2012 Volume 53 Issue 12 Pages 2195-2199
The influence of polyethylenimine (PEI) dosage on the dispersibility of precipitated calcium carbonate (PCC) particles was systematically investigated. The results for the zeta potential of PCC particles and the viscosity and turbidity of PCC suspension showed that charge reversal (negative to positive) of PCC particles occurred as the PEI concentration increased due to the specific adsorption of PEI onto the surface of the particles. Additionally, increasing the PEI concentration up to 5 mg/kg led to the reduction of the zeta potential of the PCC particles (almost neutral) and consequently a decrease in the particle stability, which was consistent with Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction calculation results. However, the stability of the PCC particles gradually improved when the PEI concentration > 5 mg/kg. The trend was attributed to the enhancement of the electrostatic repulsive force between two interacting particles at low PEI concentration range (5 to 10 mg/kg). On the other hand, at high PEI concentration range (>10 mg/kg), it was found that additional repulsive forces (i.e., non-DLVO force) occurred between PEI-adsorbed PCC particles due to steric hindrance, consequently resulting in the improvement in the stability of the PCC suspension when the PEI concentration > 10 mg/kg.
