Extraction chromatographic method of preconcentration, estimation and concomitant separation of vanadium (IV) with silica gel-versatic 10 composite

Abstract

A selective method has been developed for the extraction chromatographic separation of V(IV) with SSG-V-10 composite. V(IV) was quantitatively extracted at pH 5.0-6.0, and its loading has been confirmed by EDAX. XRD studies indicate that the SSG network does not get influenced by impregnation with V-10 or by the sorption of V(IV) on the surface of SSG-V-10 composite. The binding between SSG and V-10 is a hydrophobic interaction only, and it takes place at the surface of the hydrophobic SSG. TGA-DTA analysis indicates its thermal stability up to 458C. The exchange capacity (1.65 meq of H+ g21), break-through capacity (34.5 mgg21) and column efficiency (360) of the extractor have been rationalized by Brunauer-Emmett-Teller analysis (SA = 149.46 m2g21 and PV = 0.2001 mLg21 at a relative pressure of 0.9-1.0). The sorption process was endothermic (ΔH = 12.63 kJ mol-1), entropy gaining (ΔS = 0.271 kJ mol-1 K-1 and spontaneous (DG = 268.241 kJ mol21) in nature. Precon-cen-tration factor has been optimized at 182.3 ± 0.2. Formation constants (Kf) of the metal centers [Zn(II) (0.6 × 103), Cd(II) (0.9 × 104), Pb(II) (0.6 × 105), Cu(II) (0.2 × 105), Al(III) (6.2 × 105), Ga(III) (4.2 × 105), Hg(II) (2.2 × 106), Bi(III) (6.2 × 106), Tl(III) (8.9 × 106), Zr(IV) (6.8 × 109), Fe(III) (0.9 × 109) and V(IV) (0.8 × 106)] have been determined. The desorption constants kdesorption (1.9 × 10-2) and K2desorption (215 × 10-1) have been determined. Kf values and selectivity factors for diverse metal ions have been determined. V(IV) has been separated from the synthetic and real samples containing its congeners. A plausible mechanism for the extraction of V(IV) has been suggested.