Characterization of oil sands naphthenic acids treated with ultraviolet and microwave radiation by negative ion electrospray Fourier transform ion cyclotron resonance mass spectrometry

Abstract

Naphthenic acids (NAs) are concentrated in oil sand process water (OSPW) as a result of caustic oil sands extraction processes. There is considerable interest in methods for treatment of NAs in OSPW. Earlier work has shown that the combination of ultraviolet (UV) and microwave treatments in the laboratory was effective in reducing the concentration of classical NAs. Here we apply Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to further characterize NAs treated with (a) UV (254 nm) in the presence of TiO(2) catalyst; and/or (b) microwave irradiation (2.45 GHz). FT-ICR MS was used to characterize the NA fraction before and after treatment. Acidic oxygen-containing classes were most abundant in all samples whereas other heteroatomic classes were least abundant or not present in some samples. For example, the SO(2)-containing species were absent in UV- or combined UV- and microwave-treated samples. The O(2) class was dominant in all samples, indicative of NAs. However, samples treated with UV and microwave radiation have a lower relative abundance of other heteroatomic classes. We observed O(2), S(1)O(2), O(3), S(1)O(3), O(4), O(5), and O(6) classes, whereas the species with relatively high O(n) content, namely, the O(3), O(5), and O(6) classes, were present only in UV- and microwave-treated samples. The relatively high O(n) content is consistent with oxidation of the parent acids in treated samples. There may thus be potential implications for environmental forensics. For example, the monitoring of the ratio of SO(2):O(2) or tracking the relative abundances of O(2), O(3), O(4), O(5), and O(6) classes may provide insights for distinguishing naturally derived oil sands components from those that are process-related in aquatic environments.

Characterization of oil sands acids in plant tissue using Orbitrap ultra‐high resolution mass spectrometry with electrospray ionization

“…In contrast, the third diagnostic ion does not match the classical definition of a naphthenic acid with the formula indicating the presence of a third oxygen. This formula highlights the fact that FTICR-MS characterization of oil sands processed water [12][13][14] and water from hydroponic systems [10] has revealed the presence of a wide range of heteroatomic species, some of which contained O 2 , O 3 , O 4 , O 5 , O 6 , O 7 , SO 2 , SO 3 , SO 4 , SO 5 , SO 6 , and NO 4 species that may be dissipated by the plants. [10] Similar species were also detected using the Orbitrap at 100 000 resolution, and some of these interfere with the detection of classical naphthenic acids and diagnostic ions from other compounds in plant tissue at lower resolution.…”

Novel materials for environmental remediation of oil sands contaminants

“…However, this definition has become more liberally used to describe the range of organic acids found within crude oil (15,16). The expanded definition includes oil sands acid-extractable organics with aromatic functional groups, nitrogen and sulfur atoms, along with unsaturated groups (15,16). For example, oil sands acids are known to fluoresce and evidently contain unsaturated and aromatic functionality that can be exploited using synchronous fluorescence spectroscopy and UV detection (9).…”

“…Highlights of recent studies pertain to the adsorption properties of engineered polymers with single-component and multicomponent naphthenic acids in aqueous solutions. The studies highlight the advantages of ultrahigh resolution for the characterization of the selective uptake of oil sands acids in the presence of background interferences (15)(16)(17), and the results contribute to our understanding of the molecular recognition properties of naphthenic acids in aqueous solutions and the contribution to the development of novel copolymers as SPE materials for future remediation strategies of tailings ponds. The highresolution ESI-MS measurements also further contribute to the understanding of the thermodynamic sorption process and to improvements in material design of such remarkable sorbent materials (12)(13)(14).…”

“…Classical naphthenic acids are defined as carboxylic acids that include one or more saturated ring structures. However, this definition has become more liberally used to describe the range of organic acids found within crude oil (15,16). The expanded definition includes oil sands acid-extractable organics with aromatic functional groups, nitrogen and sulfur atoms, along with unsaturated groups (15,16).…”

“…OSPW contains thousands of oil Brought to you by | Western University Authenticated Download Date | 6/9/15 8:16 PM sands acids, many of which are only resolved using ultrahigh-resolution mass spectrometry. Subtle differences in the sorption properties of the engineered polymer material are masked by interferences that are not resolved using low-resolution mass spectrometry (15)(16)(17). Highlights of recent studies pertain to the adsorption properties of engineered polymers with single-component and multicomponent naphthenic acids in aqueous solutions.…”