[Purification of Al13 species in polyaluminum chloride (PAC) by column chromatography and the character of the fractions].

The polynuclear keggin species, Al12AlO4(OH)24(H2O)12(7+) (Al13), was separated and purified from polyaluminum chloride (PAC) by column chromatography method. The three fractions were characterized by Al-Ferron timed complexation spectrophotometry, TEM and ZATESIZER tester. Jar tests were performed to test the coagulation efficiency of the three fractions in treating synthetic or actual water samples. The results show that the sample purified by the column chromatography method influenced by the size of the species. The bigger molecules were eluted first, then the smaller ones. Al13 would be obtained by taking out the middle fraction. Compared with the other two fractions, the third fraction gives the best results for turbidity, humic acid and color removal, and achieves the highest charge-neutralizing ability. Al13 species is a higher positive-charged species and can be applied in a wide pH range, and it is much more steady in hydrolyzing process and most effective polymeric Al species in water and wastewater treatment.