Demonstration of solid-liquid separations using recycled supernatant that contains temperature-responsive polymer

Abstract

The effective use of recycled supernatant that contains temperature-responsive fl occulant is demonstrated for solid-liquid separations. The recyclability of poly(N-isopropylacrylamide) (PNIPAM) of several different molecular weights and a 15 per cent negatively charged derivative are compared. Batch settling tests of a-alumina suspensions are fi rst conducted at 50°C, with a subsequent 25°C period, after which the supernatant is harvested and used to fl occulate subsequent suspensions. Using this procedure consecutive separations are obtained with the repeated recycling of uncharged PNIPAM containing supernatant. Batch settling tests indicate that hindered settling rates increase with molec..