The role of polyaluminum chloride in kaolinite aggregation in the sequent coagulation and flocculation process

The role of polyaluminum chloride (PAC) in kaolinite aggregation is studied in this paper by the aggregation of kaolinite with the single and combined use of PAC and polyethylene oxide (PEO). The sequent coagulation and flocculation pattern with the combined use of PAC and PEO shows higher aggregation efficiency than that with the single use of PAC or PEO. In the sequent coagulation and flocculation pattern, the settling velocity and the Zeta potential of kaolinite steadily increase with the PAC concentration, which indicates that the role of PAC is to render the interaction between kaolinite and PEO rather than charge neutralization. This conclusion is supported by the X-ray photoelectron spectroscopy analysis, which shows steady increase of Al-OH group on kaolinite with the PAC concentration.