Results and discussions

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Response to Reviewer

Abstract

NO. LIST OF CORRECTIONS AMENDMENT IN THE PAPER PAGE/JUSTIFICATIONS 1. Please emphasize the novelty of this

study.

Thank you for your comment.

The novelty of this study was emphasized in the abstract.

- Advanced extraction method such as simultaneous ultrasonic-hydrodistillation (UAE-HD) extraction method has been proved to increased extraction yield of plant material yet the application of this method in the preparation of metal nanoparticles has not been studied.

Page 1, line 16-18

2. Page 3, line 59-61. “However, the synthesis of Ag nanoparticle by using plant phenolic compound extracted from simultaneous ultrasonic hydrodistillation method is still rare.” Since the authors claimed this research is novel, please include the related literature to support your statement.

The related literature was added in order to support the statement of “However, the synthesis of Ag nanoparticle by using plant phenolic compound extracted from simultaneous ultrasonic hydrodistillation method is still rare.”

- This is because most of the studies used conventional aqueous extraction to extract plant phenolic compound for the synthesis of nanoparticle [9-11].

Page 2, line 49-50

3. Authors have stated that the selection of C.N because of the phenolic compound content. The information on the

important role of phenolic compound in nanoparticle synthesis must be provided for better understanding. Please provide

The information and reference about the important role of phenolic compound in the synthesis of nanoparticle was added.

- Phenolic compounds such as flavonoid, terpenoids, tannins, gallic acid and sterols have been reportedly

Page 2, line 59-61

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suitable references to support your

discussion. important for the reduction of Ag ions to Ag nanoparticle during synthesis process as well as capping of nanoparticle [13-17].

Materials and methods

NO. LIST OF CORRECTIONS AMENDMENT IN THE PAPER PAGE/JUSTIFICATIONS 1. Page 4, line 86 “Cymbopogon nardus

(C.N) leaves extract were thoroughly washed using deionized water and grind until it becomes powder”. It is questionable either the C.N leaves extract was directly grind after the washing process or the additional process which is drying process was involved.

The detailed process of the preparation leaves extract was added.

- Cymbopogon nardus (C.N) leaves extract were thoroughly washed using deionized water, dried at 25°C for 3 days and grinded until it becomes powder

Page 3, line 76

2. Page 6, Line 122. “The suspension was stirred constantly for 30 min in dark condition to achieve adsorption–

desorption equilibrium with a certain rate and then the reaction irradiated for 3 hours.” Please provide details on the term of “certain rate”

The term certain rate was actually means the speed used for stirred the solution and the detailed for the speed used was added.

- The suspension was stirred constantly at 700 rpm for 30 min in dark condition to achieve adsorption–desorption equilibrium and then the reaction irradiated for 3 hour

Page 4, line 109

Results and discussions

NO. LIST OF CORRECTIONS AMENDMENT IN THE PAPER PAGE/JUSTIFICATIONS

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1. Page 7, Line 136, Fig. 1. Wrong unit of 2θ. Should be “°”

The wrong unit was already changed from (θ) to (°) in Figure 1.

Page 14

2. Page 7, Line 143. Line number overlap

with equation (1). Please check. Thank you for your comment.

The line number overlapped with equation (1) was corrected. Page 5, line 125

3. Page 7, Line 146-147. Significant difference was observed for the size of nanoparticles of AgCN and AgB. It is questionable on how the phenolic compounds can largely control the growth of the nanoparticles size. Further discussions are needed and please

The influence of phenolic compounds towards size of nanoparticle was further discussed. The suitable reference was also added.

- This result might be due to the presence of phenolic compounds in C.N leaves extract encapsulated the

Page 5, line 130-134

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include suitable reference to support the

discussion. surface of AgCN catalyst and keeps the AgCN catalyst away from each other to prevent aggregation and subsequently control the growth of particles [13].

However, large size of AgB nanoparticle was obtained due to the absence of phenolic compounds to encapsulate and control the growth of nanoparticle [24].

4. Page 9, Line 173. The value of peak at 3292 cm-1 did not match with the value of the peak in Fig. 1. Please revise. In addition, it seems that the line of 3293 cm-1 in Fig. 1 was not located at the centre point of the peak. Please revise

The peak value of 3292 cm^-1 was corrected to 3293 cm^-1 and matched with the value of the peak in Fig. 1. The line of 3293 cm^-1 in Figure 3 at page 16 was also corrected to the centre point of the peak.

Page 5, line 150

5. Page 9, Line 175-177. It is stated that

the peak at 1607 cm-1 in CN extract Thank you for your comment.

After made some revision, the result for AgB spectra was Page 16

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disappeared in AgB spectra. It is questionable that the new peak between 1607-1318 cm^-1 observed in AgB refers to what functional group?

carefully revised.

6. Page 9, line 177-179. It is stated that the peak at 1083 cm-1 was observed in AgCN, revealed the phenolic compounds in C.N. However, by referring to the Fig. 1, this peak was also observed in AgB.

Page 16

7. Page 11, Line 198-200. Authors have stated that the high activity of AgCN

mainly owed to the leaves extract that plays a crucial role as a capping agent which successfully produce a diminutive AgCN. Please provide suitable references to support your discussion.

The suitable reference to support the discussions was added.

- This is mainly owed to the leaves extract that plays a crucial role as a capping agent which successfully produce a diminutive AgCN, which subsequently have a high catalytic activity towards the photodegradation of 2, 4-D [33, 34].

Page 6, line 171

8. Page 12, line 209-211. Authors have

stated that the large number of the Thank you for your comment.

The enhancement of the extraction process using ultrasonic- Page 6&7, line 181-186

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phenolic content may due to the

simultaneous ultrasonic-

hydrodistillation extraction method that provided much higher yield as compared to conventional aqueous extraction.

Further discussion on how the ultrasonic-hydrodistillation process plays a vital role in the enhancement of the extraction process is needed. Please provide suitable references to support your discussion.

hydrodistillation extraction method was further discussed. The suitable reference was also added.

- This results may be explained by the cavitation phenomena and mechanical mixing affect [12, 36].

During the propagation of ultrasonic waves in ultrasound-assisted extraction, cavitation bubbles were generated at the surface of the solid matrix and causing a disruption of plant cell walls. Therefore, the extractable compounds was released with the increasing of contact surface area between solvent and plant material [37].

9. It is suggested to compare the result observed with the studies on the preparation of the nanoparticles using plant extract. Additionally, authors can compare the effectiveness of different types of plants on the formation of nanoparticles.

The previous study was added and compared with the current results.

- Previous study also shows that Ag synthesized using Coccinia grandis leaves extract produces small size of particle ranged between 20 to 30 nm [26].

- This result is also in agreement with previous studies reported which concluded that the size of nanoparticle have significant effect to the 2, 4-D photocatalytic degradation [35].

- Page 5, line 143-144 - Page 6,line 171-173

10. Additional studies should be included to improve the quality of the manuscript.

- Reusability study is required to determine the feasibility of the photocatalyst

- Adsorption kinetics and isotherms are required to understand the nature of the photocatalytic process

The additional studies was done and added in the section 3.5 &

3.6.

- 3.5 Kinetic Studies - 3.6 Reusability

- Page 7&8, line 191-222 - Page 8, line 223-230

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