Laval University, Canada
Tatjana Stevanovic has completed her undergraduate and graduate studies up to PhD at the University of Belgrade at which she was teaching Wood Chemistry and Chemical Transformation of Wood until 1997. Since then she is teaching these same cources at Laval University and performing research on bioactive polyphenols as well as on polymeric applications of lignins. She has published numerous scientific papers and book chapters as well as Wood chemistry textbook. She has deposited a international patent on new organoslv process leading to highly pure lignin along with cellulose pulp and bioactive extractives from pre-extraction.
The transformation of lignocellulosic biomass has become a particular interest for fuel and chemical productions. Lignins are the major polyphenolic polymers available presently from commercial pulping processes (kraft, sulfite). These industrial lignins enclose sulfur in their structures and have relatively important contents of ashes and residual carbohydrates. We are presenting here a new organosolv process which consists of pretreatment of biomass followed by pulping with the same solvent mixture in presence of Lewis acid catalyst. The lignin recovered from this process preserves the native lignin features. This new strategy of organosolv biorefinery allows not only the access to valuable secondary metabolites from the pretreatment, but also to cellulosic pulp and most importantly to high purity lignin. The comparative studies on other organosolv lignins (produced in our laboratory according to the published procedures) like Alcell and Lignol demonstrate that, our lignin has low condensation index (as calculated from FT-IR spectra), preserves the -O-4 moieties (identified in 2D HSQC NMR) and have higher free-phenol content (determined from 31P NMR ). It has high Klason lignin content, low carbohydrate (HPLC analysis) and ash content (ASTM). The Differential Scanning Calorimetry (DSC) analysis of our lignin revealed a high Tg (between 140 and 155°C) which is the property to be explored for high value applications in composites and carbon fiber production. The results obtained from melt electro-spinning assay with this high purity organosolv lignin indicate a great potential for its carbon fiber and other high value applications.