Suitability of the title:
Suggest to include the word “Intercalation” in title.
Thank you for the suggestion. The title of the manuscript has changed to ‘Intercalation and Characterization of Zinc-Aluminium Layered Double Hydroxide Cinnamic Acid’.
Abstract:
1. Please arrange the abstract according to its common format. An abstract should contain: a) Introduction b) Objective c) Result e) Conslucion in sequence.
Objective and Methodology parts are missing.
Thank you for your comments. The abstract have been reconstructed according the common format.
2. Line 16: “Cinnamic acid is known to lose its definite function and causes…” This sentence is too general.
Thank you for your comments.
“Cinnamic acid (CA) is known to lose its definite function by forming into radicals that able to penetrate into the skin and lead to health issues.” (Pg1 Line 15)
3. State the full name for “CA” before using the abbreviation in the next sentence.
Thank you for your comments.
I have made changes in the manuscript where the full name of “CA’ is cinnamic acid.
4. You were mentioning “Intercalations of cinnamic acid into the interlayer region of
Zinc/Alumium-LDHs using co-
precipitation or direct method could minimize the side effects of cinnamic acid.”
How are the results of this work able to minimize the side effects of cinnamic acid?
How is this work answered its problem statement?
Thank you for your comments.
LDH would act as a protective barrier preventing close contact between the skin and CA. It also able to reduce photodegradation of CA which then lead to breakdown of CA by sunlight exposure and from radicals.
5. The cinnamic acid was successfully inserted between the interlayer region with slow release formulation compared to naked anion itself. This is not being analysed in this work
Thank you for your comments.
The cinnamic acid were successfully intercalated into interlayer region of Zn/Al- LDH with slow release formulation
6. Keywords: anionic clay; nanohybrid are not related to this work.
Thank you for your comments.
I’ve changed to intercalation and sunscreen agent.
Problem Statement and review on past research:
1. Pg. 2 Line 9: Cinnamic acid has been mentioned as a sunscreen agent. Would intercalating the anion (cinnamate) into layered host allow the substances to be functioned exactly like the original cinnamic acid? The structure of the substances has changed accordingly.
Thank you for your comments.
The ability of CA not only maintained but been enhanced by incorporating the CA into LDH, it is known to be able to absorb UV-A, UV-BA and also UV-C exposure which supported by Del Hoyo (2007) since CA only able to absorb UV-B exposure.
2. Pg. 2 Line 13: “Thus, incorporating organic anions, cinnamate into the two dimensional; layered double hydroxides could solve the problem.” This conclusion is not correlated with early statement. Add literature studies before coming to these conclusions.
Thank you for your comments.
I have added a literature study before the statement in the manuscript.
Exposure of sunlight on these agents cause to undergoes decomposition, induce phototoxic contact dermatitis and photocross reaction when interact with other molecules. ( Hashim et. al, 2014) (Pg2 line 14)
3. Pg. 2 Line 19: what is the counter anion (An-) for cinnamate? Include among the examples.
Thank you for your comments.
C9H7O2- (cinnamate) is the counter anion. This also been added in the manuscript. (Pg2 Line 21)
4. Pg. 2 Line 26: Why zinc /aluminium-LDH chosen for this work? Any specific reason related to minimizing the side effects of cinnamic acid? Add literature survey.
Thank you for your comments.
Purpose of choosing Zn/Al as the host materials due to Zn/Al-LDH are known to have better UV blocking properties due to increase in particle size and decreased band gap energy compare to Mg/Al-LDH. (Peng et. al, 2015) (Pg2 line 29)
5. Objective and research gap highlighting the novelty of the work should be included in the last paragraph.
Thank you for your comments.
The aims of our study are to intercalate the cinnamate anion into the interlayer region LDH and investigate physiochemical properties of the zinc/aluminium LDH- cinnamic (Zn/Al-LDH-CA). To the best of our knowledge, few studies have been done on the release behavior of UV absorber from the LDH interlayer region been reported. Pg 2 line 31)
Materials and Methods:
1. Pg. 3 Line 5: Is the Zn/Al-LDH-CA named as Zinc-Aluminium Layered Double Hydroxide-Cinnamic Acid or Zinc- Alumium Layered Double Hydroxide- Cinnamate?
Thank you for your comments. I’ve check and sorry for the mistake. Zn/Al-LDH-CA should be pronounced as Zinc-Alumiunium Layered Double Hydroxide Cinnamic. Before intercalation, powder sample of cinnamic acid will be dissolved with a solvent to form cinnamic acid solution (cinnamate anion), when intercalation happen the COO- of the cinnamate anion will be a attach to the positive charge of the interlayer which then form zinc-alumiunium layered double hydroxide cinnamic. This correction also been done on the title section. (Pg3 line 8)
2. How much is the mol ratio used between the Zinc-Aluminium LDH and CA?
Thank you for your comments.
The ratio 1:2 is explaining the ratio between the zinc nitrate and aluminium nitrate since
the LDH gets its positive charge from the amount of M3+ added into it. As for CA, we do not know the exact concentration used for it to be incorporated into the interlayer region LDH as this a try and error method. The concentration may vary when used different molar ratio of the starting precursors. Thus in this study I’ve used 0.07M and 0.4M CA, for 1:2 ration of starting precursors, which can be observed from the characterized results of intercalated samples. (Pg3 Line 11)
3. Pg. 3 Line 8: Then, dropwise of anion solution were added. This seems that CA amount is smaller compared to Zinc Aluminium LDH. Would this maintain the function of CA itself as a sunscreen agent?
Thank you for your comments.
In this study, I used two different concentrations which is 0.07 M and 0.4 M.
When using 0.07 M, the FTIR and PXRD results stated that the amount of CA are to smaller to replace the nitrate anion which are at first present in the first place. Thus, increasing the concentration, as for in this study is 0.4 M, are needed to remove out the nitrate form the interlayer region of the LDH.
The ability of CA not only maintained but been enhanced by incorporating the CA into LDH, it is known to be able to absorb UV-A, UV-BA and also UV-C (Del Hoyo, 2007) exposure since CA only able to absorb UV-A exposure. (Pg3 line12)
4. Pg. 3 Line : What do you mean by anion solution? Cinnamic acid itself? State.
Thank you for your comments.
Anion solution is the cinnamic acid solution and been corrected in the manuscript. (Pg3 line 12)
5. Pg. 3 Line 20: Use room temperature instead of RT.
Thank you for your comments and sorry for the mistakes. I’ve corrected in the manuscript with red text colour.(Pg3 Line 24)
6. Pg3 Line 26: 2.4 Sustained Released Profile. Combine with characterization section.
Thank you for your comments.
I’ve corrected in the manuscript with red text colour. (pg2 line 29)
Results and Discussions:
1.Decide whether to use Zn/Al-LDH or Zn/Al-LDH-NO3. Be consistence in text and figures.
Thank you for your comments and sorry for the mistakes. Throughout the text I’m using Zn/Al-LDH. And been corrected using red text colour. (pg4 Line 6)
2. Figure 1: What is meant by 0.07M Zn/Al- LDH-CA and 0.4M Zn/Al-LDH-CA?
Which concentration are you varying?
Zn/Al-LDH or CA? Variation of concentration is not clearly explained in the methods.
Thank you for your comments. The 0.07M and 0.4M are the concentration of CA used in the intercalation of CA into LDH interlayer region. The concentration explanation also been corrected in the methods section with red text colour.
3. Figure 1: Label the FTIR spectra as Figure 1a, Figure 1b, Figure 1c Figure 1d for clarity during explanation.
Thank you for your comments.
The figure has been corrected.
4. Pg. 4 Line 7: An intense peak at 3452cm-1.
The word intense is not suitable. Thank you for your comments.
The word been change to broad and corrected with red text color. (pg 4 Line 10)
5. Pg. 4 Line 19: Intercalated spectra in Figure 1 shows the presence of the all- important functional group present in the cinnamic acid. What are the important functional group present in the cinnamic acid? Also the statement seems incorrect.
Strecthing vibration for C-H actually diminhed in all intercalated samples.
Thank you for your comments.
The important functional group that determines the incorporation of CA into Zn/Al-LDHs interlayer region are C=C , C=O and C-O groups.
(Pg4 line 22)
6. Pg. 4 Line 23: This shows the incorporation of cinnamate anion between the LDHs was happening. This is also INCORRECT. C=O and C-O strecthings were absent in 0.07 M Zn/Al=LDH-CA sample
Thank you for your comments.
As for Figure 1c, the presence of small peak at 1638 cm-1 which are stretching mode of C=C group and the incomplete intercalations due to presence of intense peak at 1354cm-1, which contribute to stretching vibration of N- O (NO3-) were observed. Thus, the concentration of CA were increased to 0.4 M and the presence peak at 1641 and 1206 cm-1 in Figure 1 (d) spectra indicates the presence of C=C stretching and C-O stretching were observed. This shows that the incorporation of cinnamate anion in between the LDHs was completely happened when the concentration of CA were increase up to 0.4 M. (pg4 line24) 7. Pg. 4. What is the conclusion from this
FTIR analysis in term of concentration varied?
Thank you for your comments.
The effects of concentration influence the intercalation process of CA into the Zn/Al- LDH where it need a certain amount of anion to replaced nitrate which first existed in the interlayer of LDH (pg5 line 4)
8. Figure 2: Label the PXRD spectra as Figure 2a, Figure 2b, Figure 2c, Figure 2d for clarity during explanation.
Thank you for your comments.
The labelling has been corrected in the manuscript.
9. Figure 2: Which peaks belong to which
element/oxides? Thank you for your comments.
10. Pg. 5 Line 15: The presence of new peak at lower region of XRD pattern was observed. What is this peak referred to?
Any important info related to intercalation of cinnamic acid into Zinc/Aluminium-LDHs at various concentrations.
Thank you for your comments.
The presence of new peak at lower region of XRD pattern was observed. This shows that the intercalation process has taken placed when using 0.07 M CA. CA has started to replaced nitrate that are existed first placed in the inteerlayer layer region of LDH, so the peak at 18.0 Ǻ are smaller compared to the peak at 9.0 Ǻ were observed. Successful intercalation can happen when the concentration were increased up to 0.4 M, where the peak at 18.0 Ǻ are more sharp and intense compared to 9.0 Ǻ. (Pg6 line5)
11. Pg. 5. Line 16: However, the presence of co-intercalation of guest anion and the nitrate exited in between the interlayer spacing corresponded to the FTIR spectrum were observed. What the author meant by co-intercalation? Also, except a single peak at 30˚, the peaks for guest anion are NOT observed in all intercalated samples. Please re-check.
Thank you for your comments.
Co-intercalation is co-existed of nitrate and CA element in the interlayer region of LDH.
Basically, for PXRD pattern, we are going to compare the pattern for Zn/Al-LDH and the intercalated samples. Since our intercalated samples are inorganic-organic hybrid materials, the PXRD peak will show an important peak at 5˚, which is the basal spacing of organic inorganic hybrid.
(Pg6 line 7) 12. Pg. 6 Line 2: …the basal spacing
increases from 9.0 Ǻ to 18.0 Ǻ, concludes that the cinnamate was presence in between the interlayer region of the LDHs…. This conclusion is not strongly supported by [17]. Please revise.
Thank you for your comments.
This to the topotactic ion exchange reaction between the cinnamate from the solution and the nitrate in the interlayer region in gaining the enthalpy and entropy causes the cinnamate to replaced nitrate position. 9Pg6 line 12)
13. Pg. 6 Line 8: The presence of the intense and sharper peak observe in 0.4M Zn/Al-LDH-CA. Which peak are you referred to? What elements belong to this peak?
Thank you for your comments.
The sharp and intense peak were observed at 5˚ are the hybrid material which are Zn/Al- LDH-CA (Pg6 line16)
14. Pg. 6 line 14: …when subtracted the layer thickness of the Zn/Al-LDH (4.8Ǻ)..
How is the value is obtained.
Thank you for your comments.
The value of 4.8 Ǻ were obtained fform a journal written by Chibwe & Jone (1989) entitled ‘Intercalation Of Organic And Inorganic Anion Into Layered Double Hydroxide’. (pg7 line4)
15. Figure 3: Label the LDH interlayer region. How can you conclude your finding
Thank you for your comments.
From this finding, we could deduce that the
from this illustration? anion which are cinnamate are being orientated in a bilayer arrangements since the interlayer distance is much larger than the cinnamte sizes, where the functional group of carboxylate were facing the hydroxide layers.
(Pg7 line 4) 16. Figure 4: Correction needed for
caption. Which thermogram belongs to which sample? Label figure a Figure 4a.
Figure 4b. Figure 4c. Figure 4d.
Thank you for your comments.
The caption has been corrected.
17. Pg. 8 Line 1: … leave only the less volatile metal oxide, which in this case is cinnamic anion? Reference [15] does not said so. Add relevance reference to support your findings.
Thank you for your comments.
I’ve checked the reference and truly sorry for the mistakes. Comparisons on decomposition temperature were made between the pure CA, Zn/Al-LDH and intercalated compound. The intercalated compounds were observed to achieve three stages of exothermic reactions as shown in Figure 4 (c). First exothermic reaction indicates the decomposition at temperature of 74˚ C with weight loss 3.3 % indicates the removal of water or moisture in the interlayer region. The next thermal decomposition happens at 219 ˚C with 6.2 % weight loss indicates the removal of interlayer anion and the dihydroxylation of the OH- layer. Last stages exothermic reactions occur at 389 ˚C with 58.9 % weight loss. The third exothermic reactions lead to the major decomposition on the organic moiety leaving only less volatile metal oxide. [15], which in this study is the zinc oxide and aluminium oxide comes from the layered structure of hydroxides. (pg7 line 23)
18. Table 1: CHNS analysis results should be placed earlier in the Results and Discussions since this analysis only measure elements in the sample. It is not considered as an important analysis. Plus XRD will verify the results better.
Thank you for your comments.
I’ve arrange the table to be placed earlier in the Results and Discussion section.
19. Pg. 8 line 10: The total percentage of cinnamate anion being intercalated in between the interlayer region of the LDHs was calculated to be 40%. This is INCORRECT. The total percentage is not cinnamte anion, yet the total percentage of
Thank you for your comments.
The total percentage loading of cinnamate anion being intercalated in between the interlayered region of the LDHs was calculated to be 40%.
The calculation are as follows:
C, H and H element found in the
intercalated samples. Weight of C in sample = x (obtained from CHNS data sheet)
Mole of C in sample = y
There is y mole of carbon present in 1 mole anion.
Thus,
Mole of anion in sample =
Weight of intercalated anion = moles of anion in sample/ molecular weight of anion Percentage on intercalated anion = 100%
(Pg9 line3) 20. Figure 5. Focus should be made on
CA rather than Zinc/aluminum LDHs. Do you have the FESEM picture for pure CA for a comparison with the intercalated cinnamic acid.
Thank you for your comments.
As for now, I only have two FESESM images as shown in the manuscript. I could not provide the FESEM images of CA due to constraint of time but will take note on the future work.
21. Pg. 10 Line 3: ….the presence of
‘burst effect’ were observed. Which featured in the release profile show this effect? At what time (seconds)?
Thank you for your comments.
The presences of “burst effect” were observed 100 seconds and 399 second for carbonate salts solutions and phosphite salts solutions.
(Pg10 line 3) Conclusions
1. Pg. 10 Line 20. “The presence of new generation peak in FTIR-ATR such as at 3381 cm-1 for OH group, 1641 cm-1 for C=O group, 1543 cm-1 for C=C group and 1206 cm-1 for C-O and increases in basal spacing from 9.0 Ǻ to 18.0 Ǻ in basal spacing in 0.4 M Zn/Al-LDH-CA stipulate that the intercalation were successful.”
Mention for which sample. What about the effect of various concentrations?
Thank you for your comments.
The effect of concentration plays major roles for the guest anion to replace the existed anion which are nitrate. In both FTIR and PXRD pattern of 0.07 M CA shows that the CA are started to replaced nitrate. Thus, the concentration were increased up to 0.4 M and the presence of new generation peak in FTIR- ATR such as at 3381 cm-1 for OH group, 1641 cm-1 for C=O group, 1543 cm-1 for C=C group and 1206 cm-1 for C-O and increases in basal spacing from 9.0 Ǻ to 18.0 Ǻ in basal spacing in 0.4 M Zn/Al-LDH-CA stipulate that the intercalation were successful. (Pg 11 line21)
2. Pg. 11 line 4. The nanohybrids were thermally stable.. This is not accurate conclusion derived from the TGA.DTG results. Revise according to the result.
Thank you for your comments.
Ive check and corrected in results and discussions section. Intercalated compound are thermally stable compare to its anion.
3. Pg. 11 Line 7. …but still in slow release manner compare to the naked anion itself..
This is not being analysed in this study.
Not possible to have this conclusiobns.
Thank you for your comments.
I’ve corrected this sentence. (pg11 line10)
4. Pg. 11 Line 8. Throughout the observations, different type of solvent also plays important role in intercalation process and, thus, being investigated further in our next project. This is not related to this current work Yet conclude the results with the objective of the work.
Thank you for your comments.
Throughout the observations, the intercalations were successful using 0.4 M CA anion concentration with slow releae formulation under different salt solutions.
(pg11 line10)
