Sorption Dynamics of Rare Metals into a Matrix-Type Microcapsule Containing an Organophosphorus Extractant
Advancing the chemical engineering fundamentals
Distillation, Absorption & Extraction (T2-10P)
Keywords: Microcapsule, Rare Metal, Sorption
Sorption Dynamics of Rare Metals into a Matrix-Type Microcapsule Containing an Organophosphorus Extractant
Kazuo Kondo1*, Michiaki Matsumoto1, and Eiji Kamio2
1 Dept. of Chemical Engineering and Materials Science, Doshisha University,
Tatara Miyakodani 1-3, Kyotanabe-shi, Kyoto 610-0321, Japan
2 Dept. of Environmental Chemistry and Materials, Okayama University,
Tsushima Naka 3-1-1, Okayama-shi, Okayama 700-8530, Japan
*E-mail address: kkondo@mail.doshisha.ac.jp
Keywords: Microcapsule, Rare Metal, Sorption
Solvent extraction method has been remarkably developed for a metal recovery and purification technique. In recent years, studies of novel metal recovery methods such as supported liquid membrane method, emulsion liquid membrane method and impregnated resin method using an extractant, which is conventionally used for solvent extraction system, have been carried out vigorously. These techniques have a large number of advantages as a metal recovery method from a dilute aqueous solution. In addition, these are also suitable techniques for the demand of recent environmental protection. Therefore, it is expected to make them fit for a practical use. Metal recovery system using supported liquid membrane was already investigated for a practical use. Impregnated resin method are also been investigated. However, it is hard to say that a valuable sorption dynamics model has been established.
In this study, sorption dynamics model for microcapsule system is derived. The investigated system is sorption of gallium and indium into a matrix type microcapsule containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA). The proposed model takes into account of both the complexation reaction of metal ion and EHPNA at the interface between aqueous bulk and EHPNA phase, which exists on the microcapsule surface, and the intraparticle diffusion of the formed metal-EHPNA complex. The proposed model describes the pH and the metal concentration dependencies on sorption behavior not using any fitting parameters. As a result, the sorption mechanism of metals into a microcapsule is estimated as follows: (1) diffusion of metal ion through the aqueous film surrounding a microcapsule, (2) complexation reaction of metal ion and extractant adsorbed on the interface, and (3) diffusion of the extracted complex into a microcapsule through the pore.
Presented Tuesday 18, 13:30 to 15:00, in session Distillation, Absorption & Extraction (T2-10P).
