Synthesis and characterization of polymeric inorganic coagulants for water treatment

This research explored the feasibility of preparing and utilizing preformed polymeric solution of Al(III) and Fe(III) as coagulants for water treatment. The differentiation and quantification of hydrolytic Al and Fe species in the coagulants were done by utilizing spectrophotometric method based on the interaction of Al or Fe with ferron as a complexing agent. In addition, 27A1-NMR, FT-IR, and powdered XRD were used to characterize the nature and structure of the hydrolytic species in these coagulants. The properties of the polyaluminum chloride (PAC1) and polymeric iron chloride (PIG) showed that the mass fractions of the maximum polymeric Al produced at r(OH/Al)=2.2 and Fe at r=1.5(OH/Fe) were 85% and 20% of the total aluminum and iron in solution, respectively. Coagulation tests were conducted under various coagulant dosages and pHs for each coagulant prepared. In case of PAC1 coagulants, a coagulation test on Nakdong river waters with three PACls (r=2.0, 2.2, 2.35) showed that the effectiveness of coagulation was in the order, r=2.2>2.0>2.35, corresponding to the order of polymeric aluminum contents. And, for the PIC1 coagulants, the PIC1 of r=1.5 was most effective for the removal of turbidity and TOC from the raw water. Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University.