The basal spacings of the homoionic (Na⁺, K⁺ and Ca2⁺) montmorillonite (T1) and saponite (SapCa-1) were examined by X-ray powder diffraction (XRD) analysis under the atmospheres of relative humidity (RH). RH was controlled by ReCX (Relative humidity Control system for X-ray diffractometer) precisely in the range of 0 to 100% RH.
The variations of basal spacing were almost similar in both minerals at the range of 0 to 80% RH. However, noticeable differences between the hydration state of T1 and SapCa-1 were observed at 100% RH. It was explained that the differences were caused by charge localization and hydroxyl orientation in silicate layer because of these specimens having similar layer charge.
In the region between 2 hydration states, irrational and asymmetrical reflections were observed. These reflections indicated interstratified structure of 2 hydration states. Especially at 60% RH, that the segregation structure was recognized. The existence of 2 phases indicates that there is heterogeneity in its charge density of layer.

View full abstract

pH-and concentration-dependency of the adsorption of 16 phenolic acids on the three different type clay minerals, allophane (amorphous), halloysite (1: 1 type layer silicate) and illite (2: 1 type layer silicate), were investigated by batch method. Both the equilibrium pHs and concentrations were not kept constant. In order to compare the amount of adsorption at a defined pH and concentration, the two-dimensional.C^k interpolation and the linearly multiple regression equation were applied.
Three types of adsorption characteristics were observed relating to the pH-dependency. A-type showed the maximal adsorption in the region of pH 5 to 7. B-type showed the adsorption decreasing with pH increase. C-type showed the adsorption increasing with pH increase. The two-dimensional C^k interpolation was not applicable in the extrapolate region but applicable in the intrapolate region. The relationship among the amount of adsorption (n:μM/g), equilibrium pH and concentration (C: M) was represented by the following equation:
log (n)=a pH+b log (C)+c pHxlog(C)+d pH²+e
where a, b, c, d and e were the inherent constants applied between a phenolic acids and a clay minerals.

View full abstract

Beidellite occurs from pyrophyllite deposit at the Sano mine, Kakuma, Nagano Prefecture. The chemical analysis, X-ray diffraction, thermal analysis and electron microscopy were performed. It has similar mineralogical properties to the Blak Jack Mine beidellite. Expansibility of the mineral shows small variation in expansibility depending on the chemical composition.

View full abstract

Ammonium-bearing dioctahedral mica was found in an argillized vein in the hydrothermally altered andesite from the Aira district, Kagoshima Prefecture. X-ray, thermal and infrared absorption data agree with those of ammonium-bearing micas studied earlier. However the hkl reflections from x-ray analysis and a doublet band due to the Si-O vibration in infrared absorption spectra after heating at 700°C indicate that the specimen belongs to 2M₁ polytype. The unit cell parameters are a₀=5.16 (2)Å, b₀=9.02 (2)Å, c₀=20.28 (7)Å and β=96.36°. Chemical analysis of the mineral shows a structural formula of ((NH₄) _0.20K_0.51Na_0.18Ca_0.00)(Al_1.89Ti_0.00Fe³⁺_0.03Mg_0.06)(Si_3.25Al_0.75) O₁₀ (OH) ₂, and the specimen is relatively rich in sodium, and has a larger total layer charge than that of ammonium-bearing micas reported so far.

View full abstract

Allophane was converted into type-A zeolite by the treatment with NaOH aqueous solutions of the concentrations of 1-5 N. The+ conversion process was analyzed by the measurements of the adsorption of NH⁺₄, PO^3-₄ and methylene blue to the products separated in the course the treatment. The conversion process can be divided into five successive reaction steps;(1) dissolution of alumina-rich surface, (2) development of a new surface, (3) formation of zeolite precursor, (4) formation of type-A zeolite and (5) conversion of type-A zeolite to hydroxysodalite.

View full abstract

The synthesis of Al, Fe-ferrierite solid solution was carried out at 150°C using tetramethylammonium hydroxide as a template, and the continuous solid solutions in the range of 0.55 to 1.00 for Fe₂O₃/(Al₂O₃+Fe₂O₃) molar fraction of gel was obtained. The Al end-member was also synthesized, but in the range between 0 and 0.55 for Fe₂O₃/(Al₂O₃+Fe₂O₃) molar fraction of gel a small amount of mordenite coexisted with ferrierite. The Fe end-member contained a minute quantity of alumina which came from alumina present in a silica source, and hence the solid solutions were contaminated with the impurity. They show pale brown color, and do not contain ferrous ions.
Two kinds of crystal habits were observed in the solid solution: one is platy crystals and the other spherical aggregates of radiating blades. The lattice constants a, b and c of the solid solutions increased with increasing Fe content due to the difference between ionic radii of Fe³⁺ and Al³⁺, and the a-axis varied markedly. The lattice constants a, b and c for the Al and Fe end-members are 19.04, 14.19 and 7.53Å, and 19.20, 14.23, 7.55Å, respectively.

View full abstract