As exhibited in Fig. 3, the van der Waals force between the mixedsurface and bubble is repulsive force, which increases with increas-ing of the amount of CaCO3but decreases with decreasing of theamount of DnOP. The LW interaction between the mixed surfaceand bubble leads to hydrophobic attraction, whose value decreasessignificantly with increasing of the amount of CaCO3but increaseswith increasing of the amount of DnOP. Under the effects of LW–ABinteractions, the addition of CaCO3impairs the adhesion of bubbleon the mixed surface, and thus reduces the flotability of plastic par-ticles, while the addition of DnOP enhances the adhesion of bubbleon the mixed surface and thus improves the flotability of plasticparticles.