Alternative Uses for Lignin Lisa Lai Tuesday, April

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

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

Lignin monomers Lignin SourceGrassesSoftwoodHardwood ρ-Hydroxyphenyl10-25% %Trace Guaiacyl25-50%90-95%25-50% Syringyl25-50%0-1%50-75%

Lignin linkages LinkageSoftwoodHardwood β-O-450%60% α-O-42-8%7% β-59-12%6% %5% 4-O-54%7% β-17% β-β2%3%

Lignin: proposed structures AdlerFreudenberg

Lignin: more proposed structures Forss Nimz

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

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

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: °C – Polystyrene: ~240°C Thermally stable up to 105°C Can be injection molded similar to conventional plastic

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

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

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

Lignosulfonates Produced in the acid sulfite pulping process One metric ton of pulp produces kg of lignosulfonate

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 $ million

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

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

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

Thank you! Questions?