caa a22 4500 465743161 CHVBK 20180323111813.0 cr unu---uuuuu 170327e19900101xx s 000 0 eng 10.1007/BF02697343 doi (NATIONALLICENCE)springer-10.1007/BF02697343 A study on ion exchange mechanisms of zeolite NaA crystallites [Elektronische Daten] [Jeikwon Moon, Hanju Lee] The mechanism of Ca2+ ion exchange in zeolite NaA powders were studied with varying its crystal size. It was reasoned that the rate of ion exchange at corners and edges of a crystal would be faster than that al the center portion of each crystal face. Therefore, as the degree of ion exchange advances, the front of ion exchange will loose its sharp edges and approaches to a near spherical shape. To lake into account of this phenomenon in the analysis of experimental on exchange rates, rate equations for sphere and cube were combined together in the following form, which may be called as the transition model. 1 $$f_\tau (\phi ) = \frac{{F(\phi )}}{{\ln (\phi )}} = [1 - g(\theta )]f_c (\phi ) + g(\theta )f_s (\phi )$$ The transition time function, g(θ). was assumed to be expressed by g(θ) αθβ and Ihe constants were found to be α 2.79, β 0.43 in this experiment. Using the transition model equation, the ion exchange rate of zeolite NaA powders would be represented belter than either by Ihe spherical or the cubic model alone. Korean Institute of Chemical Engineering, 1990 Moon Jeikwon Department of Chemical Engineering, Yonsei University, Seoul, Korea aut Lee Hanju Department of Chemical Engineering, Yonsei University, Seoul, Korea aut Korean Journal of Chemical Engineering Springer-Verlag 7/1(1990-01-01), 61-68 0256-1115 7:1<61 1990 7 11814 https://doi.org/10.1007/BF02697343 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02697343 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Moon Jeikwon Department of Chemical Engineering, Yonsei University, Seoul, Korea aut NATIONALLICENCE 700 1- Lee Hanju Department of Chemical Engineering, Yonsei University, Seoul, Korea aut NATIONALLICENCE 773 0- Korean Journal of Chemical Engineering Springer-Verlag 7/1(1990-01-01), 61-68 0256-1115 7:1<61 1990 7 11814 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer