单一尺寸球形氢氧化铝颗粒的形成及其机理

用尿素均相沉淀法首次制得了单一尺寸的球形氢氧化铝颗粒。为获得单一尺寸的颗粒,需仔细控制沉淀过程:如温度、保温时间及Al~(3+)的浓度。在沉淀过程中通过对溶液pH值的测量,研究了单一尺寸颗粒的形成机制。氢氧化铝的成核极限仅达到一次,可形成单一尺寸的颗粒。相反,如溶液多次达到成核极限,则导致颗粒的多尺寸分布。另外,影响单一尺寸形成的因素尚有阴离子种类等。

FORMATION AND MECHANISM OF MONOSIZED SPHERICAL ALUMINUM HYDROXIDE PARTICLES BY HOMOGENEOUS PRECIPITATION

Monosized spherical aluminum hydroxide particles were first prepared by homogeneous precipitation using the urea method below its boiling temperature. To obtain monosized particles a careful control of temperature, holding time and concentration of Al~(2+) during the precipitation process is required. The formation chemistry of monosized particles is studied through the measurement of pH and concentration of Al~(2+) during precipitation. It is found that when the nucleation limit of aluminum hydroxide is reached only once, monosized particles can be formed; if the nucleation limit is attained more than once, a multisize particle distribution would appear. Other factors like types of an ons would also affect the formation of monosized particles. Monosized parti les can only be obtained with SO_4~(2-), not with NO_3~- or Cl~-.