Synthesis of sodium dithionite through in-situ electrochemical method at the cathode in a gap-flow bipolar membrane electrolysis cell

Abstract

Global demand for sodium dithionite (Na2S2O4, TDS) has been steadily rising, as it is an effective flame retardant, bactericide, and bleaching agent. However, conventional manufacturing methods often involve high operational costs, excessive use of reducing agents, and significant environmental pollution, which hinder sustainable industrial production. To address these issues, this study focused on the design of efficient electrochemical reactor, optimizing reaction parameters, investigating the electrochemical reaction mechanisms, and developing high-performance carbon-based electrocatalysts. A micro-gap-flow electrochemical reaction system for the electrosynthesis of TDS was successfully developed. This system integrates traditional chemical synthesis with electrochemical reduction, enabling the efficient creation of TDS in an aqueous sodium bisulfite solution. The current efficiency of this electrical synthesis process was notably improved, increasing from 85% to over 90%. Furthermore, the energy consumption for TDS production was 0.81 kW·h·kg−1 when using the Cu/NC electrode. The processes and pathways of TDS electrochemical synthesis were explored using electrochemical tests and theoretical calculations.