Biosorption Potential of Sargassum for Removal of Aqueous Dye Solutions
, Supattra Maneein, Jahanvi Dipakbhai Anghan, Riya Mukeshbhai Anghan, Md Mahmud Al Farid and John James MilledgeRound 1
Reviewer 1 Report
See attached word document.
Comments for author File: 
Comments.pdf
Author Response
We thank the reviewer for comments and suggestions and have amended the document accordingly.
R.1.1 Go through to double check spelling, grammatical, and formatting errors. A major issue is that the last sentence of the abstract is unclear.
Resp. We have reviewed and edited the text and the abstract.
R1.2 In the introduction mention that Sargassum has been studied previously but they used chemical modifications, wherein CaCl2 is specifically mentioned. How does this work go beyond what was previously done with CaCl2 as a pretreatment to improve dye uptake?
Resp. This study is the first to our knowledge to examine biosorption by both 'untreated' pelagic Sargassum and S. muticum. Other studies have used treated material, which could significantly increase costs. This study compares the biosorption of untreated and CaCl2 treated. Although CaCL2 treatment increased the removal of dyes, this may not be economically practicable, but the economics of the use of Sargassum was beyond the scope of this brief technical note.
R1.3 More should be included in the introduction on Brilliant Blue and if any work has been done previously to remove this dye.
Resp. We have included a reference on the biosorption of BB
R1.4 Why were two anionic dyes chosen if seaweed is known to complex better with metals and cationic compounds given the functional groups present on the seaweed?
Resp. The basis of choice of dyes is limited to availability in the labs.
R1.5 Why was CaCl2 used as a treatment to enhance dye uptake? More should be included on the chemical effects this has on the seaweed structure.
Resp. We have now expanded on this point in the introduction.
R1.6 An R2 value of 1 is extremely rare and unlikely for all dosage amounts and all adsorbents. How was this calculated? Please include more to explain such a perfect fit to the calculated results.
Resp. We also were initially surprised by the high values of R2 (>0.9996 and recorded as 1). The values were calculated from the difference in the sum of squares between the average value of the dye removed and the values from the optimised first-order rate equation using the software described in the method. Removing a substance from a solution by bioabsorption is typically a first-order rate equation, and one would generally expect a high degree of agreement. Our group has in the past used Excel to optimise equations with data using minimisation of the differences in the sum of squares; however, this is time-consuming. SPSS is a proven and reliable statistical software. Although the high R2 values are unusual, the reliability of the software and close correlation of the estimated and actual values give us confidence in our results.
R1.7 The graphs should be presented in a more professional manner and more consistent with the formatting.
Resp. We have made corrections to the formatting to ensure consistency.
R1.8 The discussion should be expanded on, in particular, an explanation of why the removal of the anionic dyes was unsuccessful.
Resp. We have included an explanation in the discussion.
Author Response File: Author Response.pdf
Reviewer 2 Report
The manuscript reports the use of Sargassum for removal of aqueous dye
solutions, which looks generally ok, but some questions have to be resolved.
- For figures 1-3, the removal results of the dyes can be focused on the range from 60% to 100% to show the difference.
- Why does CaCl2 pretreatment improve the adsorption?
- Please keep the units and decimals consistent for all the figures.
- It would be very nice if some photos of the samples can be added.
- Why does 0.4 g SM show decreased biosorption property after 120 min?
- How many cycles can these Sargassum be used for the dye degradation?
Author Response
We thank the reviewer for comments and suggestions and have amended the document accordingly.
R2.1 For figures 1-3, the removal results of the dyes can be focused on the range from 60% to 100% to show the difference.
Resp. We acknowledge the reviewer's comment, however, the Standard approach is to show the entire scale and we have left the scale 0-100%.
R2.2 Why does CaCl2 pretreatment improve the adsorption?
Resp. We have added a reference to explain this in the manuscript.
R2.3 Please keep the units and decimals consistent for all the figures.
Resp.We have made edites throughout the document to ensure consistency.
R.2.4 It would be very nice if some photos of the samples can be added.
Resp: We have previously published several papers cited in the references that have photographs of Sargassum and do not believe that they would be relevant to this brief technical note.
R2.5 Why does 0.4 g SM show decreased biosorption property after 120 min?
Resp: after 120 mins at 0.4g, the concentration in the solution increased’ indicating a de-sorption of the dye, decreasing the removal efficiency to 76.09% compared to 82.91% at 0.1 g which is a significant difference (p= 0.048).
R2.6 How many cycles can these Sargassum be used for the dye degradation?
Resp. We have not investigated this but have added a not in the conclusion that this could be of value to determine.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The questions have been addressed. It can be accepted now.
