Ion Exchange in Selected Low Rank Coals. Part II: Kinetics
- 1 January 1983
- journal article
- research article
- Published by Taylor & Francis in Solvent Extraction and Ion Exchange
- Vol. 1 (4) , 813-825
- https://doi.org/10.1080/07366298308918430
Abstract
The kinetics of ion exchange in a subbituminous coal have been investigated. The rate determining step in the exchange processes was determined to be intraparticle diffusion for particle sizes of 9,500 × 4,000 μm, 425 × 250 μm and 180 × 125 μm. The kinetics of exchange for the 180 × 125 μm particles was very rapid and approached film diffusion control. A relatively simple mathematical model developed by Helfferich (1) describe adequately ion exchange kinetics. The model was effective in predicting the extent of exchange as a function of time and the time required to reach complete exchange. Interdiffusion coefficients at 298 K obtained from the model for exchange of H for Na +, Mg2+and Ca2+ranged from 2.0 × 1010−6to 2.6 × 10−8cm2/s with the values decreasing in the order: $Keywords
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