Preparation and characterization of poly-silicic-cation coagulants by synchronous-polymerization and co-polymerization

Poly-silicic-cation coagulants (PSiCs) were prepared from industrial wastes such as fly ash, pyrite slag and wasted sulfuric acid by synchronous-polymerization and co-polymerization, and were denoted as PSiCs and PSiCc respectively. Their structures and morphologies were characterized and compared by X-ray diffraction (XRD), infrared spectra (IR), ultraviolet/visible absorption (UVA) scanning and microscopic imaging, and their coagulation performances were evaluated by papermaking wastewater treatment. The results show that new complexed compounds are formed in both PSiCs and PSiCc, but the polymerizations and conformations of Fe, Al and Si are different between the two coagulants. Compared with PSiCs, the contents of high polymers and ionic polymerized bonds are decreased obviously, and the cross-copolymerization between Fe(III) and Al(III) hydroxyl polymers disappeared in PSiCc. Morphologic analysis shows that PSiCc has fewer branch-like units than PSiCs, and coagulation experiments indicate that PSiCs exhibits higher coagulation efficiency in removing COD.