Studies On The Adsorptive Stripping Voltammetry Of Vanadium(Ⅴ),Aluminum(Ⅲ) Complexes

In this paper, with alizarin red S(ARS) as ligand, Two new methods were described for the determination of vanadium( V) based on the adsorptive catalytic stripping voltammetry and adsorptive stripping voltammetry. and the voltammetric behavior of aluminum(III)-ARS complexes at carbon paste electrodes was studied in detail.This paper consists of two chapters:In chapter 1, the two methods of determination of vanadium( V) were introduced. In the first part of chapter 1, the adsorptive catalytic voltammetric behavior of V( V )-ARS-NaClO3 system was investigated on hanging mercury drop electrode. A sensitive adsorptive catalytic wave of vanadium( V )-Alizarin red S complex was obtained in 0.4 mol.L-1 hexamethylenetetraamine-hydrochloric acid buffer solution containing 1.0×10-5 mol.L-1 ARS and l.8mol.L-1 sodium chlorate at pH5.3.The peak potential appears at -0.68V (vs.Ag/AgCl).The peak height is linear with the concentration of vanadium in the range from 2.0 × 10-10 to 1.0 × 10-6 mol.L-1 .The detection limit for vanadium is 1.0 ×10-10 mol.L-1 .The electrode processes of the adsorptive catalytic wave have been discussed. The molar ratio of each component in the complex has been determined as n v(v):n_ARS =1:2.The method has been applied to the determination of vanadium in water samples with satisfactory results. In the other part of chapter 1, the adsorptive stripping voltammetry for the determination of vanadium was studied at carbon paste electrode (CPE) in detail. In acetate buffer solution (pH5.1) the complex is adsorbed on the surface of CPE and produces a sensitive reduction peak current. The peak potential is at about-0.52V (vs.SCE). The second order derivative peak height is linear with the concentration of vanadium in the range of 2.0 × 10-9 -1.0× 10-7mol/L , and the detection limit for vanadium is as low as 8.0× 10-10mol/L(for a 240s accummulation). The mechanism of electrode process was studied. The developed method was applied to determination of vanadium in water samples with satisfactory results.In chapter 2, A sensitive adsorptive reduction wave of Aluminum(III)- ARS complex was obtained in 0.12mol/L acetate buffer solution (pH4.9) containing 8.0 × 10-6mol/L ARS at a carbon paste electrode. The calibration curve is linear in the range from 1.0 μ g/L to 15.0 μ g/L Al(III). The detection limit for aluminum(III) is 0.8 μ g/L for a accumulation time of 120s. The electrode processes of the adsorptive wave have been discussed. The method has been applied to the determination of aluminum in water samples with satisfactory results.In a word, we have established several new methods for the determination of vanadium and aluminum. These systems have high sensitivity, better selectivity, wide linear rang and good stability. All these advantages make these methods full of practical value.