Chitosan and mixtures with aqueous biocompatible temperature sensitive polymer as flocculants

A novel strategy for faster and better flocculation in solid-liquid separation processes is reported: the use of a natural polyelectrolyte (chitosan) in combination with a biocompatible thermosensitive polymer [poly(N-vinylcaprolactam) (PNVCL)]. Clay dispersions were used as model and evaluated by means of analytical centrifuge, laser diffraction, streaming potential and turbidimetry studies. Results show that at 45 degrees C the density of the sediment is up to 15% higher, as compared to the use of chitosan only. This results from the temperature sensitive behaviour of PNVCL that phase separate expelling water at temperatures higher than it's LCST (32-34 degrees C). By using this strategy the sediment is more compact, contains less water, and contains a very small amount of biodegradable chitosan and biocompatible PNVCL. (C) 2012 Elsevier B.V. All rights reserved.