Enhancement of Corrosion Resistance and Microbial Protection Analysis of a Rosin Coating with the Incorporation of Leucaena leucocephala

Round 1

Reviewer 1 Report

1. Image resolutions of fig1, fig2, fig4, fig6, fig7, fig14 are too low. The authors must show images with much higher resolution.
2. In fig11, fig12, Table 5 and Table 6, the reviewer think that the authors should show average values, standard deviation and sample numbers per each condition. At least in fig11 and fig12, the author should show error bars. In addition, the reviewer recommends to carried out statistical analyses between each condition to evaluate significance of difference accurately.
3. In fig15, length of each axis must kept same in Nyquist plots to evaluate shape of the ark accurately. (This means that length from 0 ohm/cm2 to 8000 ohm/cm2 on both X and Y axis must be same.)

Author Response

1. The figures listed has been replaced with a better version (with resolution above 1000 px for width/height).
2. The average values for data in Table 5 and Table 6 has already been inserted with the corresponding standard deviation is also included. The sample number per each condition is stated in page 9 line 268. Additionally, the error bars per the reviewer suggestion is added to both Figure 11 and Figure 12.
3. The length of each axis for Nyquist plots in Figure 15 has been changed according to the reviewer suggestion and the resolution of each images has been enhanced per the Journal’s instructions.

 

Reviewer 2 Report

This manuscript developed a rosin coating containing LLE for the application in corrosion resistance and microbial protection on stainless steel. The samples were characterized by FTIR, XRD, EIS, potentiodynamic polarization and SEM/EDX, and the antimicrobial activity of the coatings were analyzed. Although the authors did a lot of work, the conclusions and the experiments design were not reasonable. Following are the comments: 1. The title should be corrosion resistance rather than corrosion. 2. There are too many figures and tables in the manuscript. Some of them were not significant, and could be deleted, such as Fig.4, Fig. 6. Some of them can be rearranged as one figure, for example, Fig. 8 and Fig. 9 can be integrated in Fig. 10. 3. Fig. 1, Fig. 2 and Fig. 14 were blurry, which need to be improved. 4. “The unique combination is derived from multiple studies that proved the employment of plant extract to decrease the corrosion rate is feasible and and may produce excellent outputs [11, 12]”, please check the English grammar of this sentence. 5. The component of P1-P5 has two variables, ZnO and LLE, therefore, it is not reasonable to study the effect of concentration of LLE on the coating by P1-P5. Please keep all the parameters same except for LLE. 6. The antimicrobial assessments showed that coatings with different concentration of LLE didn’t have obvious change, therefore, it is not proper to say the enhancement of microbial protection. 7. Compared Fig. 11 and Fig. 12, the inhibition efficiency of LLE against S. aureus and P. aeruginosa were 22.5% and 66.7%, respectively, however the inhibition efficiency of the coating against S. aureus and P. aeruginosa were about 45% and 33%, why some inhibition efficiency increased while other decreased? 8. There are no legend for the top two images of Fig. 17. 9. “The most outstanding performance was showed by the crude extract of LLE towards P. aeruginosa (-) with the highest value of resistancy”, the research object should be the coatings, therefore this conclusion was not meaningful.

Author Response

1. The new title is as follows: “Enhancement of Corrosion Resistance and Microbial Protection Analysis of a Rosin Coating with the Incorporation of Leucaena leucocephala”

 

2. Figure 4 is important to show the correlation between the FTIR result and its corresponding compound containing the highlighted functional groups. Figure 6 should also be included for it give the reader a better understanding of the suggested combination of the highlighted compounds. Figure 8 and Figure 9 are also combined as suggested.

 

3. The figures listed has been replaced with a better version (with resolution above 1000 px for width/height).

 

4. The sentence is corrected and presented as follows: “The use of plant extract as an additive to enhance the corrosion inhibition of a coating is eco-friendly and its feasibility has been proven by previous studies”.

 

5. The primary reason for not keeping a same parameter of ZnO is to observe its enhancing effect in comparison to the extract. For further study, ZnO with the best composition will be selected, fixed and combined with different extract concentrations.

 

6. Hence, the title is revised to be: “Enhancement of Corrosion Resistance and Microbial Protection Analysis of a Rosin Coating with the Incorporation of Leucaena leucocephala”

 

7. The probable reason for such changes is due to the synergistic effect presented when different components of coatings were combined. Such display of performance is common where usually a mixture of different materials may produce either a higher or lower efficiency.

 

8. The legend for these images has been inserted.

 

9. The following conclusion is improved as follows: “The antimicrobial screening showed that most of the samples tested displayed a good degree of microbial inhibitory action towards aureus (+) and P. aeruginosa (-) bacteria. The most outstanding performance was showed by the crude extract of LLE towards P. aeruginosa (-) with the highest value of resistancy. Additionally, the test conducted in a real environment produce a remarkable result where a coated substrate displayed no attachment of unwanted solid, and hence validates the coatings ability to reduce fouling reaction”.

Reviewer 3 Report

Here are my suggestions to the author: 

The author(s) have done an excellent job in providing clear experimental procedures and experimental results in supporting their conclusions. 

There are several minor grammatical errors that need clarification such as

page 4, paragraph 2.5.1 , the sentences starting with "There were two types of bacteria strains is to grow or cultivated .... " The word cultivated should read cultivate.  "There were two types of bacteria strains grew....  should be grown for the assessment process. "  

There are several additional sentences like this that the authors should have reviewed by authors proficient in the English language. 

Also have the authors examined the oily crude extract in section 2.2 Crude Extract Preparation?   If that information is known it could help identify the active ingredient in their anti-corrosion, anti-microbial formulations, if not the data can stand by itself for publication.

Author Response

Thank you for correcting my grammatical mistakes. I prefer for the data to stand by itself for publication.

Round 2

Reviewer 2 Report

This version of manuscript has been well revised according to my suggestions, and the authors responded all the comments one by one. I think the revised manuscript can meet the requirement of the journal, and now I recommend it to be published in Coatings.

Author Response

Thank you for your recommendation dear reviewer,. I'm appreciate it a lot.