Removal mechanism by magnetic components
With the magnetic field, NO3--N removal was 71.3%, while without magnetic field, NO3--N removal was 58.1% (Figure 8a). The mechanism of enhancing NO3--N removal under magnetic field was explored using MATLAB. When the distance between magnetic particles was constant, the greater the applied magnetic field intensity, the greater the interaction potential. Furthermore, the interaction potential between magnetic particles with magnetic field was five orders of magnitude higher than that without magnetic field (Figure 8b). Without magnetic field, the particle interactions are only vdW and electrostatic . With the applied magnetic field, an additional magnetic interaction is generated among magnetic particles34, which increases the total interaction potential. According to the collision efficiency formula and the classical flocculation model (SI), the higher the interaction potential, the higher the interparticle collision efficiency \(\alpha_{\text{ij}}\)and the coagulation efficiency.35 Therefore, the applied magnetic field can increase the interaction potential between particles, thereby enhancing the contaminant removal when using MHC.