Preparation Process for Fine Particles of Finely-Controlled Morphology using Emulsion as a Reaction Field

采用用于金属离子分离富集的W/O/W乳状液（乳状液膜）体系制备微细颗粒.稀土草酸盐球形微粒的制备稀土离子通过膜从外水相进入内水相，几乎所有的稀土、Ce-Yb和Y都得到了直径为200-600 nm的球形草酸盐微粒。稀土离子通过膜相传输的模拟表明，颗粒大小由每个水滴中草酸的量控制，也由稀土离子进入液滴的分布控制，这一点得到了实验证实。通过控制进料稀土浓度和内部水滴的大小来控制粒径是可行的.碳酸钙微粒的制备Ca ~（2+）被输送到含Ca ~（2+）的内部水滴中， ...更多信息 得到硼酸根离子和碳酸钙颗粒。采用冻融法对W/O乳状液进行破乳，得到了中空结构的微米级球文石颗粒。因此，通过使用W/O/W乳液体系，可以控制尺寸、形态以及晶体结构。在将磷酸根离子供给到内部液滴中的情况下，得到羟基磷灰石钙细颗粒。复合草酸盐颗粒的制备当二元金属离子进入外相时，预计可以通过控制离子通过膜相的传输来控制颗粒的精细结构。作为案例研究，制备了Sr-Pb草酸盐和Co或Ni铁氧体颗粒。作为前一种情况，得到含有精细分散的纳米尺寸的草酸铅的草酸锶颗粒。作为后一种情况，获得位于颗粒表面附近的含有草酸钴或草酸镍的针状草酸铁颗粒，并煅烧以得到钴铁氧体或镍铁氧体针状颗粒。少

W/O/W emulsion (emulsion liquid membrane) system, which has been used for separation and concentration of metal ions, was utilized for preparation of fine particles.1. Preparation of Spherical Fine Particles of Rare Earth OxalateRare earth ions were transported from the external water phase into the internal water phase through the membrane, and well-defined spherical oxalate particles of 200-600 nm in diameter were obtained for almost all rare earths, Ce-Yb and Y. A simulation for rare earth ion transport through the membrane phase revealed that the particle size was controlled by the quantity of oxalic acid in each water droplet and also by the distribution of rare earth ions into the droplets, and this was confirmed experimentally. The control of the particle size was feasible by control of the feed rare earth concentration and size of the internal water droplets.2. Preparation of Calcium Carbonate Fine ParticlesCa ions were transported into the internal water droplets containing ca … More rbonate ions, and calcium carbonate particles were obtained. When the W/O emulsion was demulsified by Freeze-thaw method, micrometer-sized vaterite particles of hollow structure were obtained. Thus, by using W/O/W emulsion system, size, morphology, and also crystal structure could be controlled. In the case where phosphate ions were fed into the internal droplets, calcium hydroxyapatite fine particles were obtained.3. Preparation of Composite Oxalate ParticlesWhen binary metal ions are fed into the external phase, fine structure of the particles is expected to be controlled by controlling the transport of the ions through the membrane phase. As case studies, Sr-Pb oxalate and Co or Ni ferrite particles were prepared. As the former case, Sr oxalate particles containing finely dispersed nanometer-sized Pb oxalate were obtained. As the latter case, acicular Fe oxalate particles containing Co or Ni oxalate located near the particle surface were obtained, and were calcined to give Co ferrite or Ni ferrite acicular particles. Less