This study was conducted to examine the kinetics of manganese sorption on oxide-coated filter media. Initial experimentation confirmed the findings of other investigators, the Mn²⁺ sorption capacity of oxide-coated media increases as solution pH increases. Further study revealed that uptake rate kinetics could be described by first order kinetics and also increased with increasing solution pH. The addition of free chlorine (HOCl) to solution greatly enhanced Mn²⁺ uptake rate kinetics. Later studies indicated that the oxide coating had very little impact on the physical properties of the media tested. Actual data from a water treatment plant filter confirmed laboratory experimental results by showing that sorption of soluble manganese does indeed occur on oxide-coated filters. The water treatment plant data also suggested that the sorption kinetics were relatively rapid, again upholding laboratory findings. Results from the manganese kinetics and sorption experiments were combined to formulate a theoretical model which would predict manganese breakthrough in a filter, given a known set of loading parameters. Preliminary use of the model indicated that oxide-coated filters could sorb significant quantities of soluble manganese before detectible levels of manganese appear in the effluent. / Master of Science

Manganese is typically found in all water supplies in the United States. Manganese concentrations are usually higher in water obtained from groundwater sources or resei:voir hypolinutlons. This is because manganese is more soluble in the reducing conditions normally found in these waters. Although manganese is not known to cause any health related problems, the secondary drinking water MCL for manganese is 0.05 mg/L. This standard was set to eliminate aesthetic problems associated with manganese bearing waters. In this study continuous-flow filters were operated in both pre-oxidative (oxidized Mn applied to filters) and auto-oxidative (soluble Mn applied) modes. The oxidants used were dllorine (HOCl/OCl⁻) , potassium permanganate (KMnO₄), chlorine dioxide (ClO₂), and ozone (O₃). Other experimental parameters included: filter media type - manganese coated or non-coated, filter loading rate --2 to 5 gpm/f², operating pH -- pH 6 to pH 9, and temperature --5 to 25℃. The most important experimental parameter was whether or not the filter media had a prior oxidized coating of manganese. If this was the case the filter produced an effluent concentration of manganese below the MCL under all pre-oxidative conditions and under auto-oxidative conditions when the pH was above neutral. Increased flow rate through the filter caused deeper penetration of manganese into the filter bed. This should not prove to cause an effluent breakthrough problem for filter depths typically used in water treatment plants. Temperature and pH effected the reaction rate of manganese oxidation in both the pre- and auto-oxidative modes. In most cases th.is did not effect the effluent quality from manganese coated filter media. However, when non-coated media was used and no oxidant was added, a decrease in pH or temperature usually adversely effected effluent quality. / M.S.

Soluble manganese (Mn) is a common water contaminant which can cause discoloration of water and staining if not treated properly in a water treatment plant. The "natural greensand effect" is one of the proven methods for efficient removal of Mn from water. Therefore, research is ongoing to develop different ways to effectively create the natural greensand effect in a post-filtration sorptive contactor for application at water treatment facilities. The research reported by Zuravnsky (2007) focused on the use of oxide-coated media in a post-filtration contactor and served as a starting point for the research reported in this thesis. As a part of the work conducted by Zuravnsky (2007), a preliminary model was formulated to predict soluble Mn removal via adsorption and oxidation onto large-size MnOx(s)-coated media. A major part of the current research was to calibrate the proposed model in predicting the soluble Mn removal performance by incorporating a statistical non-linear regression method to estimate a best-fit value for the fitting parameter kr, the rate constant associated with Mn oxidation by free chlorine. The research work included an 18-week pilot-plant study conducted at a water treatment facility in Newport News, VA. A contactor column loaded with 27â of pyrolucite media was operated at varying applied water conditions. Hydraulic loading rate (HLR), temperature, pH and influent free chlorine concentration were the operational parameters that were varied and their effect on the Mn removal performance evaluated. The resulting data were then used in the model to aid in its calibration and to obtain the best-fit kr values corresponding to effective Mn removal for the various operating conditions. Soluble Mn removal in the contactor column was directly dependent on solution pH and initial free chlorine concentration. The applied water temperature and HLR also had a small impact on the Mn removal profiles observed. On analyzing the results obtained from the model, it was noted that the best-fit kr values for the pilot plant data increased with increasing solution pH (When temperature = 200C and the initial Cl levels were below 1.5mg/L). Also, the Mn uptake capacity of the pyrolucite media increased with both an increase in initial Mn concentration and solution temperature. Long-term operation of the contactor also resulted in significant head loss accumulation in the upper portion of the contactor column, most probably due to MnOx(s) deposition on the media and partial blockage of contactor void spaces. Media fluidization was necessary to address this operational issue. / Master of Science

Manganese is a metal of strategic importance which is vital to the steel industry. In the production of steel, the two main uses of manganese are as a deoxidizer and as an alloying constituent. Approximately 13 pounds of manganese are used for each ton of steel, and for this use alone, the requirement of the United States in 1956 will approach two million tons of ferromanganese ore. In 1954, the United States imported over 90 percent of its manganese requirements and if these sources become unavailable, this nation will be dependent to a great extent upon abundant low-grade ores. A sample of the head ore from the Betty Baker Mine, Great Gossan Lead, Carroll County, Virginia, analyzed 0.82 percent acid soluble manganese. An analysis of the tailings from flotation of this complex sulfide ore revealed a total manganese content of approximately three percent of which two-thirds is acid soluble. The remaining one percent is in the form of a silicate-aluminate gangue which is acid insoluble. Mechanical methods such as froth flotation, sink float, and magnetic separation have not been too effective in upgrading the ore from Carroll County. Chemical procedures, such as roasting, leaching, and electrodeposition, were thought to offer a better means for the recovery of manganese from the beneficiated ore or tailings. It was the purpose of this investigation to evaluate procedures for chemically converting the manganese compounds in the tailings, from bulk sulfide flotation of the Carroll County ore, to soluble salts from which the manganese could be recovered electrolytically. / Master of Science

The biogeochemical cycles of iron (Fe) and manganese (Mn) in lakes and reservoirs have predictable seasonal trends, largely governed by stratification dynamics and redox conditions in the hypolimnion. However, short-term (i.e., sub-weekly) trends in Fe and Mn cycling are less well-understood, as most monitoring efforts focus on longer-term (i.e., monthly to yearly) time scales. The potential for elevated Fe and Mn to degrade water quality and impact ecosystem functioning, coupled with increasing evidence for high spatiotemporal variability in other biogeochemical cycles, necessitates a closer evaluation of the short-term Fe and Mn cycling dynamics in lakes and reservoirs. We adapted a UV-visible spectrophotometer coupled with a multiplexor pumping system and PLSR modeling to generate high spatiotemporal resolution predictions of Fe and Mn concentrations in a drinking water reservoir (Falling Creek Reservoir, Vinton, VA, USA) equipped with a hypolimnetic oxygenation (HOx) system. We quantified hourly Fe and Mn concentrations during two distinct transitional periods: reservoir turnover (Fall 2020) and initiation of the HOx system (Summer 2021). Our sensor system was able to successfully predict mean Fe and Mn concentrations as well as capture sub-weekly variability, ground-truthed by traditional grab sampling and laboratory analysis. During fall turnover, hypolimnetic Fe and Mn concentrations began to decrease more than two weeks before complete mixing of the reservoir occurred, with rapid equalization of epilimnetic and hypolimnetic Fe and Mn concentrations in less than 48 hours after full water column mixing. During the initiation of hypolimnetic oxygenation in Summer 2021, we observed that Fe and Mn were similarly affected by physical mixing in the hypolimnion, but displayed distinctly different responses to oxygenation, as indicated by the rapid oxidation of soluble Fe but not soluble Mn. This study demonstrates that Fe and Mn concentrations are highly sensitive to shifting dissolved oxygen and stratification and that their dynamics can substantially change on hourly to daily time scales in response to these transitions. / Master of Science / Iron and manganese are chemical elements that occur in many freshwater systems. Although they are naturally-occurring, high concentrations of iron and manganese can have negative effects on drinking water quality as well as the health of aquatic ecosystems. In temperate regions, iron and manganese can accumulate in the bottom waters of lakes and reservoirs during the summer months, but generally remain at low levels during the fall through spring. This seasonal cycle has been previously documented, but few studies have investigated the ways in which iron and manganese concentrations in a lake or reservoir change over shorter periods of time, such as hours or days. Recent advances in technology to measure chemical elements in the environment have allowed scientists to observe chemical fluctuations of other elements over relatively short time periods, which suggests that iron and manganese could potentially exhibit similar trends. In this study, we used an advanced sensor system to make hourly measurements of iron and manganese concentrations in a drinking water reservoir and observe how they changed during two time periods: in the fall of 2020, as the reservoir was transitioning from summer to winter, and in the summer of 2021, when oxygen was added to the bottom waters to improve water quality. Our observations indicate that iron and manganese concentrations in the reservoir waters were highly variable over short time scales and that they can change dramatically in as little as 24 hours, especially during transitional periods. We also successfully demonstrated the ability of our advanced sensor system to monitor these hourly changes, which could have many benefits for drinking water management and understanding metals cycling in freshwater systems.

Yes / Catalysts play a vital role in petroleum and chemical reactions. Intensified concerns for cleaner air with strict environmental regulations on sulfur content in addition to meet economic requirements have generated significant interests for the development of more efficient and innovative oxidative catalysts recently. In this study, a novel homemade nano catalyst (manganese oxide (MnO2) over tin (IV) oxide (SnO2)) was used for the first time as an effective catalyst in removing dibenzothiophene (DBT) from kerosene fuel using hydrogen peroxide (H2O2) as oxidant in catalytic oxidative-extractive desulfurization process (OEDS). The catalyst was prepared by impregnation method with various amount of MnO2 loaded on SnO2. The oxidation step was carried out at different operating parameters such as reaction temperature and reaction time in batch reactor. The extractive desulfurization step was performed by using acetonitrile as solvent under several operating conditions (agitation speed and mixing time). The activity of MnO2/SnO2 catalyst in removing various sulfur compounds from kerosene fuel at the best operating conditions was investigated in this work. The results of the catalyst characterization proved that a high dispersion of MnO2 over the SnO2 was obtained. The experiments showed that the highest DBT and various sulfur compounds removal efficiency from kerosene fuel under the best operating conditions (oxidation: 5% MnO2/SnO2, reaction temperature of 75 0C, and reaction time of 100 min, extraction: acetonitrile, agitation speed of 900 rpm, and mixing time of 30 min) via the catalytic oxidative-extractive desulfurization process was 92.4% and 91.2%, respectively. Also, the MnO2/SnO2 catalyst activity was studied after six consecutive oxidation cycles at the best operating conditions, and the catalyst prove satisfactory stability in terms of sulfur compounds removal. After that, the spent catalyst were regenerated by utilizing different solvents (methanol, ethanol and iso-octane), and the experimental data explained that iso-octane achieved highest regeneration efficiency. / This study was supported by College of Petroleum Processes Engineering, Tikrit University, Iraq and Ministry of Oil, Iraq.

No / Metal ion acquisition and homeostasis are essential for bacterial survival, growth and physiology. A family of metal ion, ABC-type import systems have been identified in Gram-positive bacteria, in which the solute-binding proteins are predicted to be membrane-anchored lipoproteins. The prediction that the MtsA protein of Streptococcus agalactiae A909 is a lipoprotein was confirmed. The expression of MtsA was co-ordinately regulated by the presence of both manganese and ferrous ions suggesting that MtsA may be involved in the uptake of both these ions. MtsA was shown to be expressed at levels of ferrous ions known to be present in amniotic fluid, a growth medium for S. agalactiae during neonatal infection.

Yes / Abstract Höganäs Astaloy CrM powder was used to prepare mixtures with 0.3-1.6 % carbon contents, both with and without 1 wt.% manganese additions. The carbon was added in three ways: as a graphite powder, as a solid CnHm hydrocarbon powder, and as a mixture of both. Green compacts were pressed at 300 - 800 MPa and sintered isothermally at temperatures in the range 1170 - 1295°C under flowing high purity nitrogen or nitrogen/hydrogen (9:1) atmosphere. Compressibility of the powder mixtures was investigated. Carbon loss occurring during sintering was carefully monitored. Sintering behaviour of numerous combinations of carbon content was investigated by dilatometry. For high carbon contents and high sintering temperatures, densification resulted from controlled generation of a liquid phase. Advantages of using solid hydrocarbon as a carbon donor and of Mn addition in powder metallurgy processing of steels are indicated.

Yes / Tensile properties of powder metallurgy 3% manganese-0·8% carbon (content of green compact) steels were determined following laboratory sintering in (nearly) full, semiclosed containers with no getter powders in dry, 0-100% hydrogen-nitrogen atmospheres. Manganese was mixed with the NC 100·24 sponge iron powder as low carbon ferromanganese and carbon as a graphite addition. Dogbone compacts were pressed at 660 MPa, the sintering temperatures were 1120 and 1250°C and cooling rates ∼65 K min- 1. In specimens sintered in nitrogen containing atmospheres at 1120°C, final carbon content was ∼0·7% and for those processed at 1250°C ∼0·6%. Sintering in dry hydrogen resulted in lower carbon and oxygen contents. Independent of the H2/N2 ratio in the furnace atmosphere, however, all the specimens were ductile and exhibited similar strengths. Yield strengths R 0·2 were in the range: 426-464 MPa, tensile strengths Rm were 724-780 MPa and strains to failure were 1·6-2·0% after sintering at 1250°C. The 1120°C sintering temperature resulted in 10-15% lower strength values. The microstructures, significantly devoid of oxide networks, comprised mainly mixtures of bainite and fine (divorced) pearlite, with very little martensite and retained austenite. Reproducibly successful sintering of manganese containing compacts requires that reduction conditions exist at the sintering temperature. Ellingham Richardson diagrams dictate that the dewpoints of hydrogen required are-55 and-40°C at 1120 and 1250°C, respectively. A semiclosed container, how ever, ensures a different microclimate. It is suggested that then the initial relevant reactions there are: Mn[vapour]+H2O=MnO+H2, 3Fe2O3 +H2= 2Fe3O4+H2O, Fe3O4+H2=3FeO+H2O, FeO+H2= Fe+H2O and C+O2=CO2, which provide hydrogen andwater vapour,also within the pores. The manganese vapour further acts as a ‘shield’ by generating further hydrogen from the water vapour. The following reactions involving carbon monoxide are postulated above 927°C, when CO is a more effective reducing agent than hydrogen: C+H2O=H2+CO, 3Fe2O3+ CO=2Fe3O4+CO2, Fe3O4+CO=3FeO+CO2, FeO+CO=Fe+CO2 and C+CO2=2CO. Accordingly, irrespective of whether it is hydrogen or nitrogen in the semiclosed container, if there is a supply of carbon, reducing conditions prevail at the sintering temperature,embrittling oxidenetworks arenot formed and ductile manganese steels are processed.

<p dir="ltr">High exposure to manganese (Mn) through the inhalation of welding fumes has been shown to have a toxic effect to the human brain, leading to parkinsonian-like symptoms such as changes in mood, cognition, and motor function. Oxidative stress and GABAergic dysfunction, two proposed mechanisms implicated in Mn neurotoxicity, can be measured by edited MR spectroscopy (MRS). Previous animal studies have found depleted levels of glutathione, the brain’s antioxidant, and GABA in response to exposure to Mn. Past welder studies have shown altered GABA levels in highly exposed welders. However, GSH has not yet been measured in welders. Recent advances in edited MRS allow for the simultaneous measurement of GABA and GSH, however, one sequence does not ‘fit all’. Thus, there is a need to ensure accurate and reproducible measurements of these metabolites in the study of neurological disorders, such as Mn neurotoxicity.</p><p dir="ltr">The overall goal of this dissertation is to establish a reproducible edited MRS protocol and ensure accurate measurement of metabolites in the context of Mn neurotoxicity. This work has been accomplished in three steps. First, we developed an optimized and reproducible HERMES sequence that allows for the consistently reliable measurement of GABA and GSH at 3T. Second, we investigated whether toenail concentrations of manganese (Mn) and iron (Fe) serve as biomarkers for levels of GABA, GSH, and Glx in the brains of welders exposed to these metals. This aim explores the potential for toenails to be used as a risk assessment tool by evaluating correlations between toenail metal levels and brain metals and metabolites. Lastly, we examined whether excessive accumulation of metals in the brain has an impact on the relaxation times of metabolites. Due to its paramagnetic properties, brain accumulation of two major components of welding fumes, Mn and iron (Fe), may be measured noninvasively through increased magnetic resonance imaging (MRI) relaxation rates, R1 and R2*, respectively. This aim delves into the potential effects of metal exposure on the physical properties of brain metabolites, which could shed light on the accuracy of quantification.</p><p dir="ltr">Overall, the dissertation is a successful step towards establishing reproducible edited MRS acquisitions, and the accurate quantification in the application of Mn neurotoxicity. This work focused on developing methodologies and assessing physical properties for accurate GABA and GSH measurements and investigating risk-assessment methods for metal-induced neurotoxicity.</p>