As exhibited in Fig. 3, the van der Waals force between the mixed surface and bubble is repulsive force, which increases with increas-ing of the amount of CaCO3 but decreases with decreasing of the amount of DnOP. The LW interaction between the mixed surfaceand bubble leads to hydrophobic attraction, whose value decreases significantly with increasing of the amount of CaCO3 but increases with increasing of the amount of DnOP. Under the effects of LW–ABinteractions, the addition of CaCO3 impairs the adhesion of bubble on the mixed surface, and thus reduces the flotability of plastic par-ticles, while the addition of DnOP enhances the adhesion of bubble on the mixed surface and thus improves the flotability of plastic particles.