Deposition of calcium carbonate particles on fiber surfaces induced by cationic polyelectrolyte and bentonite

The mechanism by which a two-component microparticle retention system, composed of cationic polyacrylamide (CPAM) and bentonite, operates was investigated by measuring the deposition of precipitated calcium carbonate (PCC) on fibers suspended in water. The results obtained by using varying amounts of polymer and bentonite indicate that CPAM by adsorbing on both the fiber and the PCC provides anchoring spots for bentonite. Thus, the bentonite acts as a bridge between fiber and PCC, and the tenacity of PCC attachment to fibers is stronger than a simple CPAM bridge. For optimum performance, a given ratio of CPAM and bentonite addition is required because in the presence of excess CPAM, the bridging ability of bentonite decreases.