Hydrolyzed Al(III) clusters: Speciation stability of nano-Al(13)

Abstract

Pure nano-Al(13) and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, (27)Al-NMR, photo correlation spectroscopy (PCS), and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al(13). The quantity of Al(b) species analyzed by ferron assay in the initial aging period corresponded well with that of Alp, which has been confirmed in a dimension range of 1-2 nm by PCS. Al(13) solutions at high concentrations (0.5-2.11 mol/L) were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al(13) basis on the (27)Al-NMR spectrum, whereas a part of Al(13) would still remain as Al(b). At low concentrations, Al(13) solution was quite stable at normal temperature, but lost its stability quickly when heating to 90 degrees C.