Abstract
A novel strategy for faster and better flocculation in solid-liquid separation processes is reported: the use of the natural polyelectrolyte chitosan (CH2500) in combination with the biocompatible thermosensitive polymer poly(N-vinylcaprolactam) (PNVCL). Silica dispersions (Aerosil OX50) were used as model and evaluated by means of analytical centrifuge, laser diffraction, and turbidimetry studies. Results show that the sedimentation velocity is doubled by addition of PNVCL and that at 45°C the density of the sediment is 33% higher, as compared to the use of CH2500 only. This results from the temperature sensitive behavior of PNVCL that phase-separate expelling water at temperatures higher than its LCST (32–34°C) leading to compaction of the flocs. By using this strategy the sediment is more compact, contains less water, and contains a very small amount of biodegradable CH2500 and biocompatible PNVCL.
Highlights
Solid-liquid separation through coagulation and flocculation is an important stage of many technological processes
We had studied the combination of CH2500 and PNVCL as flocculants for Aerosil OX50 dispersions, as a function of concentration of the polymers and temperature
The biodegradable polyelectrolyte chitosan in combination with the temperature
Summary
Solid-liquid separation through coagulation and flocculation is an important stage of many technological processes. In this work a novel strategy for a faster and better flocculation performance is reported: the use of natural polyelectrolytes like chitosan (CH2500) in combination with a biocompatible polymer that exhibit lower critical solution temperature (LCST) behavior in water, poly(N-vinylcaprolactam) (PNVCL). By this strategy we envision to speed up the flocculation process and to decrease the water content of the sediment by taking advantage of the hydrophilic to hydrophobic transition of a thermosensitive polymer by heating.
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