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Characterization of Precipitated Kraft Lignin Before and After Acetone Fractionation
( Ega Cyntia Watumlawar ),( Byung-dae Park ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.2
Extraction of kraft lignin (KL) from black liquor is a way to obtain KL as promising raw material. This study aims to investigate the characterization of precipitated lignin extracted from black liquor of mixed hardwood before and after acetone fractionation. The precipitation was conducted at various pH levels from 3 to 9 for black liquor to obtain crude KL (C-KL) which was used for the acetone fractionation to have acetone soluble KL (AS-KL) and acetone insoluble KL (AI-KL). pH 3 and 7 gave the highest and lowest yield of C-KL, respectively. As expected, infrared spectra of the C-KL showed no difference for all pH levels. As the pH increases, the molecular weight (MW) of C-KL increases. However, the MWs of AS-KL and AI-KL increase to a maximum at pH 7 and then decrease at pH 9. The smallest MWs of AS-KL and AI-KL was found at pH 9 and 3, respectively. These results suggest that AS-KL at pH 3 and AI-KL at pH 9 have a good potential as a starting lignin for further application such as cross-linking, chemical modification, or grafting in the future.
Ega Cyntia WATUMLAWAR,박병대 한국목재공학회 2023 목재공학 Vol.51 No.1
Two important steps in utilizing technical kraft lignin (KL) from black liquor to synthesize lignin-phenol-formaldehyde (LPF) resin are its extraction via precipitation and fractionation. However, the effects of precipitation pH and acetone fractionation on the characteristics of hardwood KL have not been studied for LPF resins. Therefore, this paper reports the effects of the precipitation pH of black liquor and acetone fractionation on the characteristics of KL from mixed hardwood species for LPF resins. The precipitation was conducted at various pH levels from 3 to 9 of black liquor to obtain crude KL (C-KL), which was used in acetone fractionation to produce acetone-soluble KL (AS-KL) and acetone-insoluble KL (AI-KL). Precipitation at pH 3 and 9 produced the highest and lowest yields of C-KL, respectively. As expected, the C-KL infrared spectra were similar regardless of the precipitation pH levels. As the pH increased, the molecular weight of C-KL increased. However, the molecular weight of AS-KL and AI-KL after acetone fractionation increased to a maximum of 4,170 and 47,190 g/mol at pH 7, then decreased to 3,210 and 19,970 g/mol at pH 9, respectively. The smallest molecular weights of AS-KL and AI-KL were 3,210 and 15,480 g/mol and were found at pH 9 and 3, respectively. These results suggest that both AS-KL at pH 9 and AI-KL at pH 3 have good potential as starting lignins for synthesizing LPF resins that require cross-linking for polymerization.
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.
Characterization of Precipitated Kraft Lignin Before and After Acetone Fractionation
( Ega Cyntia Watumlawar ),( Byung-dae Park ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.2
Extraction of kraft lignin (KL) from black liquor is a way to obtain KL as promising raw material. This study aims to investigate the characterization of precipitated lignin extracted from black liquor of mixed hardwood before and after acetone fractionation. The precipitation was conducted at various pH levels from 3 to 9 for black liquor to obtain crude KL (C-KL) which was used for the acetone fractionation to have acetone soluble KL (AS-KL) and acetone insoluble KL (AI-KL). pH 3 and 7 gave the highest and lowest yield of C-KL, respectively. As expected, infrared spectra of the C-KL showed no difference for all pH levels. As the pH increases, the molecular weight (MW) of C-KL increases. However, the MWs of AS-KL and AI-KL increase to a maximum at pH 7 and then decrease at pH 9. The smallest MWs of AS-KL and AI-KL was found at pH 9 and 3, respectively. These results suggest that AS-KL at pH 3 and AI-KL at pH 9 have a good potential as a starting lignin for further application such as cross-linking, chemical modification, or grafting in the future.