Quantificação de biodiesel em blendas biodiesel/diesel : comparação de modelos iPLS e LS-SVM com aplicação do método da transformada discreta Wavelet.

Abstract

Since the beginning of the year of 2008 it comes being obligatory the commercialization of biodiesel increase in diesel. The commercialized percentage comes growing with passing time, being currently 5% and tends to increase. The ANP (Brazilian National Agency for Petroleum, Natural Gas and Biofuels) - responsible for the regulation and fiscalization of biodiesel, already grants to authorization for biodiesel/diesel blend with percentage of biodiesel above of what it establishes the current legislation. In this way it makes necessary to establish methodologies capable to certify the commercialized percentage is inside of the legislation, in order to protect the consumer. For this work used mid-infrared spectroscopy associated the two tools: interval partial least squares (iPLS) and least-squares support vector machines (LS-SVM). And also, the discrete wavelet transform method (DWT) was used to reduce the number of variables and thus the computational costs. This work studied samples biodiesel/diesel blend, with concentrations of biodiesel in the range of 8% (v/v) - 30% (v/v).The models had been constructed using the spectral band that contains stretching C-O of esters present in biodiesel, that iPLS was selected by the algorithm used. The gotten results had shown a great capacity of method TDW in holding back information in new variables, created from the decomposition of the original variable, conferring economy and quickness in the construction of multivariate models. The constructed models had showing that the tools iPLS and LS-SVM are equivalents for the quantification of biodiesel in biodiesel/diesel blends for studied concentrations, even though when models simultaneous deriving spectrum of different spectrofotometer, in the case a Nicolet and Shimadzu, with error of prediction of 0.2% (v/v) - 0.4% (v/v), inferior to the limit established for Norm NBR 15568 for this band of concentration, 1.0% (v/v).