Effect of the magnetic field on the growth rate of aragonite and the precipitation of CaCO3

A series of growth experiments of aragonite, which is a polymorph of calcium carbonate (CaCO3), were carried out in a fluidized-bed crystallizer under the influence of magnetic field. In the growth process, the solution properties, including relative supersaturation (σ), pH, ionic strength (I), and Ca2+ to CO32− activity ratio (R), were maintained almost constant in the growth process using an auto-titrator. Different types and intensities of magnetic field, including a permanent magnet (PM) and a commercial magnetic water treatment device (MWTD) with an effective intensity of 212.6 and 1800.0 G, respectively, were tested. The aragonite seed crystals did not grow without magnetization at room temperature, but did grow under the influence of the magnetic field. The magnetic field with a higher intensity developed its effect in a shorter time. Aragonite crystals grew faster in a lower pH environment, in which the growth of calcite was almost stopped in the presence of an MWTD. In addition, high levels of supersaturation and activity ratios far from unity favored aragonite growth. Finally, a possible mechanism was proposed to explain the effects of the magnetic field on the crystal growth of aragonite and calcite.