Alternative Uses for Lignin Lisa Lai Tuesday, April 28 2009.
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Transcript of Alternative Uses for Lignin Lisa Lai Tuesday, April 28 2009.
Alternative Uses for Lignin
Lisa Lai
Tuesday, April 28 2009
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• 2nd most abundant
natural polymer
Sakakibara
Lignin monomers
Lignin Source Grasses Softwood Hardwood
ρ-Hydroxyphenyl 10-25% 0.5-3.5% Trace
Guaiacyl 25-50% 90-95% 25-50%
Syringyl 25-50% 0-1% 50-75%
Lignin linkages
O H
O C H 3
C
C
C
1
2
3
45
6
-O -4 L in k a g e
O RH C
O
O C H 3
C H
H C
C H 2O H
H C
H O H 2C
O H
O C H 3
Linkage Softwood Hardwood
β-O-4 50% 60%
α-O-4 2-8% 7%
β-5 9-12% 6%
5-5 10-11% 5%
4-O-5 4% 7%
β-1 7% 7%
β-β 2% 3%
Lignin: proposed structures
Adler Freudenberg
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: 105-120°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 330-540 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 $490-550 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?