Iodine value, biodiesel

Selective hydrogerration over low-loading, supported Cu catalysts has shown to be a valuable tool for the production of high quality biodiesel from Tall Oil, a byproduct of the Pulp Paper indrrstry. These resrrlts allow planning the use of a great variety of non-conventiorral oils with high iodine value for the production of biodiesel. 

A further example of process quality monitoring and reactor batch profiling using NIRS comes with oleo-chemical and biodiesel production. An established use of FT-NIR analysis (AOCS Method Cd le 01) is the determination of the key vegetable oil processing parameters - iodine value (IV) and percentage trans fat content (%Trans) (Figure 5.38). 

The degree of unsaturation of the fatty acids is normally expressed as the iodine value (IV), that is, the number of grams of iodine that have reacted with 100 g of product analyzed, under controlled experimental conditions. The higher is IV, the greater is the degree of unsaturation. For example, for biodiesel intended for haulage use, the most remunerative use, a maximum IV limit of 120 g I2 per 100 g is envisaged. 

Official methods of chemical analysis of conventional diesel are often not adequate to characterize biodiesel. Tests for the levels of sulfur and aromatic components in biodiesel are useful but usually reveal that the concentrations of compounds containing these atoms or functional groups are very low. Analysis of biodiesel chemistry can reveal characteristics conferred by the source of the oU, the method of manufacture, and duration of storage (20, 21). For example, free and bound glycerol is measured to ascertain if biodiesel has been completely formed during synthesis. Fatty acid content, residual soaps, iodine value, peroxide value, and fatty acid composition all may reflect the quality of biodiesel (Table 1) but are unimportant and inapplicable in conventional diesel fuel quality determination. 

Furthermore, biodiesel is variable depending on the source of the fuel and its age (27). For example, Monyem and Van Gerpen (27) observed decreased carbon monoxide and hydrocarbon emissions from oxidized neat biodiesel when compared with unoxidized biodiesel. In addition, cetane number is inversely proportional to iodine value (28) and proportional to biodiesel age (29). 

The ASTM standard does not give restriction to the iodine value of methyl esters but the European biodiesel standard (EN 14214) states that the iodine value should be no more than 120. JCME is within the requirements of EN 14214. The iodine number of conventional (automotive) diesel fuel is reported to be 10. Based on the results shown in Table 2, the iodine value of the methyl esters differs only slightly from that of their parent oil. The iodine value derived from the GC-MS chromatograms are higher than those derived from the Wijs solution method, mainly because Equation 1 assumes full iodonization and treats all the double bonds as being equally reactive to oxidation. ... 

Tables 6 contains, respectively, the properties of FAMES collected from the literature and the results of the prediction of quality parameters of oleaginous yeast and microalgae (Lacerda et al. 2013) compared with the American, European, and Brazilian standards. The values of heat of combustion (HC), index of oxidative stability (OSI) and iodine value (II) are out of limits imposed by these standards, however, the values of density (p), viscosity (u) and cetane number (CN) are within it. Even though the indexes are slightly out of bounds, the biodiesel obtained from Chlorella vulgaris and Lipomyces starkeyi may still be used as fuel.

Duarte and Maugeri (2014) studied lipid production by Candida sp. LEB-M3 cultivated in pure and raw glycerol. The feasibility of biodiesel production by the yeast Candida sp. LEB-M3 was indicated by predicting FAME properties for pure and raw glycerol respectively, including cetane number (56—53), heat of combustion (37—39 kJ/g), oxidative stability (8.58 h), kinematic viscosity (3.82—3.79 mm /s), density (807—872 kg/m ), and iodine index (74—115.5 gE/lOOg). Leiva-Candia et al. (2015) estimated biodiesel properties produced from SCO derived from Rhodosporidium toruloides, Lipomyces starkey, and Cryptococcus curvatus cultivated on biodiesel by-product streams. More specifically, cetane number (62.39—69.74), lower calorific value (37,393.49—37,561.68 kJ/kg), cold-filter plugging point (4.29—9.58°C), flash point (158.73—170.34°C), and kinematic viscosity (4.6—34.87 mm /sat 40°C) were determined. 

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