Photocatalysis of a Commercial Naphthenic Acid in Water Using Fixed-Film TiO2

Photolysis or photocatalysis may provide a process for mitigating ecological risks of naphthenic acids (NAs) contained in energy-derived waters such as refinery effluents and process waters. If effective, fixed-film TiO₂ photocatalysis of NAs could decrease operational expenses as well as capital co...

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Bibliographic Details
Published in:Water, air, and soil pollution air, and soil pollution, 2016-05, Vol.227 (5), p.1, Article 132
Main Authors: McQueen, Andrew D, Kinley, Ciera M, Kiekhaefer, Rebecca L, Calomeni, Alyssa J, Rodgers, John H., Jr, Castle, James W
Format: Article
Language:English
Subjects:
Acids
Acute toxicity
Aerobic biodegradation
Aquatic organisms
Atmospheric Protection/Air Quality Control/Air Pollution
Biodegradation
capital
Capital costs
Climate Change/Climate Change Impacts
Daphnia magna
Earth and Environmental Science
effluents
Energy
Environment
Environmental monitoring
Environmental risk
fish
half life
High density polyethylenes
high performance liquid chromatography
Hydrogeology
invertebrates
Liquid chromatography
Mortality
naphthenates
Oil sands
Photocatalysis
Photodegradation
Photolysis
Pimephales promelas
risk
Soil Science & Conservation
solar radiation
Sunlight
Thin films
Titanium dioxide
Toxicity
Water Quality/Water Pollution
Water treatment
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Summary:Photolysis or photocatalysis may provide a process for mitigating ecological risks of naphthenic acids (NAs) contained in energy-derived waters such as refinery effluents and process waters. If effective, fixed-film TiO₂ photocatalysis of NAs could decrease operational expenses as well as capital costs for water treatment. The overall objective of this study was to measure rates and extents of photolysis and photocatalytic degradation of commercial NAs using bench-scale fixed-film TiO₂ and confirm changes in NA concentrations using sensitive vertebrate (fish = Pimephales promelas) and invertebrate (Daphnia magna) species. Specific objectives were to (1) measure rates and extents of degradation of commercial (Fluka) NAs throughout an 8-h duration of natural sunlight (“photolysis”) and natural sunlight in the presence of fixed-film TiO₂ (“photocatalysis”) and (2) measure changes in toxicity in terms of mortality with sentinel fish and microinvertebrate species. Bench-scale chambers using thin-film TiO₂ irradiated with natural sunlight were used to measure photocatalysis, and HPLC was used to quantify NAs. After 4 h in photocatalysis treatments, >92 % decline was observed with an average removal rate of 15.5 mg/L/h and half-life of 2 h. After 5 h of photocatalysis, there was no measurable NA toxicity for fish (P. promelas) or microinvertebrates (D. magna). Photocatalytic degradation achieved efficacious rates and extents of removal of Fluka NAs and eliminated acute toxicity to sentinel aquatic organisms, indicating the potential for application of this technology for mitigating ecological risks. Coupled with existing treatment processes (i.e., aerobic biodegradation), photocatalysis can augment rates and extents of NA removal from impacted waters.
ISSN:0049-6979
1573-2932
DOI:10.1007/s11270-016-2835-x