Effect of charge balance and dosage of polyelectrolyte complexes on the shear resistance of mineral floc strength and reversibility.

We evaluated the effect of polyelectrolyte complexes (PEC) with varying balance of charges on the flocculation of precipitated calcium carbonate (PCC) particles. PECs composed of polyacrylamides carrying opposite charges (A-PAM and C-PAM) were investigated in terms of PCC floc shear resistance and re-flocculation effects. Light transmission was used in real time to monitor the dynamics of flocculation under shear fields. Compared to the single polyelectrolytes, PECs greatly enhanced particle re-flocculation while minor differences in shear resistance were observed. Shear resistance and re-flocculation depended strongly on the molecular weight and charge ratio of the PEC components. In order to achieve floc stability and re-flocculation conditions a minimum concentration of charge-asymmetric PEC should be applied.