A Fast FTIR Analysis for the Identification of Natural Asphalts and Bitumen

The natural asphalt is a black, oily, viscous organic material obtained by decomposition of complex organic materials (like plants, bones of animals, etc.), mixed with sands (tar) or rocks (natural asphalt). Well-known since the prehistory, it was used as sealant, adhesive, building binder, incense, and as decoration on pots, buildings, or human skin. It was also useful for waterproofing canoes and other water transport, pottery, ceramics, and in the mummification process toward the end of the New Kingdom of ancient Egypt. In many countries people used bituminous rocks for artistic sculpture. The modern bitumen are different from the natural asphalts because they are obtained by the distillation of petroleum and they are different in their chemical composition. The modern bitumen, principally used for road applications and as waterproofing membranes, is also used from some artists as color in their pictures. The composition of a bitumen or asphalt may be complex. The "heavy" components of bitumen, known as asphaltenes and resins, are mixtures of large polyaromatic hydrocarbons containing heteroatoms such as N, S, and O; polar functional groups are commonly present. Although a number of physiochemical methods have been used to understand the structure of a natural asphalt, the knowledge of the composition of these substances is still very limited. Fourier transform infrared spectroscopy by attenuated total reflectance (FTIR-ATR) has been applied to study several natural asphalts and modern bitumens. This technique allows to obtain relatively fast and easy answers to discriminate the natural asphalts than bitumens. In this study assignments are given for most of the FTIR bands and characteristics bands for the natural asphalts are determined.