Elucidation of Dynamics in Advanced Separation of Soft Colloid

近年来，诸如过滤、压榨、沉降和离心的颗粒-流体分离在诸如生物技术、生物质工业、功能性食品、生物医学、活生物体的多样化领域中变得被广泛接受。因此，对微生物、凝胶颗粒、乳状液、生物大分子、团聚颗粒等易变形、难分离的软胶体的先进分离技术的研究具有重要意义。以微生物、水凝胶、乳液为供试品，进行过滤、表达、沉降和离心。确定了对分离效果有重要影响的颗粒的分离行为、颗粒的变形特性以及颗粒的凝胶状聚集体（饼和沉积物）的性质。结果表明，滤饼和沉积物由软胶体组成，具有很高的压缩性。由于软质颗粒在固体压应力作用下发生变形，软质胶体的滤饼和沉淀物呈现出小于六方密堆积的无畸变球形的孔隙率。因此，优选在相对低的压力下进行软胶体的分离，因为压力的增加不一定导致分离性能的改善。这些研究结果为软胶体分离的优化操作设计和新型分离技术的开发提供了有价值的信息，并将对软胶体分离相关领域的发展做出重大贡献。

In recent years, particle-fluid separation such as filtration, expression, sedimentation and centrifugation is becoming widely accepted in such diversified fields as the biotechnology, biomass industry, functional food, biomedicine, living organism. Therefore, development of advanced separation technology for soft colloids such as microorganism, gel particle, emulsion, biomacromolecule, agglomerated particle, which are deformable and difficult-to-separate particles, is strongly desired.The main purpose of this research is to clarify the dynamics of separation of soft colloids. Filtration, expression, sedimentation and centrifugation were conducted using microorganism, hydrogel, emulsion as test sample. We have ascertained separation behaviors, deformation characteristic of particles and the properties of gelatinous aggregates of particles (cake and sediment) which had a significant influence on separating function. It was revealed that the filter cake and sediment composed of soft colloids have extremely high compressibility. It was also shown that the cake and sediment of soft colloids exhibited the porosity which was less than hexagonal close packing of undistorted spheres because of the deformation of the soft particles under the action of the solid compressive pressure. Consequently, it is preferred that separation of soft colloids is conducted under the relatively low pressure since the increase in the pressure does not necessarily lead to the improvement of the separation properties. These findings provide a valuable information for design of optimum operation and development of novel separation technology, and will be greatly contributed to advancement of diverse fields associated with separation of soft colloids.