title: Temperature- and pH-Responsive Benzoboroxole-Based Polymers for Flocculation and Enhanced Dewatering of Fine Particle Suspensions.
abstract: Random copolymers based on N-isopropylacrylamide (NIPAAm) containing 2-aminoethyl methacrylamide hydrochloride (AEMA) and 5-methacrylamido-1,2-benzoboroxole (MAAmBo) were synthesized and subsequently evaluated for their performance in solid-liquid separation at various pH and temperatures. The strong interactions between benzoboroxole residues and kaolin hydroxyl groups were evaluated for the first time in the flocculation of fine particle suspensions. The lower critical solution temperatures (LCSTs) of PAMN decreases because of the hydrophobic nature of the benzoboroxole moieties, resulting in strong hydrophobic interaction at temperatures higher than the LCSTs. Temperature and pH responsive polymer, P(AEMA51-st-MAAmBo76-st-NIPAM381) (denoted as PAMN) shows the ability to induce fastest settling at a low dosage of 25 ppm and under the condition of pH 9 and 50 °C. The accelerated settling rate is considered to be due to the strong adhesion of benzoboroxole residues to the kaolin hydroxyl groups, the electrical double layer force, and the hydrophobic force. During condensation phase, increasing the pH of sediment to pH 11 could attain the most compact structure. Random copolymers containing benzoboroxole groups act as dispersants (due to pH-responsive character) rather than flocculants at pH 11, providing repulsive force that enables particles to rearrange their position and consolidate well. Through a two-step solid-liquid separation including settling phase and consolidation phase, rapid settling and compact sediment are feasible simultaneously.
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta , 116 Street and 85 Avenue, Edmonton, Alberta T6G 2G6, Canada.
authors.forename: Han
authors.initials: H
authors.lastname: Lu
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta , 116 Street and 85 Avenue, Edmonton, Alberta T6G 2G6, Canada.
authors.forename: Yinan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta , 116 Street and 85 Avenue, Edmonton, Alberta T6G 2G6, Canada.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kotsuchibashi
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta , 116 Street and 85 Avenue, Edmonton, Alberta T6G 2G6, Canada.
authors.forename: Ravin
authors.initials: R
authors.lastname: Narain
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta , 116 Street and 85 Avenue, Edmonton, Alberta T6G 2G6, Canada.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Zeng
keywords: NIPAAm; benzoboroxole; consolidation; flocculation; pH responsive; polymerization