Viabilidade técnica do biodiesel metílico do óleo de duas variedades de Carthamus tinctorius l. como substituto do diesel de petróleo

Abstract

The safflower (Carthamus tinctorius L.) is an energetic oilseed with high oil contents ranging between 35 to 48% and has high adaptability to dry and arid regions, may be a good alternative source for biofuel production in the Brazilian semiarid. The methyl biodiesel was obtained via transesterification reaction of the oil from two safflower varieties: one with 76,87% of oleic acid (C18:1) and another with 60,1% of linoleic acid (C18:2). The reactional conditions for obtaining of biofuel from both varieties were: 2% of catalyst (KOH), preheating oil to 50 °C, with moderate agitation for 1 hour and a ratio of 1:6 oil/methanol. In these reactional conditions was possible to obtain conversions rates in esters of 97,58% for the biodiesel of oleic safflower (BOS) and 98,61% for the biodiesel of linoleic safflower (BLS). Were investigated all the quality parameters required by the ANP (National Agency of Petroleum, Natural Gas and Biofuels) for the biodiesels, in order to viabilize its use by total or partial replacement of petroleum diesel. Was carried thermo-oxidative test by method in oven at 65 °C for 25 days of continuous exposure, showing that the biodiesel of the oleic safflower variety (BOS) presented better results of resistance to thermal degradation, reaching the limit of 100 meq/Kg in 360 h, while the biodiesel of the linoleic safflower variety (BLS) exceeded this limit in less than 72 h. The same was evidenced in the Rancimat® test, where the BOS showed oxidative stability of 3,6 h, while the BLS exhibited a stability of only 1 h (what was expected, since this have higher percentage of polyunsaturated fatty acids, especially the linoleic acid). The test of generator engine was done by comparing the consumption of diesel (0.679 L/h) with the blends consumption (diesel/biodiesel); where the mixtures of Diesel/BOS presented the following consumption: 0,646 (B5); 0,554 (B20); 0,632 (B50); 0,658 (B70) and 0,687 (B100); against 0,663 (B5); 0,564 (B20); 0,643 (B50); 0,658 (B70) and 0,692 (B100) for the blends of Diesel/BLS. Practically all the parameters evaluated in this comparative study indicate the superiority of the biodiesel from the oleic safflower oil in relation to the variety of linoleic safflower.