PHOTOOXIDATION OF a REFINED PETROLEUM OIL: INHIBITION BY Β‐CAROTENE AND ROLE OF SINGLET OXYGEN

Abstract

Abstract— β‐Carotene, at concentrations 0.1 mM, inhibits the formation of hydroperoxides and other oxidation products in a refined petroleum oil exposed to Pyrex‐filtered UV. The effect appears to be due to 1O2 quenching. A mechanism incorporating 1O2 and radical processes is proposed as a model for environmental photooxidation of petroleum.

Oil, water, ice and light

“…which can combine with groundstate oxygen (302) and start a chain reaction (Hansen & Sydnes 1989;Larson et al 1977;Sydnes et al 1985b When exposed to sunlight in the marine environment the oil components are intimately mixed with oxygen, and as a result most of the products formed under these conditions are due to photooxidation reactions, albeit fragmentation and polymerisation may also take place. Detailed studies of the photooxidation of selected oil samples and oil components have shown that the reaction is facilitated by the presence of aromatic hydrocarbons, asphaltenes, and resins, and that several reaction pathways may operate at the same time (Hansen 1975;Hansen & Sydnes 1989;Larson & Hunt 1978;Sydnes et al 1985b;Sydnes et al 198%). It is therefore not surprising that oil 8-dimethylnaphthalene (1.8-DMN) on distilled water and (B) 3.…”

“…Triplet-excited organic compounds may also function as sensitisers (S) and transfer the triplet energy to ground-state (triplet) oxygen which simultaneously is excited to singlet oxygen: Most crude oils contain a number of compounds that can function as sensitisers toward triplet oxygen; polycyclic aromatic compounds. asphaltene constituents, and compounds resulting from their oxidation all possess triplet energy higher than that necessary to excite jOO2 to lo2 (92.4 kJ mol-I) and are therefore conceivable candidates (Larson & Hunt 1978;Sydnes et al 1 9 8 5~) .…”

Oil, water, ice and light

“…7): When exposed to sunlight in the marine environment the oil components are intimately mixed with oxygen, and as a result most of the products formed under these conditions are due to photooxidation reactions, albeit fragmentation and polymerisation may also take place. Detailed studies of the photooxidation of selected oil samples and oil components have shown that the reaction is facilitated by the presence of aromatic hydrocarbons, asphaltenes, and resins, and that several reaction pathways may operate at the same time (Hansen 1975;Hansen & Sydnes 1989;Larson & Hunt 1978;Sydnes et al 1985b;Sydnes et al 198%). It is therefore not surprising that oil 3.…”

“…1s -3s 3 s + 3 0 2 --f 0s + lo2 '02 + Organic compounds+ Oxidation products Most crude oils contain a number of compounds that can function as sensitisers toward triplet oxygen; polycyclic aromatic compounds. asphaltene constituents, and compounds resulting from their oxidation all possess triplet energy higher than that necessary to excite jOO2 to lo2 (92.4 kJ mol-I) and are therefore conceivable candidates (Larson & Hunt 1978;Sydnes et al 1 9 8 5~) .…”

Singlet Oxygen Production by a Crude Oil from the San Jorge Gulf Basin, Argentina

“…When crude oil and related products are exposed to light, the formation of reactive oxygen species (ROS) is possible . Several studies have been published concerning the role played by the ROS singlet oxygen [O 2 ( 1 Δ g )], in the photooxidation of crude oil and petroleum products . Due to the presence of many aromatic compounds, generation of singlet oxygen as a result of solar exposure of crude oil is expected.…”