Abstract
Hydrated alumina gel was synthesized by the homogeneous precipitation method from urea and aluminum salts, and the influence of anions in the aqueous solutions on the hydrated alumina gel was investigated by the continuous measurement of pH, the powder X-ray diffraction analysis and the microscopic observation.
When an aluminum sulfate was used, a superior filterable granular substance was obtained. On the other hand when an aluminum chloride or an aluminum nitrate was used, an inferior filterable gel-like substance was obtained, and the pH value of the precipitation obtained was about 4 in the former case and about 7 in the latter.
These products were confirmed by the microscopic observation that the granular substance has a globular form, while the gel-like substance was an indefinite form. Both gel-like and granular substance were amorphous according to the X-ray diffraction analysis.
From these results it was made clear that the hydrated alumina gels synthesized by the homogeneous precipitation method have different properties depending on the starting materials.
