Enzymatic depolymerazation of lignin by laccases

More than half of platform petrochemicals are aromatic, whereas the only large-scale, naturally-occurring, renewable source of aromatics is lignin. Chemical depolymerization of lignin requires extreme conditions, and results in extensive destruction of the aromatic rings and/or char formation. By co...

Full description

Saved in:

Bibliographic Details
Main Author:	Nor Hanimah, Hamidi
Format:	Thesis
Language:	English
Published:	2013
Subjects:	TS Manufactures
Online Access:	http://umpir.ump.edu.my/id/eprint/13534/1/NOR%20HANIMAH%20HAMIDI.pdf
Tags:	Add Tag No Tags, Be the first to tag this record!

id	my-ump-ir.13534
record_format	uketd_dc
spelling	my-ump-ir.135342021-08-24T01:22:43Z Enzymatic depolymerazation of lignin by laccases 2013 Nor Hanimah, Hamidi TS Manufactures More than half of platform petrochemicals are aromatic, whereas the only large-scale, naturally-occurring, renewable source of aromatics is lignin. Chemical depolymerization of lignin requires extreme conditions, and results in extensive destruction of the aromatic rings and/or char formation. By contrast, enzymatic lignin depolymerization occurs under mild conditions with retention of the aromatic nuclei. Therefore, laccase from Agaricus bisporus (LAB) and from Trametes versicolor (LTV) with the mediator, ABTS (2,2'-azino-bis(3 ethyl benzthiazoline-6-sulphonic acid)) were used to depolymerize lignin (sodium lignosulphonate) under mild reaction conditions with the aim to obtain high concentrations of value-added chemicals. The depolymerization in the presence of LTV was higher than LAB, which resulted from the high catalytic activity of LTV. Lignin degradation resulted in formation of complex product mixtures. Therefore the products were fractionated and analyzed by different analytical techniques including GPC (for preliminary screening), HPLC and GCMS (for product characterization and quantification), and NMR (for fingerprint analysis). Products included guaiacol, vanillin, acetovanillone, vanillic acid, homovanillyl alcohol, phenol, 4- methylbenzaldehyde, catechol, p-toluic acid, 4-hydroxybenzaldehyde, tyrosol, isovanillin, and 3-hydroxy-l-( 4-hydroxy-3-methoxyphenyl) propan-1-one, and the total yield of monomers from lignin was 9.8 % in the presence of LTV. The parameters involved in the depolymerization process were optimized to increase the yield of monomers. The efficiency of laccase mediators -was also explored by the use of 2, 2,6,6-tetramethylpiperidin-l-yloxy (TEMPO), 1-hydroxybenzotriazole (HBT), Nhydroxyphthalimide (HPI) and violuric acid (VLA) in the depolymerization of sodium lignosulphonate. However, the catalytic depolymerization in the presence of these mediators was lower than ABTS. In order to improve the solubility of the substrate for the depolymerization process, screening of ionic liquids that are compatible with LAB was deployed in order to find laccase-friendly ionic liquids for further use in lignin depolymerization. The study has found [C4mim] [L-tartrate] as the best ionic liquid tested, that increased the activity of LAB by 90 %. In conclusion, enzymatic depolymerization of lignin offers a greener process than the chemical methods, and also provides a more efficient method to obtain monomers of valuable specialty chemicals under mild reaction conditions. 2013 Thesis http://umpir.ump.edu.my/id/eprint/13534/ http://umpir.ump.edu.my/id/eprint/13534/1/NOR%20HANIMAH%20HAMIDI.pdf application/pdf en public phd doctoral University of Nottingham Department of Chemical and Environment
institution	Universiti Malaysia Pahang Al-Sultan Abdullah
collection	UMPSA Institutional Repository
language	English
topic	TS Manufactures
spellingShingle	TS Manufactures Nor Hanimah, Hamidi Enzymatic depolymerazation of lignin by laccases
description	More than half of platform petrochemicals are aromatic, whereas the only large-scale, naturally-occurring, renewable source of aromatics is lignin. Chemical depolymerization of lignin requires extreme conditions, and results in extensive destruction of the aromatic rings and/or char formation. By contrast, enzymatic lignin depolymerization occurs under mild conditions with retention of the aromatic nuclei. Therefore, laccase from Agaricus bisporus (LAB) and from Trametes versicolor (LTV) with the mediator, ABTS (2,2'-azino-bis(3 ethyl benzthiazoline-6-sulphonic acid)) were used to depolymerize lignin (sodium lignosulphonate) under mild reaction conditions with the aim to obtain high concentrations of value-added chemicals. The depolymerization in the presence of LTV was higher than LAB, which resulted from the high catalytic activity of LTV. Lignin degradation resulted in formation of complex product mixtures. Therefore the products were fractionated and analyzed by different analytical techniques including GPC (for preliminary screening), HPLC and GCMS (for product characterization and quantification), and NMR (for fingerprint analysis). Products included guaiacol, vanillin, acetovanillone, vanillic acid, homovanillyl alcohol, phenol, 4- methylbenzaldehyde, catechol, p-toluic acid, 4-hydroxybenzaldehyde, tyrosol, isovanillin, and 3-hydroxy-l-( 4-hydroxy-3-methoxyphenyl) propan-1-one, and the total yield of monomers from lignin was 9.8 % in the presence of LTV. The parameters involved in the depolymerization process were optimized to increase the yield of monomers. The efficiency of laccase mediators -was also explored by the use of 2, 2,6,6-tetramethylpiperidin-l-yloxy (TEMPO), 1-hydroxybenzotriazole (HBT), Nhydroxyphthalimide (HPI) and violuric acid (VLA) in the depolymerization of sodium lignosulphonate. However, the catalytic depolymerization in the presence of these mediators was lower than ABTS. In order to improve the solubility of the substrate for the depolymerization process, screening of ionic liquids that are compatible with LAB was deployed in order to find laccase-friendly ionic liquids for further use in lignin depolymerization. The study has found [C4mim] [L-tartrate] as the best ionic liquid tested, that increased the activity of LAB by 90 %. In conclusion, enzymatic depolymerization of lignin offers a greener process than the chemical methods, and also provides a more efficient method to obtain monomers of valuable specialty chemicals under mild reaction conditions.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Nor Hanimah, Hamidi
author_facet	Nor Hanimah, Hamidi
author_sort	Nor Hanimah, Hamidi
title	Enzymatic depolymerazation of lignin by laccases
title_short	Enzymatic depolymerazation of lignin by laccases
title_full	Enzymatic depolymerazation of lignin by laccases
title_fullStr	Enzymatic depolymerazation of lignin by laccases
title_full_unstemmed	Enzymatic depolymerazation of lignin by laccases
title_sort	enzymatic depolymerazation of lignin by laccases
granting_institution	University of Nottingham
granting_department	Department of Chemical and Environment
publishDate	2013
url	http://umpir.ump.edu.my/id/eprint/13534/1/NOR%20HANIMAH%20HAMIDI.pdf
_version_	1783731988446838784

Enzymatic depolymerazation of lignin by laccases

Similar Items