Journal de la science et de la technologie des membranes

Abstrait

Liquid Membrane Transports of Na(I) Ions by Crown Compounds into Dichloromethane and o-Dichlorobenzene: About Analytical Model Simplified for Potentiometric Experiments

Yoshihiro Kudo*, Tomohiro Goto, Saya Morioka, Chiya Numako

Membrane transport experiments into Dichloromethane (DCM) and o-Dichlorobenzene (oDCBz) were performed at 298 K using basic mixtures of NaCl, picrate ion, and crown compounds (L). Here, L shows 15-crown-5 ether (15C5), benzo-15C5 (B15C5), 18-crown-6 ether (18C6), or B18C6. A used cell was (-) ref. electrode|0.05 mol/L (C₄H₉)4NCl|org (=DCM or oDCBz) |mixture| ref. electrode (+), where the ref. electrode is a commercial one composed of 3 mol/L NaCl|AgCl|Ag. First-order rate constants (k/minute^–1) and a parameter, fΔE’, with potential differences ΔE’/V at the (C₄H₉)4NCl_aq|org interfaces and f=F/RT, were determined. The natural logarithm of the apparent distribution constant (KD’) defined before for the ion transfer into the organic phases was displaced by this parameter fΔE’. Also, a negative correlation was observed at T=298 K in the plots of fΔE vs. ln k. Here, “dep” is the abbreviation of the distribution equilibrium potential for the extraction system with L and the values were determined from re-analyzing the corresponding extraction data. Additionally, the experimental emf values were discussed based on the equation ± emf ≈ 0.02569 kt+ΔE’, where t shows an elapsed time (minute).