ZVI-loaded Biochar Composite for Effective Peroxymonosulfate Activation: Application in the Removal of Naphthenic Acids from Real Oil Sands Process Water

  • Author / Creator
    Vasquez Aldana, Adriana Marcela
  • Oil Sands Process Water (OSPW) is a byproduct generated during the extraction of bitumen from oil sands deposits in Northern Alberta, Canada. This matrix presents a critical environmental and industrial challenge due to its toxic nature, primarily associated with its complex mixture of contaminants, notably naphthenic acids (NAs). Consequently, significant efforts have been directed toward developing efficient treatment methods for the remediation and reclamation of OSPW. This thesis investigates for the first time the synergetic effect of coupling peroxymonosulfate (PMS) with a zero-valent iron (ZVI)-loaded biochar (FL600-Fe) derived from pyrolyzed flax straw (FL600-Fe) as a promising method for the efficient degradation of NAs in real OSPW.
    Characterization techniques demonstrated the successful incorporation of ZVI particles into the biochar, magnetization properties, and a suitable zeta potential value that helps in the generation of reactive oxygen species due to a positive surface charge. Following adsorption equilibrium experiments and optimal experimental parameters analyses, results indicated that the FL600-Fe/PMS system exhibited a 93.9% degradation efficiency of classical NAs (O2-NAs) after 120 min using a catalyst and oxidant dose of 1 g L–1 and 1 mM, respectively. The radicals responsible for the degradation of NAs were identified as •OH, SO4•– and O2•– using quenching experiments and electron paramagnetic resonance spectroscopy. The toxicity was evaluated through a 21-hour microbial viability assay, demonstrating a remarkable increase of over 80% in bacterial growth post-treatment. The concentration of bioavailable acid extractable organics that contribute to toxicity in OSPW was reduced by over 70% post-treatment. Furthermore, leaching tests confirmed the stability of the composite biochar, as hardly any iron leaching was detected.
    These results suggest that the FL600-Fe/PMS system has high environmental compatibility due to no secondary contamination associated with iron leaching during treatment and toxicity reduction, demonstrating its potential for the treatment of a matrix with a complex chemical composition like OSPW. Additionally, the feedstock used for the composite is a sustainable and renewable material produced from agricultural waste, which makes it a sustainable, cost-effective, and environmentally friendly process for OSPW reclamation.

  • Subjects / Keywords
  • Graduation date
    Spring 2024
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • 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.