Development of Polyaniline Based Anion Exchange Membrane for the Separation of Lactic Acid via Electrodialysis

Abstract

Nowadays, industrial waste from feedstock contains a lot of organic acids, which are being discharged into the water streams causing environment load with wastage of resources. Electrodialysis performs an important role in wastewater treatment. In this study, we have prepared different anion exchange membranes, by casting solution of poly(vinylchloride-co-vinylacetate) (PVC–VA) with uniformly dispersed micronized anion exchange resin (polystyrene–divinylbenzene–trimethyl ammonium chloride) (PS–DVB–TAC). These membranes were also processed for the deposition of polyaniline at different time intervals by in situ polymerization. The cation exchange membrane (CEM) was also produced by casting a solution, containing (PVC–VA) with micronized cation exchange resin [sulfonated poly(styrene-co-divinylbenzene)] (SPS–DVB). The separation of the model solution of lactic acid was performed by using anion exchange membrane (with coated/without coated PANI) and cation exchange membranes (CEM) in a four-compartment electrodialyzer at same voltage. These different modified forms of anion exchange membranes were characterized by FTIR/ATR for identification of functionalities within the polymer chain, SEM analysis for surface morphology, TGA for thermal stability and a four-probe method for electrical conductivity of membranes. While, % age of water uptake and ion exchange capacity were also determined. The results of electrodialysis showed that the 14.78% of the lactate ions moved through anion exchange membrane (without a coating of PANI) to the product compartment within 30 min of the experiment at (30 V). While, the membranes with polyaniline’s coating time 2, 12, and 24 h have separation efficiency of lactic acid 21.65, 27.46, and 33.36% respectively at the same voltage. The results clearly showed that higher PANI coating has a positive trend in the separation of lactic acid. This separation technique has a great potential in the separation of organic acids and amino acids from a feedstock of microbial fermentation at an industrial scale.