Development of PVA/MIDA based hybrid cation exchange membranes for alkali recovery via Diffusion Dialysis

• Methyl iminodiacetic acid (MIDA) was synthesized and incorporated with PVA.
• Novel MIDA/PVA hybrid membrane posses high thermo mechanical property.
• Prepared membranes can be proficiently used in DD process for base recovery.

We report poly vinyl alcohol (PVA) based hybrid membranes composed of methyl iminodiacetic acid (MIDA) and tetraorthoethoxysilane (TEOS) prepared by classical sol–gel process. MIDA was prepared via N-methylation of iminodiacetic acid and then successfully incorporated into the PVA backbone. The concentration of MIDA with respect to PVA was varied from 10 to 40 wt%. These hybrid membranes showed water uptake (WU) in the range of 106–125%, ion exchange capacities (IECs) of 1.14–2.13 mmol/g, dialysis coefficient (UOH) from 0.009 to 0.012 m/h as well as selectivity (S) from 16.0 to 19.9. These obtained results revealed that MIDA. It controls the hydrophilicity and ion exchange capacity by providing channels for the transportation of ions through carboxylate sites. PVA/MIDA hybrid membranes also showed good thermal stability with the initial thermal decomposition temperature (IDT) ranging around 150–160 °C and excellent mechanical properties such as tensile strength (TS) of 9–25 MPa and elongation at break (Eb) of 32–150%.

Novel MIDA/PVA based hybrid membranes were synthesized via sol–gel process. In PVA hybrid membrane MIDA acts as cross linker and as well as provides functional group for ions exchange. The structure reveals that the H-bonding between –OH group of PVA and –O–Si and nitrogen of MIDA boosts mechanical and thermal stabilities.Figure optionsDownload as PowerPoint slide