On an Expression of Extraction Constants without the Interfacial Equilibrium-Potential Differences for the Extraction of Univalent and Divalent Metal Picrates by Crown Ethers into 1,2-Dichloroethane and Nitrobenzene

Abstract

An idea on interfacial equilibrium-potential differences ( ) which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic 2 ) by crown ethers (L) into high-polar diluents was improved. These potentials were clarified with some experimental extraction-data reported before on the M = Ag(I), Ca(II), Sr(II) and Ba(II) extraction with 18-crown-6 ether (18C6) and benzo-18C6 into 1,2-dichloroethane (DCE) and nitrobenzene (NB). Consequently, it was demonstrated that the values from the extraction-experimentally obtained log K D,Pic ones are in agreement with or close to those calculated from charge balance equations in many cases, where the symbol, K D,Pic , denotes an individual distribution constant of Pic ﹣ into the DCE or NB phase. Also, it was experimentally shown that extraction constants based on the overall extraction equilibria do not virtually contain the terms in their functional expressions.