Effect Of Ultraviolet Radiation On The Aliphatic And Polycyclic Aromatic Hydrocarbon Profiles Of Agbabu Natural Bitumen

The quality of wide a variety of synthetic or naturally occurring materials which are used for outdoor applications are known to be adversely affected by environmental factors. These materials absorb solar ultraviolet radiation leading to changes in their structures and compositions. The consequences of these changes lead to degradation of the materials. Bitumen is one of the materials which is mostly used in outdoor applications, making it to be routinely exposed to sunlight during use. Sequel to this, the effects of ultraviolet radiation on the aliphatic and polycyclic aromatic hydrocarbon profiles of Agbabu natural bitumen found in South Western Nigeria were investigated. The bitumen sample was exposed to ultraviolet radiation (365nm) for seven hours and samples were withdrawn and analyzed at intervals of one , three and seven hours respectively. The irradiated sample was separated into the maltene and asphaltene fractions and the maltene fraction further subjected to column chromatography to separate it into aliphatic hydrocarbon, polycyclic aromatic hydrocarbon and polar compounds. The aliphatic and polycyclic aromatic hydrocarbon fractions were analyzed using Gas chromatograph (GC). Results of GC analysis showed that the total aliphatic and aromatic hydrocarbon contents in the ultraviolet irradiated samples were found to be less than the total aliphatic and aromatic hydrocarbon contents of the unirradiated sample. The results indicates that there was a decrease in the amount of both the total aliphatic hydrocarbon content and polycyclic aromatic hydrocarbon content of the Agbabu Natural Bitumen as a result of exposure to ultraviolet radiation.