The characterization and flocculation efficiency of composite flocculant iron salts–polydimethyldiallylammonium chloride

In this study, new composite flocculants were prepared from iron salts and polydimethyldiallylammonium chloride (PDMDAAC). The Fe(III) species and zeta potential of the composite poly-ferric chloride (PFC) and PDMDAAC flocculant (PFC–PDMDAAC) and PFC were measured by a timed complexation spectroscopy method and the Malvern Zetasizer 3000, respectively. The results showed that when PDMDAAC fraction (Wp) was 7.0%, PFC–PDMDAAC contained the smallest content of Fec and had the highest zeta potential. The flocculation efficiency of PFC–PDMDAAC and the composite FeCl3 and PDMDAAC flocculant (FeCl3–PDMDAAC) for treating actual surface water or wastewater samples was compared with that of FeCl3, PFC and PDMDAAC. The results showed that for surface water from Yellow River, PFC–PDMDAAC produced the highest flocculation efficiency, while for papermaking intermediate wastewater, the flocculation efficiency of FeCl3–PDMDAAC was the highest.