Advancing electrodeionization with conductive ionomer binders that immobilize ion-exchange resin particles into porous wafer substrates

Abstract

Electrodeionization (EDI) is an electrically driven separations technology that employs ion-exchange membranes and resin particles. Deionization occurs under the influence of an applied electric field, facilitating continuous regeneration of the resins and supplementing ionic conductivity. While EDI is commercially used for ultrapure water production, material innovation is required for improving desalination performance and energy efficiency for treating alternative water supplies. This work reports a new class of ion-exchange resin-wafers (RWs) fabricated with ion-conductive binders that exhibit exceptional ionic conductivities-a 3-5-fold improvement over conventional RWs that contain a non-ionic polyethylene binder. Incorporation into an EDI stack (RW-EDI) resulted in an increased desalination rate and reduced energy expenditure compared to the conventional RWs. The water-splitting phenomenon was also investigated in the RW in an external experimental setup in this work. Overall, this work demonstrates that ohmic resistances can be substantially curtailed with ionomer binder RWs at dilute salt concentrations.

Effects of Resin Chemistries on the Selective Removal of Industrially Relevant Metal Ions Using Wafer-Enhanced Electrodeionization

“…A recent study by Palakkal et al using SEM observed that polyethylene was partially covering their cation exchange resin (Purolite PFC100E) which had sulfonic acid functional groups and was a similar size to the Amberlite IR 120 Na + resins at around 0.3 to 0.5 mm [ 28 ]. When they used an ionomer binder rather than polyethylene, they observed significantly less coverage of their cation exchange resin.…”

“…The wafer is a mixture of immobilized cation- and anion-exchange resins using a polymer as a binding agent. Compared to conventional EDI, WE-EDI can be easily built and run more efficiently, and it prevents uneven flow distribution and leakage of ions between the compartments simultaneously [ 28 ]. Because there is less leakage, WE-EDI can be used for more selective separations such as the removal of acidic impurities from corn stove hydrolysate liquor, CO 2 capture, and purification of organic acids [ 26 , 29 ].…”

Correlating high temperature thin film ionomer electrode binder properties to hydrogen pump polarization

“…Ionomer binders strongly influence the performance and stability of numerous electrochemical processes such as fuel cells, [1][2][3][4] water 5 and carbon dioxide electrolyzers, 6 and deionization units. 7,8 In low-and high-temperature polymer electrolyte membrane (i.e., LT-PEM and HT-PEM) architectures involving hydrogen, the binders hold the electrocatalyst/electrocatalyst supports, while also delivering protons to and from the electrocatalyst to the PEM separator. Both PEM separators and ionomer electrode binders require high conductivity and stability 4,9 under a wide-range of conditions (e.g., chemical, electrochemical, and thermal), but there are nuanced differences with respect to the properties for PEM separators and electrode binders.…”

Understanding the ionic activity and conductivity value differences between random copolymer electrolytes and block copolymer electrolytes of the same chemistry

“…7 On top of these transport considerations, IEMs require mechanical integrity, 3,8 in the presence of liquids of varying composition (e.g., water-organic mixtures) and total dissolved salt (TDS) concentrations. These membranes oen physically separate two liquid compartments in electrodialysis 3 and electrodeionization 9,10 or electrodes when used in membrane capacitive deionization. 4 A subset of polymeric materials that has received signicant attention includes block copolymer electrolytes (BCEs) 11,12 as their percolated pathways of ionic domains ameliorate ionic conductivity and the non-ionic domains foster mechanical properties and curtail excess swelling.…”