Enhanced characterization of oil sands acid‐extractable organics fractions using electrospray ionization–high‐resolution mass spectrometry and synchronous fluorescence spectroscopy

Abstract

The open pit oil sands mining operations north of Fort McMurray, Alberta, Canada, are accumulating tailings waste at a rate approximately equal to 4.9 million m(3) /d. Naphthenic acids are among the most toxic components within tailings to aquatic life, but structural components have largely remained unidentified. In the present study, electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and synchronous fluorescence spectroscopy (SFS) were used to characterize fractions derived from the distillation of an acid-extractable organics (AEO) mixture isolated from oil sands process-affected water (OSPW). Mean molecular weights of each fraction, and their relative proportions to the whole AEO extract, were as follows: fraction 1: 237 Da, 8.3%; fraction 2: 240 Da, 23.8%; fraction 3: 257 Da, 26.7%; fraction 4: 308 Da, 18.9%; fraction 5: 355 Da, 10.0%. With increasing mean molecular weight of the AEO fractions, a concurrent increase occurred in the relative abundance of nitrogen-, sulfur-, and oxygen-containing ions, double-bond equivalents, and degree of aromaticity. Structures present in the higher-molecular-weight fractions (fraction 4 and fraction 5) suggested the presence of heteroatoms, dicarboxyl and dihydroxy groups, and organic acid compounds with the potential to function as estrogens. Because organic acid compositions become dominated by more recalcitrant, higher-molecular-weight acids during natural degradation, these findings are important in the context of oil sands tailings pond water remediation.

Molecular Characterization and Transformation of Dissolved Organic Matter in Refinery Wastewater from Water Treatment Processes: Characterization by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…The composition feature is similar to that found in oil sand processing wastewaters. [37][38][39]64] The predominance of O2 and O4 to O3 class species implies that carboxyl is one major type of oxygen atoms, while the predominance of N1O3 to N1O2 and N1O4 indicates the nitrogen compounds have NO function group, like nitryls instead of aza naphthenic acids. It should be note that the sulfur compounds composition are interesting; the most abundant sulfur 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 13 compound class species is O1S2, but not O1S1.…”

“…However, DOM probably contains thousands or even millions of different chemical compositions, making it impossible to characterize it on the basis of complete description of the individual compounds. [8,9] In previous studies, various analytical techniques were applied to characterize the DOM composition, including spectroscopic methods such as ultraviolet-visible spectroscopy (UV/Vis), [10][11][12][13] Fourier transform infrared spectroscopy (FT-IR), [14][15][16] nuclear magnetic resonance spectroscopy (NMR), [17][18][19] Recently, electrospray ionization (ESI) coupled to ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), has become an important tool and has been successfully applied to the characterization of DOM from different aquatic environments such as ocean, [27][28][29][30] lake,[31] bay system, [32] pore water [33][34][35] and rainwater, [36] oil sands process water, [37][38][39] as well as the water-soluble DOM from soil, [40,41] and atmosphere. [42][43][44][45] In addition, transformation of DOM through biodegradation, [46] photochemical degradation, [47,48] and chlorination [49,50] has been studied by using ESI FT-ICR MS.…”

Solubilized Chitosan Biopolymers for Sequestration of Organic Acids in Aquatic Environments after Biodegradation in a Constructed Wetland Treatment System

“…R denotes an apolar fragment of the naphthenate moiety with a variable carbon number and double-bond equivalent (DBE), where the dashed line refers to an adsorptive interaction at apolar or polar sites Figure 2A-B illustrates the trend in chitosan uptake of OSPW with variable double-bond equivalent (DBE) values for the O2 series of selected NAFCs at variable chitosan concentration. The DBE term relates to the degree of unsaturation that can be inferred as the number of ring systems by subtracting 1 from the DBE to estimate the number of rings (Bauer et al, 2015). DBE values between 3.5 and 4.5 were among the most abundant in the R-OSPW, where these species showed attenuated removal with increasing chitosan concentration.…”

Characterization of crude oil asphaltenes by coupling size‐exclusion chromatography directly to an ultrahigh‐resolution mass spectrometer

“…Additionally, separation of isomers remains a challenge as they are not detectable by direct infusion mass spectrometry. Thus, the future of crude oil analysis by mass spectrometry will involve couplings to different separation techniques …”