Inorganic Electrified Membrane: From Basic Science to Performance Translation

Abstract

Decentralized water systems necessitate intensified, robust, and modular water treatment technologies for enhanced efficacy and resilience of the water purification process. Inorganic electrified membranes (IEMs) are gaining momentum in decentralized water systems by combining the versatility of electro-filtration processes with the favorable properties of inorganic materials, namely, strong mechanical strength, chemical stability, and hydrophilicity. This review quantitatively assesses three mainstream IEMs (i.e., Ti4O7, carbon, and metallic IEMs) from a fundamental perspective of the intrinsic electrochemical properties of the IEM materials and their translation into the IEM performances. We specifically (i) analyze the •OH production selectivity by Ti4O7 IEMs based on electrochemical thermodynamics and material science; (ii) differentiate degradation mechanisms of carbon IEMs in the context of various water matrices and propose strategies to address major concerns of avoiding membrane passivation and improving Faradaic efficiency of carbon IEMs; and (iii) highlight metallic IEMs doped with Ag or Pd, i.e., elucidate the combined sterilization mechanism by Ag-IEM via Ag+ dissolution and electro-phenomena, and unravel the unique hydrogenolysis ability of Pd-IEM for hydrodeoxygenation and persulfate electro-activation. We conclude by identifying the remaining obstacles of IEMs and present possible interdisciplinary approaches for IEM optimization.

Electrochemical Anodic Oxidation-Based Membrane System for Micropollutant Removal

“…In light of the potential hazards in the preparation process, Trellu et al successfully mitigated the associated risks of Ti 4 O 7 EAM preparation through the utilization of a carbothermal reduction process. Additionally, Ti 4 O 7 powder obtained by thermal reduction of TiO 2 could be pressed and sintered to EAM as well . In Wang et al’s study, Ti 4 O 7 powders were compressed into a stainless-steel mold to create a green body using a hydraulic press, which then was sintered at 1050 °C in vacuum for 1 h to obtain Ti 4 O 7 EAM; the ECSA of the Ti 4 O 7 EAM was notably increased by 2.27 orders of magnitude compared to batch modes.…”

“…On account of the distinctions in electrochemical and material properties (e.g., OEP, specific surface area) between carbon-based and metal-based EAM systems, the mechanisms involved in pollutant degradation also exhibited variation. For example, direct oxidation plays a key role in MPs degradation by carbon-based EAM due to their low OEP, while both direct oxidation and indirect oxidation could participate in pollutant degradation on metal-based EAM . Nevertheless, the kinetics in the direct oxidation process could be limited due to the weak adsorption between the MPs and the metal-based EAM .…”

“…For example, direct oxidation plays a key role in MPs degradation by carbon-based EAM due to their low OEP, while both direct oxidation and indirect oxidation could participate in pollutant degradation on metal-based EAM . Nevertheless, the kinetics in the direct oxidation process could be limited due to the weak adsorption between the MPs and the metal-based EAM . MPs could undergo activation to a higher energy state through direct oxidation, typically forming organic radicals (incomplete degradation), which were subsequently removed by indirect oxidation in metal-based EAM systems …”

Beyond Decontamination: Organic Fouling Management of Janus Electroreactive Membrane for Sustainable Water Reclamation

“…This configuration induces a strong electric field on the membrane surface; nonetheless, the electric field strength gradually decays as the depth in the membrane pores deepens . To this end, embedding an electric field within a membrane’s internal body realm could potentially intensify the electric field strength by maximizing the usage of a spatial confinement effect within the porous membrane. − Compared to traditional nonelectrified filtration and electrofiltration with single-surface ERMs, whether such a configuration could potentially alleviate irreversible fouling at reduced energy consumption remains unknown. Given the need for developing fouling-resistant and highly efficient ERMs, it is valuable to evaluate the comprehensive performance of the ERM, especially embedding an internal electric field, for sustainable water reclamation.…”