4 research outputs found
Analytical and ecotoxicological studies on degradation of fluoxetine and fluvoxamine by potassium ferrate
<p>A large amount of pharmaceuticals are flushed to environment <i>via</i> sewage system. The compounds are persistent in environment and are very difficult to remove in drinking water treatment processes. Degradation of fluoxetine (FLU) and fluvoxamine (FLX) by ferrate(VI) were investigated. For the 10 mg/L of FLU and FLX, 35% and 50% of the compounds were degraded in the presence of 50 mg/L FeO<sub>4</sub><sup>2−</sup> within 10 minutes, respectively. After 10 minutes of the reaction, degradation of FLU and FLX is affected by formation of by-products which were likely more reactive with ferrate and competed in the reaction with FeO<sub>4</sub><sup>2−</sup>. In the case of FLU, the identified degradation by-products were hydrofluoxetine, N-methyl-3-phenyl-2-propen-1-amine, 4-(trifluoromethyl)phenol and 1-{[(1R,S)-1-Phenyl-2-propen-1-yl]oxy}-4-(trifluoromethyl)benzene. In the case of FLX, the degradation by-products were fluvoxamine acid and 5-methoxy-1-[4-(trifluoromethyl)phenyl]pent-2-en-1-imine. The results of the ecotoxicological study based on protozoa <i>Spirostomum ambiguum</i> have shown that 50 mg/L FeO<sub>4</sub><sup>2−</sup> reduced toxicity of 10 mg/L of FLU and FLX by around 50%. However, in the case of FLX, the results of the ecotoxicological study suggested formation of slightly more toxic compound(s) than FLX during reaction with FeO<sub>4</sub><sup>2−</sup>. Application of ferrate(VI) is a viable option for drinking water treatment process; however, caution is needed due to formation of by-products with unknown human health risk.</p
Impact of Peroxydisulfate in the Presence of Zero Valent Iron on the Oxidation of Cyclohexanoic Acid and Naphthenic Acids from Oil Sands Process-Affected Water
Large volumes of oil sands process-affected water (OSPW)
are produced
during the extraction of bitumen from oil sands in Alberta, Canada.
The degradation of a model naphthenic acid, cyclohexanoic acid (CHA),
and real naphthenic acids (NAs) from OSPW were investigated in the
presence of peroxydisulfate (S<sub>2</sub>O<sub>8</sub><sup>2–</sup>) and zerovalent iron (ZVI). For the model compound CHA (50 mg/L),
in the presence of ZVI and 500 mg/L S<sub>2</sub>O<sub>8</sub><sup>2–</sup>, the concentration decreased by 45% after 6 days
of treatment at 20 °C, whereas at 40, 60, and 80 °C the
concentration decreased by 20, 45 and 90%, respectively, after 2 h
of treatment. The formation of chloro-CHA was observed during ZVI/S<sub>2</sub>O<sub>8</sub><sup>2–</sup> treatment of CHA in the
presence of chloride. For OSPW NAs, in the presence of ZVI alone,
a 50% removal of NAs was observed after 6 days of exposure at 20 °C.
The addition of 100 mg/L S<sub>2</sub>O<sub>8</sub><sup>2–</sup> to the solution increased the removal of OSPW NAs from 50 to 90%.
In absence of ZVI, a complete NAs removal from OSPW was observed in
presence of 2000 mg/L S<sub>2</sub>O<sub>8</sub><sup>2–</sup> at 80 °C. The addition of ZVI increased the efficiency of NAs
oxidation by S<sub>2</sub>O<sub>8</sub><sup>2–</sup> near room
temperature. Thus, ZVI/S<sub>2</sub>O<sub>8</sub><sup>2–</sup> process was found to be a viable option for accelerating the degradation
of NAs present in OSPW
Effect of Molecular Structure on the Relative Reactivity of Naphthenic Acids in the UV/H<sub>2</sub>O<sub>2</sub> Advanced Oxidation Process
The large volume of oil sands process-affected water
(OSPW) produced
by the oil sands industry in Northern Alberta, Canada, is an environmental
concern. The toxicity of OSPW has been attributed to a complex mixture
of naturally occurring acids, including naphthenic acids (NAs). Highly
cyclic or branched NAs are highly biopersistent in tailings ponds,
thus understanding structure–reactivity relationship for NAs
is very important for OSPW reclamation. In this study, we hypothesized
that large, branched and cyclic NAs may be better oxidized in the
UV/H<sub>2</sub>O<sub>2</sub> process than small, linear and acyclic
NAs. Relative rate measurements using binary mixtures of model NA
compounds confirmed that reactivity favored compounds with more carbons,
and also favored NAs with one saturated ring, relative to the corresponding
linear NA. However, for model compound with three rings, no increased
reactivity was observed relative to monocyclic NA. UV/H<sub>2</sub>O<sub>2</sub> treatment of OSPW confirmed our findings with model
compounds, indicating that the compounds with more carbons are favored
for degradation. However, increasing the number of rings (or double
bond equivalents) in OSPW NAs did not show any clear structure–reactivity.
Microbial degradation studies of the UV/H<sub>2</sub>O<sub>2</sub> treated OSPW should be conducted to examine the overall benefit
of this treatment for the real applications
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