Continuous Flow Low Gradient Magnetophoresis of Magnetic Nanoparticles: Separation Kinetic Modelling and Simulation

In recent years, magnetophoresis of magnetic nanoparticles (MNPs) has been emerged as one of the most appealing separation technologies in water treatment and biomedical applications. Magnetophoresis of MNPs can be further divided into two classes: high gradient magnetic separation (HGMS) and low gradient magnetic separation (LGMS). In the past decades, LGMS has been revealed to outperform HGMS in several aspects, such as simplicity, energy-saving and low cost. Therefore, in this work, we intend to extend the LGMS to continuous flow operation mode so that the wide implementation of this technology in the industry can be facilitated. Here, a mathematical model was developed to depict the kinetic of continuous flow LGMS (CF-LGMS) process by using poly(diallyldimethylammonium chloride) (PDDA)-coated MNPs with 64.4 nm core diameter and 107.4 nm hydrodynamic diameter (saturation magnetization = 71 Am2/kg) as the particle model system. By using this model, the effect of several critical design parameters on the separation efficiency was evaluated. According to our simulation result, it can be revealed that the separation efficiency of CF-LGMS is improved by performing the separation under low flowrate of MNP solution (~ 98.04% separation efficiency under low flow velocities of 5 and 10 mm/s) and high particle concentration (~ 98.04% separation efficiency under high particle concentration of 100, 500 and 1000 mg/L). Nevertheless, the magnetic field that is vertically symmetry will impose higher separation efficiency on the CF-LGMS, as compared to its asymmetry counterparts. Lastly, we performed a cost analysis on the batchwise (RM 22.19/h) as well as continuous flow magnetic separators (RM 37.47/h) and found that LGMS conducted under continuous flow mode is more economically friendly to be implemented in the real-time industry.