EFFECTS OF A MAGNETIC-FIELD ON THE FORMATION OF CACO3 PARTICLES

Characteristics of CaCO3 crystals formed by mixing CaCl2 and Na2CO3 solutions, which were exposed to magnetic fields before mixing, were investigated by measuring the variation of absorbance of suspensions of CaCO3 particles, observing sedimentary CaCO3 particles at the bottom of a cell by a video system, and analyzing the crystal structure of CaCO3 particles by X-ray diffractometer. It is found that (l) the nucleation frequency of CaCO3 particles is suppressed but the growth of particles is accelerated, if the exposed magnetic flux density is greater than about 0.3 T and the exposure time is greater than 10 min; (2) the magnetic effect is attributable mainly to the magnetic exposure on Na2CO3 solutions but not to that on CaCl2 solutions; (3) the magnetic effect was observed even if CaCl2 and Na2CO3 solutions were mixed at 120 h after the magnetic exposure; and (4) the formation of aragonite structure of CaCO3 crystals is accelerated by the magnetic exposure. © 1993 Academic Press, Inc.