We demonstrate the valorization of technical lignins into advanced materials. First, 0D systems, namely lignin micro and nanoparticles were developed for stabilization of oil-water interfaces. We introduce spherical particles with sizes ranging from 30 nm to few microns and that were synthesized in an aerosol flow reactor with in-situ fractionation. This method allowed, for the first time, high throughput and high yield production of dry lignin particles.1 By varying the lignin source, systems with different surface energy were obtained and, as demonstration, the particles were used to stabilize oil-water interfaces, particularly, in Pickering emulsions. Depending on the particle size and hydrophobicity, emulsions with different morphologies and stability were obtained. We extended our work to 1D systems: Highly mesoporous carbon fibers were obtained from lignin aqueous solutions and used as webs for conductive electrodes with supercapacitance.2 Polyvinyl alcohol (PVA) was used as sacrificial polymer to facilitate electrospinning of lignin and, note, to produce microphase separation that induced high surface area and mesoporosity3,4. An optimized sequential thermal treatment that included a stabilization step allowed the formation of a lignin-continuous structure in the as-spun fibers upon carbonization, while PVA evolved to the gas phase. The resultant mesoporous carbon fiber networks yielded flexible freestanding films. Their main morphological and chemical characteristics were assessed by SEM and Raman spectroscopy, respectively. Nitrogen gas adsorption revealed extremely high surface area (&gt; 2000 m2/g) and pore volume (0.7 cm3/g). The carbon fiber networks were used directly as electrodes with electrochemical double layer capacitance as elucidated. The excellent electrochemical capacitance was demonstrated, including a high rate capability, and long-term cycling stability. A specific capacitance as high as 205 F/g in 0.5M Na2SO4 electrolyte was delivered, one of the highest recorded for electrodes obtained from biopolymer precursors. Besides providing a route to enable nano-manufacturing, this work shows two examples of lignin valorization into organic and safe nanomaterials.

Valorization of lignin in 0D and 1D advanced systems: Particles for emulsification and fibers for energy storage

253rd National Meeting (2017)

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