The chemical species distribution of aluminum in composite flocculants prepared from polyaluminum chloride (PAC) and polydimethyl-diallylammonium chloride (PDMDAAC)

In order to improve the coagulation/flocculation efficiency of polyaluminum chloride (PAC), a composite flocculant of PAC and polydimethyldiallylammonium chloride (PDMDAAC), or PAC-PDMDAAC, was prepared. The chemical species distribution of aluminum in PAC and PAC-PDMDAAC, which has a close relationship with their coagulation/flocculation performance, was investigated by Al-Ferron complexation timed spectrophotometry and Al-27-NMR. The factors affecting the chemical species of aluminum in PAC-PDMDAAC, such as the weight concentration of PDMDAAC (Wp), basicity (B) of PAC, and viscosity (eta) of PDMDAAC, were studied. The flocculation efficiencies of PAC-PDMDAAC, PAC and PDMDAAC were studied on a six-spindle multiple stirrer unit. The results showed that the aluminum species distribution in PAC-PDMDAAC depends on the Wp, B and eta value. When the B value is 1.5 and eta value is 1.22 dL/g, the composite flocculant with Wp = 15% gives highest Al-b and Al-13 contents, and its flocculation efficiency is highest in the test flocculations.