Multifunctional CO₂‐switchable polymers for the flocculation of oil sands tailings

Abstract

A series of multifunctional homopolymer and copolymer of 2‐dimethylamino ethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAM) were designed and used to flocculate oil sands mature fine tailings (MFTs). Carbon dioxide (CO2) protonated the tertiary amine groups of P(DMAEMA) and P(DMAEMA–NIPAM) making their chains positively charged. The pH sensitivity of these polymers favored the flocculation of the negatively charged clays in MFT due to charge neutralization. Three different polymers, P(DMAEMA), P(NIPAM33–DMAEMA67), and P(NIPAM67–DMAEMA33) were synthesized via aqueous free‐radical polymerization and used to flocculate MFT in the presence of CO2. Experimentally, CO2 was introduced in the system in three different ways: (1) CO2 was first bubbled into polymer solution, then the polymer solution was added to MFT, (2) CO2 was first bubbled into MFT and then the CO2‐free polymer solution was added to MFT, and (3) both polymers and MFT were bubbled with CO2 separately, then mixed together. We compared the effects of the method of CO2 addition, copolymer composition, and polymer molecular weight on MFT flocculation performance. Our results indicate that CO2‐switchable polymers can be employed to enhance the dewatering of challenging wastewaters such as oil sands tailings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47578.

Exploring Alternatives to Polyacrylamide: A Comparative Study of Novel Polymers in the Flocculation and Dewatering of Iron Ore Tailings

“…After an optimal dosage, typically covering 50% of the particle surface, the polymer molecules start hindering bridge formation (overdosing), which results in smaller flocs that settle more slowly. In addition, steric repulsions between polymer chains may stabilize the suspension [34,[51][52][53]. A similar effect was observed for PAM1, where ISR increased up to 3000 ppm, but unlike PAM2, reached a plateau.…”

Flocculation Efficiency and Spatial Distribution of Water in Oil Sands Tailings Flocculated with a Partially Hydrophobic Graft Copolymer

“…Recent studies on PAM modification involve the addition of hydrophobic groups to increase dewatering rates. − Partially hydrophobic flocculants, including UV-initiated, , thermosensitive, , CO 2 responsive, and pH-responsive polymers, have been studied. Although most of them flocculated and dewatered tailings well, they are hard to scale up .…”

Evaluation of a Novel Polymeric Flocculant for Enhanced Water Recovery of Mature Fine Tailings

“…While these PAM-based flocculants are effective at inducing initial settling, the MFT aggregates formed are susceptible to higher levels of water retention, resulting in sediment that is less-closely packed [3,9,[13][14][15]19]. To improve the densification of MFT over extended periods, partially hydrophobic polymers have been developed [12,16,[20][21][22]. However, these generally require an external trigger such as heat or added chemicals, making them more energy intensive to implement on an industrial scale [12].…”