Alkaline Pretreatment Severity Leads to Different Lignin Applications in Sugar Cane Biorefineries

11 páginas.-- 5 figuras.-- 6 tablas.-- 27 referencias.--

Lignin, a multifunctional major biomass component, has a prominent potential as feedstock to be converted into high value-added products. Lignin is available in high amounts as side streams during cellulosic ethanol production, and within the biorefinery context, it is important to assess its structural characteristics in order to explore its potential to replace some petroleum-based reactants. In this study, some important features were evaluated for different lignins such as lignin purity and the amounts of syringyl (s), guaiacyl (G), and p-hydroxyphenyl (H) units. Four alkaline lignins, generated from a pilot-scale pretreatment of sugar cane bagasse (NaOH 1.5%, 30 min), were evaluated according to the severity of the alkaline pretreatment (130 or 170 degrees C, with or without the addition of anthraquinone). The different pretreatments produced lignins with different chemical characteristics that can be used for different purposes in sugar cane biorefineries. As the severity of alkaline pretreatment increased, the recovered lignins presented higher amounts of H- and lower amounts of S-lignin units. In particular, the lignin obtained at 170 degrees C with the addition of anthraquinone presented the highest content of H- and the lowest content of S-lignin units, which would present higher reactivity toward formaldehyde in phenolic resins.

This study has been partially funded by the Spanish projects AGL2014-53730-R and CTQ2014-60764-JIN (cofinanced by FEDER funds) and the CSIC project 2014-40E097. We thank Dr. Manuel Angulo (from the NMR facilities of the General Research Services of the University of Seville−SGI-CITIUS) for performing the NMR analyses that were acquired on a Bruker Avance III 500 MHz instrument. We also thank the Saõ Paulo Research Foundation (FAPESP) for partial financial support (project 2013/11961-1) and the Amazonas Research Foundation (FAPEAM) for providing a doctoral scholarship (project 253/2014).

Peer reviewed