Integrated Ion-Exchange Membrane Resin Wafer Assemblies for Aromatic Organic Acid Separations Using Electrodeionization

Abstract

Aromatic acids, such as p-coumaric acid, are valuable chemical intermediates that are used in the specialty chemical industries because they are precursors to phenylpropanoid compounds. The separation of p-coumaric acid from fermentation broths is a critical step in the biochemical production process and more broadly the circular carbon economy. Electrodeionization (EDI) has been applied toward separations of low-carbon chain acids, but purifying p-coumaric acid has been challenging due to fouling and irreversible binding with ion-exchange membranes and resins. Here, we report a new membrane wafer assembly (MWA) consisting of laminated ion exchange membranes to porous ionomer-binder resin wafers for EDI. The MWAs in an EDI stack showed a 7-fold increase in p-coumaric acid capture while also using 70% less specific energy consumption when benchmarked against state-of-the-art resin wafer EDI modules. The more efficient p-coumaric acid recovery was ascribed to (i) the 38% reduction in interfacial transport resistance between the membrane and resin wafer and (ii) using imidazolium anion exchange membranes and ionomer binders in the MWA. MD simulations revealed enhanced transport rates for p-coumarate in imidazolium ionomers through π–π interactions. Adopting the new MWA significantly reduced the amount of ion-exchange membranes in EDI and may lead to drastic capital cost savings.

Bipolar membrane capacitive deionization for pH-assisted ionic separations

“…For creating alkaline pH conditions in the cell, the BPM was placed at the negative electrode with the AEM side of the BPM facing the spacer channel as shown in Figures 1c and 1d (configuration 3: BPM-CDI, and configuration 4: BPM-MCDI, respectively). In configuration 2, the negative electrode was covered with a lab-synthesized sulfonated poly(arylene ether sulfone) (SPSf) CEM 10 . In the BPM-CDI assembly for acidic pH (configuration 1), the negative electrode was not covered.…”

“…Mining effluents (e.g., hydrometallurgy process streams 6,7 ) contain valuable metals that can be further processed into materials that support defense technologies, communications, and green energy. Selective electrochemical separations can valorize waste streams to recover vital nutrients, like nitrogen and phosphorus 8 , to derive fertilizers and organic acids 9,10 from processed biomass to support circular economy initiatives.…”

Determining ion activity coefficients in ion-exchange membranes with machine learning and molecular dynamics

“…Electrically-driven ionic separations has been historically important for water desalination and the production of ultra-pure water for semiconductor, food, and pharmaceutical manufacturing. They are also emerging as platforms for the recovery of organic acids from processed biomass streams 1,2 and valuable metals from waste and hydrometallurgy streams 3 as well as remediating water streams with bad actors (e.g., PFAS 4 , 5 and heavy metals 6 ). Electrically-driven ionic separations include electrodialysis (ED), membrane capacitive deionization (MCDI) and electrodeionization (EDI) [2][3][4][5][6] , and each of these processes utilize ion-exchange membranes (IEMs).…”

“…They are also emerging as platforms for the recovery of organic acids from processed biomass streams 1,2 and valuable metals from waste and hydrometallurgy streams 3 as well as remediating water streams with bad actors (e.g., PFAS 4 , 5 and heavy metals 6 ). Electrically-driven ionic separations include electrodialysis (ED), membrane capacitive deionization (MCDI) and electrodeionization (EDI) [2][3][4][5][6] , and each of these processes utilize ion-exchange membranes (IEMs). The two main types of IEMs are anion exchange membranes (AEMs) and cation exchange membranes (CEMs)…”

“…Operating at high current density is important to reducing the size of the separation system and reducing capital costs that arise from ion-exchange membranes and electrodes. 1,2,14 There are many parameters within polymeric IEMs that affect conductivity and permselectivity and they include repeat unit sequence 14 repeat unit chemistry, microstructure 14 , concentration of tethered charge groups, the external salt concentration, [14][15][16][17] the types of salts, 15,18 and water content 16 . Establishing the said descriptors to ion transport rates within IEMs is time consuming and expensive because many experiments must be performed for a given structure and chemistry.…”