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.