Alternative Uses for Lignin

1. Alternative Uses for Lignin Lisa Lai Tuesday, April 28 2009

2. Outline • A review of lignin chemistry • Current use and isolation • Arboform: lignin plastic • Lignosulfonates • In building materials • Other uses • Conclusions

3. Lignin • 3-dimensional phenolic polymer • Complex structure • Composes ~15-40% of lignocellulosic biomass • 2nd most abundant natural polymer Sakakibara

4. Lignin monomers

5. Lignin linkages

6. Lignin: proposed structures Adler Freudenberg

7. Lignin: more proposed structures Nimz Forss

8. Lignin: current use • In Kraft pulping, lignin is recovered in black liquor • 50 million metric tons produced annually worldwide • ~95% of this is incinerated for thermal electrical energy • Burning generates an average fuel value of 23.4 Mj/kg

9. Arboform • A lignin-based thermoplastic • Made from a mixture of lignin, plant fibers, and waxes • Developed by German company Tecnaro in 1998 • Appearance and some physical properties similar to wood • Moldable like plastic

10. Arboform: chemical properties • Pelletized mixture of lignin, fine fibers of wood, hemp or flax, and wax • Up to 50% lignin • Liquifies at temperatures as low as 170°C • Polypropylene: ~160°C • Polyethylene: 105-120°C • Polystyrene: ~240°C • Thermally stable up to 105°C • Can be injection molded similar to conventional plastic

11. Arboform: physical properties • Better molding capabilities than plastic • Irregular fiber orientation resists warping • Flooring & building material • Good acoustic properties (speakers & musical instruments) • Currently 300 metric tons produced annually

12. An alternative to plastic? • More than 100 million metric tons of plastics originating from crude oil are produced annually (worldwide) • The pacific trash vortex is twice the size of Texas, reaches 300 feet below sea level, and 90% of it is plastic

13. Disadvantages: Some forms are not water resistant Requires removal of sulfur Cost: $1.60/lb, compared with less than $1/lb for polypropylene Arboform: Pros and Cons • Advantages: • Completely biodegradable • Can be burned after use • Not made from crude oil • At least as strong as plastic

14. Lignosulfonates • Produced in the acid sulfite pulping process • One metric ton of pulp produces 330-540 kg of lignosulfonate

15. Sodium lignosulfonates as plasticizers for concrete • Concrete is formed by mixing: • Water • Cement • Aggregate • Lignosulfonates reduce the amount of water needed, making concrete stronger • World revenue generated from lignosulfonates estimated at $490-550 million

16. Sodium lignosulfonates as plasticizers for concrete • SEM images of Portland cement (b) without, and (c) with the addition of lignosulfonate • Lignosulfonate inhibited hydration of cement • Exact mechanism is unknown, but adsoption of lignosulfonates on the surface of cement particles is suspected

17. Other uses for lignosulfonates • Dispersant • Chemical dyes, plasterboard • Binder • Dirt roads • Emulsifier • Chelating agent • Food additives • Vanillin

18. Conclusions • Lignin has a number of potentially valuable uses • More research will be needed in order to make production of these materials cost-effective • Market conditions will have to change in order for Arboform to become competitive with conventional plastic

19. Thank you! Questions?