title: Coupled acoustic-gravity field for dynamic evaluation of ion exchange with a single resin bead.
abstract: A coupled acoustic-gravity field is efficient for entrapping a particle at the position determined by its acoustic properties rather than its size. This field has been applied to the dynamic observation of ion-exchange reactions occurring in a single resin bead. The replacement of counterions in an ion-exchange resin induces changes in its acoustic properties, such as density and compressibility. Therefore, we can visually trace the advancement of an ion-exchange reaction as a time change in the levitation position of a resin bead entrapped in the field. Cation-exchange reactions occurring in resin beads with diameters of 40-120 microm are typically completed within 100-200 s. Ion-exchange equilibrium or kinetics is often evaluated with off-line chemical analyses, which require a batch amount of ion exchangers. Measurements with a single resin particle allow us to evaluate ion-exchange dynamics and kinetics of ions including those that are difficult to measure by usual off-line analyses. The diffusion properties of ions in resins have been successfully evaluated from the time change in the levitation positions of resin beads.
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kanazaki
authors.forename: Shungo
authors.initials: S
authors.lastname: Hirawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Harada
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Okada