raman, XRD and FTIR characterization of those nanomaterials. Some EDS analysis would enrich the characterization / discussion of this section.

SEM and TEM images of GO and GO-NH2 images were added (see figures 1 and 2). The discussion was enriched (Lines 158-168)

4-The authors should mention how the distribution of sizes of HPAN and PAN particles is calculated and show the histograms;

 

Fig 1g related to the distribution of sizes was added. The average particle size was calculated by measuring the diameters nanoparticles in TEM image (Fig.1a) by ImageJ software (Lines 271-274).

 

5-The discussion of Raman spectroscopy characterization could be improved. The authors should mention how many Raman spectra were acquired per sample to calculate the ID/IG intensity ration and its standard deviation.

This ratio was calculated from three peaks and the value was the average of three values. D band to G band intensity ratio (ID/IG) was discussed.

 

6-The XRD discussion could be enriched / improved adding the calculated interlayer spacing for GO, GO-NH2;

Based on Bragg’s Law, the interlayer spacing for GO and GO- NH2 was 8.753 Å and 8.185 Å, respectively.

Bragg, W.H.; Bragg, W.L. The reflection of X-rays by crystals. Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character. R. Soc. 1913, 88, 428–438.

7-The typical absorption spectra of the SM3+ in solution could be presented.

We thank the reviewer for this comment. However, we think there is no need to present the typical absorption spectra of the Sm3+. Since  its concentration was determined using atomic absorption spectrometry

Round 2

Reviewer 2 Report

The responses given by the authors are satisfactory and the manuscript can be considered for publication. Although it is suggested that the authors transfer the sentence “The average particle size was calculated by 174 measuring the diameters nanoparticles in TEM image by ImageJ software” (page 4, line 174) to the experimental part.