Design of tropinium-functionalized anion exchange membranes for acid recovery via diffusion dialysis process

Abstract

Diffusion dialysis (DD) process utilizing anion exchange membranes (AEMs) is an environmentally-friendly and energy-efficient technology. From acidic wastewater, DD is needed for acid recovery. This research reports the development of a series of dense tropinium-functionalized AEMs via solution casting method. Fourier Infrared transform (FTIR) spectroscopy verified the successful preparation of AEMs. The developed AEMs exhibited a dense morphology, featuring 0.98-2.42 mmol/g of ion exchange capacity (IEC), 30-81% of water uptake (WR) and 7-32% of linear swelling ratio (LSR). They displayed exceptional mechanical, thermal and chemical stability and were employed for acid waste treatment from HCl/FeCl2 mixtures via DD process. AEMs possessed 20 to 59 (10-3 m/h) and 166 to 362 of acid diffusion dialysis coefficient (UH+) and separation factor (S) respectively at 25 °C. Compared to DF-120 commercial membrane (UH+ = 0.004 m/h, S = 24.3), their DD efficiency was improved under identical experimental conditions.