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Title: Multicomponent liquid ion exchange with chabazite zeolites

In spite of the increasing commercial use of zeolites for binary and multicomponent sorption, the understanding of the basic mass-transfer processes associated with multicomponent zeolite ion-exchange systems is quite limited. This study was undertaken to evaluate Na-Ca-Mg-Cs-Sr ion exchange from an aqueous solution using a chabazite zeolite. Mass-transfer coefficients and equilibrium equations were determined from experimental batch-reactor data for single and multicomponent systems. The Langmuir isotherm was used to represent the equilibrium relationship for binary systems, and a modified Dubinin-Polyani model was used for the multicomponent systems. The experimental data indicate that diffusion through the microporous zeolite crystals is the primary diffusional resistance. Macropore diffusion also significantly contributes to the mass-transfer resistance. Various mass-transfer models were compared to the experimental data to determine mass-transfer coefficients. Effective diffusivities were obtained which accurately predicted experimental data using a variety of models. Only the model which accounts for micropore and macropore diffusion occurring in series accurately predicted multicomponent data using single-component diffusivities. Liquid and surface diffusion both contribute to macropore diffusion. Surface and micropore diffusivities were determined to be concentration dependent.
Authors:
; ;
Publication Date:
OSTI Identifier:
10191341
Report Number(s):
ORNL/TM--12403
ON: DE94001780; TRN: 93:024149
DOE Contract Number:
AC05-84OR21400
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Oct 1993
Research Org:
Oak Ridge National Lab., TN (United States)
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ION EXCHANGE; MASS TRANSFER; DIFFUSION; ZEOLITES; SODIUM; CALCIUM; MAGNESIUM; CESIUM; STRONTIUM; MICROSTRUCTURE; POROSITY 400105; SEPARATION PROCEDURES