化学処理による斜プチロル沸石系凝灰岩の物理化学的特性の変化 Ｉ 酸処理による影響

Abstract

The effect of acid treatment on some physico-chemical properties of clinoptilolite tuff from Futatsui, Akita Pref., was investigated by means of a powder method of X-ray diffraction, chemical analyses and measurement of gas adsorption. Aluminium was dissolved by acid treatment and consequently the ratio of silica to alumina increased as follows: 10.2-33.2 for the specimens treated with 0.01-5N-HCl solu. at 97-98°C, 11.2-18.7 for the specimens treated with 0.1-6N-H2SO4 solu. at 97-98°C and 10.3-14.1 for the specimens treated with 0.24-2.4N-HF solu. at room temperature. When aluminium dissolution ratios after treatments with HCl or H2SO4 solu. are below 12.% the intensities of X-ray diffraction 132 in clinoptilolite were not virturally changed. However they decreased gradually with the increase of aluminium removal at above 12%. When the aluminium dissolution ratios were 14, 25, 35, 52 and 71% after HCl treatment, the intensity of X-ray peak 132 of clinoptilolite decreased to 95, 86, 74, 59 and 33% respectively compared with that of original clinoptilolite tuff. Thus the progressive removal of aluminium from the frameworks resulted in the gradual collapse of clinoptilolite structure. Na+ and K+ were exchanged with H+ by the acid treatments, and a little Ca++ was exchanged but the exchange of Mg++ was not detected, hence H-riched clinoptilolite was obtained. The apparent diameter of small aperture in clinoptilolite was enlarged by the acid treatments and the amount adsorbed of C3H8 increased according to the enlargement of the diameter of small pore. However the amount of CH4 and CO2 decreased with the decrease of zeolite content by acid treatments, because they adsorb on both large and small pores in clinoptilolite.