Abstract
Most of blood purification methods are grouped among separation process according to chemical engineering. This paper describes separation principles used for blood purification methods on the basis of chemical engineering. Separation process consists of three basic operations, mechanical separation, transport separation and diffusion separation. Mechanical separation suited for immiscible phases is used for plasma separation and blood cell separation. Transport separation and diffusion separation are well suited for homogeneous phases. Hemofiltration and hemodialysis are typical of transfer separation and of diffusion separation respectively. Solute transport through dialysis membranes is not caused only by diffusion, but also by filtration. So it is impossible to distinguish between three different modalities of hemodialysis, hemodiafiltration and hemofiltration. Adsorption operation is one of diffusion separation and also a typical modality of blood purifications. Adsorption operation had little been used for blood purifications because of several reasons. Recently, excellent selectivity of adsorption, especially immunoadsorption, is noted again. Toxin removal characteristics by blood purification methods depend on combination of three basic phenomena, diffusion, filtration and adsorption. To elucidate specifications of blood purification, to enable selectivity separation through affinities like immunoadsorption and to increase biocompatibility of separation media are very indispensable for further development of blood purifications.
