Structure-reactivity relationship of naphthenic acids in the photocatalytic degradation process

Livera, Diogo de Oliveira; Leshuk, Tim; Peru, Kerry M.; Headley, John V.; Gu, Frank

doi:10.1016/j.chemosphere.2018.02.049

Cited by 31 publications

(15 citation statements)

References 79 publications

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“…Lag phases were eliminated with photocatalytic pre-treatments since photocatalysis preferentially oxidizes NAs with greater structural complexity, thereby removing steric hindrances and creating labile organic forms for microbial metabolism [11]. This phenomenon has been seen for ozonation pre-treatments [36,37].…”

Section: Photocatalyticmentioning

confidence: 99%

“…Synthetic OSPW was pre-treated under varying photocatalytic pre-treatment times (0 h - shown the creation of oxy-NAs improves (biochemical oxygen demand) BOD:COD ratios (>0.3) and therefore NA biodegradability after sufficient treatment times [11,35]. Thus, NAs require ≥1 d of pretreatment to enhance biodegradability; a threshold requirement that has been observed for other NA preoxidative treatments (e.g., ozonation, persulfate oxidation, and electro-oxidation) [23], [25]- [26], [32]- [33][23], [25]- [26], [32]- [33].…”

Section: Photocatalysis Enables Effective Mineralization Of Naphtheni...mentioning

confidence: 99%

“…These reactive oxygen species collectively cause hydrogen abstraction in NAs, thereby oxidizing them to more hydrophilic forms (partial mineralization) or to CO2 (complete mineralization). Overall, BPCs are a promising passive treatment for OSPW since they enable simple TiO2 recycling and have demonstrated high reactivity on pertinent NA structures [8,10,11]. However, since PC treatment follows Langmuir-Hinshelwood kinetics, treatment rates exponentially diminish with decreasing NA concentrations.…”

Section: Introductionmentioning

confidence: 99%

“…TiO2 activation creates internal valence band holes that react with water and generate hydroxyl radicals, a potent oxidant [8]. Simultaneously, electrons are photogenerated in TiO2 which reduce oxygen in solution and, in turn, produce superoxide anions capable of initiating ring-opening reactions [11]. These reactive oxygen species collectively cause hydrogen abstraction in NAs, thereby oxidizing them to more hydrophilic forms (partial mineralization) or to CO2 (complete mineralization).…”

Section: Introductionmentioning

confidence: 99%

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Mild Photocatalysis Removes Microbial Inhibition and Enables Effective Biological Treatment of Naphthenic Acids

Chidiac

Leshuk

2022

Preprint

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Bitumen extraction from the Athabasca oil sands involves large volumes of water known as oil sands process affected water (OSPW). OSPW contains naphthenic acids (NAs), a class of aliphatic and cyclic carboxylic acids that can be toxic and are recalcitrant to natural attenuation. A passive advanced oxidation process (P-AOP), such as solar photocatalysis (PC) with buoyant photocatalysts (BPCs, TiO2-coated buoyant microspheres), is promising for NA treatment, through conversion to more hydrophilic forms (partial oxidation) or to CO2 (complete mineralization), depending on the solar dose. Although BPCs exhibit strong reactivity, full NA mineralization can require impractical hydraulic retention times. Biodegradation is another promising passive approach, but biodegradation rates are ultimately inhibited by the toxicity and structural complexity of NAs. We hypothesized that biological NA removal kinetics could be enhanced through BPC pre-treatment, since partial oxidation can lower NA toxicity and improve their biodegradability. Different PC exposure durations were used to pre-treat simulated OSPW prior to a biological treatment stage (with natural microbial culture from OSPW), to understand their impacts on NA chemical speciation and biodegradation kinetics. PC pre-treatment (2 d) enabled full mineralization (to <3 mg/L COD) and >99.9% removal of acid-extractable organics (AEO) in secondary biological treatment (21 d). Mineralization was achieved earlier in the combined PC+bio treatment than by photocatalysis alone (33 d vs. >42.2 d), and microbial growth rate was accelerated 23-fold compared to the non-pre-treated water. Overall, BPCs can improve NA biodegradability to achieve mineralization through a fully passive combined treatment process, without chemical or energy inputs.

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Section: Photocatalyticmentioning

confidence: 99%

Section: Photocatalysis Enables Effective Mineralization Of Naphtheni...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mild Photocatalysis Removes Microbial Inhibition and Enables Effective Biological Treatment of Naphthenic Acids

Chidiac

Leshuk

2022

Preprint

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“…OSPW contains several hundred NAFCs that can be further divided into O o , N n O o , O o S s , N n S s and N n O o S s compounds [5,11]. Several of these molecules are unsaturated, and the degree of unsaturation of an NAFC can be inferred from its double bound equivalents (DBE) [12,13], which is estimated as c + 1 2 (n − h) + 1. Most of the debate surrounding the toxicity of OSPW in the popular press, however, has centered on a specific sub-group of NAFCs known as classic naphthenic acids (NAs).…”

Section: Introductionmentioning

confidence: 99%

Transcriptome Analysis of Environmental Pseudomonas Isolates Reveals Mechanisms of Biodegradation of Naphthenic Acid Fraction Compounds (NAFCs) in Oil Sands Tailings

et al. 2021

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Naphthenic acid fraction compounds (NAFCs) are highly recalcitrant constituents of oil sands tailings. Although some microorganisms in the tailings can individually and synergistically metabolize NAFCs, the biochemical mechanisms that underpin these processes are hitherto unknown. To this end, we isolated two microorganisms, Pseudomonas protegens and Pseudomonas putida, from oils sands tailings and analyzed their transcriptomes to shed light on the metabolic processes employed by them to degrade and detoxify NAFCs. We identified 1048, 521 and 1434 genes that are upregulated in P. protegens, P. putida and a 1:1 co-culture of the strains, respectively. We subsequently enumerated the biochemical activities of enriched genes and gene products to reveal the identities of the enzymes that are associated with NAFC degradation. Separately, we analyzed the NAFCs that are degraded by the two pseudomonads and their 1:1 co-culture and determined the composition of the molecules using mass spectrometry. We then compared these molecular formulas to those of the cognate substrates of the enriched enzymes to chart the metabolic network and understand the mechanisms of degradation that are employed by the microbial cultures. Not only does the consortium behave differently than the pure cultures, but our analysis also revealed the mechanisms responsible for accelerated rate of degradation of NAFCs by the co-culture. Our findings provide new directions for engineering or evolving microorganisms and their consortia for degrading NAFCs more stably and aggressively.

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Cyclohexanecarboxylic acid degradation with simultaneous nitrate removal by Marinobacter sp. SJ18

Zan

Wang

Fan

et al. 2022

Environ Sci Pollut Res

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Naphthenic acid (NA), a new kind of toxic pollutants, is labeled as the potential threat to human health.However, the transformations of NAs in marine environments are still unclear. In this study, the characteristics and pathways of cyclohexylcarboxylic acid (CHCA) biodegradation were explored in the presence of nitrate. Results showed that CHCA was completely degraded with pseudo-rst-order kinetic reaction under aerobic and anaerobic conditions, accompanied by nitrate removal rates exceeding 70%, which was positively correlated with CHCA degradation(P<0.05). Degradation pathways of CHCA were proposed the cyclohexane was dehydrogenated to form cyclohexene, then ring-opened to generated fatty acid by dioxygenase under aerobic conditions, yet the cyclohexene was cleaved through β-oxidations under anaerobic condition. Whole genome analysis indicated that nitrate was removed via assimilation and dissimilation pathways and denitri cation pathways under aerobic and anaerobic conditions, respectively. This study provides a basis for the combined pollution of NA and nitrate in marine environments.Highlights 1.CHCA degradation in the presence of nitrate in marine environment was rstly studied 2.Strain SJ18 could rapidly degraded the combined pollutants of CHCA and nitrate 3.CHCA degradation pathways were proposed under aerobic and anaerobic conditions 4.Strain SJ18 contained functional genes for CHCA degradation and nitrate removal

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Structure-reactivity relationship of naphthenic acids in the photocatalytic degradation process

Cited by 31 publications

References 79 publications

Mild Photocatalysis Removes Microbial Inhibition and Enables Effective Biological Treatment of Naphthenic Acids

Mild Photocatalysis Removes Microbial Inhibition and Enables Effective Biological Treatment of Naphthenic Acids

Transcriptome Analysis of Environmental Pseudomonas Isolates Reveals Mechanisms of Biodegradation of Naphthenic Acid Fraction Compounds (NAFCs) in Oil Sands Tailings

Cyclohexanecarboxylic acid degradation with simultaneous nitrate removal by Marinobacter sp. SJ18

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