The Al₁₃ species were separated and purified with column chromatography method, precipitation with adding ethanol and acetone, and displacement method from a series of polyaluminum chloride solutions, which have the same Al₁₃ percentage but different total Al concentration. They were characterized by Al-Ferron timed complexation spectrophotometry, ²⁷Al NMR, TEM, SEM and Zetasizer 3000 HS_A. Coagulation efficiency was tested by Jar tests for Al₁₃, polyaluminum chloride and AlCl₃ in treating synthetic water samples. The results indicate that, the precipitation with adding ethanol and acetone method led to the best outcome compared to the other two methods: the biggest mean particle size of Al₁₃ species and the highest degree of polymerization. The experimental results by jar tests show that the Al₁₃ species was more positively charged and achieved the most turbidity removal results. Consequently, Al₁₃ species is the most effective polymeric Al species in water and wastewater treatment.

Key words: Al₁₃ species, separation and purification, coagulation efficiency, comparison