Asymmetric bipolar membrane electrodialysis for acid and base production

Fu, Rong; Wang, Huangying; Yan, Jun; Li, Ruirui; Jiang, Chenxiao; Wang, Yaoming; Xu, Tongwen

doi:10.1002/aic.17957

Cited by 27 publications

(15 citation statements)

References 68 publications

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“…The current efficiency ( η ) in the base compartment of the BMED was calculated using Equation () 22 :

ŋ = \frac{(C_{t} V_{t} - C_{0} V_{0}) F}{NIt},

where C t and C 0 are the concentrations (mol/L) of LiOH at times t and 0 (s), respectively; V t and V 0 are the volumes of the base stream at times t and 0 (s); Z is the absolute valence of hydroxyl ions ( Z = 1); F is the Faraday constant (96,485 C/mol); N is the number of repeating units of the stacks ( N = 5); and I is the current (A) applied to the BMED stack.…”

Section: Methodsmentioning

confidence: 99%

“…The energy consumption E (kWh/kg) was calculated using Equation () 22 :

E = \frac{\int_{0}^{t} UIdt}{(C_{t} V_{t} - C_{0} V_{0}) M},

where I is the current (A); C t and C 0 are the concentrations (mol/L) of LiOH at time t and 0 (s); V t and V 0 are the volume (L) of the base compartment; M is the molar mass of lithium hydroxide (23.9 g/mol); and U is the voltage drop (V) of the BMED stack.…”

Section: Methodsmentioning

confidence: 99%

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One‐step conversion of sulfate lithium into high‐purity lithium hydroxide crystals via bipolar membrane crystallization

Hou

Wang

et al. 2023

AIChE Journal

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To date, bipolar membrane electrodialysis (BMED) is being developed as a competitive technology for waste lithium‐ion battery recovery. However, the purity and concentration of lithium hydroxide generated from a BMED plant could not meet the product criteria for ternary lithium batteries, thus requiring additional condensation, purification, evaporation, and crystallization procedures. Herein, bipolar membrane crystallization (BMC) was proposed for the one‐step conversion of sulfate lithium into high‐purity lithium hydroxide monohydrate crystals. By mediating a continuous saturated feedstock in the salt compartment, it is possible to convert Li2SO4 into 5+ mol/L LiOH at a current density higher than 500 A/m2. Therefore, this unique design allows the production of 99.9% LiOH∙H2O by taking the principle of water dissociation in the bipolar membrane and the simultaneous crystallization procedure. This proof‐of‐concept study proves the feasibility and competitiveness of the BMC for waste lithium recovery by abandoning the condensation and evaporation procedures.

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“…The current efficiency ( η ) in the base compartment of the BMED was calculated using Equation () 22 :

ŋ = \frac{(C_{t} V_{t} - C_{0} V_{0}) F}{NIt},

Section: Methodsmentioning

confidence: 99%

“…The energy consumption E (kWh/kg) was calculated using Equation () 22 :

E = \frac{\int_{0}^{t} UIdt}{(C_{t} V_{t} - C_{0} V_{0}) M},

Section: Methodsmentioning

confidence: 99%

One‐step conversion of sulfate lithium into high‐purity lithium hydroxide crystals via bipolar membrane crystallization

Hou

Wang

et al. 2023

AIChE Journal

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“…In a bipolar membrane (BPM), for example, water is dissociated at the junction between an ionomer anion-exchange layer (AEL) and cation-exchange layer (CEL), usually accelerated by a catalyst sandwiched between the two and driven by an applied voltage (Figure 1a) [1][2][3][4][5] . This catalyzed, voltage-driven WD process is not understood, even though BPMs are used in electrodialysis to produce acid/base from brine and to desalinate water [6][7][8][9] , in food processing to adjust pH 10 , and in a variety of recycling and separations processes 11 . BPMs can also couple different-pH microenvironments leading to novel uses in fuel cells 12,13 , flow batteries 14 and water 15,16 and CO 2 electrolyzers [17][18][19] that can be impurity-tolerant 20 and enable the use of efficient and abundant electrocatalysts.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of Heterogeneous Voltage-Driven Water-Dissociation Catalysis

Chen¹,

Boettcher³

2023

Preprint

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The water-dissociation reaction (WD, H2O → H+ + OH−) affects the rates of electrocatalytic reactions and the performance of bipolar membranes (BPMs). How catalyzed interfacial WD is driven by voltage, however, is not understood. We designed a BPM electrolyzer with two reference electrodes attached laterally to each layer/side (here, poly(arylpiperidinium) and perfluorosulfonic-acid ionomers) to measure WD current and overpotential (ηwd), without soluble electrolyte and as a function of temperature and catalyst-layer properties. Using TiO2-P25 nanoparticles as a model WD catalyst, Arrhenius-type analysis yields a WD activation energy Ea of 25–30 kJ mol−1, only weakly dependent ηwd. The pre-exponential factor is unexpectedly proportional to ηwd. With D2O, ηwd is ~2 to 4 times larger than in H2O, largely due to a lower pre-exponential factor. Without catalyst, ηwd is ~10-fold larger and Ea decreases from 34 to 24 kJ mol−1 as ηwd goes from 0.1 to 1 V. To explain these data, we propose a new WD mechanism where metal-oxide nanoparticles, polarized by the voltage across the BPM junction, serve as i) proton acceptors (from water) on the negative sides of the particle to generate free OH−, ii) proton donors on the positive sides to generate H3O+, and iii) surface proton conductors that connect spatially separate donor/acceptor sites. Increasing electric-field strength with overpotential orients water for proton-transfer elementary steps comprising WD, increasing the pre-exponential factor and hence rate, but is insufficient to lower Ea. This understanding will accelerate development of electrocatalysis, electrodialysis, carbon-capture, and carbon-utilization technologies that require efficient WD.

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“…Bipolar membrane electrodialysis (BMED) is a novel, low-energy, and highly efficient technology that enables waste salts to be turned into high value-added alkali and acid. 11 Bipolar membrane (BPM) is a new type of ion exchange composite membrane. Under the action of electric field, the water in the interfacial layer is dissociated into hydrogen ions and hydroxide ions on both sides of the membrane.…”

Section: Introductionmentioning

confidence: 99%

Bipolar membrane electrodialysis: A promising paradigm for caustic soda production

Wang,

Yan

et al. 2023

AIChE Journal

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Currently, a supply‐demand imbalance between NaOH and Cl2 in the chlor‐alkali process places a great burden on the environment. Bipolar membrane electrodialysis (BMED) is a competitive technology to produce acid and base due to its water splitting characteristics. To determine the competitiveness of NaOH production between BMED and the chlor‐alkali method, BMED was evaluated at various current densities with different NaCl concentrations. Results show that NaOH energy consumption in BMED is less than that of the chlor‐alkali method at a moderate salt concentration (<9 wt.%). Interestingly, the stack voltage suddenly increases during the later stage of BMED. It is speculated that the high osmotic pressure surrounding bipolar membranes restrains water transport into the interfacial layer. In addition, economic assessment indicates that BMED has less impact on global warming than the chlor‐alkali process. Overall, the BMED technique is a promising paradigm for base production in an economical and sustainable manner.

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Asymmetric bipolar membrane electrodialysis for acid and base production

Cited by 27 publications

References 68 publications

One‐step conversion of sulfate lithium into high‐purity lithium hydroxide crystals via bipolar membrane crystallization

One‐step conversion of sulfate lithium into high‐purity lithium hydroxide crystals via bipolar membrane crystallization

Kinetics and Mechanism of Heterogeneous Voltage-Driven Water-Dissociation Catalysis

Bipolar membrane electrodialysis: A promising paradigm for caustic soda production

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