SELECTIVE WETTING OF POLYMERS BY SURFACTANT ADSORPTION DURING FROTH FLOTATION

ABSTRACT

Different components of granulated plastic mixtures can be separated by froth flotation. This technique involves selective adherence of gas bubbles onto the particles to be separated. This requires a sufficient difference in the wettability of the particles. Since the overwhelming majority of plastics are hydrophobic by nature, separation by flotation necessitates selective wetting of the components. However, a comprehensive understanding of wetting phenomena involved has not been established thus far, so that the wetting action of surfactants during flotation cannot be predicted. As a consequence, selection of suitable wetting agents is essentially based on trial-error test work. However, the test work needed can largely be reduced by more insight into the wetting mechanisms involved which is the subject of the present work.