Effect of amplitude and frequency of ultrasonic irradiation on morphological characteristics control of calcium carbonate.
We have previously reported on the morphological control of calcium carbonate by changing synthetic conditions such as temperature, pH and degree of supersaturation in liquid reaction. The present study reports the effect of amplitude and frequency of ultrasonic irradiation on the particle size of calcium carbonate using a horn type ultrasonic apparatus at two different frequencies. The calcium carbonate precipitated by mechanical stirring had a particle size of about 20mum. By contrast, the particle size of vaterite formed under ultrasonic irradiation was about 2mum, with a specific surface area of 25-30m(2)/g. The major polymorph of calcium carbonate formed by ultrasonic irradiation was vaterite with some calcite present. For 40kHz ultrasonic irradiation, the specific surface area of the calcium carbonate increased with increasing amplitude. The particle size of vaterite formed at this frequency was about 2mum, and its distribution was sharper than that obtained at 20kHz. The mode diameter of the synthesized vaterite was found to decrease with increasing amplitude at 40kHz.
Kojima
Yoshiyuki
Y
Department of Materials and Applied Chemistry, Faculty of Science and Engineering, Nihon University, 8, Kanda-Surugadai 1-Chome, Chiyoda-ku, Tokyo 101-8308, Japan. ykojima@chem.cst.nihon-u.ac.jp
Yamaguchi
Kohei
K
Nishimiya
Nobuyuki
N