[Purification and characterization of nano Al13 species in polyaluminum chloride]

The polynuclear Keggin species, Al12AlO4(OH)24(H2O)12(7+) (Al13), was firstly separated and purified from polyaluminum chloride (PAC) by the ultra-filtration and column chromatography method. The Al13 yield was characterized by Al-Ferron timed complexation spectrophotometry, 27Al-NMR, TEM and ZATESIZER 3000HSA. The results showed that the purified sample by the ultrafiltration method influenced by membrane pore radius and the concentration of PAC solution. High purity Al13 would be obtained by choosing appropriate membrane and concentration of PAC. When using the column chromatography method, the bigger molecules were eluated first, then the smaller ones. Al13 would be obtained by taking out the middle educt. From Al-Ferron timed complexation spectrophotometry, it was found that the obtained sample contained more than 90% and 100% of Al13 by using the two methods mentioned above respectively. The TEM and ZATESIZER 3000HSA results showed that Al13 was mainly aggregated as line type and branch type in B = 2.5 solution, and the size was about several decade and several hundred nm.