Liquid-Liquid Extraction of Trivalent Lanthanum and Cerium from Aqueous Solutions by Long-Chain Alkyl Quaternary Ammonium Carboxylates

Abstract

The extraction of trivalent lanthanum and cerium from aqueous solutions by long-chain alkylquaternary ammonium carboxylates, prepared by the combination of trioctylmethylammonium chloride (R₃R’NCl) and carboxylic (octanoic, decanoic and lauric) acids (R’’COOH) in benzene has been investigated around neutral pH. The organic phases were examined by infrared spectra measurements. As a result, it was found that the extraction efficiency was in the order La < Ce with R₃R’NR’’COO (R’’: CH₃(CH₂)n; n = C₆, C₈, C₁₀). In addition the extraction processes are expressed as M³⁺ (aq) + 3Cl^- (aq) + 4R₃R’NR’’COO (org) ⇋ (R₃R’’N)[M(R’COO)₄] (org) + 3R₃R’NCl (org), where M = La and Ce.