Fabrication of a Stable and Efficient Bipolar Membrane by Incorporation of Nano-MoS<sub>2</sub> Interfacial Layer for Conversion of Salt into Corresponding Acid and Alkali by Water Dissociation Using Electrodialysis
Nehal H. Rathod, Jeet Sharma, Savan K. Raj, Vikrant Yadav, Abhishek Rajput, Vaibhav Kulshrestha
Abstract
An efficient bipolar membrane has been developed by layer-by-layer assembly comprising an anion exchange layer (AEL), a cation exchange layer (CEL), and an interfacial layer. Here, the catalytic performance of nano-MoS2 has been investigated as an interfacial layer of bipolar membrane (BPM) for improved water dissociation. The thickness of the interfacial layer varied between those of commercially available anion exchange layer and sulfonated poly(ether sulfone)-based cation exchange layer. All prepared membranes have been evaluated for their water uptake, ion exchange capacity, and ionic conductivity. The bipolar membrane with the highest nano-MoS2 content (BPM-5) shows a significant improvement in the physiochemical properties with reasonable water uptake, higher ion exchange capacity, and higher ionic conductivity compared to the BPM membrane (without MoS2). UTM analysis shows the mechanical stability of the bipolar membrane. The performance of the bipolar membrane has been assessed by production of acid and alkali from the hydrolysis of different salts using bipolar membrane electrodialysis (BPMED). A power consumption of 2.16 kWh kg–1 and a current efficiency of 84.46% for BPM-5 during hydrolysis of 0.4 M NaCl solution were found at 8 V per cell pair. The correlation study of hydrolysis of different salts is carried out, in which the water dissociation efficiency is slightly reduced for Na2SO4 due to lower ionization. The interfacial layer of nano-MoS2 acts as the catalyst for water dissociation during BPMED and enhances the rate of acid and alkali production and water dissociation efficiency with a lower potential drop.