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Inedible vegetable-oil based biodiesel in Northern Viet Nam 183

4.1.5 Evaporation weathering in the marine environment
Evaporation rate and components of diesel vapors were estimated through
the previous study on diesel components and weathering behaviors.
Table 6.6 lists main components of diesel from a study of Wang et al.
(2003), which analyzed the composition of diesel fuel oil no.2 in Canada.
Data from our previous study showed that in the case of petrodiesel, 75%
of the oil spill was rapidly volatilized within 5 days after the spill (Nguyen
and Otsuka, 2016). This is also in accordance with the study from the US
National Research Council indicating that the evaporation weathering of
diesel and fuel oil no.2 spill would lead to 75% or more of fuel release into
the atmosphere (US National Research Council, 1975).
Aliphaticandaromaticcompoundscontributeabout98.4%ofdieselmass.
On the other hand, oil weathering processes also affect the concentrations of
components existing in a fuel and its evaporation process (US National
Research Council, 1975). Although aromatics have higher water solubility
than aliphatics, they also show higher vapor pressure. Since total petroleum
hydrocarbons comprise a significant amount of various components and vary
between fuels, obtaining a detailed physiochemical analysis of diesel fuel is
impossible (Brewer et al., 2013). Consequently, this study downscaled total
percentofsaturatesandaromaticsto75%withtheequalallocation.Thismade
the evaporation rates of aliphatics and aromatics become 67% and 8%, respec-
tively.Sincethepresenceofbiodieseldoesnotaffecttheevaporationbehavior
of diesel components in the blend (DeMello et al., 2007), the rate of evapo-
ration of oil spills was allocated based on its volumetric contribution.

4.2 Allocation methods
Regarding the allocation methods of biodiesel and coproducts obtained
throughout biodiesel life cycle system, several allocation approaches applied
were as follows:
– The cut-off approach was used for marketable coproducts of the system
and composts from Hibiscus leaves and Pongamia and Hibiscus-Vernicia
oil cake. Accordingly, sugar, medicinal compounds, Hibiscus calyces, and
Table 6.6 Components of diesel by hydrocarbon
groups (Wang et al., 2003)
Component Concentration (weight %)
Saturates 88.2
Aromatics 10.2
Resins 1.7
Waxes 1.7