Valorization of desalination brines by electrodialysis with bipolar membranes using nanocomposite anion exchange membranes

Abstract

Electrodialysis with bipolar membranes (EDBM) is a promising technology that simultaneously treats and valorizes desalination brines into acids and bases. An important techno-economic challenge of EDBM in this application is the purity of the products, related to the need for more selective ion exchange membranes with good stability working with acids and bases. This work presents the results of the treatment of model desalination brines by EDBM using nanocomposite anion exchange membranes in order to reduce the sulfate content as the main impurity in the acid stack. These membranes are composed by polyethylene, polypropylene, sulfonated poly (2,6dimethyl-1,4-phenylene oxide) (sPPO) and different loads of Fe 2 O 3-SO 4 2nanoparticles. A reduction of the sulfate content in the acid stack was observed when using nanocomposite membranes. The stability of these membranes was evaluated measuring the Cl-/SO 4 2selectivity after 31, 62 and 93 hours of operation. FTIR spectra before and after 93 hours of operation also confirmed the stability of the membranes. The evolution of the main impurities in the acid and the base stacks versus time when applying different current densities is included and related to current efficiency. An estimation of the proton and hydroxyl ions leakages at the different current densities is also presented.

The Novel Strategy for Increasing the Efficiency and Yield of the Bipolar Membrane Electrodialysis by the Double Conjugate Salts Stress

“…Jian et al [13] improved water dissociation by loading MoS 2 nanosheets on bipolar membranes interfaces as advanced catalysis at 90 • C, which exhibited an outstanding performance with a high current efficiency of 45% and a low energy consumption of 3.6 kWh/kg, which increased the acid concentration (from 0.04 to 0.23 mol/L) at a current density of 20 mA/cm 2 .…”

Electrochemical impedance spectroscopy of enhanced layered nanocomposite ion exchange membranes

“…, also showed a good stability in valorization of desalination brines into acids and bases by electrodialysis with bipolar membranes [29]. Scheme of the experimental setup used for the permselectivity experiments and mechanism of monovalent ion selectivity of the nanocomposite anion exchange membranes.…”

“…The monovalent selectivity of AEMs was calculated from the comparison of the transport number of Cl − and SO 4 −2 in the dilute compartment. The transport number for an ion t A can be defined as the ratio between the flux ofthe ion (J A ) and the total flux of ions (J T ) [29]:…”

“…The effective area of the cell was 100 cm 2 , and the applied current density was 12 mA•cm −2 . This current density was also used in the permeselectivity determination of our previous study [29] and Na + were calculated from the evolution of their concentration in the dilute compartment.…”

High performance cation exchange membranes synthesized via in situ emulsion polymerization without organic solvents and corrosive acids

“…[1][2][3][4][5] A recent statistical study reveals that over 20 000 research papers relating to IEMs have been published since 2001. 6 IEMs are widely used in many applications, including but not limited to fuel cells, [7][8][9][10] electrodialysis, [11][12][13] and reverse electrodialysis. [14][15][16] Generally, IEMs are classied into two categories: cation exchange membranes (CEMs) and anion exchange membranes (AEMs).…”