Activated Carbon from Paper Waste as Potential Adsorbents for Methylene Blue and Hexavalent Chromium

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript explores the use of activated carbon derived from paper waste for the adsorption of methylene blue (MB) and chromium (Cr(VI)) from aqueous solutions. The study is framed within the context of environmental sustainability and pollution mitigation. The authors describe the preparation of the adsorbents, characterize them using various techniques, and evaluate their performance through batch adsorption experiments.

·       The novelty of the work should be highlighted better  in the introduction .

 

·       The authors should include a comparisons of the activated carbon’s performance with other waste-derived adsorbents.

 

·       The authors should elaborate on how the use of green solvents could reduce the environmental footprint of producing activated carbons. Refer to general reviews on green chemistry and solvent sustainability. See for example

 

1.     . The Quest for Green Solvents for the Sustainable Production of Nanosheets of Two-Dimensional (2D) Materials, a Key Issue in the Roadmap for the Ecology Transition in the Flatland. Molecules 2023, 28, 1484. https://doi.org/10.3390/molecules28031484

2.                 Sundmacher, K. Sustainability of green solvents – review and perspective. Green Chem. 2022, 24, 410–437, doi:10.1039/D1GC03662A.

 

 

·       The authors should enhance the conclusion of their manuscript by incorporating a dedicated section on future outlook, which addresses the limitations of this study and provides guidance for future research directions.

Comments on the Quality of English Language

moderate revision 

Author Response

Please see the attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper reported the preparaiton of activated carbon from paper waste and its application as adsorbent for removal of pollutants.  This paper can be reconsidered for publication after major revision.

(1) In Figure 3, for the adsorption isotherm analysis, it is obvious that the adsorption process has not reached equilibrium state, so the currently reported data is not complete. Please supplement experimental adsorption data in more initial concentrations, until the adsorption equilibrium was reached. 

(2) Adsorption mechanism should be explored. The fitting results with different models may give some information about adsorption behaviors. It is required to characterize the adsorbent after adsorption of MB or Cr(VI) to confirm the interaction between adsorbent and adsorbates, and thereby reveal the adsorption mechanism.

(3) The components of carbon should be analyzed with Raman spectra, What is the ratio of sp3 and sp2 hybridized carbon?

(4) Please also give the pore-size distribution curves.

(5) The adsorbent should be compared with other adsorbents of MB or Cr(VI), for example,  Al-incorporated magadiite (Applied Clay Science, 2023, 231: 106745);  Acid-geopolymer (Applied Clay Science, 2023, 245: 107126); MgAlLDH modified montmorillonite (Applied Clay Science, 2023, 233: 106815); Magnetic asphalt-based activated carbon (Separation and Purification Technology, 2023, 321:124205)  and others.

(6) The english language needs to be improved thoroughly.

 

Comments on the Quality of English Language

The english language needs to be improved greatly.

Author Response

Please see the attached file

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,

 

greetings!

 

The idea of this work seems contradictory. It aims to solve problems associated with pollution, but the methods applied to produce the solution use chemicals that are also environmental problems (such as H2O2 and KMnO4). Incineration is also a step of the procedure. Future scale-up wouldn’t be a problem? I would like you to explain that.

 

Regarding “Introduction”, it lacks some examples of activated carbon adsorbing methylene blue and chromium. It also needs to dimensionate (to scale the extent) the problem you want to solve. Regarding waste paper, numbers were provided. But how big is the problem of dye and heavy metal pollution? It is necessary to cite references that inform the estimated quantity of these released into the environment in a given time interval, for example.

 

When it comes to “Materials and methods”, it is necessary to perform adsorption-desorption experiments to allow readers to access the regeneration performance of the proposed adsorbent. It is also necessary to offer to readers an idea of the materials’ dimensions. I recommend performing laser diffraction particles size analysis.

 

Regarding “Results” it is important to present SEM images in a different scale to allow details’ observation. FTIR results lack discussion on why transmittance varies for each peak in each material. Table 4 lacks standard deviation of thermodynamic parameters.

 

When it comes to “Conclusion” it is necessary to review it after new experimental data, and also to include the new aspects there.

Author Response

Please see the attached file

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I recommend the publication of this work

Comments on the Quality of English Language

moderate revision 

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,

greetings!

The manuscript was successfully improved.

Best regards