Estudo de compostos voláteis de níquel e vanádio em cimento asfáltico de petróleo virgem e envelhecido

Abstract

Among the heteroatoms present in petroleum, nickel and vanadium are the most abundant metals. Thus, these can be found in large quantities in petroleum derivatives, such as Asphaltic Petroleum Cement (APC). The presence of these metals compounds in the asphalt matrices is important to trace the geological origin of the crude oil, as well as the migration and maturation, besides having interference in the processes of fractionation, corrosion and environmental pollution. We can also relate the presence of these compounds with occupational health problems, since some have a known carcinogenic and mutagenic potential. In this work, Energy Dispersive X-ray Fluorescence (ED XRF) and High Resolution Continuum Source Atomic Absorption Spectrometry (HR CS AAS) were used to investigate Ni and V compounds present on virgin and aged asphalt cements from different refineries of Brazil aiming the minimum sample preparation. First, the total content of these metals was determined in the virgin matrix by ED XRF with a simple sample dilution in toluene. Then the same procedure was employed on the aged samples submitted to the Rolling Thin Film Sample Test (RTFOT) and the SUNTEST®. Finally, the volatile fraction of Ni and V were extracted with the support of a device for extraction and collection (DEC) developed in our work group and quantified by HR CS AAS. The results showed an appreciable variation in these metals content after the aging process with vanadium presenting the most considerable losses both after the aging and in volatile form. The obtained results give an important parameter related to the best crude oil source used to obtain the asphalt cement for paving processes, this way reducing the environmental and occupational problems.