Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Oct 22;15(48):40299-40310.
doi: 10.1039/d5ra05244k.

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

M K Ismayilova  1 , I I Mustafayev  1   2 , R F Khankishiyeva  1   2   3 , H N Akhundzada  1   4   3   5 , S Z Melikova  1 , R A Bayov  1
Affiliations

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

M K Ismayilova et al. RSC Adv. .

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.

PubMed Disclaimer

Conflict of interest statement

There are no conflicts to declare.

Figures

Fig. 1
Fig. 1. Experimental workflow for gamma-irradiated crude oil with Na-bentonite clay.
Fig. 2
Fig. 2. FTIR spectra of crude oil samples obtained from the Gunashli oil field: (a) platform no. 8 (mature oil); (b) latform no. 14 (immature oil); (c) latform no. 10 (mature oil).
Fig. 3
Fig. 3. Effect of irradiation dose (D, kGy) on the concentration (Ni, 10−16 molecules mL−1) of hydrocarbon gases formed during γ-radiolysis of mature crude oil samples, with and without Na-bentonite catalyst: (a) CH4, (b) C2H6, (c) C2H4, (d) ∑C3, (e) ∑C4, (f) ∑C5, (g) ∑C6, (h) ∑C7, (i) ∑C8.
Fig. 4
Fig. 4. Dose-dependent formation of molecular hydrogen and hydrocarbon gases (CH4 to ∑C8) in crude oil samples from platform 8 and platform 10 under gamma irradiation, with and without Na-bentonite catalyst.(a) H2, (b) CH4, (c) C2H6, (d) C2H4, (e) ∑C3, (f) ∑C4, (g) ∑C5, (h) ∑C6, (i) ∑C7, (j) ∑C8.
Fig. 5
Fig. 5. Correlation between gamma irradiation dose and the concentration of arenes and isomeric structures in aromatic crude oil.
Scheme 1
Scheme 1. Structural transformations of hydrocarbons from aromatic to aliphatic forms.
Fig. 6
Fig. 6. UV spectra showing the transformation of condensed polycyclic aromatic hydrocarbons in crude oil samples from the Guneshli field under increasing radiation doses. (a) Anthracene + naphthalene + benzene derivatives; (b) naphthalene + benzene derivatives; (c) benzene derivatives only; (d) absence of aromatic bands – full transformation; (e) persistent aromatic peaks in immature crude oil from platform 14.
Fig. 7
Fig. 7. Variation in density (ρ, g cm−3) of immature crude oil from platform 14 as a function of gamma irradiation dose (D, kGy), indicating progressive transformation of arenes.
Fig. 8
Fig. 8. EPR spectra of crude oil samples obtained from platforms 8 and 10 of the Gunashli oil field: 1 and 2 – before and after irradiation of oil from platform 8; 3 and 4 – before and after irradiation of oil from platform 10.
Fig. 9
Fig. 9. EPR spectra of crude oil samples from platform 14 of the Gunashli oil field: 1 – before irradiation; 2 – after irradiation.
Fig. 10
Fig. 10. Dose-dependent decrease in arene content in mature crude oil samples from platforms 8 and 10: 1 – platform 10; 2 – platform 8.
Fig. 11
Fig. 11. Variation in density of mature crude oil samples under increasing gamma dose:1 – platform 8; 2 – platform 10. The density decreases by ∼1%, indicating radiolytic fragmentation of aromatic structures.
See this image and copyright information in PMC

References

    1. Liu H. Yuan P. Qin Z. Liu D. Tan D. Zhu J. He H. Thermal degradation of organic matter in the interlayer clay–organic complex: A TG-FTIR study on a montmorillonite/12-aminolauric acid system. Appl. Clay Sci. 2013;80:398–406. doi: 10.1016/j.clay.2013.07.005. - DOI
    1. Le G. C. Bernard S. Brearley A. J. Remusat L. Evolution of organic matter in Argueil, Murchison and Renazzo during parent body aqueous alteration: In situ investigation. Geochim. Cosmochim. Acta. 2014;131:368–392. doi: 10.1016/j.gca.2013.11.020. - DOI
    1. Catrinescu C. Fernandes C. Castilho P. Breen C. Influence of exchange cations on the catalytic conversion of limonene over Serra de Dentro (SD) and SAz-1 clays: Correlations between acidity and catalytic activity/selectivity. Appl. Catal. Gen. 2006;311:172–184. doi: 10.1016/j.apcata.2006.07.029. - DOI
    1. Drouin S. Boussafir M. Robert J. L. Alberic P. Durand A. Carboxylic acid sorption on synthetic clays in sea water: In vitro experiments and implications for organo-clay behaviour under marine conditions. Org. Geochem. 2010;41(2):192–199. doi: 10.1016/j.orggeochem.2009.09.006. - DOI
    1. Geatches D. L. Clark S. J. Greenwell H. C. Role of clay minerals in oil-forming reactions. J. Phys. Chem. A. 2010;114(10):3569–3575. doi: 10.1021/jp9095654. - DOI - PubMed