Syunichi Oshima

Use of 8-sulfonamidoquinoline derivatives as chelate extraction reagents in ionic liquid extraction system.

Possible use of 8-sulfonamidoquinoline derivatives as chelate extraction reagents for solvent extraction of several divalent metal cations using an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) as extraction phase was investigated as fundamental approach to develop novel extraction reagents for ionic liquid extraction system. The studied reagents were able to be used as extractants for the metal cations in the [bmim][PF(6)] extraction system. Furthermore, their extractability in the [bmim][PF(6)] system was superior to that in chloroform system. Most of the extracted species were (hydrated) neutral complexes, whereas, in use of the derivative having trifluoromethyl group, Cd(2+) was extracted as anionic complex accompanied with anion-exchange process.

Adsorption Behavior of Cadmium(II) and Lead(II) on Mesoporous Silicate MCM-41

Abstract This investigation examines metal ion adsorption on mesoporous silicate, MCM‐41, synthesized from sodium silicate solution and cethyltrimethylammonium bromide (CTAB). MCM‐41 has potential as an adsorbent material, with a regular hexagonal pore structure, large specific surface area, and large pore volume. The MCM‐41 synthesized for this investigation is characterized using powder X‐ray diffraction and nitrogen adsorption and desorption isotherms data. The adsorption behavior for cadmium(II) and lead(II) onto MCM‐41 was studied by contacting the mesoporous silicate with an aqueous solution of metal salts and acetylacetone. Both Cd2+ and Pb2+ were found to quantitatively adsorb onto MCM‐41. The results of this study suggest that MCM‐41 may have applications in the recovery of toxic metals from waste waters.

Synthesis, characterization and evaluation of mesoporous silicates for adsorption of metal ions

Abstract —In this study mesoporous silicates MCM-41 and SBA-15 were investigated for their potential as metal ion-selective adsorbents. The greatest advantage of these materials is their large surface area, uniform pore size and controlled surface chemistry, and hence their potential for adsorption processes. The studies of the adsorption of transition metal ions onto MCM-41 examined the comparative adsorption behavior of Zn(II) and Cu(II), using acetylacetone (Hacac) as a chelating agent. The results showed that the MCM-41/Hacac system has potential as an ion-selective adsorbent material. However, due to the relatively small pore size and potential instability of MCM-41 when immersed in water for long time periods, a second mesoporous silicate, SBA-15, has been investigated. The SBA-15 was coated with octadecyltrichlorosilane (C18), and then loaded with a chelating agent (Cyanex 272) and assessed for its potential as an adsorbent material. The surface-modified SBA-15 has been found to have high metal ion selectivity and extractability, and hence good potential as an alternative to established solvent extraction systems.

Adsorption Behavior of Metal Ions with β-Diketone Type Chelating Agents Supported on Hydrophobized Mesoporous Silicate MCM-41

To investigate the adsorption behavior of metal ions with β-diketone type chelating agents, thenoyltrifluoroacetone (Htta) and benzoyltrifluoroacetone (Hbfa) supported on mesoporous silicate MCM-41 that has been hydrophobized (hMCM-41) using trimethylchlorosilane was synthesized. The hexagonally arranged pore structure of MCM-41 was not significantly changed by the hydrophobic treatment and attachment of chelating agents, although the pore size, pore volume and surface area were slightly smaller than those of untreated MCM-41 as a result of the chemical modification of the surface. The amount of chelating agents adsorbed on hMCM-41 was 0.47 for Htta and 0.33 mmol g for Hbfa, respectively. All metal ions examined, except for Cd, were quantitatively adsorbed on hMCM-41 as metal complex, M(tta)2 or M(bfa)2. The order of the adsorption selectivity of the metal ions was similar to the stability constants of metal ions with Htta or Hbfa. Furthermore, most of the metal ions adsorbed onto hMCM-41 at lower pH compared with the results of having used MCM-41 as a support of chelating agents. This suggests that the adsorption ability of metal ions with chelating agents was improved by the hydrophobic treatment of MCM-41.