Methyl ethyl ketone (MEK) is a good solvent for polyvinyl chloride (PVC) and it has been proposed for use in PVC recycling. In the recycling process, fine particles of 3PbO·PbSO₄·H₂O, used as a thermal stabilizer in PVC products, are dispersed and not dissolved in the solvent. To establish methods for removing of 3PbO·PbSO₄·H₂O particles from the solvent, factors affecting the dispersion-flocculation behavior of the particles in MEK were investigated.
The zeta potential and particle distribution of 3PbO·PbSO₄·H₂O particles in MEK solutions containing known amounts of H₂O were measured. Above 5 vol%H₂O in MEK solutions, the zeta potential of 3PbO·PbSO₄·H₂O particles approached zero and the flocculation of particles was achieved. In addition, it was found that Pb²⁺ and Cl⁻ affect the zeta potential of the particles. These results indicate that the dispersion-flocculation behavior of lead particles can be influenced by the concentration of H₂O, Pb²⁺, and Cl⁻ in MEK.