3 research outputs found
Comparison of Nitrilotriacetic Acid and [<i>S</i>,<i>S</i>]‑Ethylenediamine‑<i>N</i>,<i>N</i>′‑disuccinic Acid in UV–Fenton for the Treatment of Oil Sands Process-Affected Water at Natural pH
The application of
UV–Fenton processes with two chelating
agents, nitrilotriacetic acid (NTA) and [<i>S</i>,<i>S</i>]-ethylenediamine-<i>N</i>,<i>N</i>′-disuccinic acid ([<i>S</i>,<i>S</i>]-EDDS),
for the treatment of oil sands process-affected water (OSPW) at natural
pH was investigated. The half-wave potentials of FeÂ(III/II)ÂNTA and
FeÂ(III/II)ÂEDDS and the UV photolysis of the complexes in Milli-Q water
and OSPW were compared. Under optimum conditions, UV–NTA–Fenton
exhibited higher efficiency than UV–EDDS–Fenton in the
removal of acid extractable organic fraction (66.8% for the former
and 50.0% for the latter) and aromatics (93.5% for the former and
74.2% for the latter). Naphthenic acids (NAs) removals in the UV–NTA–Fenton
process (98.4%, 86.0%, and 81.0% for classical NAs, NAs + O (oxidized
NAs with one additional oxygen atom), and NAs + 2O (oxidized NAs with
two additional oxygen atoms), respectively) under the experimental
conditions were much higher than those in the UV–H<sub>2</sub>O<sub>2</sub> (88.9%, 48.7%, and 54.6%, correspondingly) and NTA–Fenton
(69.6%, 35.3%, and 44.2%, correspondingly) processes. Both UV–NTA–Fenton
and UV–EDDS–Fenton processes presented promoting effect
on the acute toxicity of OSPW toward <i>Vibrio fischeri</i>. No significant change of the NTA toxicity occurred during the photolysis
of FeÂ(III)ÂNTA; however, the acute toxicity of EDDS increased as the
photolysis of FeÂ(III)ÂEDDS proceeded. NTA is a much better agent than
EDDS for the application of UV–Fenton process in the treatment
of OSPW
Impact of Ozonation on Naphthenic Acids Speciation and Toxicity of Oil Sands Process-Affected Water to <i>Vibrio fischeri</i> and Mammalian Immune System
Oil sands process-affected
water (OSPW) is the water contained
in tailings impoundment structures in oil sands operations. There
are concerns about the environmental impacts of the release of OSPW
because of its toxicity. In this study, ozonation followed by biodegradation
was used to remediate OSPW. The impacts of the ozone process evolution
on the naphthenic acids (NAs) speciation and acute toxicity were evaluated.
Ion-mobility spectrometry (IMS) was used to preliminarily separate
isomeric and homologous species. The results showed limited effects
of the ozone reactor size on the treatment performance in terms of
contaminant removal. In terms of NAs speciation, high reactivity of
NAs with higher number of carbons and rings was only observed in a
region of high reactivity (i.e., utilized ozone dose lower than 50
mg/L). It was also found that nearly 0.5 mg/L total NAs was oxidized
per mg/L of utilized ozone dose, at utilized ozone doses lower than
50 mg/L. IMS showed that ozonation was able to degrade NAs, oxidized
NAs, and sulfur/nitrogenated NAs. Complete removal of toxicity toward <i>Vibrio fischeri</i> was achieved after ozonation followed by
28-day biodegradation period. In vitro and in vivo assays indicated
that ozonation reduced the OSPW toxicity to mice
Advanced Analytical Mass Spectrometric Techniques and Bioassays to Characterize Untreated and Ozonated Oil Sands Process-Affected Water
Oil sands process-affected water
(OSPW) is a toxic and poorly biodegradable
mixture of sand, silt, heavy metals, and organics. In this study,
qualitative and quantitative comparisons of naphthenic acids (NAs)
were done using ultraperformance liquid chromatography time-of-flight
mass spectrometry (UPLC TOF-MS), Fourier transform ion cyclotron resonance
(FT-ICR) MS, and ion mobility spectrometry (IMS). The unique combination
of these analyses allowed for the determination and correlation of
NAs, oxidized NAs, and heteroatom (sulfur or nitrogen) NAs. Despite
its lower resolution, UPLC-TOF MS was shown to offer a comparable
level of reliability and precision as the high resolution FT-ICR MS.
Additionally, the impacts of ozonation (35 mg/L utilized ozone dose)
and subsequent NAs degradation on OSPW toxicity were assessed via
a collection of organisms and toxicity end points using Vibrio fischeri (nonspecific), specific fish macrophage
antimicrobial responses, and fish olfactory responses. Fish macrophages
exposed to ozonated OSPW for 1 week showed higher production of reactive
oxygen and nitrogen intermediates; however, after 12 weeks the responses
were reduced significantly. Fish olfactory tests suggested that OSPW
interfered with their perception of odorants. Current results indicate
that the quantification of NAs species, using novel analytical methods,
can be combined with various toxicity methods to assess the efficiency
of OSPW treatment processes