| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1996: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
One of the important factors governing ion-exchange processes is diffusion of an ion in an ion-exchange resin (particle diffusion). Because of a lack of experimental methods, a direct observation of the particle diffusion process is very difficult. Recent progresses in spatially-resolved microspectroscopic techniques such as laser trapping-micro-spectroscopy have provided a powerful means to study various phenomena occurring in microparticles. Here we report direct observation of the particle diffusion process by using laser trapping-microspectroscopy and confocal fluorescence micro-spectroscopy techniques.
Two different methods were applied to determine concentration profiles of ionic dyes in single ion-exchange resins. One was confocal fluorescence microspectroscopy, which provided an information on fluorescence intensity profiles along 3D-axs. The fluorescence intensity profile of Rhodamine B (RhB) along the particle diameter, corresponding to the concentration profile of the dye in
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the resin, was measured. From the change in the profile during RhB diffusion, we determined the diffusion coefficient of RhB in the resin. An energy transfer quenching method was also applied. Initially, RhB was pre-adsorbed homogeneously on the ion-exchange resin. Then, Malachite green (MG) as an energy acceptor was adsorbed on the resin. Since MG diffuses from the resin surface to the inside, the RhB fluorescence is quenched only in a MG-diffused layr. The quenching efficiency corresponds to the volume ratio of the MG-diffused layr to the non-diffused layr in the resin, so that the value gives the penetration depth of MG in the resin. On the basis of the change in the fluorescence intensity of RhB during MG diffusion or that in the penetration depth, we determined directly the diffusion coefficient of MG in the ion-exchange resin.
The single-particles based spectroscopic techniques provide a useful information on the dynamic processes of the ion-exchange and can e further applied to study photochemical processes in single microparticles. Less
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