Bipolar membrane electrodialysis in aqua–ethanol medium: Production of salicylic acid

• The aqua–ethanol medium was introduced in BMED.
• The obstacle to the production of water-insoluble aromatic acid was removed.
• Factors that influence the salicylic acid production were investigated.
• A scale-up experiment was conducted.

To overcome the low solubility of salicylic acid (SAH) in the production process by bipolar membrane electrodialysis (BMED), the water–ethanol mixture as solution medium was introduced in the BMED technique. The results indicated that the highest acid concentration was obtained when ethanol content was 50 v/v%, and the current efficiency reached 98.2%. Moreover, the BMED stack of BP–C (BP, bipolar membrane; C, cation exchange membrane) configuration was proved as most cost-effective configuration, and using this configuration the highest current efficiency could reach 99.6% and the lowest energy consumption was 2.1 kW h kg−1.