Poly(propylene imine) dendrimers as retention aid for the deposition of calcium carbonate on pulp fibres

The kinetics of deposition of calcium carbonate particles of about 2 mu m diameter has been studied with poly(propylene imine) dendrimers as retention agent. The adsorption process is shown to follow Langmuir kinetics. The measured kinetic parameters are of a similar magnitude to those found for poly(ethylene imine), as retention aid Since larger particles were used ii? this study the expected increase lit detachment rate was cancelled by a larger bond strength, caused by a higher charge density of the dendrimers. It is concluded that dendrimers are a somewhat better retention aid than poly(ethylene imine) for the retention of calcium carbonate.