Lead compounds have legitimately been used in old PVC products as highly cost-effective heat stabilizers. After thorough risk assessments, they were phased out across Europe by 2015 but the long service life of many PVC products (e.g. window profiles) means they will be present in the waste stream for the coming decades as legacy additive. Very recently, Europe renewed its attention towards legacy additives with for example the Sustainable Products Initiative and the implementation of the European Chemical Strategy for Sustainability.
Within the REMADYL project, CENTEXBEL focuses on the removal of these lead compounds from End-Of-Life rigid PVC via solvent-liquid extractions with innovative green solvents. The main objective is to extract the lead compounds down to 0.1 wt% to comply with REACH regulations. To be able to have potential for future implementation by industry, this requires a scalable, cost-effective and CO2 efficient process.
In the first project period, different solvent classes with distinct solubility parameters have been screened for extraction efficiency of lead from rigid PVC. Key parameters such as extraction time, extraction temperature, PVC-to-solvent ratio and the PVC particle size have systematically been optimized. Extraction efficiencies up to 85% have been achieved (Figure 1).
Figure 1: Lead extraction efficiency for different green solvents (a) and PVC particle size (b).
Ongoing efforts are now dedicated to further increasing the obtained efficiencies, up-scaling the process to pilot scale, and evaluating the end-properties of the clean PVC closing the gap towards REACH compliant End-of-Life rigid PVC