Environmental Engineering Reference
In-Depth Information
O
Tr iglyceride
derived
HO
OH
HO
O
10
10
OH
Te rpenes
Extracts
e.g.
triglycerides,
mannitol,
terpenes, PHAs
OH
OH
OH
Reduced sugars
HO
OH
OH
OH
HO
OH
Hydroxacids
HO
O
O
Figure 4.10
Example platform molecules obtained via direct extraction or derived from extracts
of biomass.
applications such as in dietary supplements, food additives, flavours and
fragrances, pharmaceuticals, dyes and cosmetics. However, some extracts are
available from biomass in larger quantities and via cheaper processing routes;
they could therefore be treated as viable platform molecules (Figure 4.10) as part
of an integrated biorefinery, the two most promising being the triglycerides
(vegetable oils) and terpenes.
Of the platform molecules obtained via extraction from biomass, those derived
from triglycerides represent the largest by volume. Indeed, the utilisation of plant
triglycerides for the production of chemicals has been practised for centuries, the
most obvious example being the formation of soap. Other uses of molecules
derived from vegetable oils include lubricants, dicarboxylic acids, resins, alkyds,
stabilisers, plasticisers, fatty alcohols (including di- and polyols) and methyl
esters, the last being predominately utilised as bio-diesel [104].
The fatty acids chains of the triglycerides can be of varied length and have a
varied functionality (Table 4.3) from saturated, one or multiple carbon-carbon
double bonds (mono- or polyunsaturated), and even include hydroxy or epoxide
groups. Different biomass sources will give different oils with varied fatty acid
composition. Palm oil, for instance, is rich in the saturated palmitic acid (>40%),
along with high levels of oleic acid (>30%) [105]. Genetically engineered crops
have been used to produce high-oleic acid oils where levels of oleate chains in the
oils can be in excess of 80%, while olive oil is naturally high in oleate (>70%).
Linoleic acid is found in high quantities (>50%) in corn and soybean oil, while
linolenic is prevalent in linseed oil (>50%). Ricinoleic acid is the dominant fatty
acid (>80%) in castor oil while vernolic acid, with its natural epoxide, is found in
vernonia oil (>70%) [106]. Other important unsaturated fatty acids include erucic
acid (C
22
), prevalent in rapeseed oil, and eicosapentaenoic acid (EPA, C
20
) and
docosahexanenoic acid (DHA, C
22
) from marine oils (e.g. fish and seaweed),
though the importance of these fatty acids in food and as essential oils could limit
their use as platform chemicals.
