Gamma radiation-induced molecular transformation of hydrocarbons in the presence of nanostructured sodium bentonite clay

Abstract

This study investigates the molecular transformation of hydrocarbons under gamma radiation in the presence of nanostructured sodium bentonite clay. Crude oil samples from the Gunashli oil field (Azerbaijan) were exposed to ⁶⁰Co gamma radiation across a dose range of 0–260 kGy. Using a combination of FTIR, UV-vis, EPR spectroscopy, and gas chromatography, we evaluated the structural evolution of both mature and immature oils. The results demonstrate a dose-dependent degradation of aromatic compounds, accompanied by increased formation of isomeric and low-molecular-weight hydrocarbon gases. Nanostructured Na-bentonite acted as a radiation-sensitive catalyst, significantly enhancing fragmentation, isomerization, and π–σ bond transformation. In mature oils, a pronounced reduction in arenes and density confirmed advanced molecular restructuring. In contrast, immature oils retained substantial aromatic content, indicating partial metamorphism. UV-vis data revealed a sequential transformation pathway from polycyclic aromatics to saturated hydrocarbons. The findings underscore the catalytic synergy between gamma radiation and nanoclay, offering mechanistic insights into radiolytic upgrading and mimicking natural geochemical maturation processes.