The Application of Modified Natural Polymers in Toxicant Dye Compounds Wastewater: A Review
, Hazizan Md Akil 2, Norli Ismail 3, Siti Zalifah Md Rasib 2 and Adel Ali Saeed Al-Gheethi 4Round 1
Reviewer 1 Report
This review paper nicely describes the application of natural polymers and their modification for the removal of dye from wastewater. The manuscript is nicely written and bring new information and insights to the filed. I recommend the manuscript for publication if the authors comment and answer the questions.
" Over 100,000 types of commercial dye, for a total of more than 7×105 tons of dyestuff, are" it should be 7×10^5, isn't it? also in another place in the text.
" chemicals are being released into the environment. Thousands of types of synthetic dyes are commercialized to obtain multicolour fabrics [34]. It is estimated that when 120L of a dye is used per 1 kg of fabric, 50 % ends up as effluent [35]. Another concern associated with the traditional" does not make sense, you should explain how much is the concentration of solution which you have used 120L, please clarify it.
"Meanwhile, Jordan and Bangladesh did not list the permissible concentrations of certain pollutants, such as Cr3, Sn, Ag, Al, Ba, formaldehyde, and colour, according to their regulations. One possible reason is that these countries follow the similar guidelines to those of the US EPA, except for Cr3 and colour limits. It must be Cr3+ and for other ions properly too.
"Moreover, the existing branches of natural polymers have been modified
in many studies, by inserting an acetyl group into the chitosan, resulting in more functional groups being added to the polymeric chain, thus improving its absorbance capacity of the polymers for azo dyes from the wastewater [86]. " please explain in detail"
Nature polymers can be grafted on the surface of GO for removal of dyes as GO showed good potential for deys removal from aqueous solutions as investigated by experimental and computational methods. Das et al.
J. Phys. Chem. C, 2016, 120 (26), pp 14088–14100
For these effects "Functional groups, Molecular weight (MW) of flocculant/ coagulant aid, Type of Charge Density" some references for molecular-level understanding the mechanism it needs to introduce some computational evidence from computational chemistry studies as mentioned before as the work of Das et al.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
In line 80, the authors do not explain what the physical or chemical treatment of polymers is. Examples and literature should be given.
Line 137-140 - The authors write that both Jordan and Bangladesh do not provide acceptable concentrations for any impurities, and that these countries follow the similar guidelines to those of the US EPA, except for Cr3 and color limits. However, it is not clear what this means. What guidelines are used in these countries. Is this information not available? Literature is required here.
Table. 5 is located too high. It should be moved to chapter 3 where the authors refer to it.
Table 5 should have a better literature review.
in chapter 5 is a big haos in the text, this is not read well, the text should be more coherent and divided into parts. It could use some sort of order. Otherwise, the text will be hard to understand for the reader.
in the chapter "conclusions", authors should have more to say, especially about the future of modified natural polymers.
Author Response
Please see the attachment;
Author Response File: Author Response.pdf
