Preparation and Emulsifying Properties of Carbon-Based Pickering Emulsifier
Ming Jiang
Round 1
Reviewer 1 Report
This paper presented the preparation and characterization of a Pickering emulsifier by modifying graphene oxide with an amine group. Although the results are meaningful, however, it requires a fuller explanation and more sufficient proof to support the conclusions. The following concerns should be appropriately addressed.
1．In Material and Reagent, graphite, the main raw material used in the experiment, is not mentioned, but information on CNTs is given, which is confusing.
2．The process of surface grafting and emulsion preparation of GO does not seem to be described in Preparation of Materials and Emulsions, which is one of the most critical information for this study.
3．It is advisable for the authors to explain how the interfacial area of the emulsion system is calculated in the manuscript to facilitate the reader's understanding.
4．There is a labeling error in Figure 4d.
5．When comparing the FTIR and XPS of GO and GO-NNDB, the samples of NNDB should also be compared.
6．Authors had better provide characterization data related to emulsions with an oil to water volume ratio of 1:2.
7．It is mentioned that the emulsion can remain stable for 2 months, if you can please take a picture of the emulsion at different times.
8．The authors have only briefly demonstrated the thermal stability of the emulsion, but considering that stability is the core advantage of this emulsion, a more comprehensive characterization of this is recommended.
9．The paper is basically limited to the description and proof of the emulsion properties, but lacks the explanation of the relevant mechanism.
10．It is recommended that the authors rewrite the abstract.
11．The manuscript contains many clerical errors and the overall English expression is poor and needs to be carefully polished.
Overall, this manuscript does not reach the standard of a rigorous scientific research paper. I do not recommend it for publication in Processes unless the author can systematically improve the work and thoroughly revise the paper.
Author Response
Dear reviewer,
Thank you for your guidance and invaluable suggestions. We carefully revised the manuscript. Our response to your comments please see the attachment.
Yours Sincerely,
Yuanyuan Shan
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Processes Graphene O emulsifier
H. Lv et al.,
02 2023
General comments
The publication project is scientifically interesting and probably will deserve its presence in future “Processes” volumes. However, presently, the submitted draft lacks from critical analysis of the potential limitations of the idea, of a better English writing, of a clear description of amine modification of GO, of a good quality (presentation) of SEM and mapping data, of good quality of FTIR spectra. Further, the authors did not follow abbreviations homogeneity, chemical precision in the writing (toluene cannot be considered as “oil”), among other details to be partially recalled thereafter.
Details
Abstract
Lines 14-19: this text is not part of the work, but appears as a general information better located in the introduction section.
Line 20: a low-toxicity emulsifier : for reviewer the low toxicity is not proven and the problems with graphene nanoparticles must be recalled (see for example Particle and Fibre Toxicology volume 13, Article number: 57 (2016), L. OU et al, Toxicity of graphene-family nanoparticles: a general review of the origins and mechanisms
as well as the toxicity of amines
Lines 58-59: “GO is obtained from the oxidation of graphite powder, which is a derivative of graphene.” Are the authors sure of this statement?
Lines 86-88: “a Pickering emulsifier with excellent wettability is obtained by a ring-opening reaction between the amine group (N,N-dimethyl-1,4-butanediamine, NNDB) and the epoxy group on the GO surface.”: In no place of the work the amination was described and no reaction schema was proposed. The reader cannot imagine the yield of the modification and the technical problems to be solved or dominated (NNDB used pure or diluted in solvent, contact time, temperature of interaction).
Line 95: “The CNTs with”: what is the purity of this precursor (presence of residual metals?), and what is its use in the study? Is it this same product named after “graphite”? If not, what was the origin of graphite used to form GO?
Lines 102, 107 and other: particles of GO in liquid phase cannot form solution, only suspension.
Line 112: if the magnification is associated to “various”, magnification must show plural
Line 122: as the sample support in SEM images is probably an adhesive polymer, the support also contributes to C and O signal: only places where only sample is observed must be used for element mapping.
Line 123: here the modified GO is presented by Go-NNDB, whereas in other places it is named GO-NNDB.
Line 132: in Figure 2 d, the quality of the mapping is poor and it impossible to observe what was said by the authors.
Line 138: the functional groups in GO must be associated with literature references, and to the different wavelengths produced.
Line 142: “GO and GOND”: what is GOND?
Lines 142-144: “Clearly, the interaction mode of NNDB and GO tends to be the chemical reaction between NNDB and the epoxy group on the GO surface instead of the simple physical adsorption.”: this sentence must be associated to model of possible reaction between oxygenated functional groups and the diamine modificatory: please also introduce literature references.
Line 146 + Figure 3: the spectra quality is poor: the range 750 – 2000 cm-1 must be amplified and be registered with a higher number of paths. Reviewer expects link C-N or C-O-N, and not N-H (this signal is not a proof of interaction between the diamine and the GO surface).
In Figure 3, the spectrum of GO shows tiny presence of bands at around 3000 cm-1 generally found for CH stretching in hydrocarbons. Can the authors explain this point?
Lines 149-150: “It is shown in Figure 4a that the XPS spectral comparison of GO and GO-NNDB”: this sentence needs new writing.
Line 165: Figure 4: reader is expecting see a C-N signal, in the (c ) spectrum (GO-NNDB) and this is not the case. In the (d) spectrum, two different C-C binding energies are given: why?
In Figure 4 (b), can the authors explain how their NNDB can form di and triamines during chemical interaction with GO surface (reaction scheme)
Line 168 and following lines: ratio oil to water, oil-water volume…… Reviewer as the majority of chemists cannot consider toluene as an oil. Eventually, the word “aromatic” can be used.
Line 179: Figure 5: As the conditions of emulsion formation were not described (intensity and time of agitation, temperature of mixture, waiting time after agitation before photo), Figure 5 does not present interest to reader.
Line 201: Figure 6: the observations with optical microscope need in the present case particular attention: i/ the object to be examined is inserted between two glass slides, and the pressure between them, and the way they were cleaned, may affect the observation; ii/ all mixtures to be observed must present the same aging time. No precision was given by the authors.
The Figure caption must recall to what material is referred “concentration”: pure GO, GO-NNDB, dry samples, suspension,…
In the images of Fig.6, some droplets appear clear blue, other rose, and some red. What the origin of these differences. Is the droplets size distribution taking these differences in consideration?
In Fig.6 (a), the largest clear blue droplet seems in fact composed of different smaller droplets (white and clear blue fraction). Origin of this situation?
Line 204: “of emulsion droplet sizes formed”: are these sizes including or not the small sizes inside the largest droplets?
Lines 220-221: “Moreover, the size and dispersion of the emulsion changed significantly after two months, implying that the emulsion enjoyed long-term stability.”: are the authors sure of this statement? Is a long-term stability existing when size and dispersion of the emulsion change?
Line 223: Figure 9 (a) and 9 (b): In figure 9 (a), reviewer observed more areas with clear presence of black zones, not so visible in previous micrographs. Figure 9 (b) cannot be compared with other histograms: then, is the reader obliged to think that the corresponding statement is true?
Line 228: “amino group was successfully grafted onto GO.”: this point is not chemically proven.
Line 229: “forming a new C−N bond instead”: this statement was also not really demonstrated
Line 231: “stability when the oil-water volume ratio is 2:1.” The word “oil” is inappropriate.
Line 234: “dispersion and droplet size at high temperatures”: not really proven.
Author Response
Dear reviewer,
Thank you for your guidance and invaluable suggestions. According tu your suggestions, we carefully revised the manuscript. Our response to your comments please see the attachment.
Yours Sincerely,
Yuanyuan Shan
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed all my comments and have thoroughly revised the manuscript. Therefore, we believe that this revised manuscript can be accepted for publication in the journal.
Author Response
Dear reviewer,
Thank you for your recognition of our manuscript.
Yours Sincerely,
Yuanyuan Shan
Reviewer 2 Report
Processes pickering emulsion V2
General comments.
The authors improved considerably their original draft and presentation. Some points however need still consideration. 1/ the English quality is still limited, especially in the new added sections;2/ in the added sections, a careful reading seems absent as duplicate information is visible; 3/ The FTIR results need further consideration.
Some points are listed there-after.
Line 116-117 : »potassium permanganate (> 99.0%), concentrated sulfuric acid (> 95.0%), hydrochloric acid (36-38%), potassium permanganate (≥ 99.5%) »
Why two different potassium permanganates ?
Lines 120-121: “Hydrogen peroxide (30%) purchased from Tianjin Albokai Chemical Co., LTD.; was purchased from Tianjin Guangfu Technology Development Co., LTD”.
why two companies for buying H2O2?
Lines 136-140: “Add 5 mL GO, 40 mL deionized water and 160 mg NaOH into 100 mL beaker. Disperse the mixture ultrasonic for 30 min after stirring for 10 min, then 515 μL NNDB was added into the above suspension. After that, suspension was treated at 70 °C for 3 h under stirring. After the reaction, the mixture was cooled to room temperature naturally, centrifuged and washed with deionized water until pH = 7, and dried in a freeze dryer for use.”: English to optimize
Line 146 and line 154 and 166: photographed for preservation : what does this mean?
In this added section, English is poor; further did the authors use two different microcopes, a fluorescence one and an optical one?
Line 152: temperature unit is missing (°C)
Line 175: “Material water phase contact antennae were”: what does this mean?
Line 212: Figure 3: the red spectrum is not run in transmittance mode, but in absorbance mode: then, the band measured at 1500 cm-1, attributed to C-N bond is highly improbable. These FTIR experiments needs a very specific attention or must be suppressed.
Line 245: “environment, we selected the oil phase volume as”: the word oil is still present .
Lines 286-287; “In order to investigate the stability of the Pickering emulsion formed by GO-NNDB. We first heated the emulsion”: must be part of only one sentence.
Line 301: “It was observed that the emulsion type was oil-in-water”. The word “oil” is one more time used without necessity.
Lines 343-345: “Moreover, the emulsion prepared in this work can maintain good dispersion and droplet size at high temperatures as well as long time storage, and it can still maintain a stable state after heating at 85 °C for 5 h.”
The stability of the emulsion with temperature was cited two times in the same sentence.
Line 355-356: “recovered with simple stimulation”: what does this mean?
Author Response
Dear reviewer,
Thank you for your guidance and invaluable suggestions. According to your suggestion, we carefully revised the manuscript. Please see the attachment.
Yours Sincerely,
Yuanyuan Shan
Author Response File: Author Response.pdf
