Effect of Polyoxyethylenen-Alkyl Ethers on Carrier-Mediated Transport of Lanthanide Ions through Cellulose Triacetate Membranes

Abstract

Fluxes of 14 kinds of lanthanides across cellulose triacetate membranes were determined by using mixtures of o-nitrophenyl n-octyl ether and a series of polyoxyethylene n-alkyl ethers (POE ethers) as plasticizers, and hinokitiol as carrier. Effects of alkyl and polyoxyethylene (POE) chains of the POE ether on the flux were demonstrated. The transport of the lanthanides was coupled to a flow of hydrogen ions. The POE ethers used [C _n H_2n+1(OCH₂CH₂) _x OH, referred to as C _n E _x ] were C₁₀E₃, C₁₂E₃, C₁₄E₃, C₁₆E₃, C₁₂E₂, C₁₂E₄, C₁₂E₆ and C₁₂E₈. In all cases, high fluxes were observed for the lanthanides from samarium to lutetium. On the contrary, the fluxes for lanthanum to neodymium were extremely low. In experiments testing the effect of the alkyl chain, the order of the POE ethers in the lanthanide flux for samarium to lutetium was C₁₂E₃ > C₁₀E₃ > C₁₄E₃ > C₁₆E₃. In experiments testing the effect of the POE chain, the flux decreased with an increase in the chain length.