Study of Polymers for Membrane and for Flocculation/Dewatering of Mature Fine Tailings

  • Author / Creator
  • This thesis is composed of two parts. The first part deals with the fabrication of antifouling membranes based on polyethersulfone (PES) and cellulose nanocrystals (CNC). PES/CNC nanocomposite membranes were prepared by non-solvent phase-inversion method. The effects of PES/CNC composition on membrane properties and performance were investigated. The contact angle and water content results revealed that the hydrophilicity of the membranes enhanced significantly by increasing the CNC content in the casting solution. The pure water flux was improved with an increase of CNC concentration up to 1.0 wt. %, and decreased with further addition of CNC in the casting solution up to 5.0 wt.%. Bovine serum albumin (BSA) rejection was also improved by increasing CNC content due to the formation of smaller pore size and thicker skin layer of the nanocomposite membranes. The antifouling property was significantly improved after blending CNC as quantified by measuring the flux recovery ratio, which can be attributed to the improved hydrophilicity. The second part of the thesis deals with the preparation of new temperature-responsive and cationic polymers for flocculation and dewatering of mature fine tailings (MFT). In this section, N-isopropylacrylamide (NIPAM) homopolymer and statistical copolymer of NIPAM and 2-aminoethyl methacrylamide hydrochloride, poly(AEMA-st-NIPAM), were synthesized by conventional free-radical polymerization for flocculation and dewatering of MFT. A mixture of polyNIPAM and cationic poly(AAm-st-DADMAC) was studied and the effects of mixture ratio, temperature and polymer dosage on MFT settling rate, supernatant turbidity, solid content and water recovery were evaluated to determine the flocculation performance. Temperature-responsive polyNIPAM can achieve high initial settling rates (ISR) and water recovery. However, the addition of only polyNIPAM cannot achieve high clarity of supernatant. The addition of both cationic poly(AAm-st-DADMAC) and polyNIPAM can improve significantly the clarity of supernatant. Enhanced solid content can be achieved by polyNIPAM when temperature decreased from 50 to 25 °C. Copolymer poly(AEMA-st-NIPAM) can improve both ISR and clarity of supernatant, while the secondary enhanced solid content is lower due to the strong electrostatic force between particles and AEMA, which is not affected by temperature. Dosing an optimum mixture ratio of polyNIPAM and poly(AAm-st-DADMAC) can improve ISR, clarity of supernatant, water recovery and solid content.

  • Subjects / Keywords
  • Graduation date
  • 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.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Chemical and Materials Engineering
  • Specialization
    • Chemical Engineering
  • Supervisor / co-supervisor and their department(s)
    • Thomas Thundat (Chemical and Materials Engineering)
    • Ravin Narain (Chemical and Materials Engineering)
  • Examining committee members and their departments
    • Hyun-Joong Chung (Chemical and Materials Engineering)