Integration of Bipolar Membrane Electrodialysis with Ion-Exchange Absorption for High-Quality H₃PO₂ Recovery from NaH₂PO₂

Abstract

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.

Preparation of Hypophosphorous Acid by Bipolar Membrane Electrodialysis: Process Optimization and Phosphorous Acid Minimization

“…The current efficiency (η) represents the ratio of the molar mass of the product and the charge units passing in the system and was calculated using eq , where F is the Faraday constant (96485 C/mol); Z is the ion’s valence (e.g., H 2 PO 2 – , Z = 1); C 0 and C t are the concentrations of H 3 PO 2 in the acid chamber (mol/L) at time 0 and t (min), respectively; V 0 and V t are the volumes of the acid in the acid chamber (mol/L) at time 0 and t (min), respectively; t is the test time (min); I is the current (A); and N is the number of cell triplets in the BMED stack ( N = 15).…”

“…Regarding the electrodialysis method, Guo has successfully applied a six-compartment electrodialysis cell to prepare H 3 PO 2 . However, the electrodialysis process always has a low current efficiency and a high unit energy consumption. , Moreover, the large amounts of O 2 and H 2 generated by the electrodes represent a potential explosion risk in the industrial production of H 3 PO 2 . Considering environmental protection and efficiency issues, an alternative method for producing H 3 PO 2 is urgently required.…”

“…When taking into account the importance of H 3 PO 2 purity, sodium ion leakage becomes a problem worthy of attention. Shen et al proposed a novel process integrating the BMED technique with ion-exchange absorption for preparing high-quality H 3 PO 2 aqueous solution with low Na + content . However, as far as we know, there has been no report regarding the effect of operating conditions on sodium ion leakage during the production of H 3 PO 2 in BMED.…”

Recent Advances in Bipolar Membrane Design and Applications

“…Ammonia and phosphate have been recovered from biological waste using BPMED, − producing phosphoric acid and ammonium hydroxide with high recovery rates (>80%). Hypophosphorous acid, useful for electroless nickel plating, can be extracted from waste plating solutions with high efficiency and economically feasible process costs. , The regeneration of flue-gas desulfurizing agents (alkanolamines) can be conducted using BPMED at process costs competitive with the market value of alkanolamines. − Toxic metal wastes such as chromium and cadmium can be extracted from wastewater and soil, − while textile dyes can be removed from solution via the in situ generation of a dye absorbent, Ni­(OH) x , at the BPM interface, with minimal membrane scaling . Overall, the use of BPMED for waste valorization or removal is versatile, where the number of applications will increase as interest in developing “green”, sustainable chemical processes grows.…”

“…Hypophosphorous acid, useful for electroless nickel plating, can be extracted from waste plating solutions with high efficiency and economically feasible process costs. 200,201 The regeneration of flue-gas desulfurizing agents (alkanolamines) can be conducted using BPMED at process costs competitive with the market value of alkanolamines. 202−205 Toxic metal wastes such as chromium and cadmium can be extracted from wastewater and soil, 206−208 while textile dyes can be removed from solution via the in situ generation of a dye absorbent, Ni(OH) x , at the BPM interface, with minimal membrane scaling.…”