FTIR Characterization of Acetone Fractionation of Industrial Softwood and Hardwood Kraft Lignin

( Ega Cyntia Watumlawar ),( Eko Setio Wibowo ),( Byung Dae Park ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1

Lignin as the largest reservoir of aromatic polymer is being discarded as waste or burnt to recover heat and electricity even though it has a great potential as a feedstock of new bio-based wood adhesives. The structural complexity and heterogeneity of lignin is known as a limitation to convert it into value-added products. Hence, in this study, we prepared the homogeneous or reduced polydispersity Kraft lignin by one-step fractionation with acetone. The objective of this study is to investigate chemical characteristics of acetone-soluble and acetone-insoluble Kraft lignin from hardwood and softwood, using Fourier transform infrared (FTIR) spectroscopy. The results showed that 65% portion of hardwood Kraft lignin is dissolved in acetone while 35% remained insoluble. By contrast, 55% of softwood Kraft lignin is dissolved in acetone, whereas 45% is insoluble in acetone. Furthermore, FTIR results revealed the presence of aromatic skeletal vibrations of both hardwood and softwood Kraft lignin. As expected, syringil and guaiacyl bands were detected in hardwood Kraft lignin, whereas guaiacyl band was present only in softwood Kraft lignin. However, acetone-soluble and acetone-insoluble of Kraft lignin showed considerable different peaks.

Preparation of Lignin-based Carbon Aerogels as Biomaterials for Nano-Supercapacitor

양봉숙,강규영,정명준 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.8

Kraft and organosolv lignins, generally produced in chemical pulping and bio-refinery processes of lignocellulosic biomass, were used to prepare lignin-based carbon aerogels for supercapacitors as raw materials. The difference between lignins and lignin-based aerogels were compared by analyzing physical and chemical properties, including molecular weight, polydispersity, and reactivity with formaldehyde. Also, density, shrinkage, Brunauer-Emmett-Teller (BET) surface area and scanning electron microscope (SEM) images of the lignin-based aerogel were investigated. Kraft lignin consisting of coniferyl alcohol (G) and p-coumaryl alcohol (H) increased the reactivity of formaldehyde, formed a hydrogel well (porosity > 0.45), and specific surface area higher than organosolv lignin. In the case of kraft lignin, there were irregular changes such as oxidation and condensation in the pulping process. However, reaction sites with aromatic rings in lignin impacted the production of aerogel and required a long gelation period. The molecular weight of lignin influences the gelation time in producing lignin-based aerogel, and lignin composition affects the BET surface area and pore structures of the lignin-based carbon aerogels.

Characterization of Residual Lignins from Chemical Pulps of Spruce (Picea abies) and Beech (Fagus sylvatica) by KMnO₄ Oxidation

Choi, J.-W.,Faix, O. 한국목재공학회 2003 목재공학 Vol.31 No.6

The enzymatic isolation of residual lignins obtained from spruce and beech pulps (obtained by sulfite, kraft, ASAM and soda/AQ/MeOH pulping processes) and their characterization was described in previous publications. Here, the residual lignins have been submitted to potassium permanganate oxidation (KMnO₄degradation), and 9 aromatic carboxylic acids (3 of them are dimeric) were identified after methylation with diazomethane by GC/MS. The analytical challenge during qantification by the internal standard methods was the partly high protein content of the samples, which resulted in elevated anisic acid yields in the degradation mixture of sulfite residual lignins. The results are compared with the KMnO₄ degradation of the corresponding MWLs and discussed in terms of S/G ratios and degrees of condensation. The latter was calculated as a quotient between the aromatic carboxylic acids derived from condensed and non-condensed lignin structures. Typical degradation patterns for the various processes have been observed. Among other parameter, the relative compositions between iso-hemipinic acid (which is for condensation in pos. 5 of the aromatic ring) and meta-hemipinic acid and 3,4,5-trimethoxyphthalic acid (both are for condensation in pos. 6 of the aromatic ring) was found to be process specific. Kraft and soda/AQ/MeOH residual lignins yielded higher amounts of iso-hemipinic acid. In contrast, the relative yields of meta-hemipinic acid and 3,4,5-trimethoxyphthalic acid (the latter in beech lignins) are higher in sulfite and particularly in ASAM residual lignin. In case of beech residual lignins the amount of acids originated from non-condensed syringyl type lignin units was surprisingly high. The condensation degree of residual lignins was shown to be generally higher than that of MWLs. This was especially true for the G units. ASAM residual lignin exhibited very high S/G ratios and degrees of polymerization. Causality between condensation degree and total yield of degradation products was demonstrated.

Effect of Process Parameters and Kraft Lignin Additive on The Mechanical Properties of Miscanthus Pellets

Chang Ha Min,Byung Hwan Um 한국목재공학회 2017 목재공학 Vol.45 No.6

Miscanthus had a higher lignin content (19.5 wt%) and carbohydrate (67.6 wt%) than other herbaceous crops, resulting in higher pellet strength and positive effect on combustion. However, miscanthus also contains a high amount of hydrophobic waxes on its outer surface, cuticula, which limits the pellet quality. The glass transition of lignin and cuticula were related to forming inter-particle bonding, which determined mechanical properties of pellet. To determine the effects of surface waxes, both on the pelletizing process and the pellet strength were compared with raw and extracted samples through solvent extraction. In addition, to clarify the relationship between pellet process parameters and bonding mechanisms, the particle size and temperature are varied while maintaining the moisture content of the materials and the die pressure at constant values. Furthermore, kraft lignin was employed to determine the effect of kraft lignin as an additive in the pellets. As results, the removal of cuticula through ethanol extractions improved the mechanical properties of the pellet by the formation of strong inter-particle interactions. Interestingly, the presence of lignin in miscanthus improves its mechanical properties and decreases friction against the inner die at temperatures above the glass transition temperature (T_g) of lignin. Consequently, it could found that the use of kraft lignin as an additive in pellet reduced friction in the inner die upon reaching its glass transition temperature.

Bio-tar production by liquefaction of Kraft lignin in super- and subcritical solvents

( Kazmi Wajahat Waheed ),( Asim Riaz ),이인구 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Lignin which is one of three major components consisting of lignocellulosic biomass is generated about 7 million ton annually from pulping mills. Recently lignin has received high attention as a source for the production of energy and/or value-added chemicals. Among the technologies under development, liquefaction is considered the most favorite route for the production of high quality biofuel or valuable chemicals from technical lignins like Kraft lignin. In this work, lignin residue obtained from a Kraft pulping process was used for production of bio-tar that can be used as a precursor for carbon fiber via bio-pitch formation. The effect of liquefaction parameters such as temperature, reaction time and kind of solvent on the conversion of lignin in superand subcritical solvents was investigated. The characterization of liquefaction products was also carried out by GC, GC-MS, TGA, proximate, and ultimate Analyses.

Adhesion Performance of Phenol-Formaldehyde Resins with Demethylated Softwood Kraft Lignin

( Minjeong Kim ),( Byung-dae Park ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1

In recent years, various studies about lignin are being actively conducted. However, because lignin has complex molecular structure and high molecular weight, it needs to be modified for its application. In the phenol-formaldehyde (PF) resins replaced by lignin, it is beneficial to increase the content of hydroxyl groups in order to increase the reactivity with formaldehyde. Therefore, in this study, demethylation of acetone-soluble lignin obtained from the acetone fractionation to decrease the polydispersity and the molecular weight of kraft lignin was employed. For the practical use of the demethylation process, this study is conducted in the ambient environment. P-NMR spectroscopy and ATR-IR measurement are also used to examine the performance of the modified lignin. In addition, the wettability and adheison performance on the wood surface of the phenol-formaldehyde (PF) resins synthesized by replacing the phenol with 10, 20, 30 and 50% of the demethylated lignin are investigated.

유기용매를 이용한 Hardwood Kraft Lignin의 분획 및 특성분석

최철순(Cheol Soon Choi),배진호(Jin Ho Bae),박제환(Je Hwan Park),서진호(Jin Ho Seo),김용식(Yong Sik Kim) 한국펄프·종이공학회 2018 펄프.종이기술 Vol.50 No.6

Hardwood kraft lignin was fractionated with various organic solvents to obtain more homogeneous lignin. Using organic solvent solubility, hardwood kraft lignin was clearly separated into six fractions (F1-F5 and FI) by molecular size. Compared with hardwood kraft lignin, the molecular weight (MW) distribution of each fraction was in a relatively small range and the MW of each fraction (F1-F5) gradually increased from F1 to F5. In addition, thermal stability of the fraction was improved by increasing MW and the resulting glass transition temperature also increased with increasing MW. As a result of Fourier-transform infrared (FT-IR) analysis, the functional groups of each fraction, except for FI, were very similar. The methoxyl group contents of fractionated lignins from F1 to F5 were 6.2 mmol/g, 2.4 mmol/g, 2.0 mmol/g, 1.9 mmol/g, and 1.6 mmol/g, respectively. Furthermore, the methoxyl group and phenolic OH group contents tended to decrease with increasing MW. It was confirmed by the result of pyrolysis gas chromatography/mass spectrometer (Py-GC/MS) analysis that there were many sulfur-bonded structures in the F1 fraction.

Effect of compressed liquid CO₂ antisolvent treatment on the synthesis of hierarchically porous nanocarbon from kraft lignin

Myint, Aye Aye,Seo, Bumjoon,Son, Won-Su,Yoon, Junho,Shin, Naechul,Kim, Jaehoon,Lee, Youn-Woo Elsevier 2017 The Journal of supercritical fluids Vol.123 No.-

<P><B>Abstract</B></P> <P>Carbon nanoparticles with hierarchical micro/mesoporous structure were developed from a commercial kraft lignin using a facile, one-pot green technology of a compressed liquid CO<SUB>2</SUB> antisolvent treatment, followed by thermostablization and carbonization processes. The as-synthesized carbon nanoparticles were systematically characterized by investigating the surface properties of morphology, particle size, and chemical states with FESEM, HRTEM and XPS, respectively; surface areas and porous structures with BET analyzer; crystalline state with XRD and Raman spectroscopy; chemical features with FTIR; and elemental compositions with an elemental analyzer. The results indicated that the carbon nanoparticles fabricated from the smallest quasi-spherical lignin nanoparticles contained high nanocrystalline and amorphous carbons levels. The enhanced phenolic, carbonyl, and carboxylic functional groups on the particle surface promoted the dispersibility of the particles in deionized water. The size and morphology of the lignin precursor particles significantly affected the fabrication of the carbon nanoparticles by carbonization. The experiment suggested that such dispersible and porous carbon nanoparticles could be applicable in the fields of energy, biotechnology, and environmental pollution control.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We have developed hierarchically porous carbon nanoparticles from kraft lignin. </LI> <LI> The carbon nanoparticles’ surfaces contain enhanced oxygen-containing functional groups. </LI> <LI> They have high surface areas and show good dispersibility in deionized water. </LI> <LI> The size and morphology of lignin precursors are important in the carbonization step. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

국내산 소나무 기반 Kraft 흑액으로부터 크라프트 리그닌 석출 및 특성 평가

노진호(Jin Ho Noh),김동성(Dong Sung Kim),성용주(Yong Joo Sung) 한국펄프·종이공학회 2017 펄프.종이기술 Vol.49 No.4

The lignin precipitation from the black liquor of the kraft pulping of Korean red pine was conducted to evaluate the effects of the pH conditions on the efficiency of the precipitation and the properties of the precipitated lignin. The sulfuric acid was added to the black liquor for adjusting pH. The lower pH condition resulted in the higher amount of precipitated lignin, which was evaluated by using UV spectrophotometer. The significant increase of the lignin yield was observed between pH 4-5. However, the purity of the precipitated lignin was increased at the higher pH condition. The changes in the properties of the precipitated lignin depending on the pH condition of precipitation were indirectly evaluated with the changes in the phenolic hydroxyl group contents in the lignin structure by using the differential spectrum from the UV spectrum. The contents of the phenolic hydroxyl group of each precipitated lignin were not significantly changed.

NMR study on residual lignins isolated from chemical pulps of beech wood by enzymatic hydrolysis

최준원,Oskar Faix 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.1

Two residual lignins isolated from kraft and ASAMpulps of beech wood (Fagus sylvatica L.) were analyzed by 1H and 13C NMR spectra to confirm the structural features previously obtained from wet chemical degradation methods. 1H NMR spectra revealed that the most distinct features of ASAM lignin was the signal at dH 5.9 ppm and dH 6.6 ppm for Ha in b-O-4 linkage and protons for syringyl units. The abundance of syringyl units in ASAM lignin was also evidenced by the signals at dC 154 ppm and dC 104 ppm in the 13C NMR spectra, responsible for aromatic C3/C5 and C2/C6 of syringyl units. The important functional groups, such as phenolic OH, aliphatic OH and methoxyl groups, were indirectly evaluated by 13C NMR spectra of acetylated residual lignin. In particularly, the increment of phenolic OH,one of the parameter for cleavage of b-O-4 linkages,was determined to relative low in of b-O-4 linkages in ASAM residual lignin as compared to kraft residual lignin, indicating that ASAM procedures may run by quite different pathway for delignification unlike the fragmentation of b-O-4 linkages and cleavage of side chain in the general alkaline pulpings.