Tuesday, April 20, 2010
LL Conference Facility (Hilton Clearwater Beach)
Biofuels produced by pyrolysis converting the biomass resources to provide renewable energy show growing importance in satisfying environmental concerns over fossil fuel usage. Lignin which can be degraded by white rot fungi is one of the most complex compounds during thermal decomposition. This study aims at exploring the improvement and alteration of lignin chemical and thermogravimetric characterization caused by biopretreatment.
Lignin degraded by Irpex lacteus CD2 was isolated from corn stover to better understand how white-rot fungi decomposed lignin, and the structure alterations were analyzed by elemental analysis, FTIR, 13C NMR, 1H NMR, and UV spectra. These investigations illustrate significant structure differences that, in biodegraded lignin, aliphatic hydroxyl groups decreased remarkably, while conjugated carbonyl groups increased obviously. Moreover, the content of etherified guaiacyl units enhanced nearly twice, with the content of etherified syringyl units declining simultaneously. There also existed a high level of CH3 in OAr and a relatively low level of guaiacyl and syringyl units in degraded lignin.
The studies on lignin pyrolysis showed that biopretreatment can decrease the final yields, increase the weight loss rates, and release much more heat at a relatively lower heating rate in lignin pyrolysis. In the initial stage of pyrolysis, the activation energies of biopretreated lignin were lower with pre-exponential factors much higher than unpretreated lignin. It indicates that the structural alterations caused by biopretreatment were responsible for the differences of pyrolysis kinetics. By using biopretreatment, it is possible to start the lignin pyrolysis at a relatively gentle condition and improve the availability of biomass pyrolysis as a renewable energy.
Lignin degraded by Irpex lacteus CD2 was isolated from corn stover to better understand how white-rot fungi decomposed lignin, and the structure alterations were analyzed by elemental analysis, FTIR, 13C NMR, 1H NMR, and UV spectra. These investigations illustrate significant structure differences that, in biodegraded lignin, aliphatic hydroxyl groups decreased remarkably, while conjugated carbonyl groups increased obviously. Moreover, the content of etherified guaiacyl units enhanced nearly twice, with the content of etherified syringyl units declining simultaneously. There also existed a high level of CH3 in OAr and a relatively low level of guaiacyl and syringyl units in degraded lignin.
The studies on lignin pyrolysis showed that biopretreatment can decrease the final yields, increase the weight loss rates, and release much more heat at a relatively lower heating rate in lignin pyrolysis. In the initial stage of pyrolysis, the activation energies of biopretreated lignin were lower with pre-exponential factors much higher than unpretreated lignin. It indicates that the structural alterations caused by biopretreatment were responsible for the differences of pyrolysis kinetics. By using biopretreatment, it is possible to start the lignin pyrolysis at a relatively gentle condition and improve the availability of biomass pyrolysis as a renewable energy.