Heterogenous bipolar membrane with amino methyl phosphonic acid functionalized cation exchange layer and montmorillonite nanoclay based interfacial layer

Heterogeneous bipolar membranes (HBMs) synthesized with cation exchange resin bearing amino methyl phosphonic acid group as cation exchange layer and montmorillonite (MMT) nanoclay as interface layer was investigated. All HBMs were synthesized through layer-by-layer solvent casting technique using Polyvinyl chloride (PVC) as common binder for both cation and anion exchange layers. MMT suspensions were prepared with 5 w/v% Polyvinylpyrrolidone (PVP) solution to improve coating stability and hydrophilicity of the interface layer. The water dissociation performance of each HBM was investigated through current voltage characteristics and electrodialysis test of estimate its acid-alkali generation from salt solution. Presence of the hydrophilic MMT nanoclay at the membrane interface reduced water dissociation potential (Udiss) and the lowest Udiss of 2.15 V was obtained at 1.0 mg center dot cm- 2 MMT loading at the interface. Cross-sectional morphology of HBMs shows strong binding between all the layers in the membrane matrix. Acid- alkali production capability of HBMs could be significantly improved in presence of MMT nanoclay producing 0.50 mol center dot L-1 (300 mL) of H+/OH-at 75 mA center dot cm- 2 in 5 h of electrodialysis experiment.