| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1993: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
Zirconium (IV) complexes with hydrophilic chelating polymer, -RZr (OH) _2, adsorbed fluoride ion in an acidic medium, which was desorbed in a weakly alkaline medium. Both reactions proceeded quite rapidly. The adsorption-desorption mechanisms were studied. Adsorption by an ion-exchange mechanism [formation of -RZr(OH) F] is predominant in a strongly acidic medium, whereas fluoride is adsorbed with a counter ion in a weakly acidic medium [formation of -RZr (OH) _2 F・K]. The adsorbed fluoride is released throught the formation of -RZr(OH) _3・K type complex, which regenerates the original polymer complex under the influence of an acid.
In a batch system, 10^<-4> mol dm^<-3> F^- was quantitatively adsorbed in the presence of halides, alkali and alkaline earth metal ions. Recovery for F^- less than 10^<-5> mol dm^<-3>, however, was not satisfactory. Using the flow adsorption system, the sufficient recovery was obtained even for 10^<-6> mol dm^<-3> F^-.
This preconcentration was applied to flow-injection spectrophotometry of fluoride to increase the tolerance limit of Al almost 10-fold. Similar adsorbents for other halide such as bromide and iodide were also studied.
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