Two-step persulfate and Fenton oxidation of naphthenic acids in water

WILEY: "This is the peer reviewed version of the following article: Journal of Chemical Technology and Biotechnology 93 (2018): 2262-2270, which has been published in final form at http://doi.org/10.1002/jctb.5569. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."BACKGROUD: In the current study, two-step persulfate and Fenton oxidation has been investigated for the mineralization of naphthenic acids at 80 °C and initial pH ≈ 8. This pH evolves during the persulfate oxidation step towards the optimum for Fenton oxidation (≈ 3). The effects of persulfate and H2O2doses, iron concentration, duration of the persulfate oxidation step and operating temperature have been assessed. RESULTS: The combined treatment allowed up to ≈ 80% mineralization of cyclohexanoic acid using fairly low relative amounts of reagents (20 and 30% of the stoichiometric for persulfate and H2O2, respectively). For mineralization of cyclohexanoic acid, 115 and 87 kJ mol-1were obtained as representative values of the apparent activation energy for the persulfate and Fenton oxidation steps, respectively. The system was also successfully tested with other naphthenic acids, including cyclohexanebutyric acid, 2-naphthoic acid and 1,2,3,4-tetrahydro-2-naphthoic acid. Treatment of the naphthenic acids tested by this system gave rise to easily biodegradable effluents consisting mainly of short-chain organic acids. The biodegradability was confirmed by the BOD5/COD ratio and respirometric tests. CONCLUSION: The results show the potential application of this approach as a promising cost-effective solution for the treatment of naphthenic acids-bearing aqueous wastes. This approach has significant advantage compared with the single thermally-activated persulfate or Fenton oxidation, since it allows a high mineralization at reduced reagent cost upon replacing part of the persulfate by less expensive H2O2.We are grateful to the Chinese Scholarship Council (CSC) for supporting the Ph.D. program of Xiyan Xu (CSC, File No. 201308410047). Spanish MINECO is also gratefully acknowledged for the financial support through the project CTQ2013-41963-

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

Eliminacion de ácidos nafténicos en agua por oxidación con persulfato y mediante el sistema Fenton

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada. Fecha de lectura: 05-07-2017Esta tesis tiene embargado el acceso al texto completo hasta el 05-01-201

Sub-lethal effects of oil sands process-affected water (OSPW) in two aquatic organisms : Daphnia magna and rainbow trout

My thesis contributes to a better understanding of the impacts of OSPW on aquatic organisms by investigating its sub-lethal effects on an invertebrate (Daphnia magna) and a vertebrate (rainbow trout) model species. Studies conducted on D. magna demonstrated that OSPW impairs feeding, reduces hemoglobin content, increases oxygen consumption, and reduces growth, reproduction and macronutrient reserves of exposed animals at 1 to 10% concentrations. I also investigated the interaction of OSPW with the chemosensory system of rainbow trout (Oncorhynchus mykiss). I demonstrated that rainbow trout are able to detect and behaviourally avoid low concentrations (0.1%) of OSPW. However, even a short-term (< 5 min) interaction with OSPW reduced olfactory acuity. The toxic effect of OSPW on the fish olfactory system gradually increased with increasing exposure time. Overall, the results of my thesis suggest that untreated OSPW, even at low concentrations (1% OSPW), can affect different aspects of aquatic animals.The present study was financially supported by the Forest Watershed & Riparian Disturbance Project (FORWARD III) funded by the Natural Sciences and Engineering Research Council of Canada Collaborative Research and Development Program and Syncrude Canada Ltd., Canadian Natural Resources Limited, Total, Suncor Energy, Tervita Corporation, Alberta Newsprint Company, Alberta-Pacific Forest Industries, Hinton Pulp, Millar Western Forest Products Ltd., Slave Lake Pulp, Oil Sands Research and Information Network and Environment Canada