Biosynthesis of Fe2O3@SiO2 nanoparticles and its photocatalytic activity

Author’s Accepted Manuscript Biosynthesis of Fe2O3@SiO2 nanoparticles and its photocatalytic activity Moushumi Hazarika, Indranirekha Saikia, Jadumoni Das, Chandan Tamuly, Manash R Das www.elsevier.com

PII: DOI: Reference:

S0167-577X(15)30871-5 http://dx.doi.org/10.1016/j.matlet.2015.11.042 MLBLUE19870

To appear in: Materials Letters Received date: 26 August 2015 Revised date: 7 October 2015 Accepted date: 7 November 2015 Cite this article as: Moushumi Hazarika, Indranirekha Saikia, Jadumoni Das, Chandan Tamuly and Manash R Das, Biosynthesis of Fe 2O3@SiO nanoparticles and its photocatalytic activity, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2015.11.042 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Biosynthesis of Fe2O3@SiO2 nanoparticles and its photocatalytic activity Moushumi Hazarikaa, Indranirekha Saikiaa, Jadumoni Dasa, Chandan Tamulya*, Manash R Dasb a

CSIR-North East Institute of Science and Technology. Branch Itanagar Arunachal Pradesh-791110, India, b CSIR-North East Institute of Science and Technology. Jorhat, Assam-785006, India, e-mail: [email protected], Telefax: +913602244220

Abstract Biosynthesis of Fe2O3@SiO2 nanoparticles with an eco-friendly, green approach is reported here. It was characterised by XRD, SEM, TEM and EDX analysis. The Fe2O3@SiO2 nanoparticles was efficiently used as a photocatalyst for degradation of methyl red (MR) dye. The results revealed that the Fe2O3@SiO2 showed significant photocatalytic activity compared to SiO2, Fe2O3 and Fe2O3@SiO2 (commercial) nanoparticles/nanocomposite. There is no significant loss of its photocatalytic activity of Fe2O3@SiO2 in degradation of MR dye up to 5th cycle run. Key words: Green synthesis; Nanoparticles; Biomaterials; Photocatalyst

1. Introduction Iron oxide is one of the mostly used catalysts in chemical industry, gas sensors materials, pigments and photo electrochemical cells [1-2]. In general, synthesis of this metal oxide involves the usage of template or expensive chemicals which are potentially may not be eco-friendly. So, use of microorganism or plant extract could be an alternative to chemical and physical methods [3]. Extract of Azadirachta indica (Neem) [4], Caricaya papaya [5], Carob leaves [6] etc were used to synthesized iron and iron oxide nanoparticles. In this study, iron oxide nanoparticles are synthesized using Musa balbisiana peel extract. The peel of the plant helps in normalizing digestive disorder of stomach [7]. SiO2 is an interesting material having highly ordered nanopores and large surface area. It is widely used as an excellent supporting agent because of its surface area and large pore diameter. Moreover, the other advantages such as easy surface modification, possibility of recovery from the reaction mixture and reusing of the catalyst are important aspects from economical and environmentally point of view [8].

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In this study, biosynthesis of Fe2O3 nanoparticles using Musa balbisiana loaded in bio-derived SiO2 nanoparticles from rice husk is reported. The photocatalytic activity of Fe2O3@SiO2 nanoparticles in degradation of MR dye under visible light at room temperature also is studied.

2. Methods and Materials 2.1. Synthesis of Fe2O3 nanoparticles The peel of Musa balbisiana was dried and grinded to powder form. 2 gm of the powder was added in 20 ml of distilled water and boiled for 1 h and filtered it. 5 ml 1mM FeCl3.6H2O solution was added to the filtrate and stirred for 10 min. As the result, brown precipitate was formed. The precipitate was then filtered, washed and heated for 3 h at 150ºC for the formation of Fe2O3 nanoparticles. 2.2. Synthesis of silica from rice husk: In this method, 20 gm of the rice husk was burnt at 600oC for 6 h. The 2 gm of burnt ash was stirred in 100 ml of 2.5 M NaOH solution and the mixture was boiled for 4 h. The solution was filtered and the filtrate was treated with 5 M H2SO4 acid. When PH of the solution was around 8.5-9, jelly like precipitation was occurred and the resulting material was finally dried at 100oC for 3 h to produce the pure silica. 2.3. Synthesis of Fe2O3@SiO2 nanoparticles: Fe2O3 nanoparticles were loaded in SiO2 surface. In this procedure, Fe2O3 and SiO2 were (1:10) refluxed in 10 ml methanol for 3 h. The composite material was filtered and washed for three/four times. The residue was dried at 100ºC temperature for 1 h. As the result, light brown coloured Fe2O3@SiO2 was formed. The other nanocomposite i.e. Fe2O3@SiO2 (commercial) was prepared by similar procedure using bio-derived silica synthesized from rice husk and Fe2O3 procured from the Sigma-Aldrich (USA). The Fe2O3@SiO2 (commercial) nanocomposite was characterized by TEM and EDX analysis. 2.4. Photocatalytic activity: The photocatalytic activity of Fe2O3@SiO2 nanoparticles was evaluated in degradation of MR in aqueous solution was considered as a model system [9]. The 0.1 mol% Fe2O3@SiO2 nanoparticles were added to 10 ml of 1×10-4M MR solution. The solution was put under the visible light. The absorbance of the solution was measured at 523 nm. Similarly, photocatalytic degradation of 10 ml of 1×10 -4M MR was observed in presence of 0.1 mol% SiO2, Fe2O3 and Fe2O3@SiO2 (commercial) nanoparticles as above. After

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completion of reaction, the mixture was centrifuged, filtered and washed with water several times. The residue was reused in photocatalytic degradation of MR up to 5th cycle. 2.5. Characterization X-ray diffraction (XRD) measurement were carried out by Rigaku X-ray diffractometer (Model: ULTIMA IV, Rigaku, Japan) with Cu-K X-ray source ( = 1.54056 Å) at 40 kV. Scanning electron microscopy (SEM) characterization was performed on JEOL JSM - 6360 at 15 kV. The high resolution transmission electron microscopy (HR-TEM) image were recorded by a JEOL Model 2100 EX, Japan operated at voltage of 200 kV. Specific surface area, pore volume, average pore diameter were measured with the Autosorb-1 (Quantachrome, USA).

3. Results & Discussion 3.1. Characterization of Fe2O3@SiO2 nanoparticles Fe2O3 nanoparticles were synthesized using the peel of Musa balbisiana. Addition of peel extract in FeCl36H2O solution, the reduction take place Fe3+ to Fe3O4. The C=O group of phenolic acid and the flavonoid of extract may chelated with Fe3+ ion to form ferric protein chains. The HO----Fe3+ bond further transformed to ferric hydroxide. Subsequently on slow evaporation, ferric hydroxide in a core is dehydrated (-H2O) which further heated at 150ºC in presence of controlled air to produced Fe2O3 nanoparticles. It is supported by reported information [8]. The SiO2 nanoparticles were biosynthesized from rice husk which is a waste material. It was characterized by SEM and TEM analysis. The SEM image revealed the flake like structure of SiO2 surface [Figure 1S(A), supporting information (SI)]. The TEM image indicated the presence pentagonal, hexagonal array overlap each other [Figure 1S (B), SI]. The formation of Fe2O3@SiO2 nanoparticles was confirmed using XRD, SEM, EDX and TEM analysis. The diffraction peaks appeared at 2θ value 36.7, 44.1, 54.4, and 63.1 were assigned to (311), (400), (422), and (440) reflection respectively, which are indexed to the spinal structure of pure stoichiometric Fe 2O3 (JCPDS Card No.19–0629). The corresponding ‘d’ spacing value of Fe2O3 nanoparticles are 2.56, 2.30, 1.90 and 1.42 respectively (Figure 1).

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The SEM image indicated the formation of sheet like morphology of Fe2O3@SiO2. The size of Fe2O3@SiO2 is in the range of 50-90 nm (Figure 2A-B). This morphology consists of small Fe2O3 nanoparticles on SiO2 surface. However, it is difficult to examine the surface structure by SEM image and therefore it was examined by HR-TEM analysis. The HR-TEM results showed the formation cluster of Fe2O3@SiO2 nanostructure. It revealed that most of Fe2O3 nanoparticles dispersed over the SiO2 surface (Figure 2C-D). The size of Fe2O3@SiO2 was found in the range of 3.0±0.2 – 19.0±1.2 nm. The average size of the particles was 9.2±0.6 nm. It is supported by dynamic light scattering (DLS) study (Figure 2S, SI). The EDX analysis was carried out to evaluate the presence of elements in Fe2O3@SiO2 nanoparticles. It showed that weight% of O, Si and Fe are 60.16, 34.99 and 4.86 and atomic % is 73.83, 24.46 and 1.71 respectively. It strongly supported the presence of Fe, O and Si elements respectively in nanoparticles (Figure 3S, SI). 3.2. Photocatalytic activity The relationship between the rate of photocatalytic degradation of MR in presence of Fe2O3@SiO2 nanocatalyst using the following equation [10] Ln(C0/C) = k Kt = kt

(1)

Where, K is the adsorption coefficient of the reactant, k is the reaction rate constant and C is the concentration of the reactant at time t, C0 is initial concentration, k = kK is the pseudo first order reaction rate constant. The absorption peak of aqueous solution of MR at 523 nm tested at different time interval in presence of Fe2O3@SiO2 nanocatalyst [Figure 3A]. Simultaneously, the absorption peak at 415 nm is increased gradually. [10]. By plotting Ln(C0/C) versus the corresponding time (min) yield a linear relationship [Figure 3B]. Therefore the photocatalytic degradation reaction of MR by Fe2O3@SiO2 nanoparticles belongs to the pseudo first order reaction. The rate of reaction was studied using i) Fe2O3 ii) SiO2 iii) Fe2O3@SiO2 (commercial) and iv) Fe2O3@SiO2 nanoparticles synthesized by Musa balbisiana respectively. The TEM and EDX image of Fe2O3@SiO2 (commercial) were shown in Figure 4S.A-B [SI]. In presence of Fe2O3, SiO2 and Fe2O3@SiO2 (commercial) nanoparticles (0.1-0.5 mol%) as photocatalyst, the rate constant

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ranged 0.0150 - 0.0270, 0.0039 – 0.0089 and 0.0170 – 0.0209 min-1 respectively (Table 1). When Fe2O3@SiO2 nanoparticles were used, the rate constant ranged 0.0589 - 0.0775 min-1 respectively. It was observed that the rate of degradation of MR was found significantly high while Fe2O3@SiO2 nanoparticles were used as photocatalyst. The rate constant was found highest (0.0775 min-1) when 0.5 mol% Fe2O3@SiO2 nanoparticles was used as photocatalyst. In the photocatalytic system, a photon could be absorbed by the metallic Fe2O3 nanoparticles under the visible light which would be further efficiently decomposed into an electron and hole [10]. As the result, the electron can more easily move from valence band to conduction band. The Fe2O3@SiO2 nanoparticles play a major role in photocatalytic degradation of MR. In photocatalyst reaction on SiO2 surface can enhance the activity due to lower crystal size, higher surface area and higher efficiency for the electron hole regeneration. The reusability of Fe2O3@SiO2 nanocatalyst in degradation of MR was tested after 5th cycle of photocatalytic reaction. It was observed that the activity of the nanocatalyst almost same after 5th cycle of reaction [Figure 5S-6S, SI]. The rate constant was found almost similar after 5th cycle of photocatalytic reaction (Table 1S, SI). So, it is one of the advantages in the study. The fresh and recovered catalyst was further investigated through N2 adsorption–desorption study. The specific surface area of the recovered catalyst after 5th cycle decrease marginally to 150 (5th run) compared to 225 m2g−1 of freshly catalyst (Figure 7S, SI). The BJH pore size distribution curve of the recovered catalyst showed a slight broadening of the distribution pattern compared to fresh catalyst (Figure 8S, SI). It indicated slight broadening of the pore size. 4.

Conclusions A simple efficient and inexpensive process of biosynthesis of Fe2O3@SiO2 nanocatalyst was developed

using Musa balbisiana. The catalyst was further used for the photocatalytic degradation of MR dye. The Fe2O3@SiO2 nanocatalyst was found to be efficient, highly active and could be recycled for five consecutive runs without significant loss of photocatalytic activity.

Acknowledgement The authors thank Director, CSIR-North East Institute of Science & Technology, Jorhat, Assam for valuable advice. I.S. thanks to CSIR, New Delhi for fellowship.

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References [1] P. Li, D.E. Miser, S. Rabiei, R.T. Yadav, M.R. Hajaligol, Appl. Catal. B: Environ. 43(2003)151-162. [2] J. Chen, L. Xu, W. Li, X. Gou, Adv. Mater. 17(2005)582-586. [3] K. Leonard, B. Ahmmad, H. Okamura, J. Kurawaki, Colloid. Surfac. B, 82(2011)391-396. [4] M. Pattanayak, P.L. Nayak, World J Nano Sci & Tech. 2(1)(2013)06-09 [5] N. Latha, M. Gowri, Int. J. Sci. Res. 3(2014)1551-1556. [6] A.M. Awwad, N.M. Salem, Nanosci and Nanotech. 2(6) (2012)208-213 [7] D.C. Deka, N.N. Talukdar. Ind. J. Trad. Knowledge. 6(2007)72-78. [8] M. Pattanayak, P. L. Nayak, Int. J. Plant Animal Environ. Sci. 3(2013)68-78 [9] J.L. Gardea-Torresdey, J.G. Parsons, J.G.E. Gomez, J. Peralata-Videa, H.E. Troinai, P. Santiago, M.J. Yacaman. Nano Lett 2(2002)397-401. [10] R. Comparelli, E. Fanizza, M.L. Curri, P.D. Cozzoli, G. Mascolo, A. Agostiano. Appl. Catal. B: Environ. 60(2005)1-11.

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Figure 2: (A-B) SEM (C-D) TEM images of Fe2O3@SiO2 synthesized using Musa balbisiana 0.9

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Figure 3: A) The absorption spectra of Methyl Red tested at different time in the presence of Fe2O3@SiO2 (0.1 mol%) nanoparticles. B) The logarithm of the ratio between the original and the final concentration after photocatalytic degradation versus corresponding irradiation time (min) for Fe2O3@SiO2 nanoparticles.

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Table 1: The rate constant of photocatalytic degradation of Methyl red in presence Fe2O3, SiO2, Fe2O3@SiO2 (commercial) and Fe2O3@SiO2 nanoparticles Rate constant(min-1) Catalyst (mol%) 0.1 0.2 0.3 0.4 0.5

Fe2O3 nanoparticles 0.0150 0.0195 0.0219 0.0231 0.0270

SiO2 nanoparticles 0.0039 0.0048 0.0059 0.0072 0.0089

Fe2O3@SiO2 (commercial) 0.0170 0.0176 0.0185 0.0198 0.0209

Fe2O3@SiO2 nanoparticles 0.0589 0.0631 0.0689 0.0721 0.0775

Highlights 

Biosynthesis of Fe2O3 nanoparticles was achieved using peel of Musa balbisiana

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Fe2O3 nanoparticles were loaded in bio-derived SiO2 surface.

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Fe2O3 nanoparticles were characterized by XRD, SEM and TEM techniques.

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Cost effective, efficient, simple synthesis method of Fe2O3 nanoparticles

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Fe2O3@SiO2 is a suitable photocatalyst of degradation of methyl red dye. Graphical Abstract

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FeSO4.7H2O

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