Edible oils can be refined by either a chemical or a physical refining process.
entrained neutral oil. Soapstock is usually split with sulfuric acid, resulting in
a low value, difficult-to-valorise ‘acid oil’ and a difficult-to-treat wastewater
oil quality. For these reasons, it is still the preferred refining process for many
refining more attractive.
NEXT-GENERATION CHEMICAL REFINING WITH NANONEUTRALISATION
finally implemented in industrial practice as the valorisation potential of
Ca/K soaps was lower than expected, and soapstock-related problems thus
In the last decade, process improvements in chemical neutralisation focused
on increasing process automation and the use of better, more powerful mixing
systems. This resulted in an overall better process control and the need for less
(excess) chemicals. However, these developments did not have a significant
positive impact on neutralised oil yield, and the need for acid pretreatment
and excess caustic still remains.
In the search for a new neutralisation process that could further reduce
the use of (excess) chemicals and oil losses in soapstock, the potential
of so-called Nano Reactor
technology was investigated. Nano Reactors
are hydrodynamic cavitation reactors. Their working principle and possible
applications in the chemical industry (for process intensification), biotech-
nology (cell disruption) and drinking water treatment (microbial disinfection
and degradation of contaminants) are well described in recent literature
The use of ultrasound cavitation (created by a cavitational effect) for edible
oil degumming was studied by Moulton & Mounts (1990). Although the
results were promising, this process was never industrially applied due to
some inherent drawbacks: (1) no uniform cavitational effect; (2) very high
energy requirement; and (3) applicability only as a batch process.
Hydrodynamic Nano Reactors
are inherently more suitable for use in
large scale oil processing as these can be used in continuous operation
and require less energy. As a first industrial application, nanoneutralisation
was recently developed and successfully introduced in edible oil processing
(Svenson & Willits, 2012). A typical process flow diagram is given in Figure 5.1.
Crude or water degummed oil is blended with the caustic solution and then
transferred by a high-pressure feed pump through the Nano Reactors
a typical pressure of 40–80 bar. The combination of this high pressure and
the unique internal design of the Nano Reactors
creates a high turbulence
and strong shear forces, resulting in a very good mixing of the crude oil and
the caustic solution in the Nano Reactor
. Discharge pressure is 3–4 bar,
which allows direct feeding of the nanotreated oil to the centrifugal separator.
Afterwards, the nanoneutralised oil can flow on to the water washing or silica
The proven industrial advantages of the nanoneutralisation process are a
significant reduction (up to 90%) in phosphoric/citric acid consumption and
a corresponding significant reduction (over 30%) of caustic soda use. The
latter is due to the lower acid consumption and the very good mixing effect
in the Nano Reactors
, which render nonhydratable phospholipids more