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Application of UV-irradiated Fe(III)-nitrilotriacetic acid (UV-Fe(III)NTA) and UV-NTA-Fenton systems to degrade model and natural occurring naphthenic acids.
- Source :
-
Chemosphere [Chemosphere] 2017 Jul; Vol. 179, pp. 359-366. Date of Electronic Publication: 2017 Mar 28. - Publication Year :
- 2017
-
Abstract
- Naphthenic acids (NAs) are a highly complex mixture of organic compounds naturally present in bitumen and identified as the primary toxic constituent of oil sands process-affected water (OSPW). This work investigated the degradation of cyclohexanoic acid (CHA), a model NA compound, and natural occurring NAs during the UV photolysis of Fe(III)-nitrilotriacetic acid (UV-Fe(III)NTA) and UV-NTA-Fenton processes. The results indicated that in the UV-Fe(III)NTA process at pH 8, the CHA removal increased with increasing NTA dose (0.18, 0.36 and 0.72 mM), while it was independent of the Fe(III) dose (0.09, 0.18 and 0.36 mM). Moreover, the three Fe concentrations had no influence on the photolysis of the Fe(III)NTA complex. The main responsible species for the CHA degradation was hydroxyl radical (OH), and the role of dissolved O <subscript>2</subscript> in the OH generation was found to be negligible. Real OSPW was treated with the UV-Fe(III)NTA and UV-NTA-Fenton advanced oxidation processes (AOPs). The removals of classical NAs (O <subscript>2</subscript> -NAs), oxidized NAs with one additional oxygen atom (O <subscript>3</subscript> -NAs) and with two additional oxygen atoms (O <subscript>4</subscript> -NAs) were 44.5%, 21.3%, and 25.2% in the UV-Fe(III)NTA process, respectively, and 98.4%, 86.0%, and 81.0% in the UV-NTA-Fenton process, respectively. There was no influence of O <subscript>2</subscript> on the NA removal in these two processes. The results also confirmed the high reactivity of the O <subscript>2</subscript> -NA species with more carbons and increasing number of rings or double bond equivalents. This work opens a new window for the possible treatment of OSPW at natural pH using these AOPs.<br /> (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Subjects :
- Caproates chemistry
Carboxylic Acids radiation effects
Ferric Compounds chemistry
Hydrogen Peroxide chemistry
Iron chemistry
Oil and Gas Fields chemistry
Oxidation-Reduction
Ultraviolet Rays
Water Pollutants, Chemical radiation effects
Carboxylic Acids chemistry
Environmental Restoration and Remediation methods
Nitrilotriacetic Acid chemistry
Photolysis
Water Pollutants, Chemical chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1879-1298
- Volume :
- 179
- Database :
- MEDLINE
- Journal :
- Chemosphere
- Publication Type :
- Academic Journal
- Accession number :
- 28388447
- Full Text :
- https://doi.org/10.1016/j.chemosphere.2017.03.112