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In a clinical situation, since membrane fouling often causes the reduction of solute removal performance of the dialyzer, it is necessary to evaluate the performance of the dialyzer, considering the effects of fouling even in aqueous in vitro experiments that are useful for the better design of dialyzers. We replicated the membrane fouling by immobilizing albumin on the membrane in a dialyzer using glutaraldehyde as a stabilizer. The modules of various membrane surface areas with and without replication of the fouling were used for performance evaluation of solute (creatinine, vitamin B12, and inulin) removal in dialysis experiments in vitro. Clearances for these solutes in the modules with fouling were lower than those without fouling. Furthermore, the smaller the surface area, the larger the fouling effect was observed in all solutes. Calculated pressure distribution in a module by using a mathematical model showed that the solute removal performance might be greatly affected by the rate of internal filtration that enhances the solute removal, especially for larger solutes. The increase in the rate of internal filtration should contribute to improving the solute removal performance of the dialyzer, with a higher effect in modules with a larger membrane surface area.

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We investigated the effects of particle concentration and an additive amount of a dispersant on the adsorption behavior of dispersant. Ammonium polycarboxylate, one of the typical polyelectrolyte was used as a dispersant in this study. Alumina slurries were prepared by changing the concentrations of both the particle and dispersant and kept in a test tube for at least 2 d. After that, the adsorbed dispersant amount was calculated from the residual dispersant concentration measured by a total organic carbon analyzer. It was found that the adsorbed dispersant amount strongly depends on the additive dispersant amount on the basis of the unit mass of particles in the slurry regardless of the particle concentration. It was also shown that polycarboxylic acid strongly absorbs onto an alumina surface and can not be desorbed by dilution, suggesting that its adsorption behavior differs from physical adsorption.

No abstract