Selective recovery of carboxylic acid through PVDF blended anion exchange membranes using electrodialysis.

• Interactions of anions with three different FAB-PK-130, BM-1, BM-2 membranes. • Selective AA/MA/CA recovery from ternary mixture using electrodialysis. • BM-2 microstructure resulted higher selectivity for AA− compared to other anions. • Order of ion selectivity remained at pH ∼ 7.5 is as follows: AA1− > MA2− > CA3−. • Current efficiency of 63.7% was noted with BM-2 for AA− ions at 6.0 mA·cm−2. Selective transport of carboxylic acids (acetic, AA; malic, MA; and citric, CA) from their equimolar (0.1 mol·L-1) ternary mixture was investigated through electrodialysis (ED) using three different anion exchange membranes [(i) Fumatech, FAB-PK-130, and two indigenous membranes made by solution blend of polyvinylidene fluoride (PVDF): copolymer of polymethyl methacrylate- co -polychloromethyl styrene (PMMA- co -PCMSt) at (ii) 50:50 wt% (BM-1), and (iii) 30:70 wt% (BM-2) followed by aminating them using tetramethyl 1,6 diamino hexane]. Recovery ratio (RR) for AA/MA and AA/CA mixtures were 1.97 and 2.71 respectively, indicating higher selectivity for AA through BM-2 and the same was explained based on highest ion exchange capacity (2.10 meq·g−1) and ion conductivity (2.3 mS·cm−1) data. Selective transport of AA was further endorsed by ED performance separately done with AA, MA and CA (0.1 mol·L-1 each) and equimolar binary (AA/MA) mixture at pH 7.5. Increasing trend in AA recovery: FAB-PK-130 < BM-1 < BM-2 at pH 7.5 was further supported by physical properties of the electrolyte (transport number from binary/ternary mixture) and membrane (water uptake, fractional adsorption, and ion conductivity) separately with each membrane. Highest current efficiency of 63.7% (energy consumption 5.13 kWh·kg−1) could be achieved with AA during ED analysis of ternary mixture through BM-2. [ABSTRACT FROM AUTHOR]