Storage oxidation during long-term

Tertiary amines are known for their propensity to oxidize to the amine oxide (N-oxide) during long-term storage (54) (Fig. 34). A classic example of... 

Double bonds between carbon atoms in fuel components are active sites for oxidative attack and polymerization. During long-term storage and during the combustion process, oxidation and polymerization of olefinic compounds can result in the following ... 

Figure 75 The thioether of pergolide mesylate oxidizes to the sulfoxide and sulfone in the presence of light or during long-term storage.

Oxidative Deterioration During Long-Term Storage... 

The oxidation of HDPE during long-term storage is mainly due to the hemolytic decomposition process of hydroperoxide. Hydroperoxide undergoes thermolysis or photolysis, producing radicals by the following processes [4,9-10],... 

The presence of unsaturated fatty acids in biodiesel makes it susceptible to oxidation or autoxidation during long-term storage. Several studies carried out by assaying different antioxidants to improve the oxidative stability of biodiesel have shown the usefulness of PG for this purpose [48-50],... 

Although biodiesel is an excellent source of fuel, it has some disadvantages which include relatively poor cold flow properties and dilficulty in maintaining fuel quality during long-term storage. The latter is a matter of oxidation stability and will be discussed in this part. 

During long-term storage biodiesel can be easily subject to oxidation under ambient conditions due to the presence of double bonds in the chains of fatty compounds. The reaction of oxidation increases with the increasing of unsaturation level (polyunsaturated compounds are many times more reactive that monounsaturated ones). Some parameters such as acid value, peroxide value or kinematic viscosity increase when autoxidation occurs, thus the fuel s quality is affected. Degradation of the quality of this alternative fuel leads to an increase of deposits on injectors and pump parts and therefore an increase in pressure across filters. 

During the process, the product loses more than 90% of the water it initially contains. One feature of freeze-drying that singles it out from other dehydration techniques is that dehydration takes place from a frozen — and hence less chemically active — product and in vacuum — which minimizes the effects of oxidation. These assets have made freeze-drying a widely accepted technique for processing heat-labile products such as enzymes and proteins for long-term storage. 

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