化学処理によるモルデンフッ石系凝灰岩の物理化学的特性の変化 (第2報)

イオン交換処理による影響

抄録

The effect of cation exchange treatment on some physico-chemical properties of mordenite tuff was investigated by X-ray powder diffraction, chemical analyses, thermal analyses and gaschromatography. Mordenite tuff from Shirasawa, Miyagi-cho, Miyagi Pref., Japan was used as a starting material, from which Na-, K-, Ca-, NH₄-and Hmordenite were prepared by cation exchange treatment.
It was recognized that Na in the mordenite tuff was easily exchanged by other cations, however K was not exchanged easily, at the mild condition. The cation ratios of Na, K, Ca and NH₄ for Na-, K-, Ca-and NH₄-mordenite were 78, 94, 49 and 63 mole%, respectively.
The X-ray diffraction peak intensities of mordenite were affected by cation exchange and consequently the slight differences among the X-ray diffraction patterns for different cation exchanged mordenite were observed. The intensities of the main peak, mordenite (202) plane, relative to that (=100) of the original tuff, were 101, 78, 84, 106 and 105 for Na-, K-, Ca-, NH₄-and H-mordenite respectively.
The following sequence of thermal stability was found by DTA method in the cation exchanged mordenite: NH₄->H->K->Na> original tuff>Ca-mordenite.
Separations of hydrogen (or helum), argon, oxygen, nitrogen, krypton, methane and carbon monoxide were investigated using cation exchanged mordenite as column packings. Hydrogen (and/or helium), oxygen (and/or argon), nitrogen, krypton, methane and carbon monoxide were completely separated on the original tuff and Na-mordenite columns, but nitrogen, krypton and methane were eluted with overlap on the Ca-mordenite column. Methane and carbon monoxide were overlapped on the both NH₄-and K-mordenite columns. The values of the separation factor for nitrogen over oxygen, α, on NH₄-, H-and K-mordenite were 1.6, 1.8 and 2. 1, and were much smaller than those on original tuff (α=4.5), Na-(α=4.8) and Ca-mordenite (α=4.2) activated at 350°C.