Cu(II)アンミン水溶液の高温加水分解における晶析反応速度と球状CuO酸化物の粒子サイズの関係

抄録

In a previous paper, the present authors reported that the preparation of spherical fine CuO powders was achievable by applying hydrolysis method at elevated temperature to Cu(II) ammine solution.
Based on this finding, the effect of hydrolysis reaction rate on CuO particulate diameter was investigated in this study. It was elucidated that the precipitation of spherical CuO particulates proceeds according to a typical building up mode: super-saturation, nuclear formation and crystal growth.
Generally, the increase in NH₃ concentration, Cu(II) concentration under the constant ratio of [CuSO₄]⁄[Ammonia]=8.5, and (NH₄)₂SO₄ concentration at the constant ratio of [Ammonia]+2[(NH₄)₂SO₄]=1.7×10² mol·m⁻³ resulted in the decrease of crystallization rate. The concentration-dependence in crystallization rate was more sensitive at 353 K than 373 K. The apparent activation energy of 11.7 kJ·mol⁻¹ obtained in the temperature range 363∼378 K suggested mass transfer mechanism.
Mean diameter of CuO spherical particles and their size distribution increased with an increasing ammonia, CuSO₄ and (NH₄)₂SO₄ concentrations, on the contrary, the yield of CuO decreased. No differences of particle size were detected by the change of temperature from 353 to 373 K.
There existed a correlation among crystalliration rate, mean particle size and size distribution range when the temperature was kept constant. The increase in crystallization rate resulted in the decrease in particle size.