Study on PET Recovery from Polymeric Mixtures, Using the Floatation Technique, and Valorization of the Collected Particles by Dyeing Them

The aim of this study is to separate PET flakes by applying floatation technique, initially from binary polymer blends and later from the mixture of five common polymers such as polypropylene, polyethylene, poly(vinyl chloride), polstyrene and poly(ethylene terephthalate). A connection line between polymer and fiber is presumed in this study, because the dyeing of recovered polyester with three disperse dyes followed. The separation of plastics was performed in a Plexiglas air floatation column. The Lutensol ® TO 8 surfactant of non-ionic origin was used to selectively wet the plastics. The parameters studied were pH values, surfactant concentration and treatment time. The dyeing of the recovered PET was performed with Serilene Blue RL , Serisol Crimson ECF and Serisol Yellow ECF dyes at 90 °C, 110 °C, 130 °C and pH = 4.6. The results obtained showed a good separation of polyester from both the binary mixtures and the mixture of five polymers with a recovery rate of up to 95 ± 2%. The influence of pH and concentration of surfactant is significantly demonstrated, while the effect of the treatment time is considered negligible. Finally, recovered polyester showed very good dyeing properties with all three disperse dyes, since the color exhaustion rate reached approximately 95% for the temperature of 130 °C, which is the usual dyeing temperature of polyester.