Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008. / The competitive transport, extraction, and coordination chemistry for a series of N- (thio)phosphorylated (thio)amide and N-(thio)phosphorylated (thio)urea ligands were investigated with the seven transition and post-transition metal ions Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II) and Pb(II). Three N-benzylated derivatives of 1,4,7,10- tetraazacyclododecane (cyclen) were synthesized and a similar study carried out with the same metal ions and the deprotonated precursors. The ligands were all potential specific carriers (ionophores) in the organic phase. The seven metal ions had equal concentrations in the source phase. The experimental arrangement for the transport studies employed a set-up involving three phases: a source phase and a receiving phase (both aqueous), separated by a chloroform membrane (organic phase). Competitive metal ion solvent extraction involved two phases: an aqueous phase and an organic phase. Similar conditions were used in transport and extraction studies. The metal ion concentrations in the aqueous phases were analyzed by atomic absorption spectroscopy (AAS). The transport results of deprotonated N-(thio)phosphorylated (thio)amides and N- (thio)phosphoryated (thio)ureas showed that PhC(S)NPO(OPri)2 (L1), BrPhC(S)NPO-(OPri)2 (L11) and PriNHC(S)NPO(OPri)2 (L16) transported Ag(I) into the receiving phase. Under these experimental conditions, L1 had the highest Ag(I) transport efficiency, at 36.3%, while L11 only transported one metal ion, viz. Ag(I). With NH2C(S)NP(S)(OPri)2 (L4), 94.6% of Ag(I) remained in the membrane phase. Thus L4 appeared to have the highest formation constant with Ag(I). A small amount of Cu(II) was also transported by L1, NH2C(S)NP(O)(OPri)2 (L9), L16 and ButNHC(S)-NPO(OPri)2 (L20). L20 had the highest selectivity for Cu(II). Results of competitive metal ion extraction studies revealed that most ligands extracted up to 100% Ag(I), except L1 and morpholine substituted ligands (L7, L17) . The formation constant of L1 effects a subtle balance between metal uptake and metal loss into and out of the respective membrane phase. HL7 and HL17 had low solubility in chloroform. L4 extracted the highest percentage of Cu(II) (49%). Two neutral ligands, PhCONHPO(OPri)2 (1) and BrPhCONHPO(OPri)2 (2) were isolated and their molecular structure determined. They had monoclinic unit cells in the space groups C2/c and P21/n, respectively. An unprecedented octanuclear [Ag(I)(L4-S,N)]8 (3) complex was also crystallized. The extended structure showed three different cavities alternating with two unique 16-membered rings, creating a novel AgS2N2 cage. Two polynuclear Cu(I) chelates with deprotonated L4 and L6 (tBuNHC(S)NP(S)(OPri)2) were isolated by the same crystallization method. The complex [Cu(I)(L4–S,S)]9 (4) consisted of a hexagonal-prismatic hexamer, which exhibited an unusual and unprecedented supramolecular “honeycomb” packing. The trinuclear [Cu(I)(L6–S,S)]3 (5) consisted of a 6-membered Cu3S3 ring attached to a hydroxy tetrahydrofuran molecule. Di-, tri- and tetra-benzyl-1,4,7,10-tetraazacyclododecane (cyclen) was synthesized, and characterized. None of these compounds was effective in metal transport under these experimental conditions. Nevertheless, Tetra-benzyl cyclen showed the highest extraction efficiency for Ag(I), at 100%, and the highest selectivity for Ag(I) extraction, compared to Cu(II). An intermediate of dibenzyl cyclen compound dibenzylated dioxocyclen (6) was crystallized and found a host THF molecule in the lattice. The crystal and molecular structure confirmed the cis-configuration. The X-ray structure of the Cu(II) complex with dibenzylated cyclen (7) was determined for the first time. It was found to have an ideal square pyramidal coordination geometry around the central metal ion. A serendipitous organic compound of isopropylammonium(isopropylamino)- oxoacetate mono-hydrate (8) was crystallized. The crystal was held together by inter-molecular hydrogen bonds, which lead to two-dimensional layers with hydrophobic interactions.

Mechanistic aspects of phosphorylation, dephosphorylation, pyrophosphorylation and depyrophosphorylation reactions that mimic phosphorylases, dephosphorylases, pyrophosphorylases and depyrophosphorylases have been studied in the biologically important middle pH region. The different systems monitored are; (a) the reactions between [{CoN4(OH)(OH2)}]2+ and [HPO4]- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to [HPO4]2- ratios. (b) the reactions between [{CoN4PO4] and [O2NC6H4O]- (abbreviated as NP-) for 1:1, 2:1 and 3:1 [{CoN4PO4] to [O2NC6H4O]- ratios. (c) the reactions between [{CoN4(OH)(OH2)}]2+ and [O2NC6H4PO4]2- (abbreviated as NPP2-) for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to [O2NC6H4PO4]2- ratios. (d) the reactions between [{CoN4(OH)(OH2)}]2+ and [H2P2O7]2- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to [H2P2O7]2- ratios. (e) the reactions between [{CoN4P2O7}]- and [O2NC6H4O]- for 1:1, 2:1 and 3:1 [{CoN4P2O7}]- to [O2NC6H4O]- ratios. Significant phosphorylation was noted for systems containing 1:1 molar ratio [{CoN4PO4] and [O2NC6H4O]-. Enhanced phosphorylation was depicted for system containing 1:1 molar ratio of [{CoN4(OH)}2PO4]+ and [O2NC6H4O]-. Pyrophosphorylation was noted for reactions of 1:1 molar ratio of [{CoN4P2O7}]- and [O2NC6H4O]-. The rate of pyrophosphorylation was substantially reduced for systems that were 2:1 in molar ratio of [{CoN4P2O7}]- and [O2NC6H4O]-. No appreciable pyrophosphorylation was noted for systems, which has a 3:1 molar ratio of [{CoN4P2O7}]- and [O2NC6H4O]-. Specific mechanistic features and the possible roles metal ions play in phosphorylase, dephosphorylase and pyrophosphorylase are highlighted from results of UV-Visible spectroscopy, 31P {1H} NMR spectroscopy and Surface Enhanced Raman Scattering (SERS) studies / Chemistry / D.Phil. (Chemistry)

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: In this study, two novel ligands were synthesized and separately two crown ether derivatives were all immobilized onto four different silica substrates. These immobilized ligand systems were used to extract six different metal and metalloid ions in water. The extraction capacity of the different immobilized ligands was compared with each other to determine whether the substrates had any influence on the extraction capabilities of these ligands. After the extraction experiments, recovery of the immobilized ligands was attempted by re-protonating the ligands so as to displace the metal ions. Two free parent ligands, 1,4,7-tris-[(S)-2-hydroxypropyl]-1,4,7-tri-azacyclodecane (THTD) and 1,4,8-tris-[(S)-2-hydroxypropyl]-1,4,8-tri-azacycloundecane (THTUD), were synthesized. Previous formation constant data indicated that THTD and THTUD form very stable complexes with Cd2+ which should make these ligands ideal for the extraction of Cd2+. These two ligands are less symmetric due to the carbon bridges between the nitrogen atoms, which differ in length. This gives the ligands the special feature that they can form five - and six membered rings during complexation with the metal ions. The ligands were fully characterized by NMR, mass spectrometry and elemental analysis. Characterization of the silica substrates was done using BET, low angle X-ray diffraction and FTIR. MCM-41 has the highest surface area, followed by SBA-15, Si gel (60 Å) and HMS. Although MCM-41 has the largest surface area, it was not the best support to use. HMS and Si gel (60 Å) have the smallest and almost identical surface areas. Yet, Si gel (60 Å) was a far better support to use than HMS, and even better than MCM-41. The worst supports were SBA-15 and HMS. A spacer, 3-Glycidyloxypropyl-trimethoxysilane (glymo), was introduced to immobilize the ligands to the silica substrates. Solid state NMR and FTIR analysis confirmed that the spacer could indeed be successfully immobilized on the various silica supports. The immobilized ligands were fully characterized with the use of solid state NMR and FTIR. The thermal stability of the immobilized ligands was determined by means of TGA. The immobilized ligands are stable up to 200ºC where after they started to disintegrate. According to literature, 15-crown-5 and 18-crown-6 are suitable ligands for the extraction of Sr2+ and UO22+. Since these ligands were to be immobilized, (2-aminomethyl)-15-crown-5 and (2-aminomethyl)-18-crown-6 were used because of the amino group that can be used as an anchor for immobilization. To immobilize these ligands onto the activated silica substrates, two methods were used: 1) directly onto the substrate by using the amino groups at the end of the carbon arm and 2) by means of the glymo spacer which connects the (2-aminomethyl)-15-crown-5 and (2-aminomethyl)-18-crown-6 to the silica substrates. The immobilization was confirmed and the ligand-substrate moiety fully characterized by solid state NMR and FTIR. The thermal stability of the immobilized crown ethers was determined by means of TGA as stable up to 200ºC where after they disintegrated. Extraction experiments were conducted at 25ºC and atmospheric pressure. The extractions were done at pH values of 4.5 and 5.9. The extraction capacity of the immobilized ligands was determined by ICP analysis. As expected, the extraction done at pH 5.9 was significantly better than at pH 4.5. Cr6+ was the best-extracted metal ion. The best extraction results were obtained with Si gel (60 Å) as support. It was also noticeable that the extraction capacity increased with a spacer added to the support, except for the extraction of UO22+. Better extraction for the uranyl was obtained using the 15-crown-5 and 18-crown-6 immobilized directly onto the supports, rather than with a spacer added. Recovery of the metal ions and the immobilized ligands was attempted, but without success. This aspect will be examined again in future work. In conclusion, ligands were successfully synthesized and immobilized. These immobilized ligands produced moderate extraction results with a number of metal ions from aqueous solution. / AFRIKAANSE OPSOMMING: Hierdie studie behels die sintetisering van 2 nuwe ligande en die immobilisering daarvan, te same met 2 kroon eters, op vier verskillende silika substrate. Die geïmobiliseerde ligande is gebruik vir die ekstraksie van verskillende metaal - en metaloied ione uit water. Die ekstraksie kapasiteit van die onderskeie geïmobiliseerde ligande is vergelyk om te bepaal of die substrate ‘n uitwerking op die ekstraksie vermoeë van die ligande het. Herwinnings eksperimente is uitgevoer deur die verplasing van die geadsordeerde metaal ione deur middel van reprotonasie van die ligande. Twee nuwe azamakrosikliese basis ligande, 1,4,7-tris-[(S)-2-hidroksipropiel]-1,4,7-tri-azasiklodekaan (THTD) en 1,4,8-tris-[(S)-2-hidroksipropiel]-1,4,8-tri-azasikloundekaan (THTUD), is gesintetiseer. Vormings konstante data dui daarop dat THTD en THTUD uiters stabiele komplekse met Cd2+ vorm wat hierdie ligande dus geskik behoort te maak vir die ekstraksie van Cd2+. Die twee ligande toon ook ‘n mindere mate van simmetrie as gevolg van die verskillende lengtes van die koolstof brûe tussen die stikstof atome. Hierdie eienskap verskaf aan die ligande die moontlikheid om beide vyf- en sesledige ringe vorm tydens kompleksering met die metaal ione. Die ligande is ten volle gekarakteriseer deur middel van KMR-metings, massa-spekstroskopie en element analise. Karakterisering van die silika substrate [Si gel (60 Å), MCM-41, SBA-15, and HMS] sluit in BET, lae hoek X-straaldiffraksie en FTIR. MCM-41 het die grootste oppervlakte, gevolg deur SBA-15, Si gel (60 Å) en HMS. Ten spyte van die feit dat MCM-41 die grootste oppervlakte het, was dit egter nie die beste subtraat om te gebruik nie. Die interne areas van die uiters groot porie-oppervlaktes van MCM-41 is nie toeganklik vir immobilisering nie a.g.v. die uiter klein porie-openinge. Si gel (60 Å) en HMS het die kleinste oppervlak areas. Si gel (60 Å) is ‘n baie beter substraat om te gebruik as HMS, en selfs ook beter as MCM-41 aangesien die totale oppervlakte van die Si gel (60 Å) gebruik kan word. Die mees ongeskikte substrate was SBA-15 en HMS. Die alreeds klein oppervlak areas word verder “verklein” a.g.v. die klein porie openinge wat die interne oppervlekte van die porieë ontoegangklik maak. ‘n Verbinder, 3-Glysidieloksipropiel-trimetoksisilaan (glymo) is gebruik om die ligande op die silika substrate te immobiliseer. Vaste toestand KMR en FTIR analise het bevestig dat die verbinder suksesvol geïmmobiliseer is op die onderskeie silika substrate. Die geïmmobiliseerde aza makrosikliese ligande is ten volle gekarakteriseer deur vaste toestand KMR en FTIR. Die termiese stabiliteit is bepaal d.m.v GTA en die geïmmobiliseerde ligande is stabiel tot 250ºC. Die basis ligande 15-kroon-5 an 18-kroon-6 is uiters geskik vir die ekstraksie van Sr2+ en UO22+. Om hierdie kroon eters te immobiliseer, is (2-aninometiel)-15-kroon-5 en (2-aninometiel)-18-kroon-6 gebruik. Die amino groep dien as anker vir die immobilisering. Twee metodes van immobilisering op silika is gebruik: 1) direkte immobilisering op die substraat en 2) immobilisering d.m.v. die glymo verbinder. Die immobilisering is bevestig en die ligand-substraat funksionel groep is gekarakteriseer d.m.v. vaste toestand KMR en FTIR. Die termiese stabiliteit van die geïmmobiliseerde kroon eters is bepaal d.m.v. GTA en is stabiel tot 200ºC. Ekstraksie eksperimente is uitgevoer by 25ºC en atmosferiese druk. Die ekstraksies is uitgevoer by pH waardes van 4.5 en 5.9. Die adsorpsie kapasiteit van die geïmmobiliseerde ligande is bepaal d.m.v. IGP analise. Soos verwag is die ekstraksie by pH 5.9 beter as by pH 4.5. Cr6+ ekstrksie was die hoogste met al die die ligande geïmmobiliseerd op die onderskeie substrate. Si gel (60 Å) was die beste substraat om te gebruik. Die ekstraksie kapasiteit van al die metaal ione het verbeter met die toevoeging van ‘n verbinder, behalwe vir UO22+. Beter ekstraksie van die UO22+ is verkry met die gebruik van die kroon eters wat direk op die substrate geïmmobiliseer is, eerder as met ‘n verbinder toegevoeg. Herwinning van die metaal ione en die ligande is probeer deur standard filtrasie. Na die filtrasie is die geïmmobiliseerde ligande en substrate met water gewas. Die filtreerpapier en ligande is met HNO3 behandel, maar van die metaal ione het egter op die filtreer papier agter gebly en die IGP resultate het ‘n hoër herwinning getoon as wat tydens die ekstraksie verkry is. Hierdie aspek sal weer in die toekoms ondersoek moet word. Die ligande is suksesvol gesintetiseer en geïmmobiliseer. Hierdie geïmmobiliseerde ligande toon gemiddelde ekstraksie resultate met ‘n aantal metaal ione uit waterige medium by ‘n pH van 5.9.

A demanda crescente por água tem feito de seu reúso planejado um tema atual e de grande importância, já citada na Agenda 21, que recomendou implementação de políticas de gestão dirigidas para o uso e reciclagem de efluentes, integrando proteção de saúde pública de grupos de risco com práticas ambientais adequadas. De acordo com as Resoluções CONAMA nº 357 e 420 os efluentes somente podem ser descartados em corpos d´água se os seus parâmetros característicos se situarem de acordo com o balizamento dado para cada classe de corpo de água. Íons metálicos podem ser removidos de soluções aquosas por diferentes processos sendo a adsorção em argilas um método que pode ser considerado efetivo e barato quando comparado aos demais. Neste estudo foi avaliada a capacidade de adsorção dos íons metálicos Cr3+, Zn2+, Cd2+, Pb2+, Cu2+ e Ni2+ em solução utilizando-se caulinita comercial com a finalidade de reúso e/ou descarte. A caracterização mineralógica e química das amostras comerciais obtidas indicou que aquela denominada caulinita C foi a que mais se adequou ao estudo visto que apresenta elevado teor de pureza mineralógica, baixos teores de elementos traço, e maior capacidade de troca catiônica. O estudo da remoção dos íons em solução indicou que o aumento razão adsorvente:adsorvato aumenta a eficiência de adsorção. O estudo da influência do pH indicou que a maior adsorção ocorre em pH levemente alcalino, pH 8. E o estudo do tempo de contato indicou que o equilíbrio de adsorção é atingido em menos de trinta minutos para todos os íons, exceto para o Ni. A análise das isotermas de adsorção indicou que a caulinita empregada neste estudo é adequada principalmente à remoção dos íons Zn (II), Cu (II) e PB (II). / The growing demand for water has made its planned reuse a current topic of great importance, as already mentioned in Agenda 21, which recommended a management policy implementation directed to the use and recycling of waste, integrating public health protection of risk groups with appropriate environmental practices. According to the 357 and 420 CONAMA Resolutions, effluents can only be dropped into water bodies if their characteristic parameters are located in accordance with the marks given for each body of water class. Metal ions can be removed from aqueous solutions by different processes being clay adsorption a method that can be considered effective and cheap when compared to others. In this study, the commercial kaolinite adsorption capacity was evaluated for the metal ions Cr3+, Zn2+, Cd2+, Pb2+, Cu2+ and Ni2+ in solution with the purpose of reuse and / or disposal. The mineralogical and chemical characterization of commercial samples obtained indicated that the one called \"kaolinite C\" was the one most suited to the study because of its high purity mineral content, low levels of trace elements, and higher cation exchange capacity. The study of ions removal in solution indicated that the increment in the dsorbent: adsorbate ratio increases the adsorption efficiency. The influence of pH indicated that most of the adsorption occurs in a slightly alkaline pH, pH 8. The study of the contact time indicates that the adsorption equilibrium is reached in less than thirty minutes for all ions except for Ni. The analysis of adsorption isotherms indicated that the kaolinite used in this study is suitable for the ion removal mainly of Zn (II), Cu (II) and Pb (II).

A demanda crescente por água tem feito de seu reúso planejado um tema atual e de grande importância, já citada na Agenda 21, que recomendou implementação de políticas de gestão dirigidas para o uso e reciclagem de efluentes, integrando proteção de saúde pública de grupos de risco com práticas ambientais adequadas. De acordo com as Resoluções CONAMA nº 357 e 420 os efluentes somente podem ser descartados em corpos d´água se os seus parâmetros característicos se situarem de acordo com o balizamento dado para cada classe de corpo de água. Íons metálicos podem ser removidos de soluções aquosas por diferentes processos sendo a adsorção em argilas um método que pode ser considerado efetivo e barato quando comparado aos demais. Neste estudo foi avaliada a capacidade de adsorção dos íons metálicos Cr3+, Zn2+, Cd2+, Pb2+, Cu2+ e Ni2+ em solução utilizando-se caulinita comercial com a finalidade de reúso e/ou descarte. A caracterização mineralógica e química das amostras comerciais obtidas indicou que aquela denominada caulinita C foi a que mais se adequou ao estudo visto que apresenta elevado teor de pureza mineralógica, baixos teores de elementos traço, e maior capacidade de troca catiônica. O estudo da remoção dos íons em solução indicou que o aumento razão adsorvente:adsorvato aumenta a eficiência de adsorção. O estudo da influência do pH indicou que a maior adsorção ocorre em pH levemente alcalino, pH 8. E o estudo do tempo de contato indicou que o equilíbrio de adsorção é atingido em menos de trinta minutos para todos os íons, exceto para o Ni. A análise das isotermas de adsorção indicou que a caulinita empregada neste estudo é adequada principalmente à remoção dos íons Zn (II), Cu (II) e PB (II). / The growing demand for water has made its planned reuse a current topic of great importance, as already mentioned in Agenda 21, which recommended a management policy implementation directed to the use and recycling of waste, integrating public health protection of risk groups with appropriate environmental practices. According to the 357 and 420 CONAMA Resolutions, effluents can only be dropped into water bodies if their characteristic parameters are located in accordance with the marks given for each body of water class. Metal ions can be removed from aqueous solutions by different processes being clay adsorption a method that can be considered effective and cheap when compared to others. In this study, the commercial kaolinite adsorption capacity was evaluated for the metal ions Cr3+, Zn2+, Cd2+, Pb2+, Cu2+ and Ni2+ in solution with the purpose of reuse and / or disposal. The mineralogical and chemical characterization of commercial samples obtained indicated that the one called \"kaolinite C\" was the one most suited to the study because of its high purity mineral content, low levels of trace elements, and higher cation exchange capacity. The study of ions removal in solution indicated that the increment in the dsorbent: adsorbate ratio increases the adsorption efficiency. The influence of pH indicated that most of the adsorption occurs in a slightly alkaline pH, pH 8. The study of the contact time indicates that the adsorption equilibrium is reached in less than thirty minutes for all ions except for Ni. The analysis of adsorption isotherms indicated that the kaolinite used in this study is suitable for the ion removal mainly of Zn (II), Cu (II) and Pb (II).

Metal homeostasis in plants is regulated by diverse mechanisms that act together to maintain optimal metal ion concentrations inside the cell. P1B-ATPases are heavy metal transport ATPases that are likely to be related to these processes. The sequencing of the genome of Arabidopsis thaliana revealed the presence of eight putative P1B-ATPases, HMA1-8. The main goal in this work is to characterize of the role of P1B-ATPases in plant metal homeostasis. Toward this goal, the P1B-ATPases HMA1 and HMA6 from Arabidopsis thaliana were cloned from leaves and sequenced. Results from RT-PCR experiments show ubiquitous expression in planta of this two ATPases, except for HMA1 that does not express in roots. Upon Cu2+ exposure during growth, expression of HMA6 increases in seedlings. HMA1 expression increases when seedlings are grown in high Cu2+ and Co2+ media, and decreases when grown in high concentrations of Zn2+ and Ni2+. hma1-1 plants have smaller size and less chlorophyll content than WT plants. Growth is affected in hma1-1 seedlings when grown in Zn2+, Mn2+, Fe2+, Co2+ and Cu2+ deficient media, or when these metals are in excess. Moreover, hma1-1 plants show an increase in Zn2+, Mn2+ and Fe2+ content in whole plants compared to WT plants. Mutant plants also show increased levels of HMA3 and HMA4 transcripts (Zn2+/Cd2+/Pb2+ P1B-ATPases), upregulation of metallothioneins 1a and 2b, downregulation of metallothionein 1c, and a decrease in the phytochellatin synthases 1 and 2 transcripts, compared to WT plants. Homozygous for mutation in HMA6 seems to be lethal, given that none was recovered after screening. These results indicate HMA1 and HMA6 as essential components of plant metal homeostasis in Arabidopsis thaliana.

Em virtude das várias aplicações do cobre, acredita-se que a demanda por esse metal irá aumentar nos próximos anos, e consequentemente, o seu preço. Dessa forma, as mineradoras enfrentam o desafio de aprimorar e aperfeiçoar os processos produtivos a fim de atender sua futura demanda. Frações de cobre podem ser encontradas no licor de lixiviação do minério limonítico de níquel e a troca iônica com adsorvente sólido é uma das tecnologias disponíveis para promover a sua recuperação e o seu reaproveitamento. O presente trabalho teve como objetivo estudar o processo de adsorção dos íons de cobre presente em um licor sintético baseado no licor de lixiviação atmosférica do minério limonítico de níquel através de um sistema de resina de troca iônica utilizando a resina quelante Dowex XUS43605. A viabilidade da técnica escolhida foi analisada em função da influência de parâmetros por meio de ensaios em batelada e coluna de leito fixo utilizando uma solução sintética. O tempo de contato, o pH, a massa de resina e a temperatura foram avaliados. A resina quelante Dowex XUS43605 mostrou-se mais seletiva para o cobre em pH igual a 1,5, tendo sido definido esse pH como o de trabalho. Verificou-se que 1g é uma dosagem suficiente para recuperar o cobre da solução em escala laboratorial considerando 50mL de solução sintética. O incremento na temperatura não alterou a adsorção do cobre pela resina, sendo determinado que a temperatura de trabalho esteja entre 25-35°C. O modelo de isotermas de adsorção de Langmuir apresentou melhor ajuste entre a resina e o cobre do que os modelos de Freundlich e de Temkin. O modelo cinético pseudosegunda-ordem descreveu o processo de adsorção considerando a quimiossorção como a etapa limitante. Os ensaios em coluna de leito fixo possibilitaram a produção de uma solução com concentração reduzida de Cu2+ em 93% na etapa de carregamento. Pela etapa de eluição com ácido sulfúrico (H2SO4) 1mol/L, obteve-se uma solução 10 vezes mais concentrada em Cu2+ com relação à solução sintética. A solução resultante da etapa de eluição seguiu para os ensaios de precipitação, a qual permitiu a separação do cobre dos íons metálicos pela ação do agente precipitante CaCO3 e a geração de um precipitado composto por três fases: brochantite [Cu4SO4(OH)6], posnjatike [Cu4SO4(OH)6.H2O] e gesso (CaSO4.2H2O). / Considering the various applications of copper, it is believed that the demand for copper will increase in the coming years and, consequently, its price. Hence, the mining companies face the challenge of improving the productive processes to supply their future demand. Copper fractions can be found in liquor leaching nickel limonite ore and ion exchange with solid adsorbent is one of the available technologies which promote its recovery and reuse. The present work was aimed at studying the adsorption process of copper ions present in a synthetic liquor based on the atmospheric leaching liquor of the nickel limonite ore through an ion exchange resin system using Dowex XUS43605 chelating resin. The feasibility of the chosen technique was analyzed in relation to the influence of parameters by means of batch and fixed bed tests using a synthetic solution. The contact time, pH, amount of resin and temperature were evaluated. Dowex XUS43605 chelating resin showed to be more selective for copper at pH 1.5, and this pH was defined as the working pH. It has been found that 1g is a sufficient dosage to recover copper from the solution on a laboratory scale considering 50mL of synthetic solution. The increase in temperature did not change the adsorption of the copper by the resin, and it was determined that the working temperature is between 25-35°C. The Langmuir adsorption isotherms model showed a better fit between resin and copper than the Freundlich and Temkin models. The pseudosecond-order describes the sorption process and it indicates that the rate-limiting step is chemisorption. The fixed bed column tests allowed the production of a solution with reduced concentration of Cu2+ in 93% the loading step. By the elution step with 1mol/L of sulfuric acid (H2SO4), a solution 10 times more concentrated in Cu2+ was obtained in relation to the synthetic solution. The solution from the elution step followed to the precipitation tests, which allowed the separation of copper from the metal ions by the action of the precipitating agent CaCO3 and the generation of a precipitate composed of three phases: brochantite [Cu4SO4(OH)6], posnjatike [CuSO4(OH)6.H2O] and gypsum (CaSO4.2H2O).

Wong, Kin Shing Kinson. / Thesis submitted in: November 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 145-158). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / 摘要 --- p.v / Contents --- p.viii / List of figures --- p.xv / List of plates --- p.xx / List of tables --- p.xxi / Abbreviations --- p.xxiii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Heavy metals --- p.1 / Chapter 1.1.1 --- Characteristics of heavy metals --- p.1 / Chapter 1.1.2 --- Heavy metal pollution in Hong Kong --- p.2 / Chapter 1.1.3 --- Common usage of heavy metals --- p.4 / Chapter 1.1.3.1 --- Copper --- p.4 / Chapter 1.1.3.2 --- Nickel --- p.4 / Chapter 1.1.3.3 --- Zinc --- p.5 / Chapter 1.1.4 --- Toxicity of heavy metals --- p.5 / Chapter 1.1.4.1 --- Copper --- p.6 / Chapter 1.1.4.2 --- Nickel --- p.7 / Chapter 1.1.4.3 --- Zinc --- p.7 / Chapter 1.1.5 --- Treatment techniques for metal ions --- p.8 / Chapter 1.1.5.1 --- Chemical precipitation --- p.9 / Chapter 1.1.5.2 --- Ion exchange --- p.10 / Chapter 1.1.5.3 --- Activated carbon adsorption --- p.10 / Chapter 1.2 --- Biosorption --- p.11 / Chapter 1.2.1 --- Definition of biosorption --- p.11 / Chapter 1.2.2 --- Mechanism --- p.12 / Chapter 1.2.3 --- Advantages of biosorption --- p.13 / Chapter 1.2.4 --- Selection of biosorbents --- p.15 / Chapter 1.3 --- Chitinous materials --- p.17 / Chapter 1.3.1 --- Background of chitin --- p.17 / Chapter 1.3.2 --- Structures of chitinous materials --- p.18 / Chapter 1.3.3 --- Sources of chitinous materials --- p.18 / Chapter 1.3.4 --- Application of chitinous materials --- p.20 / Chapter 1.3.5 --- Mechanism of metal ion adsorption by chitin --- p.22 / Chapter 1.4 --- Activated carbon --- p.25 / Chapter 1.4.1 --- Characteristics of activated carbon --- p.25 / Chapter 1.4.2 --- Applications of activated carbon --- p.26 / Chapter 1.4.3 --- Factors affecting adsorption ability of activated carbon --- p.27 / Chapter 1.4.4 --- Advantages and Disadvantages --- p.28 / Chapter 1.4.4.1 --- Advantages (Adsorption) --- p.28 / Chapter 1.4.4.2 --- Advantages (Regerneration) --- p.28 / Chapter 1.4.4.3 --- Disadvantages (Adsorption) --- p.28 / Chapter 1.4.4.4 --- Disadvantages (Regeneration) --- p.29 / Chapter 1.5 --- Cation exchange resin --- p.29 / Chapter 1.5.1 --- Usages of cation exchange resin --- p.29 / Chapter 1.5.2 --- Characteristics of cation exchange resin --- p.30 / Chapter 1.5.3 --- Disadvantages of using cation exchange resin --- p.30 / Chapter 1.6 --- Magnetite --- p.31 / Chapter 1.6.1 --- Reasons of using magnetite --- p.31 / Chapter 1.6.2 --- Characteristics of magnetite --- p.31 / Chapter 1.6.3 --- Immobilization by magnetite --- p.32 / Chapter 1.6.4 --- Advantages of using magnetite --- p.33 / Chapter 1.7 --- The biosorption experiment --- p.33 / Chapter 1.7.1 --- The batch biosorption experiment --- p.33 / Chapter 1.7.2 --- The adsorption isotherms --- p.34 / Chapter 1.7.2.1 --- The Langmuir adsorption isotherm --- p.34 / Chapter 1.7.2.2 --- The Freundlich adsorption isotherm --- p.36 / Chapter 2. --- Objectives --- p.38 / Chapter 3. --- Materials and methods --- p.39 / Chapter 3.1 --- Adsorbents --- p.39 / Chapter 3.1.1 --- Chitin A --- p.39 / Chapter 3.1.2 --- Pretreatment of chitin A --- p.39 / Chapter 3.1.3 --- Magnetite --- p.39 / Chapter 3.1.4 --- Activated carbon --- p.41 / Chapter 3.1.5 --- Cation exchange resin --- p.41 / Chapter 3.1.6 --- Pretreatment of cation exchange resin --- p.41 / Chapter 3.2 --- Chemicals --- p.43 / Chapter 3.2.1 --- Metal ion solution --- p.43 / Chapter 3.2.2 --- Buffer solution --- p.43 / Chapter 3.2.3 --- Standard solution --- p.43 / Chapter 3.3 --- Immobilization of chitin A by magnetite --- p.44 / Chapter 3.3.1 --- Effect of chitin A to magnetite ratio --- p.44 / Chapter 3.3.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.45 / Chapter 3.3.3 --- Effect of pH --- p.45 / Chapter 3.3.4 --- Effect of immobilization time --- p.46 / Chapter 3.3.5 --- Effect of temperature --- p.46 / Chapter 3.3.6 --- Effect of agitation rate --- p.46 / Chapter 3.3.7 --- Effect of salinity --- p.46 / Chapter 3.3.8 --- Mass production of magnetite-immobilized chitin A --- p.47 / Chapter 3.4 --- Batch adsorption experiment --- p.47 / Chapter 3.5 --- "Optimization of physicochemical condition on Cu2+，Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.48 / Chapter 3.5.1 --- Effect of equilibrium pH --- p.48 / Chapter 3.5.2 --- Effect of amount of adsorbent --- p.49 / Chapter 3.5.3 --- Effect of retention time --- p.49 / Chapter 3.5.4 --- Effect of agitation rate --- p.49 / Chapter 3.5.5 --- Effect of temperature --- p.50 / Chapter 3.5.6 --- Effect of initial metal ion concentration --- p.50 / Chapter 3.5.7 --- Adsorption isotherms --- p.50 / Chapter 3.5.8 --- Dimensionless separation factor --- p.52 / Chapter 3.5.9 --- Kinetic parameters of adsorption --- p.52 / Chapter 3.5.10 --- Thermodynamic parameters of adsorption --- p.53 / Chapter 3.6 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.54 / Chapter 3.6.1 --- Performances of various solutions on metal ion recovery --- p.54 / Chapter 3.6.2 --- Multiple adsorption and desorption cycles of metal ions --- p.55 / Chapter 3.7 --- Statistical analysis of data --- p.55 / Chapter 4. --- Results --- p.56 / Chapter 4.1 --- Immobilization of chitin A by magnetite --- p.56 / Chapter 4.1.1 --- Effect of chitin A to magnetite ratio --- p.56 / Chapter 4.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.59 / Chapter 4.1.3 --- Effect of pH --- p.59 / Chapter 4.1.4 --- Effect of immobilization time --- p.59 / Chapter 4.1.5 --- Effect of temperature --- p.59 / Chapter 4.1.6 --- Effect of agitation rate --- p.64 / Chapter 4.1.7 --- Effect of salinity --- p.64 / Chapter 4.1.8 --- Mass production of magnetite-immobilized chitin A --- p.64 / Chapter 4.2 --- Batch adsorption experiment --- p.67 / Chapter 4.2.1 --- Screening of adsorbents --- p.67 / Chapter 4.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.70 / Chapter 4.3.1 --- Effect of equilibrium pH --- p.70 / Chapter 4.3.2 --- Effect of amount of adsorbent --- p.74 / Chapter 4.3.3 --- Effect of retention time --- p.78 / Chapter 4.3.4 --- Effect of agitation rate --- p.82 / Chapter 4.3.5 --- Effect of temperature --- p.82 / Chapter 4.3.6 --- Effect of initial metal ion concentration --- p.86 / Chapter 4.3.7 --- Summary of optimized conditions for three metal ions --- p.87 / Chapter 4.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.87 / Chapter 4.3.9 --- Performance of reference adsorbents (AC and CER) --- p.87 / Chapter 4.3.10 --- Adsorption isotherms --- p.99 / Chapter 4.3.11 --- Dimensionless separation factor --- p.103 / Chapter 4.3.12 --- Kinetic parameters of adsorption --- p.106 / Chapter 4.3.13 --- Thermodynamic parameters of adsorption --- p.113 / Chapter 4.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.113 / Chapter 4.4.1 --- Performances of various solutions on metal ion recovery --- p.113 / Chapter 4.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.117 / Chapter 5. --- Discussions --- p.121 / Chapter 5.1 --- Immobilization of chitin A by magnetite --- p.121 / Chapter 5.1.1 --- Effect of chitin A to magnetite ratio --- p.121 / Chapter 5.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.121 / Chapter 5.1.3 --- Effect of pH --- p.122 / Chapter 5.1.4 --- Effect of immobilization time --- p.122 / Chapter 5.1.5 --- Effect of temperature --- p.122 / Chapter 5.1.6 --- Effect of agitation rate --- p.123 / Chapter 5.1.7 --- Effect of salinity --- p.123 / Chapter 5.2 --- Batch adsorption experiment --- p.123 / Chapter 5.2.1 --- Screening of adsorbents --- p.123 / Chapter 5.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.124 / Chapter 5.3.1 --- Effect of equilibrium pH --- p.125 / Chapter 5.3.2 --- Effect of amount of adsorbent --- p.126 / Chapter 5.3.3 --- Effect of retention time --- p.127 / Chapter 5.3.4 --- Effect of agitation rate --- p.128 / Chapter 5.3.5 --- Effect of temperature --- p.128 / Chapter 5.3.6 --- Effect of initial metal ion concentration --- p.129 / Chapter 5.3.7 --- Summary of optimized conditions for three metal ions --- p.130 / Chapter 5.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.132 / Chapter 5.3.9 --- Performance of reference adsorbents (AC and CER) --- p.133 / Chapter 5.3.10 --- Adsorption isotherms --- p.133 / Chapter 5.3.11 --- Dimensionless separation factor --- p.135 / Chapter 5.3.12 --- Kinetic parameters of adsorption --- p.136 / Chapter 5.3.13 --- Thermodynamic parameters of adsorption --- p.139 / Chapter 5.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.140 / Chapter 5.4.1 --- Performances of various solutions on metal ion recovery --- p.140 / Chapter 5.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.141 / Chapter 6. --- Conclusions --- p.143 / Chapter 7. --- References --- p.145

Thesis (M.Sc. (Biochemistry)) --University of Limpopo, 2005 / Refer to document

Abstract not available