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Soluble manganese (Mn) presents a significant treatment challenge to many water utilities, causing aesthetic and operational concerns. Surface water treatment plants using ozonation followed by biofiltration are unable to apply free chlorine across the filter, a method used by many utilities for soluble Mn control. These facilities are vulnerable to periodic problems of elevated Mn in the finished water. Manganese-oxidizing bacteria (MOB) readily oxidize Mn in groundwater treatment applications, which normally involve pH values above 7.0.  However, the ability of MOB to facilitate Mn oxidation under lower pH conditions (6.2--6.3) often employed to optimize organics removal has not been demonstrated. Laboratory-scale biofilters were operated to evaluate the ability of MOB to accomplish soluble Mn control at a range of pH (6.3--7.3).  The biofilters were able to oxidize Mn at a pH as low as 6.3 at greater than 98% removal.  Ozonation by-product removal was also greater than 90% in all filter columns. Stress studies indicated that well-acclimated MOB can withstand variations in Mn concentration, hydraulic loading rate, and temperature typically found at surface water treatment plants, at least for relatively short (1-2 days) periods of time. Pilot studies demonstrated that there are unknown factors that affect MOB acclimation, and MOB may be present in full-scale biofilters already. MOB are difficult to identify with current biological analysis techniques and comprise small percentages of the total microbial population. MOB have demonstrated potential for use in surface water treatment plants, but further research is needed before this application is fully feasible. / Master of Science

Anhydrous monophenylphosphinates of manganese(II), Mn[H(C₆H₅)PO₂]₂ (Form I, Form II and Form 1(B)) and cadmium(II), Cd[H(C₆H₅)PO₂]₂ (Form I and Form II) were synthesized and characterized by solubility tests, Differential Scanning Calorimetry (DSC), Infrared Spectroscopy, X-ray Powder Diffractometry, Electron Spin Resonance (ESR) spectroscopy, magnetic susceptibility measurements and Electron Spectroscopy for Chemical Analysis (ESCA). These materials are considered to be polymeric with metal ions connected in chains by double bridging phosphinate groups with cross-linkage forming sheets and octahedral metal centers. Magnetic susceptibility studies showed that Mn[H(C₆H₅)PO₂]₂ (Form I) exhibits relatively strong antiferromagnetic exchange interactions (J is about -4.50 cm⁻¹) and the effects on this magnetic exchange of doping diamagnetic cadmium ions into the material have been investigated. A series of mixed metal phosphinates of the form Mn₁₋x Cdx [H(C₆H₅)PO₂]₂ (Form I) where x=0 to 1.00 were prepared and investigated. The effect of doping with cadmium is to break the infinite manganese(II) monophenylphosphinate chain into finite segments and to generate monomer impurities in odd numbered segments. As the extent of doping is increased the average chain length decreases and the fraction of monomer increases. In addition, the exchange coupling constant, J, was found to decrease (from -4.50 to -2.70 cm⁻¹) as the average chain length decreases. Mn[H(C₆H₅)PO₂]₂ (Form 1(B)), which is precipitated from concentrated solutions, contains much shorter chain fragments than the pure Form I material. Mn[H(C₆H₅)PO₂]₂ (Form II) has a distinct infrared spectrum and X-ray powder diffraction pattern and shows much weaker antiferromagnetic behavior (J is about -2.40 cm⁻¹) than the Form I compound. Magnetic studies suggest that in this compound the average chain length is significantly smaller than in Mn[H(C₆H₅)PO₂]₂ (Form I). The hydrated monophenylphosphinates of manganese(II), Mn[H(C₆H₅)PO₂]₂•H₂0 and Mn[H(C₆H₅)PO₂]₂•2H₂0, were synthesized and characterized in this work. The structures of these compounds are considered to be similar to those of the anhydrous materials except in the hydrated compounds one or two of the metal coordination sites are occupied by water molecules. The dihydrate shows only very weak antiferromagnetic properties (J is about -0.50 cm⁻¹). The diphenylphosphinates of manganese(II) and cadmium(II) were also prepared and characterized. The infrared spectra and X-ray powder diffraction patterns for these materials are distinct from each other,which indicates the compounds are not isomorphous. Only rather weak magnetic exchange was observed in the manganese compound. Zn[H(C₆H₅)PO₂]₂ has also been synthesized and partially characterized in this work. The infrared spectrum and X-ray powder diffraction pattern obtained for this compound are unique among all the metal phosphinates studied in this work. / Science, Faculty of / Chemistry, Department of / Graduate

Ph.D. / The economically important sedimentary manganese deposits of the Paleoproterozoic Kalahari and Postmasburg manganese fields, are situated in close geographic vicinity to each other in the Griqualand West region of the Northern Cape Province, South Africa. This thesis describes aspects of mineralogy, petrography and geochemistry of the manganese ores with the purpose to establish genetic models for genesis and alteration of manganese ores of both manganese fields. The Kalahari manganese field, situated some 60 km northwest of Kuruman, is the largest known land-based manganese deposit. Manganese ores occur interbedded with iron-formations of the Hotazel Formation of the Voelwater Subgroup of the Late Archean-Paleoproterozoic Transvaal Supergroup. The sediments of the Voelwater Subgroup are preserved in five erosional relics, of which the Kalahari manganese deposit is by far the largest and the only one of economic importance. Two types of ore are mined, low-grade sedimentary Mamatwan-type ore and high-grade Wesselstype ore. Mamatwan-type ore is represented by microcrystalline laminated braunite-lutite composed of kutnahorite, Mn-calcite, braunite and hematite, modified by the occurrence of late diagenetic or metamorphic hausmannite, partridgeite, manganite and calcite. Mamatwan-type ore contains up to 38 mass % Mn and constitutes about 97 % of the ore reserves in the Kalahari manganese deposit. High-grade Wessels-type ore, with a manganese content of between 42 to 48 mass % Mn (on average), constitutes about 3 % of the ore reserves. It occurs only in the northwestern part of the main Kalahari deposit, and in small deposits at Hotazel and Langdon, in association with a system of north-south striking normal faults. The Wessels alteration event is thought to be related to the Kibaran orogenetic event (about 1.1 Ga). Fault zones are ferruginized and alongside faults sedimentary Mamatwan-type ore has been hydrothermally upgraded to Wessels-type ore. Metasomatic fronts are defined by changing mineral associations. These associations clearly illustrate that decreasing degrees of alteration relate to increasing distance from the fluid feeders. Areas of unaltered Mamatwan-type ore are preserved in the core of fault blocks. Wessels-type ore consists mostly of hausmannite, bixbyite, braunite II and manganite and subordinate gangue minerals such as clinochlore and andradite but the mineral assemblage associated with the Wessels alteration event is unusually diverse. More than 100 minerals have been identified, amongst them 8 new mineral species and an unusual, ferrimagnetic, Fe-rich variety of hausmannite. Mass balance calculations illustrate that the upgrading of the Wessels-type manganese ore is a consequence of leaching of CaO, MgO, CO 2, and Si02 from a low-grade Mamatwan-type precursor. This metasomatic process results in increasing secondary porosities, compaction of the orebody to two thirds of its original thickness and consequently residual enrichment of manganese in the ores. Three younger alteration events are observed in the Kalahari manganese deposit. These are only of minor economic importance. Wallrock alteration associated with the Mamatwan alteration event is characterized by reductive leaching of Fe and Mn around syntectonic veins and joints with pyritechalcopyrite- carbonate mineralization. The alteration is explained by infiltration of epithermal solutions that were introduced along veins or joints. The timing of the alteration event has tentatively been placed into the Pre-Karoo era. The Smartt alteration event is associated with intensive faulthosted brecciation and replacement of braunite and carbonates of the Mamatwan-type ore by todorokite and manganomelane, a process that causes considerable upgrading of the manganese ore next to a fault breccia at Mamatwan mine, and the formation of stratiform cross-fibre todorokite veins at Smartt mine. The Smartt alteration event postdates the Mamatwan alteration event and has tentatively been correlated with Pre-Kalahari groundwater circulation. Supergene alteration of the ores took place in Kalahari and Post-Kalahari times. It is characterized by the occurrence of cryptomelane, pyrolusite and other typically supergene manganese oxides along the suboutcrop of the Hotazel Formation beneath the Cenozoic Kalahari Formation. The Postmasburg manganese field is situated about 120 km to the south of the Kalahari manganese field on the Maremane dome. Two arcuate belts of deposits extend from Postmasburg in the south to Sishen in the north. Two major ore types are present. The ferruginous type of ore is composed mainly of braunite, partridgeite and bixbyite and occurs along the centre of the Gamagara Ridge, or Western belt. The siliceous type of ore consists of braunite, quartz and minor partridgeite and occurs in small deposits along the Klipfontein Hills (or Eastern belt) and the northern and southern extremities of the Gamagara Ridge. Geological and geochemical evidence suggest that the manganese ores represent weakly metamorphosed wad deposits that accumulated in karst depressions during a period of lateritic weathering and karstification in a supergene, terrestrial environment during the Late Paleoproterozoic. The dolomites of the Campbellrand Group of the Transvaal Supergroup are host and source for the wad accumulations. Contrasting geological settings are suggested for the accumulation of the siliceous and the ferruginous types of ore respectively. The former originated as small pods and lenses of wad in chert breccia that accumulated in a karst cave system capped by the hematitized Manganore iron-formation of the Transvaal Supergroup. The cave system finally collapsed and the hematitized iron-formation slumped into the sinkhole structures. The ferruginous type of ore accumulated as mixed wad-clay sediment trapped in surficial sinkhole depressions in the paleokarst surface. The orebodies are conformably overlain by the Doornfontein hematite pebble conglomerate or aluminous shales belonging to the Gamagara Formation of the Late Paleoproterozoic Olifantshoek Group. Well preserved karst laterite paleosol profiles, described from the basal section of the Gamagara Formation, provide a strong argument for the terrestrial, supergene origin of the manganese ores. The manganese ores in the Postmasburg manganese field were affected by diagenesis and lower greenschist facies metamorphism. Metamorphism resulted in recrystallization to braunite in the siliceous ores of the Eastern belt, and to massive or mosaic textured braunite and idioblastic partridgeite in the ferruginous environment of the Western belt. Secondary karstification and supergene weathering are evidence for renewed subaerial exposure of the manganese ore and their host rocks. The metamorphic mineral assemblage is replaced by abundant romanechite, lithiophorite and other supergene manganese oxides. Comparison between the Kalahari- and the Postmasburg manganese field shows that sedimentary manganese accumulation took place in entirely different depositional environments and owing to different mechanisms. Their close geographic relationship appears to be coincidental. Apparent similarities arise as a consequence of regional geological events that postdate the deposition of the manganese ores. These similarities include the lower greenschist facies metamorphic overprint, an event tentatively related to thrusting and crustal thickening during the Kheis orogenetic event, and syn- to Post-Kalahari supergene alteration. The correlation of structurally controlled hydrothermal alteration events in the Kalahari manganese field and the Postmasburg manganese field remains difficult due to the absence of the necessary geochronological constraints.

La thèse se concentre sur la synthèse et la caractérisation de nouveaux complexes de manganèse comme alternative possible aux complexes de gadolinium, actuellement les agents de contraste de choix pour l’Imagerie par Résonance Magnétique (IRM). Dans cette perspective, nous nous sommes intéressés à trois groupes de ligands pentadentés pour la complexation de Mn2+. Des nombres de coordination de 6 ou 7 ont été déterminés par cristallographie pour ces complexes, permettant la coordination d’une ou deux molécules d’eau en première sphère de coordination de Mn2+. La stabilité thermodynamique de ces complexes est plus faible que celle de complexes polyaminocarboxylates et leur dissociation est très rapide comparée à [Mn(nota)] et [Mn(dota)]2-. Seuls les complexes de Mn2+ avec des ligands macrocycliques à 12 atomes sont oxydés en Mn3+ à l’air. Les relaxivités des complexes bishydratés sont deux fois plus élevées que celles des complexes monohydratés et elles sont comparables à celles des agents de contraste commerciaux. Les données de RMN d’17O mesurées à différentes températures ont montré que l’échange d’eau peut être lent, intermédiaire, ou rapide selon le ligand. Les mesures à hautes pressions ont confirmé que le mécanisme d’échange est de type dissociatif pour les complexes avec un nombre de coordination de 7 et de type associatif pour les complexes avec un nombre de coordination de 6. Les petits anions bidentés endogènes peuvent remplacer une molécule d’eau dans les complexes bishydratés de macrocycles pentaazotés à 15 atomes, alors que pour les autres soit le complexe se décompose, soit il n’y a pas d’influence. / The thesis is focused on the synthesis and characterization of novel manganese complexes as alternative to Gd3+ chelates which are wide-spread contrast agents in Magnetic Resonance Imaging (MRI). In this perspective, three structurally different groups of pentadentate ligands for Mn2+ complexation have been investigated. Coordination numbers of 6 or 7 were determined in the crystal structure of the Mn2+ complexes enabling one or two water molecules in the first sphere. The thermodynamic stability of the chelates is lower than that of polyaminocarboxylate complexes and their dissociation is very fast in comparison to [Mn(nota)] and [Mn(dota)]2–. Only Mn2+ complexes with 12- membered ligands undergo oxidation in air to Mn3+ species. The proton relaxivities of the bishydrated complexes are two times higher than those for monohydrated complexes and are comparable to those of commercial contrast agents. Variable-temperature 17O NMR data revealed that the water exchange varies from slow to intermediate or to extremely fast, depending on the ligand. High-pressure 17O NMR measurements confirmed dissociative water exchange mechanism on complexes with CN = 7 and associative mechanism on complexes with CN = 6. Small endogenous bidentate anions are capable of replacing only one water molecule in the bishydrated complex with the 15-membered pentaaza ligand (L2), while in other cases the complex is decomposed or no influence is observed.

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Thesis (Ph.D.) -- University of Glasgow, 2008. / Ph.D. thesis submitted to the Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, 2008. Includes bibliographical references. Print version also available.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1940. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed March 10, 2010) Includes bibliographical references (p. 56-57) and index (p. 58-59).

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1940. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed March 10, 2010) Includes bibliographical references (p. 26-27).

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