Especiação de enxofre orgânico em cimento asfáltico de petróleo e suas frações

Abstract

The asphalt binder is composed mostly of aromatic hydrocarbons. However, the presence of sulfur in the matrices warrant special attention, since it stands out for being the major heteroatom. Sulfur compounds are known for their influence as a precursor of the asphalt matrix aging process. An undesirable process that affects pavement durability, making it became less resistant, with holes and cracks that lead to pavement deterioration. In addition, the presence of sulfur compounds in fumes emitted through the matrix heating have relation to health problems that can affect workers of the area. Therefore, this work aims to develop and validate a high-performance liquid chromatography method with pulsed amperometric detection (HPLC-PAD) and an ultra-high performance liquid chromatography with atmospheric pressure photoionization and detection by tandem mass spectrometry (UHPLC-APPI-MS/MS), which allows the speciation of sulfur compounds in the asphalt matrices, the fumes and the particulate matter emitted during the samples heating. With these in mind, three methodologies of sample preparation were evaluated. In order to verify the presence of the organosulfur compounds in the crude sample a procedure of solid phase extraction using ion exchange cartridges was used. And to evaluate sulfur compounds emitted in the volatiles an extractor and collector device (DEC) was used. While the particulate matter emissions were extracted using ultrasound. In addition, the determination of total sulfur in the asphalt matrix and its fractions, was made through dispersive energy X-ray fluorescence (FRX-ED). To study the samples and their fractions before and after forced aging methods, so that the impact of this process on the chemistry of the asphalt cements were evaluated. In an attempt to probe the transformations that occur with the sulfur during the process, and the migrations of it between the fractions. In addition, the chemical changes caused by aging were also surrounded by the alterations in the molecular fluorescence spectra of the samples.