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Accepted Manuscript Original article Heterogeneous Catalysis in 4-Nitrophenol Degradation and Antioxidant Activities of Silver Nanoparticles Embedded in Tapioca Starch Katayoon Kalantari, Amalina Binti Muhammad Afifi, Saadi Bayat, Kamyar Shameli, Samira Yousefi, Norrashidah Mokhtar, Alireza Kalantari PII: DOI: Reference:

S1878-5352(16)30262-3 http://dx.doi.org/10.1016/j.arabjc.2016.12.018 ARABJC 2030

To appear in:

Arabian Journal of Chemistry

Received Date: Accepted Date:

2 October 2016 24 December 2016

Please cite this article as: K. Kalantari, A. Binti Muhammad Afifi, S. Bayat, K. Shameli, S. Yousefi, N. Mokhtar, A. Kalantari, Heterogeneous Catalysis in 4-Nitrophenol Degradation and Antioxidant Activities of Silver Nanoparticles Embedded in Tapioca Starch, Arabian Journal of Chemistry (2016), doi: http://dx.doi.org/10.1016/ j.arabjc.2016.12.018

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Heterogeneous Catalysis in 4-Nitrophenol Degradation and Antioxidant Activities of Silver Nanoparticles Embedded in Tapioca Starch

Katayoon Kalantari *a,b E-Mail: [email protected] Amalina Binti Muhammad Afifi *a E-Mail: [email protected] Saadi Bayat c E-Mail: [email protected] Kamyar Shameli d E-Mail: [email protected] Samira Yousefi e [email protected] Norrashidah Mokhtar d E-Mail: [email protected] Alireza Kalantari f [email protected]


Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala lumpur, Malaysia b

Centre of Advanced Materials (CAM), Faculty of Engineering, University of Malaya, 50603 Kuala lumpur, Malaysia c

Institute Of Molecular Science (LIMS), La Trobe University, 3086, Melbourne, Australia


Malaysia–Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, 54100 Kuala Lumpur, Malaysia e

Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia f

Faculty of Engineering, Islamic Azad University of Karaj, Alborz Province, Iran

*Corresponding author: Katayoon Kalantari, Amalina Binti Muhammad Afifi,

Heterogeneous Catalysis in 4-Nitrophenol Degradation and Antioxidant Activities of Silver Nanoparticles Embedded in Tapioca Starch

Katayoon Kalantari *a,b E-Mail: [email protected] Amalina Binti Muhammad Afifi *a E-Mail: [email protected] Saadi Bayat c E-Mail: [email protected] Kamyar Shameli d E-Mail: [email protected] Samira Yousefi e [email protected] Norrashidah Mokhtar d E-Mail: [email protected] Alireza Kalantari f [email protected]


Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala lumpur, Malaysia b

Centre of Advanced Materials (CAM), Faculty of Engineering, University of Malaya, 50603 Kuala lumpur, Malaysia c

Institute Of Molecular Science (LIMS), La Trobe University, 3086, Melbourne, Australia


Malaysia–Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, 54100 Kuala Lumpur, Malaysia e

Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia f

Faculty of Engineering, Islamic Azad University of Karaj, Alborz Province, Iran

*Corresponding author: Katayoon Kalantari, Amalina Binti Muhammad Afifi,

Abstract: In this study, a simple, green and eco-friendly method was used for the synthesis of silver nanoparticles (Ag-NPs) in alkaline treated Tapioca starch. The XRD results indicated that Ag-NPs were produced after stirring for several hours at 80 °C. TEM image showed the Ag-NPs were in spherical shape with average size of 11 nm. The UV-vis results revealed clearly the formation of AgNPs in the range from 410 to 420 nm. Moreover, the prepared nanoparticles showed good catalytic activity in the reduction of 4-nitrophenol (4-NP). The results confirmed the catalytic activity of them in the short induction period, the completion reaction continued within 15 min. The finding revealed also significant shift in the DPPH radical scavenging ability for studied samples. The recorded scavenging ability for the lowest concentration of the synthesized AgNP (50 μg/ml) was 17.29 ± 0.06 and this scavenging ability was increased to 78.60 ± 0.05, when concentration was increased to 250 μg/ml. Silver nanoparticles have many catalytic and antioxidant activities in environmental and biomedical fields.

Key words: Silver nanoparticles; Tapioca Starch, Catalytic degradation; 4Nitrophenol; Antioxidant activity

1. Introduction

Metal nanoparticles have been used in different fields ranging from optical applications to catalysis (Ataee‐Esfahani, Imura, & Yamauchi, 2013; Kalantari, 2013; C. Li & Yamauchi, 2013; Y. Li et al., 2015; Malgras et al., 2016; Ramasami et al., 2015). Of all these metal nanoparticles, silver nanoparticles have an industrial wide applications and have a special place in sensor and optical sensor technology (Filippo, Manno, Buccolieri, & Serra, 2013; Kang, Wu, Liu, Wang, & Du, 2014), cancer treatment (Austin, Mackey, Dreaden, & El-Sayed, 2014) and catalytic activities (Joseph & Mathew, 2015). Silver nanoparticles can be fabricated using different techniques such as electrical (Khaydarov, Khaydarov, Gapurova, Estrin, & Scheper, 2009), chemical reduction (Mohan et al., 2016), photochemical (Huang et al., 1996) and γradiation (Rao et al., 2010). Reduction technique is most used and cost effective method due to its large scale fabrication and easy processing. Some reducing agents such as NaBH4, NH3 and NaOH have been applied for the synthesis of silver nanoparticles ( as s

, Piella, & Puntes, 2014; Hebeish,

Shaheen, & El-Naggar, 2016). Silver nanoparticles are applicable in biomedical area due to their special properties such as antioxidant and catalytic activities (Shankar & Rhim, 2015). In particular, nano-sized silver particles have highly heterogeneous catalysts activity, special electronic properties and specific surface areas (Bindhu & Umadevi, 2015). Different industries such as dyes and pharmaceuticals produce some byproducts, and among them 4-nitrophenol (4-NP) are the most common which have toxicity for the environment (Kiasat & Davarpanah, 2013; Mustafa et al., 2011). 4-aminophenol (4-AP) is produced from (4-NP) via chemical reduction. (4-NP) is required for various drugs such as acetaminophen, acetanilide, etc. Zheng et al. (2015) used guar gum (GG) for reducing and green synthesise of

Ag-NPs and then crosslinking to produce [email protected] beads in crosslinked shape, then tested as a solid-phase heterogeneous catalyst for the reduction of (4-NP) to (4-AP). The results indicate that these final product exhibited high catalytic activity (Zheng, Zhu, Tian, & Wang, 2015). Wild ranges of free radicals with high reactivity are produced by aerobic organisms in cells through respiration and metabolism. Some chemical changes are induced in cell organelles and finally lead to cell death. The formation of free radicals named oxidative stress is the main reason of some pathological disorders such as cancer and aging. In small quantities, materials often acted as antioxidants. They reduce the damaging influence of oxidative stress on the oxidation of cellular organelles (Aqil, Ahmad, & Mehmood, 2006; Rajan, Vilas, & Philip, 2015). Use of natural reducing agent for the synthesis of silver nanoparticles, makes them a powerful antioxidant. In recent decades, natural materials with availability, non-toxicity, low cast and biodegradability have attracted increasing attention. Starch is a water insoluble carbohydrate polymer, but by the addition of sodium it can converted to water soluble. Addition of sodium hydroxide to starch combining mechanical grinding promotes swelling of the starch immediately and rapidly. The swelling starch acted as stabilizer in the synthesis of Ag-NPs. Moreover, in glucose unit, the group in C6 positions can act as reducing agent. All these reactions have taken place without organic or aqueous solvents addition. Here, in this study, we present the fabrication of tapioca starch capped silver nanoparticles, its heterogeneous catalysis in the degradation of (4-NP) into nontoxic aromatic group (4-AP) and the in vitro antioxidant activity in terms of 2, 2-diphenyl-1-picrylhydrazyl (DPPH).

2. Materials and Methods 2.1 Materials

Tapioca starch was purchased from Sigma Aldrich. (AgNO3) and NaOH were supplied from Sigma–Aldrich Co., USA (analytical grade). Deionized water was used for all dilutions and characterizations.

2.2 Methods

At the first, (1.0 g) of Tapioca starch was mixed with 0.35 g of NaOH platelets together using pestle, then added to 100 mL of distilled water and heated at 40 ◦C for 20 min. Then, certain amount of (AgNO3) is dissolved in 5 ml of water along with 3 ml isopropyl alcohol to volatile easily during the synthesis of AgNPs. AgNO3 solution was added drop wise to alkaline treated starch under continuous stirring. The reaction temperature was set to 80 °C and allowed to react for several hours. At the end of reaction, the system colour turns to dark brown which confirms the synthesis of Ag-NPs.

2.3 Characterization of Silver Nanoparticles (Ag-NPs)

UV–vis absorption measurements were done using a (Shimadzu UV 2401pc) spectrophotometer in the 300–700 nm wavelength range as the first indication for Ag-NPs. Fourier infrared (FT-IR) spectroscopy of starch and Ag-NPs are recorded with Nicolet-Nexus 670. The XRD measurements were conducted using an X-ray diffractometer (Empyrean, PANalytical, Netherlands). The morphological features of Ag-NPs were measured by TEM (JEOL JEM-3010 electron microscope).

2.4 Catalytic Activity Examination

In starch-Ag-NPs (S-Ag-NPs)-catalysed (4-NP) hydrogenation reaction, 10.0 wt. % of (S-Ag-NPs) was added to 5 mL of a solution containing 60 mg of (4NP), 6 mg of catalyst and 180 mg of NaBH4. The sonication was used to mixture and in every 3 minutes, monitored by UV spectrophotometer in the wavelength range of 250 to 600 nm. The characteristic maximum absorbance of (4-NP) at 401 nm was used as indicator the (4-NP) remaining, and the absorbance at 300 nm was utilized to identify the (4-AP).

2.5. DPPH Radical Scavenging Assay

The DPPH assay used to show the free radical scavenging activity of the (S-AgNPs) and monitored according to the method explained by Sharifi et al. (2013) (Sharifi, Mortazavi, Maskooki, Niakousari, & Elhamirad, 2013). At the first, 0.002% of DPPH solution was prepared in methanol, and 3 ml of this solution was added to (S-Ag-NPs) samples at different concentrations (50, 100, 150, 200 and 250 μg/ml) and vortexed thoroughly. The mixtures were kept in dark condition at room temperature for 30 min. As a positive control (standard) and blank, ascorbic acid and methanol were used respectively. The experiments were performed in triplicate. The Inhibition ability of free radical DPPH in one percent was evaluated based on:

DPPH% = (Absorbance Control - Absorbance Sample / A Control) × 100

(Equation 1)

The radical scavenging ability of an antioxidants is indicated by the decrease in absorbance of DPPH mixed reaction mixture on addition of the antioxidant (Rajan et al., 2015). 3. Results and Discussion

NaOH adding to starch at high concentration leads to high swelling of starch granules which produce more Starch-O-Na. Hydroxyl groups of starch might coordinate with Ag+ during reduction process. The interaction between reducing groups of starch-O-Na situated at C6 and Ag+ is the main approach in final reduction to Ag-NPs. During the reaction, the starch-Ag+ solution colour changes from colourless to dark brown which indicate the fabrication of starch capped Ag-NPs.


mp a u

(80◦C) and m (s v al h u s) w

used during synthesis of Ag-NPs. Figure 1, shows the images of alkaline treated starch and (S-Ag-NPs) synthesized. It reveals that the alkaline starch is colourless and significantly changed when AgNO3 solution is added. The colour becomes more intensive and darker with the time. The powder of (S-Ag-NPs) is dark brown; a point which clearly shows the formation of Ag-NPs.

Figure 1. Images of the Starch-O-Na (A), S-Ag-NPs (B) and powdered (S-Ag-NPs) (C)

3.1 UV-visible Spectra and TEM Studies

Surface Plasmon Resonance (SPR) is a characteristic absorption band of metal nanoparticles in the UV–visible region, which is related to conduction electrons oscillation induced by the interacting electromagnetic field (Raghunandan et al., 2010). Fig.2 shows the UV–visible spectra of Ag-NPs. According to this spectrum, intense absorption peak at 411 nm indicated the production of AgNPs. Results show that, there is no absorption peak for alkaline starch in the range from 410 to 420.

Figure 2. UV–vis spectra of the (S-Ag-NPs)

TEM have been applied for morphological study of nanoparticles surface. The TEM images Fig. 3 (A) and histogram in Fig.3 (B) used for clear investigation of the size distribution and shape of the synthesized (S-Ag-NPs). According to Fig.3, Ag-NPs are successfully synthesized in spherical shape with good distribution and size of 11±4.75 nm. Alkaline treated starch has two main actions toward Ag+, first reducing the silver cations to Ag0 and then stabilization of Ag-NPs via capping with hydroxyl groups of starch molecules during the

fabrication process (Cano, Cháfer, Chiralt, & González-Martínez, 2016; Hebeish et al., 2016).

Figure 3. TEM micrographs of the Ag-NPs (A), Histogram illustrating the particle (B)

3.2 XRD Patterns and FT-IR Spectra of Ag-NPs According to Fig. 4 (A), the broad peaks at 1351 cm−1 and 1523 cm−1 correspond to the symmetric and asymmetric C-O stretching vibrations of carboxylate group respectively (Kizil, Irudayaraj, & Seetharaman, 2002). The absorption bands at 833 and 563 cm-1 are attributed to the whole glucose ring stretching vibrations. Another characteristic bands at around 1050 cm−1in the fingerprint region is due to the C-O-C ether–stretching vibration in glucose bonds (Hebeish et al., 2016; Rao et al., 2010). Moreover, two bands observed at 3100-3200 cm−1for C-H stretching and 1640–1660 cm−1for O-H stretching are attributed to the tightly bound water presented in the starch molecule. Starch spectrum shows also a characteristic vibration bands at 3200 cm−1 (O-H stretching).(Hebeish et al., 2016). The FTIR spectrum of (S-Ag-NPs) exhibits a similar pattern to that of starch. However, a shift in frequencies is detected for the signals associated with


OH functional group, noticeably at 3290 cm−1 (OH stretching) and 1050

cm−1 to higher 1076 cm−1 evidently indicating the interaction of

OH groups

with silver nanoparticles (Raghavendra, Jung, kim, & Seo, 2016) (Mandal, Sekar, Chandrasekaran, Mukherjee, & Sastry, 2015).

Figure 4. (A) FTIR spectrum of starch and (S-Ag-NPs), (B) X-ray diffraction patterns of synthesized (S-Ag-NPs),

Figure 4 (B) shows the XRD patterns of synthesized (S-Ag-NPs). The XRD p a s n h w d angl


f 2θ (30° < 2θ < 85°) ascertained that the peaks

in 38.63°, 44.26°, 64.75°, 77.44° and 82.20° can be attributed to the 111, 200, 220, 311 and 222 crystalline structures of the face cantered cubic (fcc) synthesized Ag nano-crystal, respectively (Ag XRD Ref. No. 00-087-0719)

(Shameli et al., 2012). The average particle size of Ag-NPs can be calculated via Debye–Scherrer equation:

Where K (shape factor) is the Scherrer constant with value from 0.9 to 1, and λ is the X- ay wav l ng h (1.5418 Å) β1/2 is the width of the XRD peak at half height and θ is the Bragg angle. From this equation the average crystallite size of silver nanoparticles is found to be around 11 nm, which are also in line with the observation of the TEM results discussed later. The peaks revealed that the main crystalline phase was silver and there were no other impurities phases were found in the XRD patterns. Therefore, this gives good evidence for the presence of silver nanoparticles in the (S-Ag-NPs).

3.3 Antioxidant Activity

An antioxidant scavenging activity widely is assessed by DPPH as a stable free radical. In 1995, Williams et al., described a method for measurement of DPPH scavenging activity, with slight modifications. In this method, with presence of a hydrogen donating antioxidant and methanol solution, DPPH is reduced due to the formation of the non-radical form of DPPH (Kharat & Mendhulkar, 2016). The antioxidant activity of S-Ag-NPs was evaluated using DPPH scavenging assay. The results obtained are summarized in Table 1. The finding shows significant shift in the DPPH radical scavenging ability for studied samples. The recorded scavenging ability for the lowest concentration of the synthesized S-Ag-NP (50 μg/ml) was 17.29 ± 0.06 and this scavenging ability was increased to 78.60 ± 0.05 (Table 1), when concentration was increased to 250 μg/ml.

Table 1. Antioxidant activity of biosynthesized (S-Ag-NPs) Sample


Ascorbic Acid

Concentration (µg/mL)

Scavenging Ability (%)


17.29 ± 0.06


49.63 ± 0.04


63.17 ± 0.03


72.14 ± 0.05


78.60 ± 0.05

30-150 (µg/mL)

80.00 ± 0.04

3.4 Catalytic Activity of S-Ag-NPs

Metal nanoparticles has high surface area to volume ratio and make them good catalysts compared to bulk materials (Rajan et al., 2015). The catalytic activities of the obtained S-Ag-NPs were evaluated for the aqueous reduction of (4-NP) to (4-AP) with Sodium borohydride. This method has been use as an effective technique for the removal of (4-NP). The UV–visible spectra for the catalytic reduction of (4-NP) by NaBH4 in the presence of S-Ag-NPs obtained from 5 ml of extract was shown in Fig.5 . According to our findings, maximum adsorption peak observed by addition of the NaBH4 into an aqueous solution of (4-NP). Moreover the UV-visible spectrum shows a shifting to the higher wavelength (red shift) from 321 to 401 nm because of the (4-NP) formation under alkaline conditions (Fig.5A). This peak at 401 nm remained unaltered in the absence of S-Ag-NPs. The maximum absorption at 401 nm did not change over time even after the addition of superfluous NaBH4 solution confirming that the reduction did not proceed by aqueous NaBH4 solution (Dong et al., 2014).

S-Ag-NPs act as the hydrogen donor, and a sample was withdrawn every 3 minutes to monitor (Fig. 5B). With the addition of prepared S-Ag-NPs to the reaction mixture, the peak at 401 nm disappeared with the appearance of new peak at 321 nm and the light yellow colour of solution is changed into a deep yellow showing the presence of (4-NP) ion indicating the formation of (4-AP) (Bindhu & Umadevi, 2015; Chen, Qiu, Wang, & Xiu, 2006). As expected, no target product could be found in the absence of catalyst after 60 min.

Figure 5. (A) UV-Vis spectra of (4-NP) and alkaline (4-NP) by NaBH4, (B) UV-Vis spectra for the reduction analysis of (4-NP)

This results confirmed the catalytic activity of S-Ag-NPs in the short induction period (3 min in water); the completion reaction continued within 15 min. Ag NPs supported can catalyse the reaction by facilitating electron relay from BH 4to (4-NP) (Rostami-Vartooni, Nasrollahzadeh, & Alizadeh, 2016). Some factors have influence on hydrogenation of nitro compounds such as electron transfer into nitro compound and proton accessibility (Khandanlou, Ngoh, Chong, Bayat, & Saki, 2016).

Briefly, catalytic reduction included essential steps: on the surface of catalyst, BH4- reacts with S-Ag-NPs to form the metal hydride, then discharging of electrons from borohydride ions via the metal to the acceptor. Hydrogen ions are required to complete the reduction reaction which provided by water as a polar protic solvent (Gopal & Vydehi, 2013). Obviously, in catalysis phenomena, adsorption has crucial role. In this work, the S-Ag-NPs catalyst had adsorption sites for borohydride ions and nitro aromatic compounds. Moreover, the electrons transfer from the borohydride ions donor to the nitro compound acceptor facilitated by catalyst. Several parameters such as reaction conditions, size of nanoparticles and the number of surface silver atoms are crucial for silver nanoparticles-mediated catalysis (Narayanan & Sakthivel, 2011).


Alkaline treated tapioca starch is prepared and used for the synthesis of silver nanoparticles. The Ag-NPs were in spherical shape and the size of them was 11 nm in average. The silver nanoparticles showed good catalytic activity in the degradation of 4-NP by Sodium borohydride. The results revealed that the reduction of (4-NP) was completed in short time. Moreover, the significantly antioxidant activity exhibited by the formed Ag-NPs may leads to apply them in the treatment of some diseases caused by oxidative stress. The green method used for the formation of Ag-NPs has many advantages like biocompatibility and low-cost which make them good candidate in commercial and biomedical applications.

Acknowledgments This work was partially funded by the Centre of Advanced Materials, faculty of Mechanical Engineering of University of Malaya.

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