I have submitted another pdf file which is my permissions for figures used in my thesis. The name this file is Clearance. / Nickel Hydroxide is one of highly active materials used in various energy conversion applications. One of the key factors in the deposition of Ni(OH)2 is the active surface area which plays an important role in improving the efficiency of transformation reactions. There are various methods to enhance the active area. One method that can be used to modify the morphology of deposited Ni(OH)2 is to generate porous structures. Ni(OH)2 can be formed in two different phases namely alpha and beta. The main objective in our work is to optimize the synthesis conditions and characterize structures at the nanoscale, and also demonstrate unequivocally the presence of alpha and beta phases. For this work, a combination of electron microscopy and electrochemistry is needed to modify the morphology of nickel hydroxide and for detailed structural characterization. Various characterization techniques are used to investigate different electrochemical depositions conditions of Ni(OH)2 in alpha and beta phase forms using Direct and Indirect methods, respectively. Kinetically, alpha-Ni(OH)2 is easier and faster to be synthesized and can be deposited directly in one step. During cyclic voltammetry of alpha-Ni(OH)2 in KOH, the volume of material involved in the oxidation reaction increases in every cycle. Scanning Electron Microscopy and Transmission Electron Microscopy characterization shows that this may be due to microbubble formation that transform deposited sheets to particulate shapes. On the other hand, conversion of nickel metal to beta-Ni(OH)2 during cyclic voltammetry causes an expansion of particles. Effectively, nickel hydroxide is formed on the shell while nickel remains in the core. High Resolution Transmission Electron Microscopy is then used to identify the distribution of these phases. Another foremost feature for the beta phase is to make nickel metal in any desired shape, which can then be converted to beta-Ni(OH)2 through Cyclic Voltammetry in KOH. The presence of both phases is demonstrated with electron diffraction. Finally, as future work, all experiments will be performed in-situ TEM using liquid cell to observe structural changes in real time. / Thesis / Master of Science (MSc)

The ability of simple oligopeptide complexes of nickel (II) to react with various dioxygen intermediates was investigated. Under physiological conditions, nickel (II)-histidine-containing oligopeptides were found to dismutate superoxide anions and disproportionate hydrogen peroxide. In the latter process, chemiluminescence was generated and a strongly oxidizing intermediate was detected capable of oxidizing uric acid, hydroxylating p-nitrophenol, and damaging 2-deoxy-D-ribose. The generation of this reactive intermediate likely occurs without the involvement of free hydroxyl radicals derived from Haber-Weiss or Fenton-type reactions. In addition, the Ni(II) complex of glycylglycyl-L-histidine (GGH) was found to react with mollecular oxygen resulting in the oxidation of the ligand. An attempt was made to relate these reactions to the involvement: of the nickel(III)/(II) redox couple which was shown to exist under physiological conditions. Similar reactivity was observed for non-histidine-containing oligopeptides but higher pH values were required. The oligopeptides used not only represent biologically relevant ligands but: the histidine containing oligopeptides mimics the specific copper(II)/nickel(II) binding and transport site of human serum albumin. The observations made in this study suggest some novel mechanism for the deleterious effects associated with excessive lifelong exposure to nickel compounds, especially in relation to cancer of the respiratory tract. / Thesis / Master of Science (MS)

This thesis focuses on development of new regents which are suitable for recovering nickel, cobalt and copper from laterite leach solutions, specifically focusing on reagent requirements for novel base metal flowsheets developed by Anglo American. The work aims to design reagents which can extract nickel(II), cobalt(II) and copper(II) from a highly acidic aqueous sulfate solutions whilst showing selectivity over iron(II) and iron(III). Chapter 1 reviews current extractive metallurgy processes for separating and concentrating metals in laterite ores and describes new flowsheets proposed by Anglo American. Chapter 2 considers whether single reagent molecules with sets of tridentate donor atoms can generate sufficiently stable nickel(II) complexes to allow selective extraction of nickel from an aqueous sulfate solution. The salicylaldimines, 3-X-4-alkyl-6-(quinolin-8-imino)phenol, 3-X-4-alkyl-6-(2- methoxyphenylimino)phenol and 3-X-4-alkyl-6-(2-thiomethoxyphenylimino)phenol (alkyl = tert-butyl or tert-octyl; X = H, Br or NO2), were selected for study. The synthesis and characterisation of these proligands and their nickel(II) complexes are reported. XRD structures of Br-substituted salicylaldimines and their nickel(II) complexes are compared and discussed. The 4-tert-octylsalicylaldimines were used to extract nickel(II) from an aqueous sulfate solution with a pH > 2.8 and 3- nitro-4-tert-octyl-6-(quinolin-8-imino)phenol was found to be the strongest extractant in the series with a pH0.5 of 3.5. Computational studies of an analogous series of salicylaldimine proligands in the gas phase calculated the formation energies of their nickel(II) complexes and the predicted trend follows the experimentally determined solvent extraction results. Chapter 3 investigates modifications to phenolic pyrazoles, which are known copper(II) extractants. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)-phenols (X = H, OMe, Br and NO2) was synthesised and characterised. Varying the 6-X-substituent of the phenolic pyrazole altered the strength of copper extraction and 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)-1H-pyrazol-3-yl)-phenol was found to be the strongest extractant in the series. Analysis of XRD structures of related phenolic pyrazoles and their copper(II) complexes showed evidence of inter- and intra-molecular hydrogen bonding. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. The double deprotonation of 4-tert-butyl-(pyrazol-3-yl)-phenol at high pH forms a polynuclear complex in the organic phase with a copper(II) to ligand ratio of 1:1, thereby increasing the mass transport efficiency of copper by the reagent. The synthesis and characterisation of the [Cu16(4-tert-butyl-(pyrazol-3-yl)- phenolate)16(EtOH)4(H2O)2] wheel complex was carried out to demonstrate how such polynuclear copper(II) complexes could be formed under solvent extraction conditions. Chapter 4 explores the solvent extraction of nickel(II) and cobalt(II) by novel combinations of neutral nitrogen-donor heterocyclic ligands with organic acids, such as dinonylnaphthelenesulfonic acid (DNNSAH). The synthesis and characterisation of 2,6-bis(5-alkyl-1H-pyrazol-3-yl)-pyridine, 2-(5- alkyl-1H-pyrazol-3-yl)-pyridine and 5,5'-alkyl-3,3'-bi-1H-pyrazole (alkyl = tert-butyl or nonyl) and their nickel(II) complexes were reported. Also reported are synthesis and 6-N-alkyl-2-(2-pyridinyl)- benzothiazole (alkyl = n-butyl or n-decyl) and 2-(1-Isopropyl-benzimidazol-2-yl)-pyridine. The extraction of nickel(II) from highly acidic mixed metal aqueous sulfate solutions by some of these ligands was studied. These synergistic mixtures demonstrated remarkable strength and selectivity for nickel(II), and cobalt(II) over iron(II). XRD structures of nickel(II) complexes of 2,6-bis(5-tert-butyl- 1H-pyrazol-3-yl)-pyridine, 2-(5-tert-butyl-1H-pyrazol-3-yl)-pyridine and 5,5'-tert-butyl-3,3'-bi-1Hpyrazole with sulfonates or perchlorates as ion-pairs have intermolecular hydrogen bonding interactions between the inner-sphere ligands and the counterions.

Late transition metal complexes bearing nitrogen-containing ligands have many applications in biotechnology or industrial catalysis. In this thesis, we react two nitrogen-containing tridentate ligands with some late transition metal salts to yield complexes (1)-(18). Besides spectroscopic characterization, complexes (3), (5)-(7), (8), (10), (12)-(16) yielded crystal structures analyzed using X-ray single crystal diffraction. From crystal structure of complexes (3), (5)- (7), we concluded that the reaction of ligand and Cu(£L£L) salts always gave the CuLX2 products. In Ni series, structures of different coordination types were obtained by using different crystal-growing methods. Crystals obtained using diffusion method take on the form of MLX2 while different structures of complexes (8), (10) were obtained using double layer method. Judging from the result of ESI-Mass analyses, complexes (8) and (10) were both of the dimeric form[NiL1Cl(£g-Cl)]2. However complex (10) was shown by X-ray single crystal to be [NiL 2(H2O)2 Cl]Cl. This could be the hydration product from [NiL1Cl(£g-Cl)]2.

Thèse--Sc. phys.--Lyon, 1970. N°: 702. / Bibliogr. p. 70-73.

The thesis examines for the first time the supercapacitive properties of three different nickel (II) phthalocyanine complexes, nickel (II) tetraamino phthalocyanine (NiTAPc), nickel (II) phthalocyanine and nickel (II) tetra tert-butylphthalocyanine as a) nanocomposites with multiwalled carbon nanotubes and as (b) an electropolymer supported on multiwalled carbon nanotube platform (MWCNT-polyNiTAPc). The supercapacitive properties of nickel (II) tetraaminophthalocyanine (NiTAPc)/multi-walled carbon nanotube (MWCNT) nanocomposite films have been found to possess a maximum specific capacitance of 981 F g-1 (200 mF cm-2), a maximum power density of 700 Wkg -1, a maximum specific energy of 134 Wh kg-1 and excellent stability of over 1500 chargedischarge continuous cycling. When compared to MWCNTs modified with unsubstituted nickel (II) phthalocyanine (MWCNT-NiPc) or nickel (II) tetra tert-butylphthalocyanine (MWCNT-tBuNiPc), MWCNT-NiTAPc exhibited superior supercapacitive behaviour, possibly due to the influence of nitrogen-containing groups on the phthalocyanine. The MWCNTpolyNiTAPc electrode had a maximum (112 mF cm-2) capacitance which was higher than that observed for MWCNT-polyNi(OH)TAPc (84.9 mFcm-2) but lower that of the MWCNT-NiTAPc (200 mF cm-2). Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Chemistry / unrestricted

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An electrochromic (EC) material is able to change colour under the influence of an electric potential. The development of energy efficient smart windows for architectural applications is at present the subject of intense research for both economic and environmental reasons. Thus there is now a considerable research effort to develop smart windows with natural colour switching properties, i.e. shades of grey. In this regard, a promising metal oxide with a brown-black anodic colouring state is NiO or hydrated nickel oxide (also called nickel hydroxide , Ni(OH)2). The present work outlines the preparation and optimisation of EC nickel oxide-based ceramic precursor films onto various conducting substrates towards smart window applications. The literature review chapter outlines the different methods used for generating ceramic materials, a review of electrochromism and history of nickel oxide-based EC materials are also provided. Thins films have been deposited by an electrochemical cathodic deposition and by aerosol assisted chemical vapour deposition (AACVD) technique. For hydrated NiO films prepared by electrochemical cathodic deposition, various deposition factors at small-scale area (30 x 7 mm) have been investigated in order to optimise the films properties towards EC applications. With deposition on fluorine-doped tin oxide (SnO2:F, FTO) on glass, use of nickel nitrate (0.01 mol dm-3) solution at an applied current of -0.2 mA (-0.1 mA cm-2) for 800 s was optimal for preparing uniform deposits with a porous interconnecting flake-like structure, which is generally regarded as favourable for the intercalation/deintercalation of hydroxide ions during redox cycling. The as-deposited hydrated NiO films showed excellent transmittance modulation (Δ%T = 83.2 at 432 nm), with average colouration efficiency (CE) of 29.6 cm2 C-1 and low response times. However, after 50 voltammetric cycles, the cycle life was found to fade by 17.2% from charge measurements, and 28.8 % from in-situ transmittance spectra measurements. In an attempt to prepare films with improved durability, AACVD has been used for the first time in the preparation of thin-film EC nickel(II) oxide (NiO). The as-deposited films were confirmed to be cubic NiO from analysis of powder X-ray diffraction data, with an optical band gap that decreased from 3.61 to 3.48 eV with an increase in film thickness (in the range 330 820 nm). The EC properties of the films were investigated as a function of film thickness, following 50, 100 and 500 conditioning oxidative voltammetric cycles in aqueous KOH (0.1 mol dm-3). Light modulation of the films increased with the number of conditioning cycles. EC response times were < 10 s and generally longer for the colouration than the bleaching process. The films showed excellent stability when tested for up to 10000 colour/bleach cycles. Using a calculation method based on the integration of experimental spectral power distributions derived from in-situ visible region spectra over the CIE 1931 colour-matching functions, the colour stimuli of the NiO-based films, and the changes that take place on reversibly switching between the bleached and coloured forms have been calculated. Films prepared by both deposition techniques gave positive a* and b* values to produce orange. However, in combination with low L* values, the films were perceived as brown-grey. Hydrated NiO prepared via electrochemical cathodic deposition suffers from two well-known limitations; firstly, it shows catalytic properties towards the oxygen evolution reaction (OER), which is a process very close to the Ni(II)/Ni(III) redox process. Secondly, hydrated NiO shows poor cycling durability in alkaline solution. The co-deposition of single or bimetallic additives is an effective way to overcome these problems. Electrochemical studies revealed that the combination of cobalt (10%) with lanthanum (5%) was found to be the optimal composition for preparing hydrated NiO films with improved film durability. Finally, the emphasis of this work was on scale-up of deposition. Therefore, optimised deposition conditions from small scale (3.0 x 0.7 cm) have been used to successfully deposit films on two different sized large-area (10 x 7.5 and 30 x 30 cm) conducting substrates.

The efficacy of using zeolitic materials for the removal of nickel (II) and vanadium (IV) ions from solution has been evaluated in order to provide a method for the removal of the metal ions during hydroprocessing of crude oil. Batches of sodium based zeolites with a variety of pore sizes and Si/Al ratios were prepared using standard methods (high causticity solutions and templating agent). Characterisation of the products was carried out using powder X-ray diffraction, infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis to confirm the presence of single zeolitic phases (zeolite A, zeolite X, zeolite Y, sodalite Na8 [AlSiO4]6Cl2 and hydrosodalite Na6 [AlSiO4]6. 6H2O). In a batch exchange process, divalent nickel and tetravalent vanadium ion solutions of concentration range 0.01M - 0.1M were placed in contact with the zeolite samples at 110°C for a period of 24h. Nickel (II) exchange was found to occur for all the zeolites at concentrations considered. Zeolite X was found to be most efficient at removing nickel from the solutions while zeolite Y was least efficient. Characterisation of zeolite X after ion exchange using powder X-ray diffraction and scanning electron microscopy showed that the structure of the zeolite had been maintained. Simplistic modelling of powder X-ray diffraction data have shown that the nickel ions are preferentially substituted on one of the four sodium sites. Vanadium (IV) exchange was also found to occur for all the zeolites at the concentrations considered. Zeolite A was found to be most efficient for the vanadium uptake. Characterisation with PXRD, FTIR and SEM-EDS however, shows that in addition to exchange at the zeolite s normal cation exchange sites, a significant amount of framework silicon species were also exchanged by the vanadium ions thus having a destructive effect on the zeolite framework leading to structural collapse. Ion exchange of the sodium-based zeolites with potassium and lithium showed that the uptake of nickel and vanadium of the zeolites significantly increased compared to the as- synthesised zeolites. Zeolite Y was surface-modified with the APTES ligand and showed a similar trend to that observed for alkali metal-zeolites; showing significantly greater nickel uptake at lower concentrations. Nickel-tetraphenylporphrin was synthesised as a mimic for the nickel-asphaltenes found in crude oil and an α-hydrogen donor solvent used to remove the nickel in the presence of zeolite ion exchangers. A similar trend was observed to that seen in aqueous solution, implying the process would be transferrable to a live medium. Analysis to determine the metal ions present in ashed Nigerian crude samples before and after solvent and/or complexing agent extraction was carried out using inductively coupled plasma mass spectroscopy (ICPMS) and energy fluorescence analysis by X-rays (XRF). The process showed varying amounts of nickel was extracted by the different media along with iron. For nickel, the extent of extraction in the order of increasing % extraction is H2O<H3PO4<EDTA<IPA. For iron the order of increasing % extraction was H2O=EDTA<H3PO4<CH3OH while zinc extraction was in the order H2O<H3PO4 <CH3OH=EDTA.