Design, Synthesis, Characterization of a new pH-Responsive Copolymer and its Application in Oil Sands Tailings Treatment

Abstract

This research aims at treating mature fine tailings (MFT) with a novel pH-responsive copolymer poly (N,N-dimethylaminoethyl methacrylate-co-acrylamide-co-acrylic acid) p(DMAEMA-co-AM-co-AA). Compared with conventional polyacrylamide (PAM), the conformation and property of this novel copolymer can be switched by pH variation, enhancing the compaction of settled/flocculated tailings furthermore. The copolymer was synthesized with 16, 20 and 24 hours respectively. The characterization, by mass spectrometry, Fourier Transform Infrared spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), turbidity and viscosity measurements, of this novel copolymer were conducted. Mechanism of conformational change by pH-switching was proposed. The flocculation of this copolymer was investigated to determine the optimal dosage. Moreover, the compaction of settled/flocculated tailings was achieved by changing the pH due to the change of conformation. Initial settling rate, supernatant turbidity, solid content, yield stress and water drainage of the sediment were examined to study the optimal condition of pH-responsive flocculant for treating MFT. QCM-D was used to study the adsorption of this copolymer on the silica surface and the copolymer’s conformational change at varied pHs.