Application of Savitzky-Golay and Fast Fourier Transform filters in the processing of derivative spectra obtained from asphaltene solutions

Asphaltenes are ultra -complex mixtures that negatively impact oil refining, production and transportation. The interest in its study ranges from its characterization to define its molecular structure, to the understanding of its interfacial behavior. Asphaltenes present a great diversity of functional groups and different types of associations such as non -covalent ones, hydrogen bonds, coordination complexes and interactions between parallel aromatic nuclei. The objective of this work was to analyze the composition present in asphaltenes extracted from heavy and extra -heavy crude oils using derivative spectroscopy. Asphaltene solutions were prepared in the concentration range of 20 mg/L to 100 mg/L and analyzed with UV-Vis spectroscopy. The selection of zero -order spectra for processing was made based on the sharpness present. The spectra were subsequently processed with OriginPro 8.5, to obtain first and second -order derived spectra. The processing of the zero order spectra was performed with the Savitsky-Golay and Fast Fourier transform (FFT) filters. The derived spectra obtained presented clear signals with the presence of little noise, which made possible the identification of aromatic functional groups, from 1 to 4 rings in the wavelength range of 200 nm to 450 nm. The use of filters improved the quality of the signals and allowed the identification of components and structures present in asphaltenes. The Savitsky-Golay filter increased the resolution of the spectra derived from asphaltenes extracted from heavy crude oils and the FFT filter increased the asphaltenes extracted from heavy crude oils. Morphological differences between asphaltenes extracted from heavy and extra -heavy crude oils were observed by SEM, which maybe related to the composition and aromatic structures present in asphaltenes.