Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Exploration of plants’ natural chelating agents for selective extraction of metal ions.
Thesis (PhD)--Stellenbosch University, 2022.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2022
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613833163440128 |
|---|---|
| access_status_str | Open Access |
| author | Tanui, Hillary Kipruto |
| author2 | Luckay, Robert C. |
| author_browse | Luckay, Robert C. Tanui, Hillary Kipruto |
| author_facet | Luckay, Robert C. Tanui, Hillary Kipruto |
| author_sort | Tanui, Hillary Kipruto |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/125076 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:42:24.259Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/125076 Exploration of plants’ natural chelating agents for selective extraction of metal ions. Tanui, Hillary Kipruto Luckay, Robert C. Mohammed, Ahmed Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Phytochemicals Metal ions Liquid chromatography UCTD Thesis (PhD)--Stellenbosch University, 2022. ENGLISH ABSTRACT: This work involved the exploration of extraction potential of polar phytochemicals available in ten different South African plants from the local reserve and commercially sourced tea. The plants were air dried and polar crude material extracted with hot water while overnight cooling to room temperature. The phytochemicals in the crude were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Some crudes had similar phytochemicals (quercetin) while others had unique compounds. Phytochemicals were used as green chelators. Iron(III), lead(II) and copper(II) ions were competitively removed from an eight-metal ion solution with iron(III) being removed at more than 80% followed by lead(II) with greater than 40% removal and copper(II) with removal values of more than 20% using deionized water with pH of 5 made using sodium acetate/acetic acid buffer. Metal ion removal was shown to occur via the pH-swing mechanism. From low pH and increasing, iron(III) was first removed followed by lead(II) and then copper(II). Iron(III) and lead(II) were selectively removed even at a 10-fold dilution level compared to the other metal ions present. Loading tests showed that iron(III) removal did not change, but for lead(II) and copper(II) there was a noticeable increase in removal with an increase in the amount of crude. Quercetin, rutin and morin have been shown to competitively extract iron(III), lead(II) and copper(II) from a concoction of eight metal ions. Iron(III) is extracted the most because the flavonoids contain the hard O-donor atom, while extraction of copper(II) and lead(II) depends on the chemical structure of the three flavonoids. Quercetin extracted twice as much lead(II) compared with copper(II), and rutin showed a similar extraction profile, while morin extracted the two metal ions on an equal level. Loading tests of the three flavonoids showed that lead(II) is synergistically extracted with iron(III) while copper(II) is not affected by the other metal ion extractions. Reduced loading level of morin affects the extraction of iron(III) while for quercetin it is not affected much. pH isotherms analysis showed that iron(III) extraction starts at pH three while lead(II) starts at pH four and copper(II) starts at pH five for morin and quercetin while for rutin extraction started at pH four with iron(III) and lead(II) being extracted first followed by copper(II) at pH five. Job’s plots analysis showed that two moles of quercetin complexes with a mole of copper(II) in solution stoichiometrically. Three moles of quercetin formed a chelate with one mole iron(III). One mole of quercetin to two moles of lead(II) chelates stoichiometrically. Two moles of morin chelates stoichiometrically with one mole of copper(II) while three moles of morin complexes with one mole of iron(III). The single-crystal X-ray analysis shows that Fe(III) is coordinated to three morin ligands in a distorted octahedral manner to form three five-membered chelate rings. Analysis on the relative ground state energies of chelate structures confirm that the Fe(III) [M/Q]3 structures for either morin or quercetin are more stable than their respective Fe(III) [M/Q]2 and Cu(II) [M/Q]2 complexes The stability constants for morin, rutin and quercetin against complexes formed with iron(III) and copper(II) were computed. The stability constants for iron(III) follows the normal trend of K1* >K2* >K3*, hence stable and concurs with the observation that almost 100% is extracted. The stability constants for Fe(III) are higher than those for Cu(II) ions, this correlates with the higher extraction of Fe(III) by the ligands as compared to Cu(II). AFRIKAANSE OPSOMMING: Hierdie werk het behels die verkenning van die onttrekkingspotensiaal van polêre fitochemikalieë wat beskikbaar is in tien verskillende Suid-Afrikaanse plante uit die plaaslike reservaat en kommersieel verkrygde tee. Die plante is met die lug gedroog en polêre rumateriaal is met warm water onttrek terwyl dit oornag tot kamertemperatuur afgekoel het. Die fitochemikalieë in die ruolie is geïdentifiseer deur gebruik te maak van vloeistofchromatografie-tandem massaspektrometrie (LC-MS/MS). Sommige ruolie het soortgelyke fitochemikalieë (quercetin) gehad terwyl ander unieke verbindings gehad het. Fitochemikalieë is as groen cheleerders gebruik. Yster(III), lood(II) en koper(II) ione is mededingend verwyder uit 'n agtmetaalioonoplossing met yster(III) wat verwyder is teen meer as 80% gevolg deur lood(II) met meer as 40% verwydering en koper(II) met verwyderingswaardes van meer as 20% deur gebruik te maak van gedeïoniseerde water met pH van 5 gemaak met behulp van natriumasetaat/asynsuurbuffer. Daar is getoon dat metaalioon verwydering via die pH-swaaimeganisme plaasvind. Van lae pH en toenemende is yster(III) eers verwyder, gevolg deur lood(II) en dan koper(II). Yster(III) en lood(II) is selektief verwyder selfs by 'n 10-voudige verdunningsvlak in vergelyking met die ander metaalione teenwoordig. Belaaitoetse het getoon dat yster(III) verwydering nie verander het nie, maar vir lood(II) en koper(II) was daar 'n merkbare toename in verwydering met 'n toename in die hoeveelheid ruolie. Daar is getoon dat quercetin, rutin en morin mededingend yster(III), lood(II) en koper(II) uit 'n konkoksie van sewe metaalione onttrek. Yster(III) word die meeste onttrek terwyl ekstraksie van koper(II) en lood(II) afhang van die chemiese struktuur van die drie flavonoïede. Quercetin het twee keer soveel lood(II) onttrek in vergelyking met koper(II), en rutin het 'n soortgelyke ekstraksieprofiel getoon, terwyl morien die twee metaalione op 'n gelyke vlak onttrek het. Beladingstoetse van die drie flavonoïede het getoon dat lood(II) sinergisties met yster(III) onttrek word terwyl koper(II) nie deur die ander metaalioonekstraksies beïnvloed word nie. Verminder laaivlak van morien beïnvloed die ekstraksie van yster(III) terwyl dit vir quercetin nie veel beïnvloed word nie. pH-isoterme-ontleding het getoon dat yster(III)-ekstraksie by pH drie begin, terwyl lood(II) by pH vier begin en koper(II) by pH vyf begin vir morien en quercetin, terwyl vir rutien-ekstraksie by pH vier begin het met yster(III) en lood(II) word eerste onttrek gevolg deur koper(II) by pH vyf. Job se plot-analise het getoon dat twee mol quercetin komplekse met 'n mol koper(II) in oplossing stoïgiometries. Drie mol quercetin vorm 'n chelaat met een mol yster(III). Een mol quercetin tot twee mol lood(II) chelaat stoïgiometries. Twee mol morien chelateer stoïgiometries met een mol koper(II) terwyl drie mol morien komplekseer met een mol yster(III). Die enkel-kristal X-straal analise toon dat Fe(III) op 'n verwronge oktaëdriese wyse gekoördineer is tot drie morin ligande om drie vyfledige chelaatringe te vorm. Analise op die relatiewe grondtoestand-energieë van chelaatstrukture bevestig dat die Fe(III) [M/Q]3-strukture vir óf morien óf quercetin meer stabiel is as hul onderskeie Fe(III) [M/Q]2 en Cu(II) [M/V]2 komplekse Die stabiliteitskonstantes vir morien, rutien en quercetin teen komplekse gevorm met yster(III) en koper(II) is bereken. Die stabiliteitskonstantes vir yster(III) volg die normale neiging van K1* >K2* >K3*, dus stabiel en stem ooreen met die waarneming dat byna 100% onttrek word. Die stabiliteitskonstantes vir Fe(III) is hoër as dié vir Cu(II)-ione, dit korreleer met die hoër ekstraksie van Fe(III) deur die ligande in vergelyking met Cu(II). Doctoral 2022-02-14T16:29:24Z 2022-04-29T12:52:55Z 2023-01-04T03:00:09Z 2022-02 Thesis http://hdl.handle.net/10019.1/125076 en_ZA Stellenbosch University xxv, 127 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Phytochemicals Metal ions Liquid chromatography UCTD Tanui, Hillary Kipruto Exploration of plants’ natural chelating agents for selective extraction of metal ions. |
| title | Exploration of plants’ natural chelating agents for selective extraction of metal ions. |
| title_full | Exploration of plants’ natural chelating agents for selective extraction of metal ions. |
| title_fullStr | Exploration of plants’ natural chelating agents for selective extraction of metal ions. |
| title_full_unstemmed | Exploration of plants’ natural chelating agents for selective extraction of metal ions. |
| title_short | Exploration of plants’ natural chelating agents for selective extraction of metal ions. |
| title_sort | exploration of plants natural chelating agents for selective extraction of metal ions |
| topic | Phytochemicals Metal ions Liquid chromatography UCTD |
| url | http://hdl.handle.net/10019.1/125076 |
| work_keys_str_mv | AT tanuihillarykipruto explorationofplantsnaturalchelatingagentsforselectiveextractionofmetalions |