Evaluation of Particle Dispersion and Aggregation State of Various Nano-Particle Suspensions by Osmotic-Pressure Measurement

摘要

要旨さまざまナノ粒子サスペンションの粒子分散状態を浸透圧測定によって評価した。ジルコニァサスペンションではpHを変化させる ことで異なる粒子分散状態のサスペンションを調製し，浸透圧および粒子径分布を測定した。アルミナ，シリカサスペンションでは イオン濃度を変化させることで異なる粒子分散状態のサスペンションを調製し，浸透圧および遠心分離後の粒子濃度を測定した。ィ ォン濃度の増加にともなつて電気二重層が圧縮され粒子が凝集したため，サスペンションの浸透圧は減少した。浸透圧と遠心分離後 の粒子濃度の間には良い相関があり，浸透圧測定法はとくに高粒子濃度のナノ粒子サスペンションにおける粒子分散状態の評価に有 効であると考えられる。%The particle-dispersion state of nano-particle suspensions was evaluated by measuring their osmotic pressure. Zirconia suspensions with different particle-dispersion states were prepared by adjusting the pH value of the suspension, and their osmotic pressure and particle-size distribution were measured. For alumina and silica suspensions, the ionic concentration was adjusted to change the particle-dispersion state, and their osmotic pressure and particle concentration after centrifugation were also measured. The osmotic pressure was found to decrease with an increase in the ionic concentration due to particle aggregation caused by compression of an electrical double layer. A good correlation between the osmotic pressure and particle concentration after centrifugation of the suspensions was exhibited; thus, we can conclude that the osmotic-pressure measurement would be a useful tool to characterise the particle-dispersion state, especially for dense nano-particle suspensions.