CONTROL OF SIZE AND ADSORPTIVE PROPERTIES OF SPHERICAL ALUMINUM PHOSPHATE PARTICLES

The size of amorphous spherical aluminum phosphate particles was contr olled by using urea and isopropylamine (IPA), and their texture was in vestigated by various means. The mean particle diameter (D-p) of the p articles decreased with increasing urea concentration due to an accele ration in the precipitation reaction from decomposition of urea at ele vated temperatures. The D-p decreased upon addition of IPA concentrati ons of up to 6 mol% to Al ions under a constant urea concentration, wh ile D-p increased above this concentration because IPA produced electr olytes by reacting with HNO3; the electrolytes may reduce the range of Coulombic repulsion between charged primary particles. All the partic les adsorbed selectively H2O molecules. IPA does not act as a template but operates as an effective additive for controlling particle size w ithout altering the inner texture of spherical aluminum phosphate part icles. (C) 1996 Academic Press, Inc.