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PRIMARY IDENTIFICATION OF EUCALYPTUS (Eucalyptus camaldulensis) WOOD LIGNIN MONOMERS BY FT-IR SPECTROSCOPY
| Content Provider | Semantic Scholar |
|---|---|
| Author | Sheet, Esam Mohammed |
| Copyright Year | 2007 |
| Abstract | Lignin samples were isolated from Eucalypt wood (Eucalyptus camaldulensis) by kraft process, and then all samples were examined and tested with Fourier Transform Infrared Instrument Technique for identifying the types of lignin monomers units from their spectra.The Lignin monomers spectra chart showed these peak bands( 616.80, 795.11, 876.96, 1057.14, 1127.19, 1458.74, 1509.21, 1542.05 , 1636.26, 1735.68, 2863.72,2922.35, 2967.95, 3447.01,and 3650.56 cm ).No evidence for methoxyl group bands were observed, though all monomers of the tested lignin in this investigation which obtained from Eucalypt wood by KRAFT process consist mainly of P-hydroxy phenyl propane units. INTRODUCTION Fourier Transform Infrared spectroscopy (FT-IR) is an analytical technique used to identify the functional groups of the organic (and in some cases inorganic) materials. This technique measures the absorption of various infrared light wave lengths by the materials interest. These bands identify specific molecular components and structures (Silverstein and Webster, 1998).The first astronomical application of Fourier Transform spectroscopy experinced in the late 1950’s and early 1960s when J. cones and coworkers obtained high resolution and high quality spectra. To day commercial Fourier Transform Infrared spectrometer are widely available aided by fast computers which perform Fourier Transforms in flash , vise infrared (Socrates,1994). Recently the Fourier Transform Infrared (FT-IR) is used as a fast, reliable and easy analytical tool for wood and wood derivatives because of its improved spectral quality and is meaning full difference spectra which can be obtained even in region of high background absorption and the ability to detected small changes in bands overlapped by strong bands undergoing (Rutherford etal., 2004). Lignin is after cellulose, the principal constituent of wood structure of higher plant. Infrared spectroscopy in the near IR region wave length 2.5-1.5μm ,wave number 4000-600 cm is useful as physical method for characterizing lignin and its derivatives, and their spectrum is characteristic property of compound with exactly known structures ,there are several uncertainties with the interpretation of lignin IR ,the variation in lignin structures and compositions due to the origin sample ,the isolation procedure are the causes of different spectra measuring of lignin(Alobydi etal.,2004). Fengel and Wegener(1989) give the elemental composition and methoxy content of the analytical and technical lignin isolated from Eucalyptus regnons , Mesopotamia J. of Agric. (ISSN 1815 – 316 X) Vol (35) No (1) 2007 the results show 56-60% of carbon content and the methoxy contents reach to 1822%, these Received 29 / 10 /2006 accepted 7/3/ 2007. results differed than the carbon content of the softwood lignin which reaches about 60-65% where as therefore, IR spectra of lignin shows several major absorption bands which can be assigned empirically to structural groups. Chemists cleared that the empirical formula of lignin based on a phenyl propane (C9)unit is C9H8.83O2.37(OCH3)0.96 in coniferous lignin ,and C9H8.9O3(OCH3)1.45 in deciduous lignin and it appears that there are about 3 sringyl propane unit for every 2 guaiacyl propane units in deciduous lignin (Sarkanen etal.,1967). So for the all reasons above our investigation was put to study the different absorption bands of the Kraft lignin extracted from Eucalyptus camaldulensis by using the Fourier Transform Infrared technique and to find out and identify the structural units and the functional groups of it. MATERIALS AND METHODS Wood & wood cooking: A log at about1.5m of Eucalyptus camaldulensis was bought from a local Mosul markets, then it was barked and chipped with a multiknifes chipper in one of a local industry according to (ASTM-584, 1968).All chips were screened by vibration tray at about 1.6-2.2 cm in size.5000 gm of the chips had been randomizing obtained and subjected in a digester in the technical institute of Mosul (Othmer, 1967). A white liquor was made by mixing 250 gm of sodium sulphate -5-hydrate RS, 550 gm of potassium hydroxide powder, 250 gm of sodium carbonate, and 30 liters of tape water, the liquor added to the wood chips in the digester and the cover of the digester closed tightly, then the mixture was cooked in the digester for 5hrs, 160C°, and at (7 bars) pressure. After the completing of the digestion periods the black liquor was separated from the digested wood chips. The black liquor was Acidified by sulfuric acid (72% Conc.) which was added to it at several batches to reduce the pH level in the black liquor from (pH12) to (pH 8)at this point the acidification was stopped at and at that level the precipitated Kraft Lignin had been seen at the bottom of the container. The precipitated Lignin was separated by decantation and washed for several times by water then put in oven for 24hrs for drying it at 50C°. Infrared spectroscopy: Several samples of Eucalypts Kraft Lignin with potassium bromide pellets were made. Each sample was prepared by milling (5 milligram) of the extracted lignin and pressed with potassium bromide to form apellet from each other (Gracin, 2001). The fourier transform infrared spectrophotometer of the name Tensor 27 Broker co., Germany. The ratio of 1:100 was used as infrared source with the adenterated triglycine sulfate detector. This instrument was scanned from 4000 to Mesopotamia J. of Agric. (ISSN 1815 – 316 X) Vol (35) No (1) 2007 400 reciprocal centimeters (cm); averaging to scans at 1.0 cm interval with a resolution of 4.0 cm .All spectra were normalized after acquisition to a maximum absorbance. RESULTS & DESCUSSION The FT-IR spectra of the Eucalyptus Kraft Lignin samples showed typical absorption bands. Figure (1) shows all spectra band result an FT-IR chart, where as table (1) summarizes all wave numbers of the peak absorption monitored in Figure (1) with there corresponding descriptions and intensities. As it is shown in Figure (1) and table (1), the first peak absorption is at the fingerprint region of about 1 cm 80 . 616 which is mean a bending vibration in an out plane of γ C H involving in the aromatic ring of the Lignin monomers with weak intensity, this result is accepted with Haw and Schultz (1985) ,and Wallis etal. (1996) indicates the region between 1 cm 580 670 which involve ion vibrations of SO4, sulfide, mercaptan with medium intensity. Table (1): Vibration descriptions, frequencies, and the intensities of lignin monomers . Description Frequency,cm Intensity Bending vibration in (γCH) in out of plane of the aromatic ring of the lignin monomers. 616.80 Weak Stretching vibration for methyl groups (CH3). 795.11 Strong Bending vibration for hydrogen atoms in an out plane of the phenyl ring. 876.96 Strong Stretching vibration for υ(C=O) of the alcohol. 1057.14 Broad &Shoulder Stretching vibration of the ether groups. 1127.19 Weak Stretching vibration of in the aromatic ring. 1458.74 1509.21 1542.05 Medium Stretching (nonconj) vibration band for υ(C=C) in aliphatic chain. 1636.26 Medium Stretching vibration of the aliphatic aldehyde and ester groups. 1735.68 Very weak Stretching vibration for methylene groups. 2863.72 2922.35 Medium Asymmetric Stretching of methyl groups. 2967.95 Medium Stretching vibration for hydrogen 3447.01 Very strong and broad --υ(CـــC) Mesopotamia J. of Agric. (ISSN 1815 – 316 X) Vol (35) No (1) 2007 bonds in lignin monomers. Stretching vibration for free separated alcohol and phenol. 3650.56 Strong and sharp The second peak band is at 1 cm 11 . 795 level in the same figure give a description of the methyl stretching vibration with strong intensity, the result agree with (Pandey, 1999),while and Raymond (2004) said that the region between |
| Starting Page | 10 |
| Ending Page | 17 |
| Page Count | 8 |
| File Format | PDF HTM / HTML |
| DOI | 10.33899/magrj.2007.26443 |
| Volume Number | 35 |
| Alternate Webpage(s) | https://magrj.mosuljournals.com/article_26443_71f5eb03fdcab025a7cc544c340d4d5f.pdf |
| Alternate Webpage(s) | https://doi.org/10.33899/magrj.2007.26443 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
