Wet synthesis of carbonated hydroxyapatite

Carbonated hydroxyapatite of predominant B-type of substitution has been synthesized at various temperatures, carbonate concentrations and time of immersion in mother solution. Carbonated hydroxyapatite synthesized at 80 °C contains the largest amount (up to 9 wt.%) of calcite impurity and has a low specific surface area (40 m2/g). Lowering the synthesis temperature to 20 °C leads to a slight decrease in the content of calcite impurity (up to 5–7 wt.%) and an increase in the specific surface up to 125 m2/g. The introduction of the maturation stage for carbonated hydroxyapatite precipitated at 20 °C for 4 days suppresses the calcite impurity formation and leads to the increase in the specific surface up to 155 m2/g.

Phenomena of crystal splitting during growth as a result of the Sternberg-Punin and Rebinder effects

The causes of growth blocking, splitting, twisting of crystals are considered. These phenomena are the result of the combined effect of the Punin effect (total autodeformation due to intersectorial heterometry, appearing when impurities are unequally captured by different faces or their parts) and the Rehbinder effect (a sharp decrease in the strength of the surface layer of a growing crystal several times covered by a film of mother solution containing active substances).

Preparation of Al2O3 from the Nepheline Ore of Nanjiang County, Sichuan Province of China

Crystalline alumina samples with Al2O3 content of 95.23 wt.% were prepared directly from the nepheline ore in Nanjiang county, Sichuan province of China. Four steps were involved in the experiment of alumina preparation, including calcination, dissolution, carbonation and re-calcination. Lime was used in the calcination process with the nepheline concentrates powders to generate soluble aluminates and insoluble silicates. NaOH solution was used as the mother solution in the dissolution process. CO2 was introduced into the solution to precipitate the Al (OH)3 precursor, which was then fired to obtain crystalline alumina. Among the crystalline alumina obtained three phases of crystals existed which were detected by XRD and SEM, including δ-Al2O3 as the major phase, while θ-Al2O3 and κ-Al2O3 as the minor phases. Various crystal phases of alumina could be ascribed to the purity and crystal structure of precursor, as well as the re-calcination temperature and time.

CONVERSION OF THE LOW QUALITY INDONESIAN NATURALLY-OCCURRING MINERALS INTO SELECTIVE TYPE OF ZEOLITES BY SEED-ASSISTED SYNTHESIS METHOD

An X-ray diffraction (XRD) revealed that Indonesian naturally-occurring mineral from Nanggung, Bogor shows to be a low quality product as it does not seem to contain any zeolite materials. As located in the volcanic area, Indonesia essentially has abundant source of natural zeolites and the country has put much efforts on these treasured materials for export commodity. In order to bring the local natural mineral into high value and to discover whether the mineral has at least zeolitic fragments, we have implemented seed-assisted synthesis to see the possibility of growing zeolite and turn this mineral into high quality. In principle, once the mineral has zeolitic fragment or nuclei, recrystallization of the mineral may occur. By utilizing this mineral as seed in aluminosilicate mother solution, selective mordenite-type (MOR) zeolite can be obtained after hydrothermal treatment. Characterization by XRD showed that this MOR zeolite has high crystallinity and scanning electron microscopy (SEM) depicted the crystal morphology. The natural mineral is conclusively essential for the formation of MOR zeolite by seeding the aluminosilicate mother solution. In the absence of aluminosilicate mother solution, natural mineral can be recrystallized into selective analcime-type (ANA) zeolite. MOR zeolite is known to be useful for several applications such as catalysis whereas ANA zeolite has been considered to be less potential due to relatively small microporosity.

Radionuclide of Process of Carbon Decomposition and Anneal of Liquor after Desilication from Nepheline

Carbon decomposition of liquor afger desilication from nephine was investigated, aluminium oxide was prepard by anneal of Al (OH)3 separated out from carbon decompositon, and analysis of radionuclide of both above process was performed. The results show decomposition rate of sodium aluminate can be obtained when experiments of carbon decomposition of liquor after desilication using CO2 of hight concentration, and it is beneifit for the crystal growth of Al (OH)3, filtration and separation. Great mass of nuclide exists in the mother solution of carbon decomposition, and few into Al (OH)3, which could be regarded as wiout radioactive contamination. .