Voltammetry and electrochemical stripping analysis for antimony in aqueous and nonaqueous media after extraction

Abstract

Cyclic voltammetry of antimony was studied in aqueous media (HCl-LiCl) and in nonaqueous media after extraction with 20% tri-n-butylphosphate in toluene, with a rotating glassy carbon disc electrode. Reduction of antimony to the element in aqueous media is nearly reversible, but irreversible in nonaqueous media. Anodic stripping voltammetric and chronopotentiometric determinations were also studied in nonaqueous media; methanol and LiCI, NH 4SCN or NH 4NO 3, were used as base electrolytes. In nonaqueous media, antimony can be determined down to concentrations of 1O −8 M by stripping voltammetry, and lO −7 M by stripping chronopotentiometry. Electrochemical stripping determinations of 10 −6 M antimony(III) were not affected by Co 2+, Ni 2+, Cd 2+, Zn 2+ or As 3+ (5 · 10 −3 M), ag + (4 · 10 +4 M in stripping voltammetry or 10 −3 M in stripping chronopotentiometry), Hg 2+ (5 · 10 −4M), Pb 2+ (3 · 10 −4 M), Cu 2+ (1.5 · 10 −4 M)Sn 2+ and Sn 4+ (7 · 10 −4 M), Fe 3+ (4 · 10 −4 M), Au 3+ (5 · 10 −5 M) and Bi 3+ (1.5 · 10 −5 M). Thestripping chronopotentiometric determination showed better selectivity.