As part of the REMADYL project, AIMPLAS is currently studying the removal of lead stabilizers from End-of-Life PVC, using layered double hydroxide (LDH) scavenger complexes. The synthesis of this LDH complex was first optimized by the University of Valencia. The LDH complex should capture lead, after which it will be removed from the PVC via a continuous melt filtration process in an extruder.
After promising results in laboratory filtration trials, the pilot plant trials have begun. For this purpose, a model PVC formulation is being used, which is supplied by project partner DECEUNINCK.
The pilot plant filtering trials are being carried out in a counter-rotating twin-screw extruder, equipped with a screen changer, for a continuous filtration process. Pilot plant trials have also included the use of the LDH scavenger, to remove the lead from the PVC.
Counter-rotating twin-screw extruder used in pilot plant filtering trials
The first pilot plant filtration trials prove the feasibility of the continuous process, separating large quantities of LDH/Lead. Currently, a design of experiments is being prepared to optimize the scavenging process, including the use of co-stabilizers, to compensate for the de-stabilization caused by the lead removal.
Filtered PVC (left), and filter and filter residue (LDH/Lead) (right)