Hiroshi Kakizaki

University of Tsukuba, Tsukuba, Ibaraki, Japan

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Publications (5)9.17 Total impact

  • Katsumi Chikama · Hiroshi Kakizaki · Kiyoharu Nakatani
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    ABSTRACT: The sorption and desorption processes of a pesticide between a single octadecylsilyl (ODS)-silica gel microparticle and the surrounding water phase were kinetically analyzed by absorption microspectroscopy combined with a single microparticle injection method. 2-Amino-3-chloro-1,4-naphthoquinone (quinoclamine) sorbed into the microparticle was completely desorbed into the water phase, and both the sorption and desorption processes could be analyzed by the intraparticle diffusion model. 5-Dipropylamino-α,α,α-trifluoro-4,6-dinitro-o-toluidine (prodiamine) sorbed into the microparticle partially remained for the desorption process. These results are discussed in terms of pore/surface diffusion and adsorption of the pesticide on ODS and silanolate groups in the pores of the ODS-silica gel.
    Colloids and Surfaces A Physicochemical and Engineering Aspects 02/2008; 315(1-3):250-253. DOI:10.1016/j.colsurfa.2007.08.007 · 2.75 Impact Factor
  • Hiroshi Kakizaki · Chiaki Aonuma · Kiyoharu Nakatani
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    ABSTRACT: The sorption of bromophenol blue or anthracene-9-carboxylic acid as a weak acid into single octadecylsilyl (ODS)-silica gel microparticles in a solution was analyzed by microcapillary injection-manipulation and absorption microspectroscopy. The distribution ratio and the sorption rate were highly dependent on the pH of the solution. These results are discussed in terms of the acid dissociation/association, distribution between the ODS and solution phases, and intraparticle diffusion of the weak acid in the nanometer-sized pores of the ODS-silica gel.
    Journal of Colloid and Interface Science 04/2007; 307(1):166-71. DOI:10.1016/j.jcis.2006.11.007 · 3.37 Impact Factor
  • Hiroshi KAKIZAKI · Kiyoharu NAKATANI
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    ABSTRACT: The sorption of phenol blue (PB), known as a solvatochromic dye, from an alcohol (methanol, ethanol, butanol or pentanol)-water mixture solvent into single spherical octadecylsilyl (ODS)silica gel microparticles {particle diameter (d) of 20 similar to 60 mu m, pore diameter of 12 nm} was investigated by absorption microspectroscopy. For similar to 0.5 vol% pentanol, similar to 0.5 vol% butanol or I vol% ethanol, the adsorption coefficient of PB in a single microparticle (K-ads), determined on the basis of the Langmuir isotherm, was much smaller than that for water although the relative permittivity of the mixture solvent was almost the same as that of water. Furthermore, the absorption maximum of PB in the microparticle (lambda(max)) for the mixture solvent was slightly shifted from that for water. For 1 vol% methanol, both lambda(max) and K-ads did not change compared with those for water. The results showed that for a mixture solvent of pentanol, butanol or ethanol the microscopic polarity in the ODS phase was larger and the polarity and hydrogen bonding in the vicinity of the ODS/solution interface were smaller than those for water because the alcohol molecules with the long alkyl chain length distributed in the ODS phase. Concerning the volume percentage of alcohol greater than similar to 5 vol%, on the other hand, lambda(max) and K-ads significantly decreased with the increasing volume percentage of alcohol, revealing a decrease in the relative permittivity of the mixture solvent as well as changes in the microscopic polarity and hydrogen bonding.
    Bunseki kagaku 06/2005; 54(6):479-483. DOI:10.2116/bunsekikagaku.54.479 · 0.27 Impact Factor
  • Kiyoharu Nakatani · Yoshiyuki Kobayashi · Hiroshi Kakizaki
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    ABSTRACT: The distribution of anthracene-9-carboxylic acid across dibutyl phthalate/gelatin-membrane/water interface of a single microcapsule was analyzed using microcapillary manipulation and microabsorption methods. The partitioning ratio and the distribution rate in the microcapsule/water system were measured for various pH values in the water phase. Results were compared with those in the dibutyl phthalate/water system in the absence of the gelatin membrane. The distribution rate could be analyzed on the basis of a first-order type reaction. The observed rate constant was linearly proportional to the inverse of the microcapsule radius, indicating that the distribution rate is limited by interfacial mass transfer. Analysis of the pH dependence of the interfacial mass transfer rate suggests that the mass transfer of the neutral species of anthracene-9-carboxylic acid (AnH) competes with the ion transfer of the dissociated species (An-) at the liquid/liquid interface in the gelatin membrane of the microcapsule.
    Analytical Sciences 12/2004; 20(11):1529-32. DOI:10.2116/analsci.20.1529 · 1.39 Impact Factor
  • Kiyoharu Nakatani · Hiroshi Kakizaki
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    ABSTRACT: Intraparticle mass transfer processes of Phenol Blue (PB) in single octadecylsilyl (ODS)-silica gel microparticles in acetonitrile-water were analyzed by microcapillary manipulation and microabsorption methods. An absorption maximum of PB, the sorption isotherm parameters, and the sorption rate in the microparticle system were highly dependent on the percentage of acetonitrile in solution. The results are discussed in terms of the microscopic polarity surrounding PB in the ODS phase and the relationship between the isotherm parameters and the sorption rate.
    Analytical Sciences 09/2003; 19(8):1211-3. DOI:10.2116/analsci.19.1211 · 1.39 Impact Factor