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Volume 34 (1994 - 199･･･
- Issue 4 Pages 213-
- Issue 3 Pages 118-
- Issue 2 Pages 71-
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Volume 34, Issue 4
Displaying 1-4 of 4 articles from this issue
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Effect of Addition of Poly (vinyl alcohol)Yoshiaki GOTO, Masahide TAKAHASHI, KOZO ARAI1995 Volume 34 Issue 4 Pages 213-220
Published: March 28, 1995
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSSynthesis of zeolite Y was studied in the presence of poly (vinyl alcohol)(PVA). Zeolite Y crystals were obtained as a single phase in small and homogeneous size distribution. As compared with the PVA-free system, induction period considerably decreased, but the rate of crystallization slightly changed. These polymer effects were considered to be due to the increase in the viscosity of the reaction system in the nucleation step.View full abstractDownload PDF (4621K) -
Effect of Addition of Poly (vinyl pyrrolidone)Yoshiaki GOTO, Masahide TAKAHASHI, Masato YOSHIDA, Kozo ARAI1995 Volume 34 Issue 4 Pages 221-227
Published: March 28, 1995
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSSynthesis of zeolite Y was studied in the presence of poly (vinyl pyrrolidone)(PVP). With increasing reaction temperature, induction period considerably decreased, and the rate of crystallization increased. As compared with PVP-free system, the induction period decreased, but the rate of crystallization slightly changed. Difference in the molecular weight of the polymer used was independent of the rate of formation of zeolites. However, the viscosity of the reaction system containing polymer seems to effect greatly on nucleation. This suggests that there exists a preferable viscosity range for the formation of zeolite crystals. At various reaction steps, the number and size of zeolite crystals formed in amorphous materials were observed by scanning electron microscope. An important conclusion is that the rate of crystal growth is much faster than the production rate in the number of crystals. It is presumed, therefore, that the rate determining step is the reaction of active species with nuclei or microcrystallites. Apparent activation energy of the reaction was determined as 19.5 kcal/mol.View full abstractDownload PDF (2702K) -
Kinue TSUNEMATSU, Hiroshi TATEYAMA, Satoshi NISHIMURA1995 Volume 34 Issue 4 Pages 228-234
Published: March 28, 1995
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSThe thermal behavior of urea intercalated into kaolinite was investigated by changing the experimental conditions such as keeping temperature, keeping time, and atmosphere. The intercalation ratio is increased as with increasing the keeping time and temperature in the closed vessel. The decomposition temperature of the urea-kaoiinite compiex is lower than that of pure urea, which is found by TG-FTIR measurements. Some kinds of gases are generated simultaneously with the decomposition of the complex. The generated gases are NH3, CO2 and isocyan at around 190°C However in the case of pure urea there are two decomposition stages at 250°C and at 370°C. The gases generated at the first stage are NH3 and CO2, and that at the second stage is Only isocyan.
The difference between the decomposition of the urea-kaolinite compiex and that of pure urea was examined by IR spectrum anaiysis. The asymmetric and symmetric υ(NH2) stretching frequencies at 3504 and 3389cm-1 correspond to NH2 groups interacting with the oxygens located on the basal tetrahedral layer. Intercaiation of urea within the kaolinite structure increases the υ(CN) stretching frequency from 1468cm-1 for the urea to 1477cm-1 for intercalated moiecules. The υ(CO) stretching frequency in the urea-kaolinite compiex does not appear in the present experiment. The shift of the 1609cm-1 absorption to 1591cm-1 shows the interaction between the innersur-face OH and the amino groups through weak hydrogen bonding OH...NH2 These results indicate that the hydrogen bonding of urea molecuies intercaiated into the interlayer site of kaoiinite is weak as compared with the hydrogen bonding of pure urea molecules. Therefore the decomposition temperature of urea in the urea-kaolinite compiex seems to be lower than that of pure urea.View full abstractDownload PDF (775K) -
Formation of clay minerals in HNO3 solutionMotoharu KAWANO, Katsutoshi TOMITA1995 Volume 34 Issue 4 Pages 235-245
Published: March 28, 1995
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSExperimental syntheses of clay minerals from obsidian were performed in 0.001N and 0.001N HNO3 solutions at 150°C and 200°C for 1 to 60 days. Formation and transformation processes of the clay minerals during the reactions were examined by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, infrared absorption spectroscopy, and X-ray photoelectron spectroscopy. At 200°C reaction, a small amount of boehmite was formed at the early stage, and spherical kaolinite appeared and grew successively as reaction proceeded in 0.01N HNO3 solution. On the other hand, a flaky smectite was mainly formed in 0.001N HNO3 solution. At 150°C reaction, boehmite, allophane, spherical halloysite, and platy kaolinite were produced in both 0.01N and 0.001N HNO3 solutions. Based on a stability diagram for the system of Na2O-Al2O3-SiO2-H2O, it was found that the spherical and platy kaolinites and smectite were formed as a stable phase, whereas allophane and halloysite appeared as a metastable phase. In this paper, we discussed the following problems: 1) formation conditions of kaolinite and smectite, 2) formation conditions of spherical and platy kaolinites, and 3) formation conditions of kaolinite and halloysite.View full abstractDownload PDF (5294K)
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