Environmental Engineering Reference
In-Depth Information
Table 5.2
Fatty acid compositions of common oils [2, 5].
Oil
Palmitic acid
Stearic acid
Oleic acid
Linoleic acid
Linolenic acid
Canola
4.1
1.8
60.9
21.0
8.8
Corn
10.9
2.0
25.4
59.6
1.2
Cottonseed
21.6
2.6
18.6
54.4
0.7
Linseed
5.5
3.5
19.1
15.3
56.6
Olive
13.7
2.5
71.1
10.0
0.6
Soybean
11.0
4.0
23.4
53.3
7.8
Tung
—
4.0
8.0
4.0
—
Fish
—
—
18.2
1.1
0.99
Castor
1.5
0.5
5.0
4.0
0.5
Palm
39
5
45
9
—
Oiticica
6
4
8
8
—
Rapeseed
4
2
56
26
10
Sunflower
6
4
42
47
1
High oleic
a
6.4
3.1
82.6
2.3
3.7
a
Genetically engineered soybean oil from DuPont [2].
5.2.1
Isolation of Vegetable Oil
The two commonly used methods for extracting vegetable oil from biomass are
mechanical separation and solvent extraction [13]. Mechanical extraction utilizes
mechanical pressure such as shearing to break the cells of the biomass, liberating
the oil. The main benefit to this method is low capital costs. Unfortunately, the
forces used to break the cells also generate a large amount of heat, which can
degrade the oil. Also, the mechanical processes reduce the oil content in the
biomass to only 5-10% by mass [13]. The more efficient solvent extraction has
therefore become the method of choice for vegetable oil recovery. Solvent extraction
requires higher capital investment but provides significantly higher oil yields than
mechanical separation [13]. The process involves soaking the biomass in an
organic solvent, typically hexane, which is able to permeate the cell walls and oil
bodies. The oil solubilizes in the hexane and is free to diffuse into the surrounding
environment. By circulating fresh hexane into the environment and removing
the oil-laden solvent, the oil is carried away from the biomass [13]. By washing
the biomass several times using this process, solvent extraction reduces the oil
content of the biomass to below 1% by mass [13]. The oil is then recovered
through distillation.
5.2.2
Thermosets of Vegetable Oils and Comonomers
Vegetable oils rich in double bonds, specifically those with conjugated double
bonds, lend themselves to cross-linking via polymerization with monomers such
as styrene, α-methyl styrene, or divinyl benzene [5]. Richard Larock's group
extensively studied the copolymerization of soybean, linseed, corn, tung, and fish
