Studies On The Adsorptive Stripping Voltammetry Of Sc (â…¢),Th(â…£) Complexs

In this paper, a new method is described for the determination of Sc(III), Th(1V), based on the adsorptive stripping voltammetry of Sc(III)-ALC, Th(LV)-ALC, Th(IV)-Zn( II )-ALC complexes at carbon paste electrode(CPE) and hanging mercury drop electrode (HMDE). This paper consists of three chapters: In chapter one, A selective, sensitive, rapid and economic adsorptive stripping voltammetric method has been developed for the determination of trace amount of scandium, after its alizarin complexan(ALC) complex is adsorbed at CPE in a mixed buffer solution(pH5.4) which consist of 0.O4moIIL acetate and 0.0 l6mol/L biphthalate, yielding one peak at .60V(vs.SCE) corresponds to the reduction of ALC in the complex at the electrode. A good linear relationship between the second order derivative peak height and Sc(llI) concentration in the range of 1.0 X 10--6.0 X lO7molIL was observed. The detection limit for Sc(HI) is 6.0 X 10 moJ/L and eight determinations of 6.0 X lO8molIL gave a relative standard deviation of 4.34%. At the same time, the voltammetric behavior of Sc(III)-ALC complex has been studied in detail at a CPE and the molar ratio of each component in the complex has also been estimated. The method was applied to the determination of the trace Sc(llI) in the mineral samples with satisfactory results. In chapter two, the voltainmetric behavior of Th(JV)-ALC complex has been studied in detail at a CPE. The optimum conditions of the determination of thorium are found. In a mixed buffer solution(pI-I5 .0) which consist of 0. lmolIL acetate and O.O4molIL biphthalate, Th(IV)- ALC complex is adsorbed at a CPE and yields a sensitive cathodic stripping peak. The second-order derivative peak height of the complex is proportional to the concentration of Th(LV) over the range of 3.0 X 9 .OX lW7molIL. The limit of detection is l.OX lW9moJIL. The molar ratio of each component in the complex has been estimated and the electrode reaction mechanism has also been discussed in detail. The method has been applied to the determination of the trace Th(IV) in the ore and clay samples with satisfactory results. In chapter three, A reliable and sensitive method is proposed for the determination of the trace amounts of thorium by single-sweep stripping voltammetry. This method is based on the adsorptive accumulation of the thorium-Zinc-Allzarin complexan mix-polynuclear complex onto a I-IMDE in 0.2moIIL acetate buffer solution(pH4.4 4.6).The peak height of the mix-polynuclear complex at .64 V(vs.Ag/AgCl)is proportional to the concentration of Th(1V)in the range of 3.OX iO,9挆 1.5 X 10,moIIL.The limit of detection is 1.5 X 109moIIL and ten determinations of 6.0 X 1(Y7mo1ILTh4, give a relative standard deviation of 1 .85%.The molar ratio of each component in the mix-polynuclear complex has been estimated as n 1NIV) , Zn(TI) : n ,1 : 1 : 2.The properties of the adsorptive stripping peak and the electrode reaction mechanism are also discussed in detail. The method has been applied to the determination of the trace amounts of Th(IV)in the ore and clay samples with satisfactory results.