Efficiency of Adsorption and Photodegradation of Composite TiO₂/Fe₂O₃ and Industrial Wastes in Cyanide Removal

Round 1

Reviewer 1 Report

The manuscript “Efficiency of Adsorption and Photodegradation of Composite TiO2/Fe2O3 and Industrial Waste in Cyanide Removal”  determines the adsorption capacity and photodegradation of three materials for cyanide removal. It needs major revision according to the following comments: 

-       Introduction must be improved by adding more relevant papers and removing some cited papers that are not strongly related to the manuscript, i.e. Seung-Mok et al. since Fe (VI) has not been mentioned or discussed in the manuscript.

-       The experimental section lacks of the exact compositions of Clay-K and BFS materials; authors only mentioned that silicon and aluminum oxides are the main components. 

-       Some figure and table numbers mentioned in the text do not correspond to figure and table numbers.

-       In Section 3.2.1, only physical property (surface area) is discussed to explain the different adsorption efficiencies of 3 materials for cyanide adsorption. Do chemical properties, i.e., functional group influence the adsorption capacities? Discussion on chemical properties impact on adsorption capacities should also be included.

-       In Fig. 6, why did the adsorption efficiency of BFS decrease with increased concentration of cyanide? This behavior is different from TiO2/Fe2O3 and Clay-K.

-       In the adsorption kinetics study, the graph to show the fit of pseudo first order to experimental data should be added and compared with the second order kinetics. The unit of K2 is also missing.

-       In Fig. 11, adding the solar irradiation was found to increase the degradation efficiency compared with UV irradiation only (Fig. 9). What is the reason behind?

-       Conclusion should be more concise. Subtitles should not be used in Conclusion section. 

Author Response

Comments and Suggestions for Authors

The manuscript “Efficiency of Adsorption and Photodegradation of Composite TiO2/Fe2O3 and Industrial Waste in Cyanide Removal”  determines the adsorption capacity and photodegradation of three materials for cyanide removal. It needs major revision according to the following comments:

1. Authors appreciate the reviewer´s comments.

In the revised version of the manuscript, we addressed all the indicated comments and corrections.

 

Introduction must be improved by adding more relevant papers and removing some cited papers that are not strongly related to the manuscript, i.e. Seung-Mok et al. since Fe (VI) has not been mentioned or discussed in the manuscript.

1. Introduction has been revised and improved.

 

The experimental section lacks of the exact compositions of Clay-K and BFS materials; authors only mentioned that silicon and aluminum oxides are the main components.

1. Thanks. Clay-K chemical composition is mainly silicon and aluminum oxides, it also contains 1.27% and 0.1% of Fe2O3 and TiO2, respectively. The material called "BFS" comes from the metallurgical industry, its main mineralogical composition is quartz, kaolinite and graphite, its chemical composition is mainly based on silicon and aluminum oxides and carbon (6%), it also contains various types of iron oxides in smaller quantities (2.4% Fe2O3 and 1.1% Fe3O4).

 

 

Some figure and table numbers mentioned in the text do not correspond to figure and table numbers.

1. Numbering of figures and tables have been corrected.

 

In Section 3.2.1, only physical property (surface area) is discussed to explain the different adsorption efficiencies of 3 materials for cyanide adsorption. Do chemical properties, i.e., functional group influence the adsorption capacities? Discussion on chemical properties impact on adsorption capacities should also be included.

In Fig. 6, why did the adsorption efficiency of BFS decrease with increased concentration of cyanide? This behavior is different from TiO2/Fe2O3 and Clay-K.

3. Detailed discussion about these technical issues was included in the final version of the manuscript (section 3.2.1).

 

In the adsorption kinetics study, the graph to show the fit of pseudo first order to experimental data should be added and compared with the second order kinetics. The unit of K2 is also missing.

8. Linear fit of the pseudo first order kinetics was included in Figure 8.

K₁ and K₂ units are indicated in Table 2.

 

In Fig. 11, adding the solar irradiation was found to increase the degradation efficiency compared with UV irradiation only (Fig. 9). What is the reason behind?

1. As indicated in the initial manuscript (line 428), natural sunlight is composed by different types of radiation (visible, UV, and infrared) and, as a result, it may generate and extended range and increased level of excitation. In agreement with the photocatalytic effect, this condition leads to an increased number of strong oxidizing species.

 

Conclusion should be more concise. Subtitles should not be used in Conclusion section.

1. Conclusion have been properly summarized and the subtitles were eliminated.

Reviewer 2 Report

Report attached. 

Comments for author File: Comments.docx

Author Response

The manuscript titled “efficiency of adsorption and photodegradation of composite TiO2/Fe2O3 and industrial waste in cyanide removal” by Amaro-Medina et al. was reviewed. The authors have described the utilization of adsorption and photodegradation as an efficient elixir for the removal of cyanide from aqueous solution. This piece of work would be a good addition in the attempt to harnessing natural energy sources to drive a green economy. The manuscript might be considered for publication subsequent upon some corrections and updates. Areas of concerns are:   

1. Authors appreciate the reviewer comments.

In the revised version of the manuscript, we addressed all the indicated comments and corrections, which are highlighted in yellow.

 

1. Line 3, TiO2/Fe2O3 should be properly presented
2. The subindexes in the composite formula were corrected.
3. Line 11, numbering of institutional affiliation should be addressed.
4. Numbering of institutional affiliation was corrected.
5. It is not clear how Fig. 2a revealed agglomeration; TEM image should be provided to enhance communication
6. Figure 2 was properly described in the new version of the manuscript.
7. In line 175, the spelling of synthesis should be updated. Check for grammatical errors throughout the whole length of the manuscript
8. Grammatical errors and typos have been corrected in the revised version of the manuscript.
9. The statement on line 256 don’t look scientific, it should be recasted and updated
10. The statement on line 256 was re-written and validated with experimental results.
11. On line 269, adjust specific surface area value for clay-K
12. Specific surface area unit was corrected.
13. The FTIR assignment of the samples need to referenced, check line 284 for assignment and consistency
14. Absorption bands were referenced.

-R. Dewi et al 2018 J. Phys.: Conf. Ser. 1116 042010 Characterization of technical kaolin using XRF, SEM, XRD, FTIR and its potentials as industrial raw materials. doi:10.1088/1742-6596/1116/4/042010

-Wu, L.; Yan, H.; Xiaoc, J.; Li, X.; Wang, X.; Zhao, T. Characterization and photocatalytic properties of nano-Fe2O3–TiO2 composites prepared through the gaseous detonation method. Ceram. Int. 2017, 43, 14334–14339. https://doi.org/10.1016/j.ceramint.2017.07.189

8. Line 346 (20 ppm – 750 mg/L), please use uniform unit in reporting. Check the whole length of the manuscript
9. All concentrations units were uniformed in the revised version of the manuscript.
10. It is important that authors utilize scheme, equation or analytical results to show evidence of photodegradation
11. A scheme about the photocatalytic process has been added in the new version of the manuscript (figure 13).
12. A comparative table on adsorption capacity with similar materials should be incorporated
13. Thanks. Very important suggestion. The objective of the work is to determine the photodegradation capacity of cyanide, previously considering the possible contribution of adsorption. In this sense, the materials have a disadvantage in adsorption compared to materials whose objective is precisely to remove cyanide by this technique.
14. Line 551, reference should be checked for format.
15. Reference section format was reviewed and corrected.

12 references out of 30 utilized are quite old. Authors should update manuscript with recent literatures

1. Revised version of the manuscript includes updated references.

Round 2

Reviewer 1 Report

The manuscript has been corrected and the queries/comments are addressed properly. English language mistake is still found, i.e., lines 99-100.