Effect of Hydroxide and Carbonate Alkaline Media on Anion Exchange Membranes
The effect of hydroxide and carbonate alkaline environments on the chemical stability and ionic conductivity of five commercially available anion exchange membranes was investigated. Exposure of the membranes to concentrated hydroxide environments (1 M) had a detrimental effect on ionic conductivity with time. Over a 30-day period, decreases in conductivity ranged from 27% to 6%, depending on the membrane. The decrease in ionic conductivity is attributed to the loss of stationary cationic sites due to the Hofmann elimination and nucleophilic displacement mechanisms. Exposure of the membranes to low concentration hydroxide (10−4 M) or carbonate/bicarbonate (0.5 M Na2CO3/0.5 M NaHCO3) environments had no measurable effect on the ionic conductivity over a 30-day period. ATR-FTIR spectroscopy confirmed degradation of membranes soaked in 1 M KOH. Apparition of a doublet peak in the region between 1600 cm−1 and 1675 cm−1 confirms formation of carbon–carbon double bonds due to Hofmann elimination. Membranes soaked in mild alkaline environments did not show formation of carbon–carbon double bonds.
Published in Journal of Power Sources, Volume 195, Issue 21, Fall 2010, pages 7176-7180.
© Journal of Power Sources, 2010, Elsevier.
William E, Mustain (2010). Effect of hydroxide and carbonate alkaline media on anion exchange membranes. Journal of Power Sources, 195(21), 7176-7180.