Separation and purification of nano-Al13 by UF method

In this paper, separation and purification of Al13 nano-species in polyaluminum chloride (PAC) solution using ultra-filtration (UF) method were investigated. The property of PAC with various PAC concentrations (0.05–0.5 mol/L Al(III)) and B (OH/Al ratio) values (1.0–2.5) was characterized by UF membrane. The influencing factors for separation and purification of Al13 during UF processing were discussed. The experimental results show that particle size distribution of PACs varies markedly with B value and total aluminum concentration under 3–6 kD molecular weight cut off (MWCO) membrane. The particle size of Al13 is close to the pore size of 1 kD MWCO membrane. The retention factor of UF membrane differs significantly with the Ala, Alb and Alc species (hydrolyzed speciation according to chemical ferron assay). By choosing the combination of 3 and 1 kD UF membrane, it is possible to separate and purify Al13. The operating pressure exhibits little effect on the selective separation of Al13 with other species, while it does decrease the separation time needed. High concentration of Al13 (about 1 mol/L) could be obtained with purity of more than 90%.