Biosorption of Eriochrome Black T Using Exserohilum rostratum NMS1.5 Mycelia Biomass

Round 1

Reviewer 1 Report

Dear author(s),

Thank you very much for inviting me to review the manuscript "Biosorption of eriochrome black T using Exserohilum rostratum NMS1.5 mycelia biomass”. The manuscript is very interesting, however, the authors should choose to revise the paper according the proposed changes, before it is finally published in Multidisciplinary Scientific Journal.

1.-  Abstract:

- Make it clear whether your work is purely theoretical or whether there is some industrial application on the horizon.

2.- Introduction:

-  What problem did your research solve? What is your contribution to the advancement of this kind of research? Better explain the urgency of your research hypothesis.

- More intensely compare your findings with existing literature, refer to methods used in developing countries. The authors should cite the following articles: "Bioremediation of waste water to remove heavy metals using the spent mushroom substrate of Agaricus bisporus" and "Valorization of bio-waste for the removal of aluminum from industrial wastewater".  

- Justify the urgency of its investigation from industrial point of view at the end of the Introduction chapter.

3.- Materials and Methods:

-  Our readers should find here only detailed description of all your procedures (step by step), anybody who reads this chapter should be able to repeat your methods and obtain exactly the same results.

 - Standards and regulatory specifications used in the present study should appear in the references.

4.- Results and discussion:

- The manuscript should show a table of results with the tests. How many experiments were carried out in the laboratory?

- There are many factors that can affect the effective adsorption of of eriochrome black T, why do the authors study the effect of Ph and the effects of initial EBT concentration?

 - Indicate direction for future research and propose some improvements.

5.- Conclusions:

- Conclusions should be improved

- Discuss relevance of your work with respect to the waste management aspect.

 6.-Others:

-  It would be convenient for the manuscript to be reviewed by a native English speaker so that any grammatical errors it may contain are corrected.

Author Response

1.-  Abstract:

- Make it clear whether your work is purely theoretical or whether there is some industrial application on the horizon.

Comment:

The presence of eriochrome black T (EBT) dye in waste water causes a significant hazard to human health and ecology. In the current study, biosorption was employed to eliminate EBT from water. Thus, we utilized Endophytic fungi strain Exserohilum rostratum NMS1.5 mycelia biomass as biosorbent agent. The process was carried out at room temperature by magnetic stirring. The result indicates that an increase in pH would decrease adsorption capacity and removal percentage. In addition, an increased EBT concentration would decrease the removal percentage and increase biosorption capacity. The equilibrium time indicates that after 300 minutes of mixing, the percentage removal and biosorption capacity were 80.5% and 100.61 mg/g, respectively. The biosorption isotherms and kinetics were compatible with the Freundlich model and the Pseudo-second-order. This research indicates that E. rostratum NMS1.5 may be utilized as an environmental friendly and affordable alternative biosorbent material for EBT removal.

2.- Introduction:

-  What problem did your research solve? What is your contribution to the advancement of this kind of research? Better explain the urgency of your research hypothesis.

- More intensely compare your findings with existing literature, refer to methods used in developing countries. The authors should cite the following articles: "Bioremediation of waste water to remove heavy metals using the spent mushroom substrate of Agaricus bisporus" and "Valorization of bio-waste for the removal of aluminum from industrial wastewater".  

- Justify the urgency of its investigation from industrial point of view at the end of the Introduction chapter.

 Comment:

Textile industry effluent is a considerable problem when dyes are present in aquatic environments, which are toxic, carcinogenic and mutagenic [1-2]. Even at a low concentration (< 1 mg/L), the colours are visible in water [3]. Eriochrome black T (EBT) is an azo dye containing sulphonate groups and aromatic rings discovered in wastewater [4]. Conventional methods such as coagulation, ion exchange, membrane filtration, adsorption and advanced oxidation processes have been investigated for dye removal [5-7]. Among these, adsorption is considered one of the famous and attractive technologies that use an adsorbent [8-9].

Numerous sorbent materials such as zeolite [8] and activated carbon [10] have been studied. However, these sorbents are still a little expensive. As a result of the above reasons, researchers have reported using biological materials such as algae, fungi and bacteria for dye removal from water, which are practical and economical [11]. On the other hand, this materials is not release toxic since it does not require supply of nutrient. These materials are referred to as biosorbents, and the process is called biosorption [12-13]. In this study, we used the Endophytic fungi strain Exserohilum rostratum NMS1.5 mycelia biomass to remove eriochrome black T (EBT) from water.

3.- Materials and Methods:

-  Our readers should find here only detailed description of all your procedures (step by step), anybody who reads this chapter should be able to repeat your methods and obtain exactly the same results.

 - Standards and regulatory specifications used in the present study should appear in the references.

Comment:

Actually, I have already mentioned in the manuscript. The biosorbent of Exserohilum rostratum NMS1.5 mycelia biomass was derived from prior studies [13]. The fungal endophytes were cultivated in a PDB medium and incubated at 28 ⁰C for seven days. Then, the medium was then filtered, and mycelia were oven-dried at 60 °C for three days for further experiment.

4.- Results and discussion:

- The manuscript should show a table of results with the tests. How many experiments were carried out in the laboratory?

Comment:

I just show the figure to make easy understand.

I was conducted three replicated and average show in the manuscript.

- There are many factors that can affect the effective adsorption of of eriochrome black T, why do the authors study the effect of Ph and the effects of initial EBT concentration?

 - Indicate direction for future research and propose some improvements.

 Comment:

Actually the contact time also was conducted. We can see in the section of adsorption kinetics. For this data I think enough to get conclusion to remove EBT from water.

5.- Conclusions:

- Conclusions should be improved

- Discuss relevance of your work with respect to the waste management aspect.

In the present study, the first report using affordable and non-toxic mycelia biomass of Exserohilum rostratum NMS1.5 to remove EBT dye from water. We studied the effect of pH, initial EBT concentration and contact time. The results obtained that the optimum conditions at pH of 2 with removal percentage and sorption capacity were 80.5% and 100.61 mg/g, respectively, for 300 minutes of equilibrium time. Increases initial EBT concentration would decrease the removal percentage and increase sorption capacity. The isotherm and kinetic model were fitted to the Freundlich and Pseudo-second-order, respectively. The result indicates that Exserohilum rostratum NMS1.5 mycelia biomass can effectively remove EBT dye from water.

Author Response File: Author Response.docx

Reviewer 2 Report

Materials and methods

Page 2 line 45 and 46: There is lack of information regarding all equipment used in experiments (pH-meter and magnetic stirrer).

Page 2 line 51: authors should have explained in more details how they determinate EBT concentration by UV-Vis spectrophotometer. 

Results and discussion

Page 3 line 76: authors should have put operation parameters in Figure 2 caption.

Page 4/6: Authors should have put axis units on Figure 4 and Figure 6. Also, many researchers agree that nonlinear method is more appropriate method for estimating the isotherm parameters in comparison to linear method. Since, it is always better to find the isotherm coefficients by nonlinear method as far as practicable, authors should present obtained date by nonlinear method in the manuscript.

Page 5: In Table 1 values of experimental q_exp are not presented in order to compare it with q_max.

Page 5 line 119: authors should have put operation parameters in Figure 5 caption.

Conclusion

In conclusion (and abstract) authors claim that sorbent removal and biosorption capacity are 80.5 % and 100.61 mg/g, but those numbers doesn’t exist in manuscript. Please check. Also maximum biosorption capacity is 155.71 mg/g from Table 1 and Langmuir isotherm model (since Freundlich doesn’t give information of maximum capacity), not 100.61 mg/g as it is in conclusion and abstract.

Author Response

Materials and methods

Page 2 line 45 and 46: There is lack of information regarding all equipment used in experiments (pH-meter and magnetic stirrer).

pH meter and magnetic stirrer were used LAQUA twin Horiba and REXIM RSH-4AN, As One, respectively

Page 2 line 51: authors should have explained in more details how they determinate EBT concentration by UV-Vis spectrophotometer. 

All experiments were conducted on a magnetic stirrer at room temperature. After treatment process, the sorbent was filtered and supernatant put in cuvette (Quartz) to check absorbance (556 nm). We analyzed the effect of pH (2-10), initial EBT concentration (10-25 mg/L), and contact time (15-300 minutes). The biosorption removal rate and capacity were calculated using Eq (1) and (2), respectively.

Results and discussion

Page 3 line 76: authors should have put operation parameters in Figure 2 caption.

Page 4/6: Authors should have put axis units on Figure 4 and Figure 6. Also, many researchers agree that nonlinear method is more appropriate method for estimating the isotherm parameters in comparison to linear method. Since, it is always better to find the isotherm coefficients by nonlinear method as far as practicable, authors should present obtained date by nonlinear method in the manuscript.

Page 5: In Table 1 values of experimental q_exp are not presented in order to compare it with q_max.

Page 5 line 119: authors should have put operation parameters in Figure 5 caption.

I have already added in manuscript.

Conclusion

In conclusion (and abstract) authors claim that sorbent removal and biosorption capacity are 80.5 % and 100.61 mg/g, but those numbers doesn’t exist in manuscript. Please check. Also maximum biosorption capacity is 155.71 mg/g from Table 1 and Langmuir isotherm model (since Freundlich doesn’t give information of maximum capacity), not 100.61 mg/g as it is in conclusion and abstract.

Comment

I have already put in Table 2 for q_exp.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear reviewer, first, thank you for your careful review of our paper and your comments corrections and suggestions.

I have only one point to make: 

1. Add some of the considerations presented in [https://doi.org/10.1016/j.jclepro.2020.121608] in the Introduction section about the biosorbent investigated. I would like to see something like this sentence:

“Numerous investigations have been conducted on the creation of inexpensive adsorbents that might replace activated carbon that is sold commercially [X].”

If you add this sentence, it is OK from my part, and I need not to refer the new version (unless more drastic changes are induced by other reviewers).