Photocatalytic Studies of MgO Nano Powder; Synthesized by Green Mediated Route

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ScienceDirect Materials Today: Proceedings 5 (2018) 22221–22228

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ICASE_2017

Photocatalytic Studies of MgO Nano Powder; Synthesized By Green Mediated Route M.R. Anil Kumara, B. Mahendraa, H.P. Nagaswarupaa*, B.S. Surendraa, C.R. Ravikumara, Krushitha Shettya,b, Research Center, Department of Science, East West Institute of Technology, Bangalore 560 091, India. Department of Nanotechnology, PG Center, VIAT, VTU, Muddenahalli, Chikkaballapur -562101, India.

a b

Abstract MgO nano powders were synthesized by a bio mediated route. The obtained products were characterized by powder X-ray diffraction (PXRD), diffuse reflectance spectroscopy (DRS) Scanning electron microscope (SEM), Transmissionelectron Microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). PXRD patterns show hexagonal single cubic phase MgO matched with JCPDS Card No 78-0430. The crystallite size obtained from TEM was found to be ~ 15-20 SEM result reveals porous nature of the obtained nano-powder. The optical energy gap is 3.20eV which demonstrates that there is a movement to the higher wavelengths of the absorption edge with reduction of the energy gap when using green fuel for synthesis. The photocatalytic studies relatively high activity for degradation of Malachite Green (MG) and Rhodamine-B (Rh-B) under sunlight irradiation compared to UV light. The good structure and excellent performance of ZnO nano-composites, suggest its promising application in dye decolarization. © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility ofInternational Conference on Advances in Science & Engineering ICASE - 2017. Keywords:Banana peel, MgO, PXRD, Rhodamine-B, Malachite green, Photocatalytic.

* Corresponding author. Tel.: +91 9945406900; E-mail address:[email protected]

2214-7853© 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility ofInternational Conference on Advances in Science & Engineering ICASE - 2017.

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1. Introduction Metal oxide nanostructures have attracted special attention in recent years because of their distinctive properties and potential applications in solar cells, photocatalysis, electro-optical devices, sensors, antimicrobial agents, light materials [1]. MgO incorporates a sodium chloride structure (fcc) (space group-fm-3m-225) with Mg2+ ions occupy sites of octahedral among the ion closed packed structure. The Mg atoms are at the corner of the cube and surrounded by 8 equivalent neighbor O atoms. (During this lattice), the symmetry of Mg sites within the cubic MgO structure (was if possible) D2d and Mg site possesses inversion symmetry. Its nanostructures wereexpected to possess novel properties superior to their bulk counterparts. Further, MgO a typical wide energy gap nonconductor attracts researchers because of its novel(glorious) physical and chemical properties, like high specific extent, giant pore volume, slender pore-size distribution and wide energy gap semiconductor thermal and chemical stability[2]. MgO finds big selection of applications in chemical change, waste water treatment, additives in refractory, paint, medicament, antifungal and dye decolorization. Recently, a lot of interest was targeted on the non-rare-earth hosts in an endeavourto lower the cost.A series of complicated metal oxides, like ZnO, ZrO2, MgO, TiO2, CuO etc were ordinarily used as non-rare-earth host materials. The wide unfold environmental pollution caused by intensive human activities will bemore and more selfaddressed to boost the environmental quality for future society. PC has emerged as a beautiful route towards the mineralization of big selection of organic, inorganic and medicines [3]. Heterogeneous PC has been found comparatively economical to eradicate venturesome materials from waste H2O. Over the years, an outsized range of semiconductor oxides specifically TiO2, ZnO, WO3, Fe2O3 etc., were used as potential photocatalysts for environmental rectification, particularly degradation of organic pollutants in H2O and air. MgO with terribly giant energy gap wonderful thermo-dynamical stability and low intensive applications in contact action, ceramics, and waste rectification and medication materials [4],the demonstration of the efficaciousness of MgO photocatalysts for organic waste matter degradation in binary compound section is scanty. From the economical purpose it absolutely noteworthy to analyze the practicability of utilizing MgO as a photocatalyst for the decolorization of organic pollutants and sunlight irradiation [5,6]. For first time we report a green route to prepare MgO nano powder(MNP) by combustion using banana peel powder as a fuel under low temperature. In the present work we are looking for photocatalytic activity about in point of interest. The photocatalytic activity carrying out of the MNPs through banana peel powder was assessed by checking the photo degradation of MG and Rh-B dyes under UV/Sunlight illumination. 2. Materials and Methods 2.1. Synthesis of MgO nano powder by green route. MgO nano powder (MNP) was synthesized by green combustion route using banana peel powder as a fuel. Banana fruit peel was cut into small pieces and collected in a container then washed with distilled water. Further keep in the autoclave for drying at 1200c. After that grindthebanana peelfor15 mints by using pestle and mortarto convertthem into a fine powder, 1 gram of [Mg(NO3)2 .6H2O] (Sigma Aldrich) and 0.1gram of banana peel powder was taken in a beaker and stirred well using magnetic stirrer for ~ 5-10 min. The mixture was placed in a pre-heated muffle furnace maintained at 350 ± 10oC. The solution boiled resulting in a transparent gel. Further heating convertsgelintowhite foam, whichthenexpanded to fill the vessel. Thereafter, the reaction was initiated somewhere in the interiora flame appeared on the surface of the foam and proceeded rapidly throughout the entire volume, leaving a white powder with an extremely porous structure. The energy released from the reaction produced temperature greater than 1200 ◦C. The reaction was self-propagating and able to sustain high temperature to form MgO nanopowder. The entire process was completed in less than 5 min.

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2.2. PXRD analysis Fig.1. shows the PXRD patterns of MNP synthesized by green combustion route using banana peel powder as a fuel. The powder prepared by solution combustion method show single cubic phase with lattice constant a = 4.212 Åwhich indicateshigh purity of synthesised MNP. All the X-ray diffraction peaks of the samples at 2θ, 36.58o (1 1 1), 42.63o (2 0 0), 62 o (2 2 0), well matched with space group fm-3m (225) and JCPDS card No. 78-0430 . (200)

Intensity (a.u)

MgO- Banana peel powder

(220)

(111)

30

40 50 2 theta (degrees)

60

70

Fig.1. PXRD patterns of MNPs prepared by banana peel powder

MNP are a cubic structure, using Scherrer’s formula the average crystallite size (D) was calculated by line broadening. Particle size was estimated from the following below relation. = [where, K; constant =0.9, ; wavelength of X-rays, and ; FWHM]. Average crystallite size was found to be 19.65 nm [7]. 2.3. UV - Visible spectroscopy The MgO nano-powder sample was analyzed by utilizing UV- visible spectroscopy. The diffused reflectance spectroscopy (DRS) is appeared in the Fig.2;there was a red shift and progressive reflectance in the visible light range as the absorbance or reflectance or transmittance of light is credited to their electronic structures [8]. The Kubelka - Munk capacity F(R) is connected to change over the diffused reflectance into equivalent absorption coefficient and utilized for examining the powder as given by below equation. The optical energy gap was calculated using Tauc relation The energy gap (3.20 eV) decreases (Fig 2) compared to the literature may be due to the fuel used during the synthesis. This demonstrates that there is a movement to the higher wavelengths of the absorption edge with the reduction of the energy gap.

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( )=

(1 − ) 2

Where R is the reflectance, F(R) is Kubelka-Munk function. The optical energy gap was calculated using Tauc relation as in equation F(R) h = A (h –Eg) n Where n = 1/2 and 2 for direct and indirect transitions respectively, R is the reflectance, F(R) is Kubelka-Munk function. MgO Banana peel powder

80

Reflectance (%)

70 MgO Banana peel powder Eg (3.2 eV)

60 fR

2

50

40

2.5

200

300

400

3.0

3.5

4.0

4.5

Energy gap (eV)

500

600

5.0

5.5

6.0

700

800

Wavelength(nm) Fig.2. DRS Spectra of MgO nano-powder (Inset Optical energy gap)

2.4. FTIR Studies 50

MgO Banana peel powder 1076

Transmitance(%)

40

890 2350

30

20

1650

3450

1490

10

0 4000

460

3500

3000

2500

2000

1500

1000

500

absorbence Fig.3. FT-IR spectra of MgO nano-powder prepared by banana peel powder

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The arrangement of nanocrystalline MNP were studiedutilizing FTIR spectra synthesized by green route (appeared) in Fig.3. The absorption peak showing up at 3450 cm-1 of MgO was ascribed to O-H stretching vibrations of adsorbed H2O particle. The recurrence band at 1650 cm-1 of green integrated MgO might be identified with amide I groups connected with proteins or vibrations because of -C=C- practical gatherings from heterocyclic mixes, which was not seenwith synthetic course. The top at 2350 cm-1 being credited to extending vibrations of C=O and extending vibrations of NH2+ and NH3+ in proteins. The retention peak at 1490 and 1076 cm-1 belongs to amines and -C-O-C-, for example, alkaloids and flavones. The solid bond at ~ 460 cm-1 was because of the characteristic vibrational symmetry(MgO6) octahedral of MgO. The top at 890 cm-1 was ascribed to Mg-O-Mg interactions. [9, 10]. 2.5. SEM Analysis SEM was predominantly utilized to contemplate the composition, grain and surface components of powders. Fig.4 show the SEM pictures of green route MNP with flakes and agglomerated morphologies. SEM results revels that the powder was very poly crystalline in nature. Further, it was surely understood that, green burning combination response was impacted by metal–ligand complex development. Contingent on the kind of fuel and metal particles, the nature of burning varies from flaming in gas phase to non-flaming and heterogeneous mixture. For the most part, flaming reactions includes freedom of little amount of gas. The pores and voids might be formed due to the more gasses getting away out of the reaction mixture amid burning [11].

Fig.4. SEM image of MgO nano-powder prepared by banana peel powder

2.6. TEM Analysis TEM studies revels the crystalline size of the NPs. TEM picture and SAED designs investigation of MNP prepared by banana peel powderwere appeared in Fig.5.(a-b). The picture demonstrated that the particles were round fit as a fiddle, very scattered and estimate ran from 15-20 nm and the same is all around coordinated with that, in Scherer's system. The SAED pattern gives the polycrystalline way of the nanopowders were identified by some bright spots and rig.The interplaner (d) spacing was calculated around 0.265 nm for the plane (200), which is near that of 0.269 nm for (200) plane of MgO. Cross section parameter figured from the PXRD estimation was in great concurrence with the TEM results [12].

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Fig.5.TEM image of MgO nano-powder prepared by banana peel powder a) TEM b) SAED

2.7. Photocatalytic activity of rhodamine-B (rh-B) and Malachite green (MG)

Absorbance (arb.units)

0.4

0.3

0.2

0.1

0.0

300

350

400

450

Wave length (nm)

500

550

600

0 min 20 min 40 min 60 min 80 min

MgO Sun light

0.5

Absorbance (arb.units)

0 min 20 min 40 min 60 min 80 min

MgO uv light

0.5

0.4

0.3

0.2

0.1

0.0

300

350

400

450

Wave length (nm)

500

550

600

Fig.6.Absorbance spectra of rh-B for MgOunder UV and Sunlight irradiation

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The rh-B and MG photo-degradation of catalyst (MNP) of UV–Visible absorption spectra changes of UV and sun light irradiation are shown in Fig.6 and 7. It is significant to make a note of that the MgO sample shownbetter photocatalytic activity under Sun compared to UV light irradiation. The UV–visible absorption spectra alterations of photocatalytic degradation for rh-B and MG under simulated sun light irradiationindicatesthat the maximum absorption band reduced slowly on the wavelength of 554 and 610nm due to greater irradiation time Additionally, there is no noticeable change on the maximum absorption band of rh-B. This might be due tothe rh-B and MG commonly suffers a comparatively too easy cleavage of the whole conjugated chromophore [13].The maximum absorption band refuse penetratingly, which shows that rh-B molecules are almost decaying completely [14,15]. Above the outcome may be attributed tofuel used during the synthesis and due to the dye sensitization, may be attributed to small crystallite size, narrow energy gap, textural properties and potential for increasing the e-– h+ pair recombination. It was apparent that the development of hydroxyl ions on the MNP used to be advanced than that of different products. Which used to be also regular with the outcome of energy gap of the substances, Additionally, confirming that MNP is an excellent path to accelerate the interfacial charge transfer and reduce the recombination of e- - h+ pairs, which resulted with increase inhydroxyl ions formation [16-19].

Absorbance (arb.units)

1.2

1.1

1.0

0.9

500

550

600

Wave length (nm)

650

700

0 min 20 min 40 min 60 min 80 min

MgO Sun light

1.3

Absorbance (arb.units)

0 min 20 min 40 min 60 min 80 min

MgO uv light

1.3

1.2

1.1

1.0

0.9

500

550

600

650

700

Wave length (nm) Fig.7.Absorbance spectra of MG for MgOunder UV and Sunlight irradiation

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3. Conclusion For the first time MNP cubic, agglomerated particles were synthesized successfully by green combustion technique using banana peel powder as fuel. The PXRD patterns confirmed MNP (cubic) and single phase. The crystallite size obtained isin nano range and the same is confirmed by TEM results. It is also observed that the structural, morphological, Photocatlytic properties are sensitively dependent on the oxygen vacancies of MNP. MNP show more photocatalytic activity under sun light compared to UV light for rh-B and MG dyes. It is a very good resultobserved in this researchwork. Thisisprimarily due to their high S/V ratio and higher content of oxygen vacancies and also due to the dye sensitization, which may be attributed to small crystallite size, narrow energy gap, textural properties and potential for reducing the e-– h+ pair recombination. The present synthesized material easily recycled withoutany insignificant loss of the PCA. Reference [1] Q. Yang, J. Sha, L.Wang, J.Wang, D. Yang, MgO nanostructures synthesized by thermal evaporation, Mater. Sci. Eng., C 26 (2006) 1097– 1101. [2] X. Yi, W. Wenzhong, Q. Yitai, Y. Li, C. Zhiwen, Deposition and microstructural characterizationof MgO thin films by a spray pyrolysis method, Surf. Coat. Technol. 82(1996) 291–293. [3] T.X. Phuoc, Bret H. Howard, D.V. Martello, Y. Soong, M.K. Chyu, Synthesis of Mg(OH)2, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents, Opt. Lasers Eng. 46 (2008) 829–834. [4] Y. Hao, G. Meng, C. Ye, X. Zhang, L. Zhang, Kinetics-driven growth of orthogonally branched single-crystalline magnesium oxide nanostructures, J. Phys. Chem. B 109 (2005) 11204–11208. [5] L. Kumari,W.Z. Li, C.H. Vannoy, R.M. Leblanc, D.Z.Wang, Synthesis, characterization and optical properties of Mg(OH)2 micro/nanostructure and its conversion toMgO, Ceram. Int. 35 (2009) 3355–3364. [6] P. Ouraipryvan, T. Sreethawong, S. Chavadej, Synthesis of crystalline MgO nanoparticles with mesoporous-assembled structure via a surfactant-modified sol–gel process, Mater. Lett. 63 (2009) 1862–1865. [7] Thanut Jintakosol, Pisith Singjai Effect of annealing treatment on luminescence property of MgO nanowires Current Applied Physics 9 (2009) 1288–1292. [8] L. Kumari,W.Z. Li, C.H. Vannoy, R.M. Leblanc, D.Z.Wang, Synthesis, Characterization and Optical Properties of Mg(OH)2 Micro/Nanostructure and Its Conversion to MgO, Ceram. Int. 35 (2009) 3355–3364. [9] G.K. Williamson, W.H. Hall, X-ray line broadening from filed aluminium and wolfram L'elargissement des raies de rayons x obtenues des limailles d'aluminium et de tungsten Die verbreiterung der roentgeninterferenzlinien von aluminium- und wolframspaenen, Acta Metall. 1 (1953) 22-31. [10] Paresh Chandra Ray,Size and Shape Dependent Second Order Nonlinear Optical Properties of Nanomaterials and Their Application in Biological and Chemical Sensing, Chem. Rev., 110 (2010) 5332–5365. [11] J. Huang, Q. Li, D. Sun, Y. Lu, Y. Su, X. yang, H. Wang, Y. Wang, W. Shao, N. He, J. Hong, C. Chen, Biosynthesis of silver and gold nanoparticles by novel sundried Cinnamomum camphora leaf, Nanotechnol. 18 (2007) 105104-105104. [12] R. A. Mirzaie, F. Kamrani, A. A. Firooz, A. A. Khodadadi, Effect of α-Fe2O3 addition on the morphological, optical and decolorization properties of ZnO nanostructures, Mater. Chem. And Phys. 133, (2012), 311–316. [13] L.C. Oliveira, E.D. Milliken, E.G. Yukihara, Development and characterization of MgO: Nd, Li synthesized by solution combustion synthesis for 2D optically stimulated luminescence dosimetry, J. Lumin. 133 (2013) 211–216. [14] A.B. Djurisic, A.M.C. Ng, X.Y. Chen, ZnO nanostructures for optoelectronics: material properties and device applications Progr. Quantum Electron. 34 (2010) 191–259. [15] R.N. Bhargava, V. Chhabra, T. Som, A. Ekimov, N. Taskar, Quantum confined atoms of doped ZnO nanocrystals, Phys. Status Solidi B 229 (2002) 897–901. [16] Khatamian M, Khandar AA, Divband B, Haghighi M, Ebrahimiasl S (2012) Heterogeneous photocatalytic degradation of 4-nitrophenol in aqueous suspension by Ln (La3+, Nd3+ or Sm3+) doped ZnO nanoparticles. J Mol Catal A Chem 365:120–127. [17] Y. Lin, W. Du, D. Tu, W. Zhong, Q. Du,Space charge distribution and crystalline structure in low density polyethylene (LDPE) blended with high density polyethylene (HDPE), Polym. Int. 54 (2005) 465–470. [18] A.S. Rao, Y.N. Ahammed, R.R. Reddy, T.V.R. Rao, Spectroscopic studies of Nd 3+-doped alkali fluoroborophosphate glasses,Optical Materials 10 (1998) 245. [19] S.M. Lam, J.C. Sin, A.Z. Abdullah, A.R. Mohamed, Degradation of wastewaters containing organic dyes photocatalysed by zinc oxide: a review, Desalin. Water Treat. 41 (2012) 131-169.