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Y. Cao et al.
Mixed oil refining technique means that the mixed oil produced from extraction
is directly refined without desolvation [8]. In mixed oil, there are lots of solvent
molecules around the glyceride molecule. These solvent molecules can prevent alkali
contacting with the glyceride, so the oil molecule will not be saponified. However,
the free fatty acid can react with alkali as a result of a smaller steric hindrance. The
purified castor oil will be produced after a combination of alkali refining process,
decoloration, evaporation, and desolvation.
Compared with the first refining method, mixed oil refining process has several
advantages [34]. Firstly, the viscosity and density of mixed oil are much smaller than
castor oil. These features make the alkali refining process, separation and filtration
simplified. Secondly, the temperature is low during the whole process, thus the pigments will not be oxidized and is easy to be adsorbed by atlapulgite. Thirdly, the
impurities have been removed before evaporation, so the quality of oil and efficiency
of the equipment are improved.
The production of raw oil needs a series of complicated procedures, and the quality
of raw oil is influenced by the parameters of these processes. Although refined raw oil
has much better properties, it cannot be used as lubricants directly. The modification
and additives are needed to further improve the properties of raw oil.
7.2.2 Preparation of Bio-Lubricant Base Oil
Plant oils are produced by photosynthesis with the characteristics of cleanness, richness, and renewability. Due to the mature cultivation, refining and processing technology, there are a wide range of sources and relatively low-cost plant oils. The
structure of plant oil is very different from that of mineral oil. The main component
is ester, whose the molecular weight is large, and it contains unsaturated Triacylglycerol (TAG). The differences among various plant oils lie mainly on the content and
species of fatty acids. According to the differences of fatty acids, it can be divided
into saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty
acids. Most oilseed crops produce TAG containing a mixture of fatty acids with a
chain length of 18 carbons and 1–3 double bonds. The structures and species of fatty
acids play a decisive role in various properties [14].
7.2.2.1 Principles of Preparation of Bio-Lubricant Base Oil
Because of the good biodegradability and excellent lubrication performances of plant
oils, they can be applied to the production of lubricants. Due to the limitation of
the structure and performance of plant oil, it is difficult to apply the raw oil to
the field of lubrication directly. The most important performances such as hightemperature oxidation stability and low-temperature fluidity of plant oil must be
improved. Because the molecular structure of plant oil determines that it is vulnerable
to be attacked by oxygen, resulting in oxidation and thermal decomposition. The
Y. Cao et al.
Mixed oil refining technique means that the mixed oil produced from extraction
is directly refined without desolvation [8]. In mixed oil, there are lots of solvent
molecules around the glyceride molecule. These solvent molecules can prevent alkali
contacting with the glyceride, so the oil molecule will not be saponified. However,
the free fatty acid can react with alkali as a result of a smaller steric hindrance. The
purified castor oil will be produced after a combination of alkali refining process,
decoloration, evaporation, and desolvation.
Compared with the first refining method, mixed oil refining process has several
advantages [34]. Firstly, the viscosity and density of mixed oil are much smaller than
castor oil. These features make the alkali refining process, separation and filtration
simplified. Secondly, the temperature is low during the whole process, thus the pigments will not be oxidized and is easy to be adsorbed by atlapulgite. Thirdly, the
impurities have been removed before evaporation, so the quality of oil and efficiency
of the equipment are improved.
The production of raw oil needs a series of complicated procedures, and the quality
of raw oil is influenced by the parameters of these processes. Although refined raw oil
has much better properties, it cannot be used as lubricants directly. The modification
and additives are needed to further improve the properties of raw oil.
7.2.2 Preparation of Bio-Lubricant Base Oil
Plant oils are produced by photosynthesis with the characteristics of cleanness, richness, and renewability. Due to the mature cultivation, refining and processing technology, there are a wide range of sources and relatively low-cost plant oils. The
structure of plant oil is very different from that of mineral oil. The main component
is ester, whose the molecular weight is large, and it contains unsaturated Triacylglycerol (TAG). The differences among various plant oils lie mainly on the content and
species of fatty acids. According to the differences of fatty acids, it can be divided
into saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty
acids. Most oilseed crops produce TAG containing a mixture of fatty acids with a
chain length of 18 carbons and 1–3 double bonds. The structures and species of fatty
acids play a decisive role in various properties [14].
7.2.2.1 Principles of Preparation of Bio-Lubricant Base Oil
Because of the good biodegradability and excellent lubrication performances of plant
oils, they can be applied to the production of lubricants. Due to the limitation of
the structure and performance of plant oil, it is difficult to apply the raw oil to
the field of lubrication directly. The most important performances such as hightemperature oxidation stability and low-temperature fluidity of plant oil must be
improved. Because the molecular structure of plant oil determines that it is vulnerable
to be attacked by oxygen, resulting in oxidation and thermal decomposition. The