Filtering and continuously separating microplastics from water using electric field gradients formed electrochemically in the absence of buffer† † Electronic supplementary information (ESI) available: Solution conductivity calibration curve; numerical simulations of filtration experiment; micrograph showing the anodic reservoir during a pH indicator experiment; parametric sweep settings for filtration simulations; line plot of the simulated microplastic concentration along the whole domain during a filtration experiment; line plots showing the simulated electric field, ionic current density, and solution resistivity when the BPE is inactive during a filtration experiment; separation efficiency, numerical simulations of continuous separation experiment; simulated domain for continuous separations; parametric sweep settings for continuous separation simulations; simulated microplastic flux during a continuous separation; line plots showing the simulated electric field during a continuous

ABSTRACT: Here we use experiments and finite element simulations to investigate the electrokinetics within straight microchannels that contain a bipolar electrode and an unbuffered electrolyte solution. Our findings indicate that in the presence of a sufficiently high electric field, water electrolysis proceeds at the bipolar electrode and leads to variations in both solution conductivity and ionic current density along the length of the microchannel. The significance of this finding is twofold. First, the results indicate that both solution conductivity and ionic current density variations significantly contribute to yield sharp electric field gradients near the bipolar electrode poles. The key point is that ionic current density variations constitute a fundamentally new mechanism for forming electric field gradients in solution. Second, we show that the electric field gradients that form near the bipolar electrode poles in unbuffered solution are useful for continuously separating microplastics from water in a bifurcated microchannel. This result expands the potential scope of membrane-free separations using bipolar electrodes. Water electrolysis at a bipolar electrode in the absence of buffer forms electric field gradients in a fundamentally new way. These electric field gradients are useful for continuously separating microplastics from water.

SUBMITTER: Thompson J 

PROVIDER: S-EPMC8549819 | biostudies-literature |

REPOSITORIES: biostudies-literature