Dr. Joan Lynam
University of Nevada-Reno
Biomass deconstruction
with ionic liquids
Dr. Joan Lynam completed
her Ph.D in Chemical
Engineering at the
University of Nevada, Reno
in August of 2015. She was
awarded a USDA-NIFA-AFRI
pre-doctoral fellowship to
pursue her research, which
involves conversion of
biomass into biofuel. She
was the "Honor the Best"
Outstanding Graduate
Student of the University of
Nevada, Reno for 2015 and
was the Outstanding
Graduate Student
Researcher of the
Engineering and Science
Colleges Division in 2014
and 2012. She has
published 14 journal
articles with over 250 total
citations. She has worked
and volunteered in
mentoring diverse firstgeneration college students
in STEM disciplines.
Lignocellulosic biomass is a renewable, sustainable resource that can replace or
supplement fossil fuels use for liquid fuels and chemicals. However, its recalcitrant
structure including interwoven cellulose, hemicelluloses, and lignin biomacromolecules
is challenging to deconstruct. Pretreating biomass so that it can be converted to useful
liquids dominates process economics. Many pretreatment methods exist, but most
require hazardous chemicals or processing conditions. Many ionic liquids (ILs), salts
molten below 100 °C, can be used to deconstruct lignocellulosic biomass and are less
hazardous than the volatile organic compounds typically used.
While effective, relatively safe, and recyclable, ILs are expensive. To reduce costs,
dilution with other safe compounds is desirable, if there is no impact on deconstruction
efficiency. Glycerol, a food additive, is inexpensive and becoming even more so since it
is a by-product of the burgeoning biodiesel industry.
Rice hulls are an abundant biomass, with over 100 million tons produced per year, but
with little practical use. The IL 1-ethyl-3-methylimidazolium formate ([C2mim][O2CH] or
EMIM Form) when mixed with an equal amount of glycerol has been shown to be
effective in pretreating rice hulls.
The IL [C2mim][O2CH] was also effective when mixed with an equal amount of glycerol
to pretreat loblolly pine, a fast-growing softwood. Loblolly pine was pretreated at 140 °
C for three hours to produce a solid rich in cellulose and hemicelluloses, while a ligninrich product could be precipitated from the IL. Similar products were obtained from
pretreatment with a mixture of 75% 1-ethyl-3-methylimidazolium acetate ([C2mim]
[OAc] or EMIM Ac) and 25% glycerol. Enzymatic hydrolysis of the pretreated solids gave
glucose, mannose, and xylose yields up to 18
times that of the raw pine. IL- Glycerol mixtures
with higher excess molar volumes, VmE, tended to
align with better carbohydrate yields after
enzymatic hydrolysis. This phenomenon may
relate to a less dense solvent structure allowing
better solvent access into the biomass.