Concentration polarization in electrodialysis: Buffer solutions experimental method☆

摘要: Abstract This research work presents a simple, original and illustrative experimental method to investigate the concentration polarization using cation exchange membrane (CEM). The nature of overlimiting current (Iov) water dissociation (WD) on CEM are particularly studied. They still widely discussed nowadays. Our is based comparison i-v (current transmembrane voltage) curves same counter ion with without buffer coions. For example we compare Na 2 SO 4 (NaH PO + HPO ), or K (KH ). role mixture hydrogen-dihydrogen phosphate coions solution at neutral pH. protons, whatever their origin, do not contribute transport. distance between two NaT (T = coions) represents then contribution issued from WD, gives unexpected interesting results: superposition shows clearly that WD occurs protons Iov; KT larger curves: many times higher than ; identical curves. It an result: have mobilities if increases voltage: necessary condition obtain H Iov negligible. more 20% total current. measures this contribution. contributes strongly better understanding phenomenon. only evidences hypothesis, speculations calculations.