Eggshell as a biomaterial can have a sorption capability on its surface: A spectroscopic research

In this study, eggshell as a biomaterial was used as an adsorbent. This natural waste material is easy to access and cost-free. The surface of the eggshell with its porous structure showed affinity to adsorb damaging chemicals. In particular insecticides cause serious environmental pollution in agriculture, and this is a general problem all over the world. The aim was to remove insecticides from the environment and monitor the pesticides on the surface of eggshells by atomic force microscopy (AFM) images, Fourier transform infrared (FTIR) and UV/Vis spectroscopic techniques. Five types of eggshells, Denizli Hen, Coturnix Coturnix Japonica, Light Brahma Chicken, Alectoris Chukar and ISA Tinted -White, were used. Since they are commonly used, Cypermethrin, Deltamethrin and Indoxacarb were chosen as insecticide samples. The interaction effect of insecticides on the surface of eggshells was determined by AFM images; it was seen that the semispherical surface structures of the eggshells were flattened after adsorption. FTIR spectroscopy was used both to detect structural analysis and to determine the adsorption influence. In addition, UV-Vis spectroscopy was performed to evaluate the adsorption and desorption process. Porous media of different types of eggshells with an aqueous solution of insecticides had an electronegativity attractive surface which makes it an ideal adsorbent via hydroxyl groups.


Recommendation?
Major revision is needed (please make suggestions in comments)

Comments to the Author(s)
The manuscript is well organized. There is some points to be clarified in the submitted manuscript. The references which support FTIR assignment should be added in Table2. The all original IR spectra in Table 3 should be given as Figure. "time (h)" should be added in Figure 5. "Referances" should be corrected as "References".

Review form: Reviewer 2
Is the manuscript scientifically sound in its present form? Yes

Are the interpretations and conclusions justified by the results? Yes
Is the language acceptable? Yes

Do you have any ethical concerns with this paper? No
Have you any concerns about statistical analyses in this paper? Yes

Recommendation?
Accept with minor revision (please list in comments) Authors have claimed that Low desorption capacity was observed at thick eggshells like LBC any specific study conducted to understand this phenomenon kindly specify.

Comments to the Author(s)
Decision letter (RSOS-210100.R0) We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below. Kınaytürk:  Title: Eggshell as a biomaterial can have a sorption capability on its surface: A spectroscopic  research  Manuscript ID: RSOS-210100 Thank you for your submission to Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry.

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Once again, thank you for submitting your manuscript to Royal Society Open Science and I look forward to receiving your revision. If you have any questions at all, please do not hesitate to get in touch. ********************************************** RSC Associate Editor: Comments to the Author: (There are no comments.) RSC Subject Editor: Comments to the Author: (There are no comments.) ********************************************** Reviewers' Comments to Author: Reviewer: 1 Comments to the Author(s) The manuscript is well organized. There is some points to be clarified in the submitted manuscript. The references which support FTIR assignment should be added in Table2. The all original IR spectra in Table 3 should be given as Figure. "time (h)" should be added in Figure 5. "Referances" should be corrected as "References". Decision letter (RSOS-210100.R1) We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below.

Dear Dr Kaya Kınaytürk:
Title: Eggshell as a biomaterial can have a sorption capability on its surface: A spectroscopic research Manuscript ID: RSOS-210100.R1 It is a pleasure to accept your manuscript in its current form for publication in Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry.

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Reviewer: 1
The manuscript is well organized. There is some points to be clarified in the submitted manuscript.
-The references which support FTIR assignment should be added in Table2.
References are added to Table 2 and the current version is submitted in the manuscript.
-The all original IR spectra in Table 3 should be given as Figure. All original IR spectra in Table 3 are added to the manuscript as a figure. The caption of the IR spectra is defined as " Fig.3. FTIR spectra of (a) CM and forms adsorbed on eggshells (b) DM and forms adsorbed on eggshells (d) IC and forms adsorbed on eggshells".
Since a new figure is added, the labels of the figures in the study have changed. The updated manuscript with new figure tags has been loaded.
-"time (h)" should be added in Figure 5.
"Time (h)" is added to Figure 5.
"Referances" is corrected as "References" All corrections requested by reviewer 1 have been made and added to the manuscript.

Reviewer 2 Authors have mentioned about the time-dependent changes of adsorption capacities in Fig 4 and about the time-dependent removal of insecticide in Fig5. How many times have they performed the experiment? Is any kind of statistical analysis done?
We performed the experiment 5 times and the results were almost the same range. So, we chose the average one, and eliminated the other results. UV-Vis analysis was carried out with a measurement that is the average value of three times repeated of the relevant measurement.
Authors have claimed that Low desorption capacity was observed at thick eggshells like LBC any specific study conducted to understand this phenomenon kindly specify.
In this study, we primarily aimed to investigate the adsorption capacity of insecticides on different egg shells, not the effects of eggshell thickness on the adsorption capacity. The purpose of our desorption study was to determine the stability of the adsorption study.
In the adsorption process, the surface area of the adsorbent is directly proportional to the adsorption capacity. The porous structure of eggshells increases the surface area and thus increases the adsorption capacity. In the examples we are interested in, Low desorption capacity includes low adsorption capacity at the same sample. For this reason, it is difficult to make a general evaluation just by looking at low desorption capacity. Because there are many factors that affect the adsorption capacity and the thickness of the eggshells. Such as the environmental condition of chicken, age of chicken, nutritional diet, incubation period. Since it was not our primary goal to examine these parameters in our study, we did not control them. Therefore, this phenomenon is difficult to explain because it requires a large number of agreements between parameters.
If there is a narrowing of the pore on the eggshells towards the inside of the shell, we can say that the insecticide molecule is more easily trapped here.
However, in order to write this view as a general comment, we need some more analytical methods such as EDX, EDS, or micro-Raman spectroscopy at the points we will choose on the pores on the eggshell, then examine the molecule belonging to the pesticide at the exact pore point.
Our study consists of only 5 types of eggshells and we can say that 3 of them are thick.
LBC, DH, and ITW are thicker than CCJ and AC. Looking at the desorption percentages in Table 4, when you look at results as they are groups; thicker and thinner. The desorption rate is lower for the thick ones among 5 types of eggshells. For CM, there is a noticeable difference in desorption between thick and thin shells, whereas for IC, this is a slight difference. For this reason, a desorption mechanism in thick eggshells is a mechanism that belongs not only to desorption but also to adsorption. Reference 47 in the manuscript is a possible article on adsorption.