Particle Growth with Oscillatory Zoning and Other Novel Structures in Gel

• Zhang Yan Lin

  Department of Chemistry and Chemical Engineering, Yamagata University, Japan

• Shioi Akihisa

  Department of Chemistry and Chemical Engineering, Yamagata University, Japan

Abstract

Oscillatory zoning of solid solution of (Ba,Sr)SO₄ was investigated in gelatin. Then, Ba²⁺ and Sr²⁺ diffused into gelatin, and SO₄^2- also diffused into opposite direction. Periodic change of molar ratio Ba²⁺/Sr²⁺, which was firstly found out by Putnis et al., was well reproduced. For elucidation of the details, we investigated effects of gelation time and gelatin concentration on the structure and chemical inhomogeneity of particles. Experiments with 12%-gelatin gave results that core portion of solid solution was composed of BaSO₄, which was easily expected by the thermodynamics. However, we were able to make various kinds of particles with novel structures by controlling gelation time and gelatin concentration. As an example, solid solution in which the core portion was mainly composed of SrSO₄ was obtained. Further, different structures of particles were successfully made in separated zone in gelatin. Then, white turbid zones were clearly separated by a transparent gel. Fine particles with peculiar physical structures were also obtained. These particles were formed spontaneously without special operations. This was achieved by a reaction-diffusion kinetics. Gelation time and gelatin concentration controlled the diffusion rate mainly, which induced dramatic change in particle growth process in gel. However, the diffusion rate cannot explain all of their effects on particle structures and the chemical inhomogeneity Based on these findings, we discussed the mechanism of oscillatory zoning and proposed a new approach for formation of particles with novel fine structures in a single chemical process.

Journal

• Asian Pacific Confederation of Chemical Engineering congress program and abstracts

  Asian Pacific Confederation of Chemical Engineering congress program and abstracts 2004 (0), 626-626, 2004

  The Society of Chemical Engineers, Japan

Keywords

• oscillatory zoning
• particle growth
• reaction-diffusion in gel

Details

• CRID: 1390001205730517248
• NII Article ID: 130005052692
• DOI: 10.11491/apcche.2004.0.626.0
• Text Lang: en
• Data Source:
  • JaLC
  • CiNii Articles
• Abstract License Flag: Disallowed