Water Science & Technology Vol 65 No 12 pp 2169–2174 © IWA Publishing 2012 doi:10.2166/wst.2012.110

Flocculation mechanism by a novel combined aluminum–ferrous–starch flocculant (CAFS)

Qintie Lin, Hanping Pan, Haoping Huang, Guoguang Liu and Guangcai Yin

A combined flocculant (CAFS) was prepared with Al₂(SO₄)₃·18H₂O, FeSO₄·7H₂O and starch. The flocculation mechanism of reactive brilliant red X-3B was studied. The results showed that CAFS was a cationic polymeric flocculant with high charge density, and its mesh starch chains grafted polyaluminum and polyferrous. At the preliminary stage, the main flocculation mechanism was adsorption and charge neutralization. At a later stage, the high molecular weight and flexible linear chains of CAFS initiated bridge-aggregation and sweep-flocculation. Moreover, the zeta potential and dynamic changes of flocs were closely related to flocculant dosages and the pH. The optimum dosage of CAFS and pH value were 0.990 mg/L and 5.0. Taken together, these results suggested CAFS as a novel flocculant in water treatment, with good results for the studied conditions.

Keywords: bridge-aggregation; charge neutralization; flocculation index; starch; sweep- flocculation; zeta potential

Full article (PDF Format)