Selective separation of elements and radioisotopes by ion exchange chromatography

Naidoo, Clive (2002-12)

Thesis (PhD)--Stellenbosch University, 2002.

Thesis

ENGLISH ABSTRACT: The equilibrium distribution coefficients of 32 metal ions [Al(llI), As(V), CdïIl), Ce(III), Ce(IV), Co(n), Cr(III), Cu(II), Fe(III), Ga(III), Ge(IV), !n(III), La(III), Mn(II), Mo(VI), Nb(V), Ni(II), Pr(III), Sb(V), Sc(III), Se(IV), Sn(IV), Ta(V), Tb(III), Te(IV), Ti(IV), Vev), W(VI), Y(III), Yb(III), Zn(lI) and Zr(IV)] on a cation exchanger (Bio- Rad® AG50W-X8) and an anion exchanger (Bio-Rad® AG1-X8) in varying oxalic acid - sulphuric acid mixtures were successfully determined. The equilibrium distribution coefficients of these selected metal ions were determined in both 0.05 M and 0.25 M oxalic acid at various concentrations of sulphuric acid (0.005 M, 0.05 M, 0.10 M, 0.25 M, 0.50 M, 1.00 M, 1.50 M and 2.00 M). Attempts to explain the sorption behaviour of the selected metal ions were made by using MINEQL+, a speciation modelling program, and the speciation systems for AI(III), Cd(II), Co(II) and Zn(lI) in varying oxalic acid - sulphuric acid mixtures were determined. Two component [Zr(IV)-La(III); AI(III)-La(III); Ga(IlI)-Zn(II); As(V)-Zn(II); Cu(II)- Ce(IV); Ga(III)-Ce(IV); Ge(IV)-Ce(III); Mo(VI)- Y(III); Nb(V)- Y(III); Ga(III)-Co(II); As(V)-Co(lI) and Fe(III)-Mn(II)] and three component [Fe(III)-Ga(III)-Zn(lI) and Zr(IV)-Ta(V)-Yb(III)] mixtures on a 10 ml or 13 ml cation exchange resin in a variety of oxalic acid - sulphuric acid mixtures were successfully separated. Two component [As(V)-Zr(IV); Co(II)-Fe(III); Ni(II)-Co(lI) and Ni(II)-Fe(III)] and three component [Ni(II)-As(V)-Se(IV); AI(III)-Zn(II)-Ge(IV) and As(V)-Cu(II)-Ge(IV)] mixtures on a 10 ml or 13 ml anion exchange resin in a variety of oxalic acid - sulphuric acid mixtures were also successfully separated and studied. It was also shown how some of the elution curves developed above could easily be adapted for radiochemical separations. Usin~ the relevant data from the above study, a separation for 68Gefrom a Ga20 target was developed according to a method based on acid dissolution of the target and chromatography on an anion exchange resin (Bio-Rad® AG1-X8). The separated 68Geshowed high radionuclidic purity and an acceptable chemical purity.

AFRIKAANSE OPSOMMING: Die ewewigsverdelingskoëffisiënte van 32 metaalione [Al(III), As(V), Cd(II), Ce(III), Ce(IV), Co(II), Cr(III), Cu(II), Fe(III), Ga(III), Ge(IV), In(III), La(III), Mn(ll), Mo(VI), Nb(V), Ni(ll), Pr(Ill), Sb(V), Sc(III), Se(IV), Sn(IV), Ta(V), Th(Ill), Te(IV), Ti(IV), vrv; W(VI), Y(III), Yb(III), Zn(lI) en Zr(IV)] op 'n katioonruiler (Bio-Rad® AG50W-X8) en 'n anioonruiler (Bio-Rad® AG1-X8) in veranderende oksaalsuurswaelsuurmengsels is met welslae bepaal. Die ewewigsverdelingskoëffisiënte van hierdie geselekteerde elemente is in beide 0.05 Men 0.25 M oksaalsuur by verskeie konsentrasies swaelsuur (0.005 M, 0.05 M, 0.10 M, 0.25 M, 0.50 M, 1.00 M, 1.50 M en 2.00 M) bepaal. Daar is gepoog om die sorpsiegedrag van die geselekteerde metaalione te verklaar deur die gebruik van MINEQL+, 'n spesiëringmodelleringsprogram, en die spesiëringsisteme vir AI(III), Cd(II), Co(II) en Zn(lI) in veranderende oksaalsuur-swaelsuurmengsels is bepaal. Tweekomponent [Zr(IV)- La(III); AI(III)-La(II!); Ga(III)-Zn(Il); As(V)-Zn(II); Cu(II)-Ce(IV); Ga(III)-Ce(IV); Ge(IV)-Ce(Il!); Mo(VI)- Y(III); Nb(V)- Y(ll!); Ga(Ill)-Co(Il); As(V)-Co(lI) en Fe(III)- Mn(II)] en driekomponent [Fe(III)-Ga(III)-Zn(ll) en Zr(IV)- Ta(V)- Yb(III)] mengsels op 'n 10 ml of 13 ml katioonruilhars in 'n verskeidenheid oksaalsuurswaelsuurmengsels is met welslae geskei. Tweekomponent [As(V)-Zr(IV); Co(II)- Fe(III); Ni(Il)-Co(lI) en Ni(II)-Fe(III)] en driekomponent [Ni(II)-As(V)-Se(IV); AI(III)-Zn(Il)-Ge(IV) en As(V)-Cu(II)-Ge(IV)] mengsels op 'n 10 ml of 13 ml anioonruilhars in 'n verskeidenheid oksaalsuur-swaelsuurmengsels is ook met welslae geskei en bestudeer. Daar is ook aangetoon hoe sommige van die elueringskrommes wat hierbo ontwikkel is, maklik vir radiochemiese skeidings aangepas sou kon word. Deur gebruik te maak van die relevante data uit die studie hierbo, is 'n skeiding vir 68Geuit 'n Ga20-teiken ontwikkel volgens 'n metode gebaseer op suurdissolusie van die teiken en chromatografie op 'n anioonruilhars (Bio-Rad® AG1-X8). Die geskeide 68Gehet hoë radionukliedsuiwerheid en 'n aanvaarbare chemiese suiwerheid getoon.

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