Acceleration of adsorption of heavy metal ion micelles onto iron/polyvinyltetrazole adsorbents with dielectrophoresis force under polarization

Abstract

Metal ions are eliminated from wastewater through absorbents via diffusion. To expedite the diffusion rate within a non-uniform electric field, an external dielectrophoresis force (FD) is introduced through frequency manipulation. Polyvinyltetrazole microadsorbents (FVTMs) incorporating iron elements are synthesized as adsorbents to bolster the FD's strength, which relies predominantly on the dielectric constants of the medium and particles. Cr(III), Cu(II), and Pb(II) are chosen to form micelles with surfactants as absorbates. These micelles (MIM) encapsulate Cr(III), Cu(II), and Pb(II) at concentrations ranging from 10 to 80 mmol L−1, driven towards the FVTMs by the attractive FD in the medium. In the absence of FD, for metal ion solutions at 80 mmol L−1, the removal ratios range from 28.6 to 32.6 % within 40 min, while in the presence of FD, the removal ratios reach the range of 89.6 to 92.3 %. The theoretical adsorption rate constants of MIMs onto the FVTMs under frequency polarization are enhanced approximately fivefold by the external FD generated at 5 V and 50 kHz. At a high frequency of 200 kHz, a repulsive FD is generated, reversing the adsorption and facilitating the recycling efficiency of FVTMs. As a result, FD can manipulate the adsorption rate with a particular frequency, enabling the removal of metal ions and the reuse of adsorbents. The FVTMs containing iron elements are reused up to 10 times under polarization switching frequencies between 50 and 200 kHz. This proposed platform introduces a novel methodology utilizing ferrous metal ion adsorbents for the rapid treatment of discharge.