Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: In this study, a number of mono- and di-substituted acyl(aroyl)thioureas were investigated
for potential application as specific carriers (ionophores) for the transport and extraction of
Ag(l) from a mixture of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(lI) ions. The experimental
arrangement for the transport experiments employed a liquid membrane set up involving a
3-phase system - 2 aqueous phases (source and receiving phase) separated by a
chloroform membrane incorporating the ligand. Competitive metal ion transport
experiments were conducted using the liquid membrane set up. The aqueous source and
receiving phases were analyzed using Atomic Absorption Spectroscopy (AAS) and results
were confirmed by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICPOES).
The transport results show that the N,N-dialkyl-substituted-N'-acyl(aroyl) (HL)
thioureas studied, with the exception of the N,N-di-(2-hydroxyethyl)-N'-benzoylthiourea
(HL3
) and N-piperidyl-N'-4-nitrobenzoylthiourea (HL9
), were efficient and selective for Ag(I).
HL9 was also selective for Ag(l) but not efficient. HL3 was selective for Cu(II). Under the
experimental conditions employed, 13% Cu(lI) was transported by HL3
. Among the N,Ndialkyl-
N'-aroylthioureas, maximum Ag(l) transport was obtained by using N,N-diethyl-N'-4-
chlorobenzoylthiourea (HL5
) and N,N-di-n-butyl-N'-benzoylthiourea (HL \ Under the
experimental conditions employed, the percentages of Ag(l) transported by HL5 and HL 1
were 48% and 42% respectively.
The transport selectivity and efficiency of 3,3,3' ,3'-tetraethyl-1 ,1'-isophthaloylbisthiourea
(H2L12
) and N,N-diethyl-N'-camphanoylthiourea (HL13)for Ag(l) were also studied. We were
particularly interested, in comparing the Ag(l) transport and extraction efficiency of these
ligands with that of the HL and H2L ligands. The experimental results reveal that, of all the
ligands we investigated in this study, HL 13 was the most efficient and selective carrier for
Ag(l) transport. The interesting result is that, depending on the ligand concentration used,
HL 13 transported 71-81% of Ag(I).
Competitive two-phase metal ion solvent extraction experiments were also performed
under conditions similar to the transport studies. The results show that by varying the
ligand concentration in the membrane phase, up to 100% Ag(l) can be selectively and
efficiently extracted from the mixture of the seven metal ions. Finally, the N,N-di-(n)-butyl-N'-benzoylthiourea (HL1) ligand and its complex with Ag(l)
were synthesized. Single crystals of the complex were grown for X-ray crystallography and
the crystal and molecular structure of the complex was determined. The crystal structure
showed that Ag(l) is bonded to the deprotonated ligand through the S,O atoms forming
interesting cluster [Ag (L - S, 0)] 4 in the solid state. This structure is monoclinic and
crystallizes in the space group P21!c with a = 17.805 (4) A, b = 21.759 (4) A, c =
36.438 (7) A, f3= 96.34(3)°, Z = 8 and a final R-factor of 5.4%. / AFRIKAANSE OPSOMMING: In hierdie proefskrif is 'n aantal mono- en di-gesubstitueerde asiel(ariel) tioureums
ondersoek vir moontlike gebruik as ionofore (spesifieke draers) vir die transportasie en
ekstraksie van Ag(l) vanuit 'n mengsel van Co(ll), Ni(II), Cu(II), Zn(II), Cd(II), Ag(l) en Pb(lI)
ione.
'n Drie-fase selsisteem is gebruik vir die transportasie eksperimente, twee waterige fases
(bron- en ontvang-fase) wat geskei is met die chloroform membraan fase wat die ligande
bevat. Kompeterende metaalioon transportasie eksperimente is uitgevoer met behulp van
hierdie vloeistof membraan stelsel. Die twee waterige fases is deur middel van
Atoomabsorpsie Spektroskopie (AAS) ge-analiseer en resultate is bevestig met gebruik
van Induktief-gekoppelde Plasma-Optiese Emissie Spektroskopie (IGP-OES). Die
resultate het getoon dat elkeen van die N,N-dialkiel-gesubstitueerde-N'-asiel(ariel) (HL)
tioureums, met uitsondering van N,N-di(2-hidroksie-etiel)-N'-benzieltioureum(HL 3) en Npiperidiel-
N'-4-nitrobenzieltioureum(HL9
), doeltreffend en selektief was vir Ag(l)
transportasie. HL9 was selektief vir Ag(I), maar die transportasie waarde was nie hoog nie,
dws. dit was nie doeltreffend nie. HL3 was selektief vir Cu(II). Met gebruik van ons
eksperimentele kondisies is 13% Cu(lI) getransporteer deur HL 3. Van die N,N-dialkiel-N'-
ariel tioureums, is maksimum transportasie van Ag(l) verkry met gebruik van N,N-dietiel-
N'-4-chlorobenzieltioureum (HL5) en N,N-di-n-butiel-N'-benzieltioureum (HL1). Met gebruik
van ons eksperimentele kondisies was die persentasie transportasie van Ag(l) deur HL5 en
HL 1 48% en 42% onderskeidelik.
Die selektiwiteit en doeltreffendheid van 3,3,3' ,3'-tetra-etiel-1 ,t-isoftaltelblstioureumtl+L 12)
en N,N-di-etiel-N'-kamfonieltioureum (HL13) vir Ag(l) transportasie is ook onderneem. Ons
was besonder ge-interesseerd om die Ag(l) transportasie en ekstraksie van hierdie ligande
te vergelyk met dié van die HL en H2L tipe ligande. Die eksperimentele resultate het
getoon dat van al die ligande wat bestudeer is, HL 13 die doeltreffendste en mees
selektiewe ionofoor was. Van besondere, belang was dat, afhangend van die ligand
konsentrasie wat gebruik is, HL13 71-81% Ag(l) getransporteer het.
Kompeterende twee-fase metaalioon vloeistof-vloeistof ekstraksie eksperimente is ook
uitgevoer onder toestande soortgelyk aan dié van die transportasie eksperimente. Die resultate toon dat met varierende ligand konsentrasie, tot soveel as 100% Ag(l) selektief
en doeltreffend geëkstrakeer word vanuit 'n mengsel van die sewe metaal ione.
N,N-di-n-butiel-N'-benzieltioureum (HL1
) ligande en die kompleks daarvan met Ag(l) is ook
gesintetiseer. Enkel-kristalle van die kompleks is verkry en X-straal kristallografiese
analiese is onderneem. Die kristalstruktuur toon hoedat Ag(l) gebind is aan die
gedeprotoneerde ligand deur die S en Q atome en toon ook interessante [Ag(L-S,Q)]4
groepe in die vaste toestand. Hierdie struktuur is monoklinies en kristaliseer in die
ruimtegroep P21!c met a = 17.805(4) Á, b = 21.759(4)Á, c = 36.438(7)Á, P = 96.34(3t, z =
8 en 'n finale R-faktor van 5.4%.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/97374 |
| Date | 12 1900 |
| Creators | Habtu, Michael M. |
| Contributors | Koch, K. R., Luckay, R. C., Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 142 pages : illustrations |
| Rights | Stellenbosch University |
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