Temperature responsive flocculation and solid-liquid separations with charged random copolymers of poly(N-isopropyl acrylamide)

Abstract

Temperature-responsive random copolymers based on poly(N-isopropyl acrylamide) (PNIPAM) with 15. mol% of either acrylic acid or dimethylaminoethyl acrylate quaternary chloride were prepared. The effect of the charge and its sign were investigated in the solid-liquid separation of silica and alumina mineral suspensions. The results were compared to PNIPAM homopolymer of similar molecular weight. PNIPAM copolymers of the same charge as the particles (co-ionic PNIPAM) act as dispersants at both 25 °C and 50 °C. Flocculation occurs when counter-ionic PNIPAM facilitates selective aggregation and rapid sedimentation of minerals at both 25 °C and 50 °C. Adsorption and desorption studies showed that..