Application of Ozone and Peroxone Processes for Naphthenic Acids Degradation in Oil Sands Process-Affected Water: Characterization of Water Before and After Treatment

• Author / Creator

  Meshref, Mohamed N.A.

• Appling ozone (O3) with high doses (>100 mg/L) to remove naphthenic acids (NAs) from oil sands process-affected water (OSPW); limits its application and feasibility in the OSPW remediation. To decrease the required doses and their associated costs, this study examined the application of ozone (O3) and peroxone (hydrogen peroxide/ozone; H2O2:O3) processes for the treatment of OSPW using mild oxidant doses (i.e., ozone doses of 30 and 50 mg/L and H2O2 doses of 10, 11 and 20 mg/L). The performance of both processes was compared in terms of structure reactivity of NAs, the dominant pathways for removal, the kinetics of individual NA species and variation of compositions and abundance of species before and after treatment. To attain/ensure better characterization for the contaminants of concern (NAs) in water samples, the initial phase of this research encompassed examining two different analytical methods (Fourier transform infrared (FTIR) spectroscopy and ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOFMS)) with different extraction/pre-treatment methods for samples; liquid-liquid extraction (LLE) and solid-phase extraction (SPE). A correlation between these methods was developed to implement the best techniques available for sample analysis. The results after examining groundwater and OSPW samples showed higher recovery of classical and oxidized NAs or (Ox-NAs) and naphthenic acid fraction compounds (NAFCs) for SPE compared to LLE, regardless the water source and quantification methods (i.e., FTIR and UPLC-TOFMS). However, higher abundance for classical NAs (O2-NAs) was found in LLE than SPE (e.g., OSPW samples: (63.1±2.1%) versus (58.5±3.0%)). A strong correlation was observed between the UPLC-TOFMS and FTIR which highlights the possibility of using FTIR and Fluka as a standard with LLE pretreated samples as an affordable substitute to the high resolution techniques (e.g. UPLC-TOFMS). In the second phase of this research, the structure reactivity and reaction pathways during ozonation and peroxone treatment were investigated. Suppressing the hydroxyl radical (•OH) pathway by adding the scavenger tert-butyl alcohol did significantly reduce the degradation in all treatments, while molecular ozone contribution was 50% and 35% for O2-NAs and Ox-NAs, respectively. Structure reactivity was observed with a degradation increase for both O2-NAs and Ox-NAs with the increase of both carbon (n) and hydrogen deficiency (i.e., |-Z| numbers, double bond equivalent (DBE)) for all treatments. The variations in the compositions of treated water were evaluated using two different high resolution mass spectrometry methods; UPLC-TOFMS and Fourier transform ion cyclotron resonance. Assessing two markers (O2S:O3S:O4S and O2:O4 ratios) revealed changes and similarities of the peroxone treated water (i.e., 20 mg/L H2O2: 50 mg/L O3 at 1:2 ratio) to natural waters. Both ratios decreased from 2.7:4.8:2.1 and 3.59 in raw OSPW to 0:1.4:0.5 and 0.7, respectively, becoming close to the reported ratios in natural waters. Although peroxone (1:2) 20+50 (i.e., 20 mg/L H2O2: 50 mg/L O3) and 50 mg/L ozone were the two most effective treatments to degrade O2-NAs and Ox-NAs (e.g., for O2-NAs: 86% and 84%, respectively) as well as to reduce the toxicity toward Vibrio fischeri (40% and 50%, respectively), the fastest kinetics treatments were observed at peroxone (1:1) 20+30 (i.e., 20 mg/L H2O2: 30 mg/L O3) and 30 mg/L ozone (i.e., reaction rate constant of 0.236 min-1 and 0.251 min-1, respectively). The increase of the DBE increased the reaction rate constant, specifically at DBE = 7-9 with similar values at DBE =3-6. With respect to in vitro assays, while the highest production of nitrite (i.e., attributed as the lowest toxicity effects on the goldfish primary kidney macrophages) was observed in peroxone (1:2) 11+30 (i.e., 11 mg/L H2O2: 30 mg/L O3) followed by peroxone (1:3) 10+50 (i.e., 10 mg/L H2O2: 50 mg/L O3), their O2-NA degradation was the lowest, 47% and 61%, respectively. The residual toxic effects after different ozone and peroxone processes, suggest that part of OSPW toxicity may be caused by specific compounds of NAs (i.e., similar reduction (50%) was achieved in both toxicity and abundance in O2 species with carbon 15-26) and/or generated by-products (e.g., O3S classes at DBE = 4 and C9H12O2 at DBE = 4). Although by-products were generated, slight enhancement in the biodegradability and the reduction of chemical oxygen demand was achieved in peroxone at 1:2 ratio compared to ozone, suggesting the possibility of using combined OSPW remediation approaches (i.e., peroxone coupled with biological process).

• Subjects / Keywords

  • Degradation
  • Advanced Oxidation Processes
  • Characterization of Water
  • Naphthenic Acids
  • Peroxone
  • Oil sands process-affected water
  • Ozone

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3BV7B86V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.