Usage
  • 49 views
  • 106 downloads

Study of Thermoresponsive Hybrid Polymer for Oil Sands Applications

  • Author / Creator
    Ng, Jason K.H.
  • Many tailings treatment technologies rely on the use of water-soluble polyacrylamides (PAM) to flocculate fine solids. However, PAM-induced flocs are often loosely-structured and retain significant volume of water due to the hydrophilicity of PAM and fine clays in oil sands fine tailings. Thermoresponsive polymers and inorganic-organic hybrid polymers are both promising alternative flocculants to accelerate solids settling and improve sediment consolidation. As such, a multifunctional hybrid polymer (Al-NIPAM) was synthesized in this study by integrating inorganic Al(OH)3 colloidal particle into the organic molecular structure of poly(N-isopropylacrylamide) (poly(NIPAM)) for the flocculation of mature fine tailings (MFT) suspension. The hybrid polymer responded to temperature changes, with a lower critical solution temperature (LCST) transition from hydrophilic coils to hydrophobic globules close to poly(NIPAM). Zeta potential measurements showed that Al-NIPAM reduced the surface charges of fine solids in MFT, indicating polymer-particle adsorption interactions. The hybrid polymer exhibited charge selective adsorption in QCM-D with strong electrostatic attraction between the cationic Al(OH)3-core in hybrid polymer and the negatively-charged surface. Furthermore, the adsorbed Al-NIPAM polymer layer became dehydrated and collapsed upon heating. Results from the adsorption and conformation experiments provided a basis for the use of Al-NIPAM as a flocculant in oil sands tailings treatment, where the cationic Al(OH)3-cores in the hybrid molecules attract and bind negatively-charged fine clays while the poly(NIPAM) chains provide the thermal response for enhanced floc densification. Laboratory settling tests and FBRM experiments showed that Al-NIPAM outperformed poly(NIPAM) and its respective mixture blend of Al(OH)3 and poly(NIPAM) in flocculation of MFT suspension, producing larger and more shear-resistant flocs that lead to higher settling rate, clearer supernatant and better sediment consolidation due to synergism of the hybrid polymer structure. Furthermore, two settling temperatures were investigated: 21°C (below LCST) and 40°C (above LCST). At elevated temperature, the coil-globule transition of thermoresponsive polymers resulted in accelerated settling and improved consolidation due to floc densification and hydrophobic interaction. The potential effects of the hybrid Al-NIPAM on bitumen extraction were also studied. The hybrid polymer was interfacially-active at the model toluene-water interface due to the amphiphilic nature of poly(NIPAM). Preliminary results showed that Al-NIPAM increased the degree of bitumen liberation and reduced the induction time for bitumen-bubble attachment in the presence of fines. This study presented some insights on the potential benefits of thermoresponsive hybrid polymer for oil sands mining applications.

  • Subjects / Keywords
  • Graduation date
    2018-11
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/R36H4D63H
  • License
    Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.