EXTRACTION EQUILIBRIUM OF MOLYBDENUM(VI) WITH SEVERAL ALKYLATED 8-QUINOLINOL DERIVATIVES

The extraction equilibria of molybdenum(VI) with several alkylated 8-quinolinol derivatives (HQ): 2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q), 5-octyloxymethyl-8-quinolinol (HO(8)Q), and 5-(4-nitrophenylazo)-7-(4-ethyl-1-methyloctyl)-8-quinolinol (HNEQ) have been investigated. Molybdenum(VI) was completely extracted with a 0.01 M extractant in chloroform from an aqueous phase at 1 M(1 M=1 mol dm(-3)) HCl-pH 5 for HMO(8)Q, 2 M HCl-pH 6 for HO(8)Q and 4 M HCl-pH 5 for HNEQ. The extraction constants, log K-ex(=[MoO2(Q)(2)](org)/[MoO42-][H+](2)[HQ](2)(org)), are 17.72+/-0.06 (HO(8)Q-CHCl3), 14.90+/-0.07 (HMO(8)Q-CHCl3), 17.00+/-0.07 (HNEQ-CCl4) and 17.18+/-0.08 (HO(8)Q-CCl4) at 25 degrees C. The molybdenum(VI)-HQ complexes, except the HO(8)Q complex in an organic phase could be easily stripped with an aqueous ammonia solution. Molybdenum(VI) was selectively separated with alkylated 8-quinolinol derivatives from many metal ions, such as iron(III), cobalt(II), nickel(II), copper(II), zinc(II) and gallium(III).