Regenerating sodium hydroxide from the spent caustic by bipolar membrane electrodialysis (BMED)

An experimental study was carried out on regeneration sodium hydroxide (NaOH) from the spent caustic by bipolar membrane electrodialysis (BMED). The effects of operation parameters, such as concentration of electrolyte, current density and initial base concentration, on regeneration were investigated. The results indicate that low energy consumption and high current efficiency can be achieved with the concentration of electrolyte in the range of 0.20–0.30 mol/L, initial concentration of the base in range of 0.10–0.25 mol/L and current density in the range of 30–60 mA/cm2. The process cost is estimated to be USD 0.97 for regenerating 1 kg NaOH with the laboratory-scale equipment, showing economically competitive.

► Regenerating NaOH from spent caustic by bipolar membrane electrodialysis was firstly reported.
► The operation parameters on the process were fully investigated and optimized.
► The process cost was estimated.