Measuring the velocity profile of spinning particles and its impact on Cr(VI) sequestration

The evolution and development of magnetic nanoparticles (MNPs) are of great interest to researchers owing to their novel properties and wide-ranging applications. Essentially, MNPs coupled with magnetic fields (MF) have been used in biomedical separation, catalysis, cell separation, magnetic target drug delivery, hyperthermia, nucleic acid separation and wastewater treatment. In that regard, this paper reports the investigation of the sorption phenomena of chromium six (Cr(VI)) to MNPs interaction spun under the influence of alternating MF utilizing this unique particle shadow velocimetry technique. Under an alternating MF, the velocity field of spinning particles was observed to increase with magnetic field intensification. The determined mean velocity field for the spinning particles in the Cr(VI) solution increases from 0.0075-0.0125 m/s at a MF range of 16.54-25.54 mT. The rotating MF was observed to improve the magnetic force and torque induced on the particles, with particle aggregates reorienting with the magnetic moment of the field. The variability observed at the liquid-particle interface led to a fast mixing, with chaotic flow behaviour in the channel wall induced by the magnetic force observed. The induced cluster particle rotation and broad magnetic velocity distributions also led to cluster particle collisions hence the enhanced sorption process.