Abstract
Extraction equilibria for a series of lanthanide ions using chloroform solutions of bjs(2, 4, 4-triraeth-ylpentyl)-phosphinic acid (HBTMPP), either alone or combined with adduct forming agents have been studied. The extracted species are Ln (HTMPP) (HBTMPP), and. Ln(BTMPP)3 (HBTMPP)(TOPO) in the presence of trioctyl-phosphine oxide (TOPO). TOPO war; found to increase both the extractability and selectivity of lanthanide metals in the system.