Iodine value of tung biodiesel fuel using Wijs method is significantly lower than calculated value

The tung tree (Vernicia fordii) is a non-edible oil plant native to southern China and was introduced in Japan in the nineteenth century. The tree produces tung oil, which is composed of approximately 80% α-eleostearic acid (9c, 11t, 13t-octadecatrienoic acid), 7% linoleic acid, and 6% oleic acid. Tung oil may be a non-edible source of biodiesel fuel (BDF) production. The iodine value (IV) is one of parameters to guarantee BDF quality, and the most common method for the determination of IV is the Wijs method. The IV can be calculated from the average molecular weight and the number of double bonds from the GC–MS data. In this study, the IVs of olive, castor, soybean, linseed, and perilla BDF using the Wijs method were found to be almost the same as the calculated IV. On the other hand, the IV of tung BDF by the Wijs method indicated a significantly lower value than that of the calculated value. To determine the cause of this discrepancy, the samples before and after halogenation using the Wijs method, were analyzed by 1H NMR. The conjugated double bond signals did not disappear, and a broad double bond signal remained in the tung BDF spectrum after halogenation. These results demonstrated that iodine, with a large atomic radius, could not react completely with the three conjugated double bonds in α-eleostearic acid. Therefore, the IV of tung BDF was significantly lower than the calculated value.

Evaluation of Analytical Results Obtained From Standard AOAC Method and Accelerated Wijs Method for the Determination of Iodine Value of Different Brands of Mustard Edible Oils

In the present work, accelerated method is used for the measurement of iodine value, wherein mercuric acetate is directly used in the powder form. The method only requires to add the catalyst mercuric acetate in the process of determination without changing the operational steps of the Wijs method. Compared with the Wijs method in which it will take at least 30 minutes to finish it, the rapid determination method can make the determination reaction finished in 3 minutes. The iodine value of different vegetable oils such as Kacchighani mustard oil (Kgmu, Dalda),Kacchighani mustard oil (Kgmu1,Mahakosh), Kacchighani mustard oil (Kgmu2,Tez),premium mustard oil kacchighaani (Pmukg, RRO Mustdil), Kacchighani mustard oil (Kgmu3,Nature fresh) and Kacchighani mustard oil (Kgmu4, Engine)oils were determined by regular Wijs method for 30 minutes whereas when we apply catalytic Wijs method with use of 2 mg, 5 mg and 10 mg of mercuric acetate to perform as catalyst then it is reducing the time of analysis to 3 minutes. When catalyst is used the different values obtained for standard deviations are 0.14 for 2mg, 0.27for 5mg and 0.3 for 10 mg whereas 0.35 for non catalyst addition. The results obtained in this present work aremore % difference in IV of pure kacchighani mustard oil (Pkgmu)and Kacchighani mustard oil (Kgmu2).

FATTY ACIDS AND THEIR ESTERS: III. IODINE VALUES BY THE BROMINE VAPOR METHOD

A modified bromine vapor method for iodine value determination that allows of the determination of substitution is described. For non-conjugated unsaturated oils free from oxidation or polymerization products, values are obtained that are in close agreement with those found by Wijs' method. The unsaturation of conjugated esters can be determined satisfactorily. Owing to substitution, the unsaturation of oxidized or polymerized esters cannot be determined by this method.

Hard Rubber. Its Carbon and Hydrogen Content

IN THE course of a study of vulcanization it became necessary to compare the ratios of carbon, hydrogen, and sulfur in hard rubber. A search of the literature revealed no analyses for carbon and hydrogen, although many analyses for sulfur in hard rubber have been recorded. Combustion analyses were therefore made on several samples of hard rubber, and the data are recorded here. The saturation of the double bonds in the rubber hydrocarbon with sulfur should give a compound, (C 5H8S)x, which contains 32.02 per cent of combined sulfur, and some of the recorded results agree with this figure. Since it is also possible to obtain products having greater amounts of combined sulfur than that called for by the theory of addition alone, some of the sulfur must consist of sulfur of substitution (7). It is theoretically possible that substitution and addition of sulfur can go on simultaneously; as the result of these two reactions, it may happen that the total sulfur in combination will equal the theoretical amount required by addition alone. In such a case there would be some free double bonds, but attempts to determine free double bonds in several samples by the Kemp-Wijs method (5) were unsuccessful.