Alkali Etching Hydrochar-Based Adsorbent Preparation Using Chinese Medicine Industry Waste and Its Application in Efficient Removal of Multiple Pollutants
Round 1
Reviewer 1 Report
1) Please discuss the legal issues related to the treatment of hazardous waste.
2) The values in table 1 are too accurate.
3) Were the sorption mechanisms presented in point 3.4 confirmed in equilibrium and kinetic studies?
4) In point 3.5 the authors write about the content of metals on the surface of the sorbent. In addition to surface layers, the EDS analysis also covers near-surface layers.
5) Fig. 6 is illegible.
6) The publication should be enriched with elemental analysis of hydrocarbon. The sorbent before the sorption process should also be a blank sample in all analyses.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
General comment:
The manuscript presents interesting results concerning the potential application of hydrochars produced from waste from the Chinese medicine industry as adsorbents of pollutants. The manuscript is of interest. However, some changes and improvements are needed before it can be accepted for publication.
Specific comments:
There are some deficiencies in a number of areas – in particular, the experimental design, analytical characterization of materials and statistical analyses. The manuscript could also be better integrated with closely related research specific to the application of hydrochars and pyrochars as pollutants adsorbents. The discussion is poor.
The summary is very imprecise.
Ex. Line 14 provide values.. how large ?.
Line 16. Had abundant pore structures and funtional groups? But the structures would be further improved... : Please re-write.
A single or a couple of physicochemical properties could not interpret complex changes in multi-factors that jointly determine the P sorption characteristics
The introduction is very poor.
Examples.
Line 35. “The annual output of CMIW is huge......etc” please improve the information provided. Provide an average composition of CMIW and amount (per year/region..).
Line 47. “Hydrochar has a porous structure”. Not always, and not specially at those used for this study. Porosity depends on the feedstock and pyrolysis conditions (Paneque et al_2017, JAAP; https://doi.org/10.1016/j.jaap.2017.09.019; Peng et al., Fuel, 176 pp110-118, 2016).
The specific areas for all the samples were low relative to other reported activated HTCs, which typically have SSA-BETs greater than 800 m² g−1 (Zhou et al., 2017; Bioresour. Technol., 232, pp. 204-210, 2017).
The introduction does not take into account previous studies with the same objectives. They should be taken into account, also when discussing the results.
Ex. Ighalo et al., 2022. https://doi.org/10.1016/j.cherd.2022.06.028
Hydrochars have been profusely used to adsorb trace elements with sucess. However, there is no a detailed review of previous studies, with similar objectives using different feedstock.
Materials and methods.
A detailed characterization of the feedstock and produced hydrochars is strictly needed including physical properties and elemental composition.
Feedstock type and pyrolysis conditions determine char properties. Thus they play a key role affecting the sorption capacity. The production conditions are essential for the properties of the HTC. They have to be explained in detail., even if the material is purchased. If a scientific experiment is not reproducible, what is the point?
Porosity and Specific Surface Area are the two most crucial physical properties that strongly affect the function of chars. In adition to specific surface area data (SSA-BET) please provide iodine index. It is used to assess the adsorption capacity of an organic filter.
Please correlate the adsorption capacity with SSA-BET (the lack of correlation would inform about the importance of other factors and mechanisms are playing).
FT-IR spectroscopy of HTC samples is not powerfull enough to provide reliable information concerning the functional groups present. In case you want to confinf these findings you should perform solid state 13C NMR spectroscopy. In fact all FT-IR spectra are the similar and the adsorption results are different.
Please provide standard deviation and level of statistical significance for all the tables and figures 1,3,4,5 and 7.
Figure 6 is of very low quality. It is not possible to obtain any result from that figure. SEM images are not informative.
Figures without a statistical significance study are not useful. The level of significance needs to be clearly stated.
Conclusions section
The conclusions are rather speculative and lack of especific information supporting the statements. Please, re-write completely. Please show your data in a more informative way.
- The removal effects of MB (60-80%), Pb2+ (≥98%) and Cd2+ (20-57%) by AE-CMIW hydrochar were various. (various) Pleas re-write.
- In addition, there were the electrostatic interaction, physical adsorption, functional group interaction between three pollutants and AE-CMIW hydrochar, as well as the differences of hydrating ion radius of metal ions. (how did you measure these parameters? I could not find the functional group interaction neither the electrostatic interaction. Please re-write.
Did you find any correlation (positive or negative) between the adsorption capacity of the metalic ions and the HTC properties measured by this study?
Other comments:
Please check the use of English. There are multiple grammatical incorrectness, check the use of verb tense.
Please provide an independent section detailing the statistical treatment of data and double check the statistical significance of the data.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
I recommend the publication of this manuscript
Author Response
Dear reviewer,
On behalf of my co-authors, we greatly appreciated your kind help on our manuscript! The English language spell have been checked and improved by a native English speaker. Please find the Editing Certificate in the attachment. I‘d like to say that the title of this manuscript at that time was "Green adsorbnet preparation using Chinese medicine industry waste and its application in efficient removal of multiple pollutants". So the certificate was the above title. Then according to the later review comments, we changed the above title into "Alkali etching hydrochar-based adsorbent preparation using Chinese medicine industy waste and its application in efficient removal of multiple pollutants".
Best regards,
Xinyan Zhang
Author Response File: 
Author Response.pdf
Reviewer 4 Report
In general, I find this manuscript to be interesting, with conclusive and applicable results in the scientific and industrial fields. The information presented is adequately presented, and the methods used are correctly selected and well applied. I have a few minor observations to improve the description of the methodology:
In line 140, please write the volume in the correct units: mL
In line 145, please provide a detailed description of the methods used for coupled plasma-optical emission spectrometry
I consider the manuscript to be in good shape for publication.
Author Response
Dear reviewer,
On behalf of my co-authors, we greatly appreciated your kind help on our manuscript! The English language have been checked and improved by a native English speaker. Based on the valuable comments, we did make careful revisions to the paper accordingly, and all revisions to the manuscript have been marked up using the “Track Changes” function. Below please find our point-by-point responses to comments.
Point 1: In line 140, please write the volume in the correct units: mL
Response 1: Thanks for your good suggestion. We have corrected the units of the volume. Please see the revised manuscript in the attachment (line 180).
Point 2: In line 145, please provide a detailed description of the methods used for coupled plasma-optical emission spectrometry
Response 2: Thanks for your good suggestion. We have added a detailed description of the methods used for coupled plasma-optical emission spectrometry. Please see the revised manuscript in the attachment (lines 160-176).
Best regards,
Xinyan Zhang
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The subject of the work is not a scientific novelty. The research cycle needs to be fine-tuned.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 2 Report
All issues raised by the reviewer have been answered and transferred to the text, so the manuscript can be accepted for publication.
One minor comment: The new title is a bit pretentious, but it is more a matter of style.
A final revision in English is suggested (possible spelling or typo mistakes).
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 3
Reviewer 1 Report
.
Author Response
Dear reviewer,
On behalf of my co-authors, we greatly appreciated your kind help on our manuscript! We have improved the contents in the revised manuscript. Please see the attachment. Thanks!
Best regards,
Xinyan Zhang
Author Response File: Author Response.docx
