CHARACTERIZATION OF RICE HUSKTHROUGH X- RAY DIFFRACTION, SCANNING ELECTRON MICROSCOPE AND FOURIER TRANSFORM INFRARED ANALYSIS

Transcription

1 CHARACTERIZATION OF RICE HUSKTHROUGH X- RAY DIFFRACTION, SCANNING ELECTRON MICROSCOPE AND FOURIER TRANSFORM INFRARED ANALYSIS Monoj Bardalai 1, Dimbendra Kumar Mahanta 2 1 Department of Mechanical Engineering, Tezpur University, Tezpur, (India) 2 Department of Mechanical Engineering, Assam Engineering College, Gauhati University, Guwahati, (India) ABSTRACT This paper has discussed the characterization of rice husk with the help of X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) techniques. The peaks observed at some particular diffraction spacings (dspacings) of the X-ray difractogram indicate the crystal structure of cellulose components present in rice husk. The various absorption bands in the FTIR spectrum of rice husk represent certain chemical compounds along with the functional groups such as alcohols, phenols, amines, methylenes, aliphatic etc. The SEM images at different magnifications reveal the morphology of the rice husk biomass.the SEM micrographsshowed some irregular long, flat and fibrous flakes on the surface of rice husk particles.some tiny white particles are found to be distributed in non-uniform manner throughout the surface of the rice husk.no significant pore has not been observed on the rice husk morphology. I INTRODUCTION The biomass can be considered as the most easily available and useful bio-material in the current days. Because of the renewable nature, the biomasses are widely used for various purposes such as direct source of heat generation, as the feedstock for thermochemical and biological conversion to produce useful fuels or chemicals.however, before using the biomass as feedstock in any conversion process, it is essentially important to have the knowledge about the physical, chemical and morphological properties of the biomass, because, these properties have significant effects over the products quality. Biomass can be categorized in two ways: the biological categorization based on types of existing biomass in nature (according to ecology or type of vegetation) and other one is based on use or application as resources. The later type is more significant in terms of making effective use of energy sources. All kinds of biomasses are biological matter 472 P a g e

2 and based on carbon, hydrogen and oxygen. The other inorganic compounds found in the biomass are N, Ca, K, Si, Mg, Al, S, Fe, P, Cl, Na, Mn, and Ti. However, the primary components of biomass are hemicellulose, cellulose, lignin, starch and proteins. The woody biomasses are mainly composed by cellulose, hemicellulose and lignin and thus it is termed as lignocellulose material, which has the great potential from the energy point of view. Most of the lignocellulosic biomass including wood wastes, waste paper, sawdust, grass, and the biomass-derived char (biochar) are considered as the non-food based biomass, and therefore, these can be used as the potential feedstock for renewable and alternative fuels (Li et al., 2011; Cardona et al., 2010). In the burning of lignocellulosic biomass derived from plants, there is no net increase of CO 2 in the atmosphere, as these biomasses accumulate equal amount of CO 2 during the time of growth which is released during its combustion. On the other hand, the fossil fuels such as coal, oil and gas are also derived from biological substance; however, the fossil fuel absorbed CO 2 from the atmosphere in millions of years ago (Ghani et al., 2013). Thus in combustion of fossil fuel releases the carbon sequestered millions of years ago and increase the atmospheric carbon concentration and greenhouse gases. The biomass has certain other advantages such as high volatile matter content, low ash, sulfur and nitrogen contents, and thus it creates low pollution to the environment when it is burned (Feng-Ke et al., 2008). The annual biomass resources from crop and wood waste, which can be used for fuel, are about 350 million tons of standard coal (Ghani et al., 2013). In general, the biomasses are treated as the waste products and often disposed. However, the uses of biomasses have several advantages over fossil fuels. For example, 1. It can be used as the fuel by direct burning or by converting it into other forms, such as gaseous and liquid. 2. The proper utilization of biomass as a source of energy, can reduce the problems of waste disposal. 3. Once the biomass is utilized for harnessing energy, it can significantly contribute to the economicgrowth of the nation. Although the primary composition of all biomasses is similar, there are certain differences, due to which the characteristics of the products derived from it vary from each other. The variouschemical compounds and functional groups present in the biomass help in selecting the biomass to be used as a feedstock in producing various yields such as bio-oil, biochar and gases. In order to identify these chemical compounds and functional groups in any biomass sample, the FTIR analysis is found to be a quite effective tool. It is a low cost, rapid and easy to use method for non-destructive screening of any biomass material (Liu et al., 2015). The crystallinity of any biomass can be defined as the weight fraction of crystalline material (crystalline cellulose) in the biomass. Biomass crystallinityhas certain important impacts on the physical, mechanical, and chemical properties of cellulose fibers (Jiang et al., 2007). For example, Young s modulus, tensile strengthalpha-cellulose 473 P a g e

3 content, dimensionalstability, density, and hardness increase with the increase of crystallinity; on the other hand, moisture regain, dye sorption,chemical reactivity, swelling, and flexibility are found to be decreased (Lee et al., 1961). The SEM analysis provides the knowledge about the surface morphology of any solid sample. This technique helps in investigating any kind of pores, irregularities, coalescences etc., present over the sample surface. These morphological natures are useful in selection of biomass for different purposes. India is one of the leading rice producercountries in the world and about 20 wt% of the paddy weight is the rice husk. Rice husk is the most widely abundant paddy wastes in India. Rice husks are relatively hard protecting cover of paddy rice grains, which are separated during milling to produce the white rice as it is mostly indigestible to humans. The main composition ofrice husk isto be known as opaline silica and lignin. Although the rice husk are used in various ways such as fertilizer, insulating material and fuels in power plants, but mostly it is treated as a waste product and often burnt or dumped in the landfills.by proper characterization, the rice huskcan be made as the useful biomaterial for different purposes or as the feedstock in various conversion processes. Therefore, the aim of this paper is to characterize the rice hush in terms of crystallinity, morphological and compositional with the help of XRD, SEM and FTIR techniques. II METHODS AND MATERIALS For this work, the rice husks were collected from a rice mill with the average particle size of mm. Before performing the experiments, the rice husk sample was dried under the sunlight to reduce its moisture content. The X-Ray diffraction technique was used for determination of the crystallinity behaviour of rice husk biomasses. In order to perform the XRD experiment, an analytical XRD diffractometer (Make: RIGAKU, JAPAN; Model: Mini flex) was used.the X-ray diffractometer used a voltage of 30 kv with a current density of 15 ma during the experiment. The scanning range varied from 2θ value 10 0 to 70 0 and the scan speed was /s. CuKα X-rays with the wavelength, λ= Å were used for the XRD study in this work. In order to determine the surface morphology of the rice husk biomass a Scanning Electron Microscope (SEM, Make: JEOL, Japan; JSM 6390 LV) was used.during the experiment, the SEM was operated on 110V, 50 Hz. The FTIR analysis of rice husk was performed with the help of Fourier Transform Infrared Spectroscopy (Make: NCOLET, USA; Model: IMPACT 410; Software: OMNIC E.S.P.5.0). The range of wave number was varied from 4000cm -1 to 500 cm -1 and the resolution of the instrument was set at 4 cm P a g e

4 Diffraction intensity 2.52 Å 4.44 Å 5.0 Å 6.5 Å 6.0 Å 5.8 Å 3.89 Å 4.04 Å IVRESULTS AND DISCUSSION The information obtained from the different experiments, i.e., XRD, SEM and FTIR is presented and discussed in the following sections one by one. 4.1 XRD Analysis The diffractogram obtained from XRD analysis of the rice husk is shown in fig.1. The shape of the diffractogram shows the amorphous nature although, it has some local crystalline structure with high conjugated aromatic compounds (Qadeer et al., 1994).The peaks at the spacing 5.8 Å and 3.89 Å indicate the crystal structure of cellulose in rice husk (Al-Wabel et al., 2013).The peak spacings at 6.5 Å and 5.0 Å can be assigned to the completely ordered crystallographic planes (Abdulrazzaq et al., 2014). Further, crystalline cellulose in rice husk can be identified by the peakspacing at 6.0 Å, 5.8Å, 4.44 Å, 4.04 Å, 3.89 Å, Å (Keiluweit et al., 2010;Al- Wabel et al., 2013). 4.2 SEM Analysis In order to studythe morphology of the rice husk sample, four SEM images were taken with the magnifications of x50, x500, x1500 and x2500, which are shown as (a), (b), (c) and (d) in fig 2. In fig. 2 (a), some irregular long, flat and fibrous flakes are observed on the surface of rice husk. Some remarkable tiny white particles are found to be distributed in the non-uniform manner throughout the surface of the rice husk. The SEM images showed no pores on rice husk morphology Angle (2 ) Fig.1. XRD of Rice Husk Biomass 475 P a g e

5 a b c d Fig.2. SEM of Rice Husk 4.3 FTIR Analysis The FTIR spectrum of rice husk can be seen from fig. 3. The broad band observed at around 3427 cm -1 indicates the presence of cellulose and hemicellulose components of the rice husk. It was found that, the band in the region cm -1 also represents the compounds with alcohol and phenolic groups having O H stretching (Ateş et al., 2004; Silverstein et al., 2005; Ahmed et al., 2007).Primary and secondary amines groups with N H stretchingare identified by the absorption band in the region of cm -1 (Sharma, 2000). The absorption peak at cm -1 is attributed to the aliphatic C H stretch vibration (Kim et al., 2012; Brewer et al., 2009). The relatively small and weak band at 2852 cm -1 can be assigned to the aliphatic C H stretch vibration (Wang et al., 2013).The absorptions in the broad region cm -1 can be assigned to methyl or methylene groups with the C-H stretching (Sharma, 2000). The peak in the wide range cm -1 (centered at 1646 cm -1 ), indicates the 476 P a g e

6 % Transmittance presence of carbonyl group, i.e., >C=O (Sharma, 2000). Further, the band near 1034 cm -1 may be assigned to cellulose, hemicellulose and lignin with C O stretching vibration (Shi et al., 2012). The acyclic anhydrides with C O stretching are detected by the band at ~ 1034 cm -1 (Sharma, 2000). The presence of esters, ethers, primary, secondary and tertiary alcohol groups has been confirmed due to the band observed in the region cm -1 (Sharma, 2000). The peaks observed at the region lower than 1000 cm -1 can be attributed to the compounds with aromatic ring (Sharma, 2000) Wavenumber (cm -1 ) Fig.3. FTIR of Rice Husk V CONCLUSION The XRD analysis has shown that although the structure of rice husk is amorphous in nature, it has some local crystallinity with conjugated aromatic structure. The peaks observed in certain positions of XRD diffractogram indicated the crystalline cellulose. The SEM images of rice husk showed the nonporous morphology.the absorption bands obtained at different wavenumbers in FTIR spectrum has identified different chemical compounds and functional groups such as alcohol, phenol, aliphatic, anhydrides, ester, ether, methylene and carbonyl groups. The FTIR also confirmed the presence the cellulose and hemicelluloses along with some possible aromatic compounds in rice husk. 477 P a g e

7 ACKNOWLEDGMENT The authors have highly acknowledged the assistance of different laboratories of Tezpur University, India, in performing required experiments in the present work. REFERENCES 1. Abdulrazzaq, H., Jol, H., Husni, A. and Abu-Bakr, R Characterisation and stabilisation of biochars obtained from empty fruit bunch, wood and rice husk. BioResources 9(2): Ahmed, A.L., Loh, M.M. and Aziz, J.A Preparation and characterisation of activated carbon from oil palm wood and its evaluation on Methylene blue adsorption. Journal of Dyes and Pigments 75(2): Al- Wabel, M.I., Al-Omran, A., El-Nagar, A.H., Nadeem, M., and Usman, A.R.A Pyrolysis temperature induced changes in characteristics and chemical composition of biochar produced from conocarpus wastes. Bioresource Technology 131: Ateş, F., Pütün, E. and Pütün, A.E Fast pyrolysis of sesame stalk: yields and structural analysis of bio-oil. Journal of Analytical and Applied Pyrolysis 71: Brewer, C.E., Schmidt-Rohr, K., Satrio, J.A. and Brown, R.C Characterisation of biochar from fast pyrolysis and gsification systems. Environmental Progress & Sustainable Energy 28(3): Cardona, C.A., Quintero, J.A. and Paz, I.C Production of bioethanol from sugarcane bagasse: status and perspectives. Bioresource Technology 101: Feng-Ke, Y., Cheng, W., Wang, Y. and Xu, K Research of bio-fuels from pyrolysis of biomass. Amino Acids &Biotic Resources 30: Ghani, WAWAK.,Mohd, A., Silva, G.d., Bachmann, R.T., et al., Biochar production from waste rubberwood-sawdust and its potential use in C sequestration: chemical and physical characterization. Industrial Crops and Products 44: Keiluweit, M., Nico, P.S., Johnson, M.G. and Kleber, M Dynamic molecular structure of plant biomassderived black carbon (biochar). Environmental Science & Technology 44: Kim, K.H., Kim, J.Y., Cho, T.S., and Choi, J.W Influence of pyrolysis temperature on physiochemical properties of biochar obtained from the fast pyrolysis of pitch pine (Pinusrigida). Bioresource Technology 118: Lee, C.L Crystallinity of wood cellulose fibers studies by X-ray methods. Forest Products Journal 11: Liang, Z.H., Yang, Z., So, C.L. and Hse, C.Y. 53: Rapid prediction of wood crystallinity in PinusIlliotii plantation wood by near-infrared spectroscopy. Journal of Wood Science 53: Li, N., Tompsett, G., Zhang, T., Shi, J., Wyman, C. and Huber, G Renewable gasoline from aqueous phase hydrodeoxygenation of aqueous sugar solutions prepared by hydrolysis of maple wood. Green Chemistry 13: P a g e

8 14. Liu, Y., He, Z. and Uchimiya, M Comparison of biochar formation from various agricultural by-products using FTIR spectroscopy. Modern Applied Science 9: Qadeer, R., Hanif, J., Saleem, M.A. and Afjal, M Characterisation of activated charcoal. Journal of Chemical Society of Pakistan 16: Sharma, Y.R Elementary organic spectroscopy, 3 rd Ed.; S. Chand & Company Ltd.: Ram Nagar, New Delhi, India. 17. Shi, J., Xing, D. and Li, J FTIR studies of the changes in wood chemistry from wood forming tissue under inclined treatment. Energy Procedia 16: Silverstein, R.M., Webster, F.X. and Kiemle, D Spectrometric Identification of organic compounds, 7 th Ed.; John Wiley and Sons: Hoboken, NJ, USA. 19. Wang, Y., Hu, Y., Zhao, X., Wang, S. and Xing, G Comparisons of biochars properties from wood material and crop residues at different temperatures and residence times. Energy & Fuels 27: P a g e