Adsorption of a lignosulphonate polymer onto PVC and PET surfaces: Evaluation by XPS

As part of the separation by froth flotation of PVC and PET from waste bott les before recycling, the adsorption mechanism of a lignosulphonate used to selectively render one of the plastics hydrophilic has been studied. As th e 'rest' method is not sufficiently sensitive for this purpose, X-ray Photo electron Spectroscopy analysis was conducted. A method of calculating the s urface coverage of both plastics by the reagent is proposed based on the fa ct that the lignosulphonate contains sulphur whereas PVC and PET do not. Th e results show that a greater quantity of lignosulphonate adsorbs on PET th an PVC, leading to a higher surface coverage of LS on PET. The surface cove rage values are a function of the lignosulphonate macromolecular configurat ion. For the sphere and film configurations hypothetised, the surface cover age values remain less than 1, which is consistent with the patchy adsorpti on assumed in the calculations. (C) 2001 Kluwer Academic Publishers.