Formation of Calcium Carbonate under Permanent Magnetic Fields: Insights from X-Ray Scattering and Molecular Dynamics Simulations

Abstract

Abstract Electromagnetic treatment has been used in water desalination to control mineral scale formation and maximize membrane performance. However, the mechanism(s) by which external fields influence mineral scale formation remain poorly understood. This study used X-ray scattering combined with classical molecular dynamics simulations to investigate the effects of a permanent magnetic field on the formation of CaCO3 minerals. Wide-angle X-ray scattering results show that the presence of a constant magnetic field (∼1 T) favored the transition of vaterite to calcite. Small- and ultrasmall angle X-ray scattering showed that the magnetic field altered the kinetics of particle growth and the nature of the particle–particle interfaces. A permanent magnetic field changed the evolution of particle distributions by accelerating the loss of intermediate-sized particles. The MD simulation showed aggregation of [Ca-CO3]0 ion pairs into larger clusters. The largest clusters formed under a 1 T magnetic field over the time scale of ∼100 ns were consistently smaller than those formed without an external field. Overall, the results imply that a permanent magnetic field can impact the particle size distribution during the homogeneous nucleation and growth of CaCO3, thereby affecting the subsequent transition between different CaCO3 polymorphs.