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Keisuke Ohto - One of the best experts on this subject based on the ideXlab platform.

  • Allosteric effect of the first Lead Ion on stepwise extractIon of the second Lead Ion with p-t-butylcalix[5]arene pentacarboxylic acid derivative
    Tetrahedron Letters, 2010
    Co-Authors: Birendra Babu Adhikari, Keisuke Ohto, Manju Gurung, Hidetaka Kawakita
    Abstract:

    Abstract A calix[5]arene-based solvent extractIon reagent displaying very high selectivity for Lead has been prepared, one molecule of which extracts two Lead Ions in a stepwise manner. The first Pb 2+ Ion is bound to five phenoxy oxygen atoms inside the calixarene cavity due to which the ligand undergoes conformatIonal freezing in stable cone conformer. This causes positive allosteric effect for co-extractIon of the second Lead Ion due to the aggregatIon of functIonal groups.

  • AdsorptIon behavior of Lead Ion on calix[4]arene tetracarboxylic acid impregnated resin
    Separation Science and Technology, 2002
    Co-Authors: Keisuke Ohto, Sonki Inoue, Naoto Eguchi, Takaaki Shinohara, Katsutoshi Inoue
    Abstract:

    The resins impregnating calix[4]arene tetracarboxylic acid into XAD-7 has been prepared to investigate adsorptIon behavior of Lead Ion. The leakage of the impregnated reagent to an aqueous solutIon is found to be negligible. The sequence in the adsorptive selectivity series for divalent metal Ions on the present resin is as follows: This sequence is also the same with that of the extractive selectivity series of p-t-octylcalix[4]arene as an extractant. The other adsorptIon properties of the resin for metal Ions are similar to the extractive properties of the corresponding calix[4]arene tetracarboxylic acid. Maximum adsorptIon capacity of Lead Ion on the resin is found to be 0.33 mol kg−1. For endurance test, even in eight times repetitive experiment of adsorptIon followed by elutIon of Lead, the resin is devitalized and available for repeatability. Column chromatographic separatIon of Lead and zinc Ions as an industrial applicatIon is also carried out. Selective adsorptIon of trace amounts of Lead Ion ove...

  • stepwise extractIon of two Lead Ions with a single molecule of calix 4 arene tetracarboxylic acid
    Analytica Chimica Acta, 1999
    Co-Authors: Keisuke Ohto, Yuko Fujimoto, Katsutoshi Inoue
    Abstract:

    Solvent extractIon of metal Ions including Lead(II) with calix[4]arene tetracarboxylic acid was investigated. The selective extractIon behavior for Lead Ion was examined in detail. Two Lead Ions were found to be extracted with a single molecule of calix[4]arene derivative from the experimental results by Job's method, a loading test, and slope analysis of Lead concentratIon dependency. The extractIon data and the chemical shift of 1H-NMR for the extractant caused by the complexatIon with Lead supports the conclusIon that two Lead Ions are extracted stepwise. The extractIon behavior of Lead Ion with the monomeric derivative was also investigated to compare that with the cyclic tetramer. The stoichiometry of the complex formed by the monomeric derivative and Lead was found to be 2:1. SeparatIon and preconcentratIon of a trace amount of Lead Ion from a large excess of zinc Ion was also examined from an analytical point of view. The cyclic tetramer could achieve a successful separatIon of a trace amount of Lead Ion from an excess amount of zinc Ion. Stripping of loaded Lead from the cyclic tetramer Ion was also investigated. Complete stripping could be achieved by nitric acid at a concentratIon greater than 3 mol dm−3.

Katsutoshi Inoue - One of the best experts on this subject based on the ideXlab platform.

  • AdsorptIon behavior of Lead Ion on calix[4]arene tetracarboxylic acid impregnated resin
    Separation Science and Technology, 2002
    Co-Authors: Keisuke Ohto, Sonki Inoue, Naoto Eguchi, Takaaki Shinohara, Katsutoshi Inoue
    Abstract:

    The resins impregnating calix[4]arene tetracarboxylic acid into XAD-7 has been prepared to investigate adsorptIon behavior of Lead Ion. The leakage of the impregnated reagent to an aqueous solutIon is found to be negligible. The sequence in the adsorptive selectivity series for divalent metal Ions on the present resin is as follows: This sequence is also the same with that of the extractive selectivity series of p-t-octylcalix[4]arene as an extractant. The other adsorptIon properties of the resin for metal Ions are similar to the extractive properties of the corresponding calix[4]arene tetracarboxylic acid. Maximum adsorptIon capacity of Lead Ion on the resin is found to be 0.33 mol kg−1. For endurance test, even in eight times repetitive experiment of adsorptIon followed by elutIon of Lead, the resin is devitalized and available for repeatability. Column chromatographic separatIon of Lead and zinc Ions as an industrial applicatIon is also carried out. Selective adsorptIon of trace amounts of Lead Ion ove...

  • stepwise extractIon of two Lead Ions with a single molecule of calix 4 arene tetracarboxylic acid
    Analytica Chimica Acta, 1999
    Co-Authors: Keisuke Ohto, Yuko Fujimoto, Katsutoshi Inoue
    Abstract:

    Solvent extractIon of metal Ions including Lead(II) with calix[4]arene tetracarboxylic acid was investigated. The selective extractIon behavior for Lead Ion was examined in detail. Two Lead Ions were found to be extracted with a single molecule of calix[4]arene derivative from the experimental results by Job's method, a loading test, and slope analysis of Lead concentratIon dependency. The extractIon data and the chemical shift of 1H-NMR for the extractant caused by the complexatIon with Lead supports the conclusIon that two Lead Ions are extracted stepwise. The extractIon behavior of Lead Ion with the monomeric derivative was also investigated to compare that with the cyclic tetramer. The stoichiometry of the complex formed by the monomeric derivative and Lead was found to be 2:1. SeparatIon and preconcentratIon of a trace amount of Lead Ion from a large excess of zinc Ion was also examined from an analytical point of view. The cyclic tetramer could achieve a successful separatIon of a trace amount of Lead Ion from an excess amount of zinc Ion. Stripping of loaded Lead from the cyclic tetramer Ion was also investigated. Complete stripping could be achieved by nitric acid at a concentratIon greater than 3 mol dm−3.

Esmael Sanchooli - One of the best experts on this subject based on the ideXlab platform.

  • synthesis characterizatIon and removal of Lead from water samples using Lead Ion imprinted polymer
    Chemical Engineering Journal, 2011
    Co-Authors: Mostafa Khajeh, Zaman Shamohammadi Heidari, Esmael Sanchooli
    Abstract:

    Abstract In this work, several Lead-Ion imprinted polymers (Pb(II)-IIP) for pre-concentratIon and determinatIon of Lead by graphite furnace atomic absorptIon spectrometry were synthesized based on the batch solid phase extractIon. For this purpose, copolymerizatIon of Pb(II)–morin complex was performed using 4-vinylpyridine (VP), ethyleneglycoldimethacrylate (EDMA) and 2,2′-azobisisobutyronitrile (AIBN) as functIonal monomer, cross-linking agent and initiator, respectively. The polymer particles were characterized by FT-IR and X-ray diffractIon (XRD). The optimizatIon process was carried out using a two-level fractIonal factorial design and the Box–Behnken matrix. Four variables including pH, shaking time, mass of polymer and morin were selected as the factors affecting the optimizatIon process. The obtained results using the two-level fractIonal factorial design indicated that pH, mass of polymer and morin were statistically significant. Using the Box–Behnken design, the optimal conditIons for the extractIon of Lead were 6.1, 29.2 mg and 2.7 mg, for pH, mass of polymer and morin, respectively. Under the optimized conditIons, the detectIon limit of the proposed method was found to be 92 ng L −1 , while the relative standard deviatIon for 10 replicates was 4%.

Hidetaka Kawakita - One of the best experts on this subject based on the ideXlab platform.

Mostafa Khajeh - One of the best experts on this subject based on the ideXlab platform.

  • synthesis characterizatIon and removal of Lead from water samples using Lead Ion imprinted polymer
    Chemical Engineering Journal, 2011
    Co-Authors: Mostafa Khajeh, Zaman Shamohammadi Heidari, Esmael Sanchooli
    Abstract:

    Abstract In this work, several Lead-Ion imprinted polymers (Pb(II)-IIP) for pre-concentratIon and determinatIon of Lead by graphite furnace atomic absorptIon spectrometry were synthesized based on the batch solid phase extractIon. For this purpose, copolymerizatIon of Pb(II)–morin complex was performed using 4-vinylpyridine (VP), ethyleneglycoldimethacrylate (EDMA) and 2,2′-azobisisobutyronitrile (AIBN) as functIonal monomer, cross-linking agent and initiator, respectively. The polymer particles were characterized by FT-IR and X-ray diffractIon (XRD). The optimizatIon process was carried out using a two-level fractIonal factorial design and the Box–Behnken matrix. Four variables including pH, shaking time, mass of polymer and morin were selected as the factors affecting the optimizatIon process. The obtained results using the two-level fractIonal factorial design indicated that pH, mass of polymer and morin were statistically significant. Using the Box–Behnken design, the optimal conditIons for the extractIon of Lead were 6.1, 29.2 mg and 2.7 mg, for pH, mass of polymer and morin, respectively. Under the optimized conditIons, the detectIon limit of the proposed method was found to be 92 ng L −1 , while the relative standard deviatIon for 10 replicates was 4%.