Integration of Bipolar Membrane Electrodialysis with Ion-Exchange Absorption for High-Quality H(3)PO(2) Recovery from NaH(2)PO(2)

[Image: see text] H(3)PO(2) has emerged as an indispensable reducing agent for electroless nickel plating. Commercial preparation of H(3)PO(2), with high purity and low cost, is a great challenge. In this work, a novel technique by the integration of bipolar membrane electrodialysis (BMED) with ion-exchange absorption was designed to prepare high-quality H(3)PO(2) aqueous solution. The critical parameters, such as voltage drop, NaH(2)PO(2) concentration, and different types of anion-exchange membranes, were systematically investigated. Continuous experiments indicated that a high yield of up to 80.06% with a low energy consumption of 4.99 kW h/kg was achieved under optimal operation conditions (voltage drop of 20 V, feed concentration of 15 wt % NaH(2)PO(2), and anion-exchange membrane of AHA). Moreover, leakage of Na(+) ions through the bipolar membrane was observed. By using T-52H cation-exchange resin, the final concentration of Na(+) ions in H(3)PO(2) aqueous solution was reduced to 20.91 mg/L. Subsequently, a long-term experiment was performed to evaluate the stability of the BMED stack, and the concentration of H(3)PO(2) in the acid compartment reached 4.15 mol/L. Under optimal conditions, the H(3)PO(2) production cost was estimated at $0.937 kg(–1), which was competitive and economically friendly for industrial application.