Abstract: The polynuclear Keggin species, AlC₄Al₁₂(OH)₂₄(H₂O)₁₂⁷⁺(Al₁₃),was firstly separated and purified from polyaluminum chloride (P AC) by the precipitation method, which involved adding ethanol and acetone continuously to the PACsolution.The solid Al₁₃ obtained with excellent dissolubility was characterized by Al-Ferron timed complexation spectrophotometry, ²⁷A1 NMRspectroscopy, SEM, TEM and XRD.The results show that the components of PAC would be separated out in soluble sequence from low to high when ethanol and acetone were added continuously to the PACsolution, and that Al with a high purity would be obtained by taking out the middle precipitate.From Al-Ferron timed complexation spectrophotometry and ²⁷A1 NMR spectroscopy, it was found that the sample obtained contained more than 95% of Al₁₃.The SEM and TEM results showed that the small Al₁₃ aggregates were about 200 nm and the big one were about 2 um in diameter.The Aln aggregates were mainly polyhedron such as prism, monoclinic rectangle and tetrahedron in solid sample and showed a branch type in solution.In the XRD spectra, the signal of Al₁₃ appeared in the range of 2θfrom 5°to 25°

Key words: Al₁₃ species, Separation and purification, Characterization of morphology and structure, Polyaluminum chloride (PAC) (Ed.: M, G)