Multiplexed and Membraneless Redox-Mediated Electrochemical Separations Through Bipolar Electrochemistry

Redox-active electrosorbents are promising platforms for selective separations. However, these platforms face intrinsic challenges in extracting multiple species simultaneously, as their binding mechanisms are typically tailored to separate a single ion preferentially. Here, bipolar electrochemistry is leveraged to introduce a new strategy for the multiplexed use of redox-active and capacitive materials for separations. Using polyvinyl ferrocene (PVF)-, Prussian blue analog (PBA)-functionalized, and carbon-based electrodes, multicomponent separations within a modular bipolar electrode (BPE) platform are demonstrated. The multiplexed BPE system provides distinct electrochemical environments within each BPE pair, enabling parallel selective separations. With three identical PVF BPEs, arsenic uptake increased linearly from 41.4 to 115.4 mg_As g_PVF ^-1, highlighting the scalability of the system. Moreover, deploying three distinct BPE pairs-PBA, PVF, and carbon-enables simultaneous potassium recovery (11.0 mg g^-1), arsenic removal (19.8 mg g^-1), and desalination (4.2 mg g^-1) from secondary wastewater, demonstrating real-world applicability. This wireless, membraneless architecture enables process-intensified selective separations by precisely controlling local electric fields on individual redox-active materials, facilitating electrosorption and regeneration across diverse BPE systems within a unified process.