Control of size and adsorptive properties of spherical aluminum phosphate particles

The size of amorphous spherical aluminum phosphate particles was controlled by using urea and isopropylamine (IPA), and their texture was investigated by various means. The mean particle diameter (D-p) of the particles decreased with increasing urea concentration due to an acceleration in the precipitation reaction from decomposition of urea at elevated temperatures. The D-p decreased upon addition of IPA concentrations of up to 6 mol% to Al ions under a constant urea concentration, while D-p increased above this concentration because IPA produced electrolytes by reacting with HNO3; the electrolytes may reduce the range of Coulombic repulsion between charged primary particles. All the particles adsorbed selectively H2O molecules. IPA does not act as a template but operates as an effective additive for controlling particle size without altering the inner texture of spherical aluminum phosphate particles. (C) 1996 Academic Press, Inc.