Influence on the magnetic field on the scale formation in a microfluidic channel under a low Reynolds number flow

Abstract

This study presents an external magnetic array to rapidly investigate the calcium carbonate formation in a microfluidic channel. The system comprises a copper coil capillary serving as the heat exchanger, a high-precision thermostatic water tank, a magnetic drive pump, and an external magnetic array. Various factors were considered during the experiment, including different concentrations (3 mM and 10 mM) of the test solution, magnetic treatment efficiency (magnet length 4.0 cm and 14.0 cm, treatment time 24 h and 72 h), and temperatures ranging from 25 ℃ to 50 ℃. The concentration of calcium ions, electrical conductivity, and pH value were measured to monitor subtle changes during water treatment. Additionally, particle size distribution and morphology of calcium carbonate were analyzed using SEM and XRD under various magnetic treatments. The experimental results revealed that (1) applying a magnetic field to the solution in a microfluidic channel under low Reynolds number flow led to a decrease in the particle size of calcium carbonate, (2) aragonite did not form in the microfluidic channel, and (3) the physicochemical properties of the solution remained unaltered by the magnetic treatment. Consequently, the reduction in particle size can prevent blockage in microchannels, providing an alternative solution to mitigate scaling issues in micro-heat exchangers.