In-situ crosslinked SPPO/PVA composite membranes for alkali recovery via diffusion dialysis

Diffusion dialysis (DD) integrated with cation exchange membranes (CEMs) is eco-friendly separation process, which has been extensively used for base recovery in various separation industries. The development of cost-effective and suitable CEMs is highly desirable to enhance process efficiency. In this work, we describe the development of SPPO/PVA composite membranes (SPVA) composed of sulfonated poly (2, 6-dimethyl-1, 4-phenylene oxide) (SPPO) and polyvinyl alcohol (PVA) backbones crosslinked with glutaraldehyde (GA). The flux was improved via PVA while SPPO catalyzed the in-situ crosslinking else induced cation channels. The anion selectivity was tuned by various amounts of GA. The physio-chemical properties of the prepared membranes such as water uptake(W-R), cation exchange capacity (CEC) and mechanical stability, confirmed the appropriateness of prepared membranes for DD application. The influence of GA concentration on the base recovery and the separation factor was explored and discussed in details. The membranes showed W-R within the range of 56-85% with CEC values of 1.37-1.42 mmol g(-1), respectively. The base recovery (mentioned as U-OH-) and separation factor (S) were found in the range of 0.00255-0.0107 m h(-1) and 45-261, respectively. Moreover, the representative membranes (SPVA-50 and SPVA-100) displayed excellent operational stability for ten consecutive cycles and validated the membrane's potential for long term application.