Series of homo- and copolyimides containing controlled degrees of sulfonic acid ion conducting pendant groups have been synthesized from both phthalic (five-) and naphthalic (six-membered) dianhydrides and appropriate wholly aromatic diamines and heterocyclic analogues. The goal is to identify thermally and hydrolytically stable ion conducting polymers (ICP) suitable as proton exchange membranes, PEM, for fuel cells. The candidate ICP's have been synthesized and characterized for molecular weight, chemical composition, film forming properties, thermal transition behavior, boiling water stability, solvent solubility and water absorption and conductivity. Commercially available five-membered ring dianhydrides such as 6FDA, BPDA, and six-membered ring dianhydrides such as naphthalene tetracarboxylic dianhydride (NDA) have been used. High molecular weight five-membered ring polyimides were obtained from an equimolar ratio of diamines and dianhydride using a one-pot ester-acid procedure by initially converting the dianhydride to a diester-diacid derivative, followed by the reaction with sulfonated and unsulfonated aryl diamines. The sulfonated diamine monomer was allowed to oligomerize with the diester-diacid of the dianhydride for 2-3 hours, before unsulfonated diamine was charged into the reaction flask. The levels of sulfonation in the polymer backbones were controlled by varying the mole ratio of sulfonated diamine to unsulfonated diamine. For the six-membered ring polyimides, phenolic solvents, e.g. m-cresol, have been used. In general, 4,4′-diamino-biphenyl-2,2′-disulfonic acid (DPS) has been employed as the source of the sulfonated unit. The chemical compositions of both sulfonated and unsulfonated polyimides were obtained using ¹H-NMR and FT-IR. The sulfonic acid contents in both diamine monomers, as well as the sulfonated polyimides were also analyzed by acid-base potentiometric titration. In all cases, high inherent viscosity values and good film forming ability of the polymers were the key indications of high molecular weight. The viscosity values increased with an increase of sulfonation degree in the polymers. This increase of viscosity in these ionomers can be attributed to the increase of polymer chain aggregation with their increasing ionic character. Polymers were fabricated into membranes via solution casting or spin casting from DMAc or m-cresol in order to study film-forming properties. The solution cast dry films of the sulfonated polyimide membranes gave tough, ductile membranes and demonstrated moderate to high water absorption, which is necessary for PEM fuel cells. However, swollen films, in general, showed poor hydrolytic stability which resulted in brittle membranes. The solution-cast membranes were thermally analyzed to study the effect of the degree of sulfonation on the thermal properties of sulfonated polymers. All the thermograms of the sulfonated polyimide films exhibited a two-step degradation behavior. The first weight loss, observed between 300-400 °C, corresponds to desulfonation in the sulfonated block, and the second weight loss, observed for a temperature around 500 °C or above, corresponds to the polymer backbone degradation. The TGA thermograms indicated that the initial weight losses were steeper for polymers with higher sulfonation degrees. Furthermore, the weight loss temperature of sulfonated polyimides decreased and broadened with increasing sulfonation levels. However, the onset temperature of the first weight loss was independent of the degree of sulfonation. Weight loss data in TGA curves of the sulfonated polymers were used to calculate the degree of sulfonation. Experimental and theoretical values were in good agreement with each other. The sulfonated five-membered polyimide membranes were aged in an air-oven at increasing temperatures (30-220 °C) for 30 min and then titrated with TMAH using non-aqueous potentiometric titration. All the films that were aged up to 220 °C were still completely soluble in DMAc. Moreover, the sulfonic acid groups were unchanged. In addition, several new flexible sulfonated and unsulfonated diamines and bis(naphthalic anhydride) monomers containing phosphineoxide [-P(O)-] or sulfone [-S(O)₂ -] moieties in their structure have been synthesized and characterized with various analytical techniques. The structural design of naphthalic polyimides by incorporating bis(naphthalic anhydrides) was one approach to give a better solubility and processability of their related products. Development of an iterative approach for defining the optimum degree of sulfonation that will produce the highest ionic conductivity while still retaining other important properties such as flexibility, strength, hydrolytic stability has been a goal of this research and will be discussed in the thesis. / Ph. D.

Agricultural soil properties exhibit variation over field plot scales that can ultimately effect the yield. This study performs multiple spatial pattern analyses in order to design spatially dependent regression models to better understand the interaction between these soil properties. The Cation Exchange Capacity (CEC) and Calcium-Magnesium Ratio (CaMgR) are analyzed with respect to Calcium, Magnesium, and soil moisture values. The CEC and CaMgR are then used to determine impact on the yield values present for the field. Results of this study show a significant measure of model parsimony (0.979) for the Geographically Weighted Regression (GWR) model of the CEC with free Ca, Mg, and soil moisture as explanatory variables. The model for CaMgR using the same explanatory variables has a much lower measure of model fit. The yield model using the CEC and CaMgR as explanatory variables is also low, which is representative of the underlying processes also impacting yield.

This research conducted equilibrium experiments to determine ion exchange equilibria data for the inorganic cations Ca2+, Na+, and NH4+ for binary cation exchange involving sulfonic acid, polystyrene gel resins saturated with Na+ or NH4+. A linear least-square fitting was developed to find representative ion exchange capacity (IEC) and selectivity coefficient (K) values. Equilibrium experiments were utilized to test the developed new linearization method for binary systems: Ca-NH4; Ca-Na; and Na-NH4 using three commercial strong acid cation (SAC) exchange resins. It was determined that SAC exchange resins saturated with NH4+ were more selective towards Ca2+ than resins saturated with Na+. The valency and the size of the hydrated radius of the counterion influenced the selectivity of binary systems. A higher valence and a smaller hydrated radius resulted in an increased affinity of the resin for ions. Results can be used to estimate the technical and economic feasibility of a design process along with the estimation of the effect of a change in operating conditions. In addition, the removal of toxic heavy metals was also investigated with an initial metal concentration of 0.1 mg/L. Results showed that the maximum percent removal of toxic heavy metal ions, Cr3+, Pb2+, Ba2+, and Cd2+ ranged from ~ 95-99% when present in a solution containing a high molar concentration of Ca2+, Na+, and NH4+. It was observed that SAC exchange resins can effectively remove toxic heavy metals at very low concentrations. The high selectivity that SAC exchange resins possess towards heavy metals proves that they can be used as a pretreatment method for the removal of toxic heavy metals from municipal and industrial wastewaters. Moreover, the performance of SAC exchange resins for the removal of Ca2+ from waste solutions was investigated through computer modelling. Results showed that ion exchange is an efficient method for the removal of Ca2+. A sensitivity analysis showed that the variation in K and IEC greatly influenced the breakthrough time as an increase in both parameters resulted in greater Ca2+ uptake. Modelling results can be used to optimize the design of ion exchange systems for the pretreatment of inorganic cations which can reduce membrane scaling. / Thesis / Master of Applied Science (MASc)

Organically overfertilization cambisoil modal after conversion to kultizem horticka was further fertilized in version P compost industry (communal) and version H compost humus (agricultural) containing 13,72% of humus and 22,78% of the primary organic matter over a period of 6 years dose 50 t / ha annually. Fertilization with an actual compost H in organically fertilized soil reflected not only by increasing the ion exchange capacity of the soil, but also a significant improvement of water regime of soil, manifested by a quarter greater ability to maintain the water in the soil and 44% lower amount of water, physiologically ineffective.

Digital soil mapping (DSM) provides a cost-effective approach for characterizing the spatial variation in soil properties which contributes to inconsistent productivity. This study utilized Random Forest (RF) models to facilitate DSM of apparent soil electrical conductivity (ECa), estimated cation exchange capacity (CEC), and soil organic matter (SOM) in agricultural fields across the Lower Mississippi Alluvial Valley. The RF models were trained and tested using in situ collected ECa, CEC, and SOM data, paired with a bare soil composite of Landsat 9 imagery. Field data and imagery were collected during the study period of 2019 through 2023. Models ranged from fair to moderate in accuracy (R2 from 0.27 to 0.68). The contrasting performance between CEC/SOM and ECa models is likely due to the dynamic nature of soil properties. Accordingly, models could have benefitted from covariates such as soil moisture, topography, and climatic factors, or higher spectral resolution imagery, such as hyperspectral.

Mechanisms of adsorption of alkaline copper quat (ACQ) components in wood were investigated with emphasis on: copper chemisorption, copper physisorption, and quat adsorption. Various factors were investigated that could affect the adsorption of individual ACQ components in red pine wood. Copper chemisorption in wood was affected by ligand types coordinating with Cu and the stability of the Cu-ligand complexes in solution. For Cu-monoethanolamine (Cu-Mea) system, the prevailing active solvent species at the solution pH, [Cu(Mea)2-H]+ complexes with wood acid sites and loses one Mea molecule through a ligand exchange reaction. The amount of adsorbed Cu was closely related to the cation exchange capacity of wood. An increase in Mea/Cu ratio increased the proportion of the uncharged Cu-Mea complex and resulted in decreased Cu chemisorption in wood. Copper precipitation is also an important Cu fixation mechanisms of Cu-amine treated wood. X-ray diffraction analysis revealed that in vitro precipitated Cu was a mixture of copper carbonates (azurite and malachite) and possibly Cu2O. Higher concentration Cu-amine solutions retarded the Cu precipitation to a lower pH because of higher free amine in the preservative-wood system. The changes in zeta potential of wood in relationship to the quaternary ammonium (alkyldimethylbenzylammonium chloride: ADBAC) adsorption isotherm showed two different adsorption mechanisms for quat in wood: ion exchange reaction at low concentration and additional aggregation form of adsorption by hydrophobic interaction at high concentration. Because of the aggregation effect, when wood was treated with ACQ, high amounts of ADBAC were concentrated near the surface creating a steep gradient with depth. This aggregated ADBAC was easily leached out while the ion exchanged ADBAC had high leaching resistance. Free Mea and Cu of ACQ components appeared to compete with ADBAC for the same bonding sites in wood.

The explosive 2,4,6-trinitrotoluene (TNT) is currently a main ingredient in munitions; however the compound has failed to meet the new sensitivity requirements. The replacement compound being tested is 2,4-dinitroanisole (DNAN). DNAN is less sensitive to shock, high temperatures, and has good detonation characteristics. However, DNAN is more soluble than TNT, which can influence transport and fate behavior and thus bio-availability and human exposure potential. The objective of this study was to investigate the environmental fate and transport of DNAN in soil, with specific focus on sorption processes. Batch and column experiments were conducted using soils collected from military installations located across the United States. The soils were characterized for pH, electrical conductivity, specific surface area, cation exchange capacity, and organic carbon content. In the batch rate studies, change in DNAN concentration with time was evaluated using the first order equation, while adsorption isotherms were fitted using linear and Freundlich equations. Solution mass-loss rate coefficients ranged between 0.0002 h(-1) and 0.0068 h(-1). DNAN was strongly adsorbed by soils with linear adsorption coefficients ranging between 0.6 and 6.3 L g(-1), and Freundlich coefficients between 1.3 and 34 mg(1-n) L-n kg(-1). Both linear and Freundlich adsorption coefficients were positively correlated with the amount of organic carbon and cation exchange capacity of the soil, indicating that similar to TNT, organic matter and clay minerals may influence adsorption of DNAN. The results of the miscible-displacement column experiments confirmed the impact of sorption on retardation of DNAN during transport. It was also shown that under flow conditions DNAN transforms readily with formation of amino transformation products, 2-ANAN and 4-ANAN. The magnitudes of retardation and transformation observed in this study result in significant attenuation potential for DNAN, which would be anticipated to contribute to a reduced risk for contamination of ground water from soil residues.

Made available in DSpace on 2017-07-10T17:37:50Z (GMT). No. of bitstreams: 1 Loana Bergamo dos Santos.pdf: 1109658 bytes, checksum: 86a9ba08470cd16b7befaff7cd272ca6 (MD5) Previous issue date: 2011-03-30 / The constant search for sustainability of production systems have driven research to find alternatives to the problems arising from the intensification of production systems. In this context the present work was to study the effects of substitution of mineral nitrogen by chicken litter in oat and corn in succession and chemical characteristics of soil. Two experiments were conducted during the period from May 2009 to March 2010 in Oxisol area located at the experimental farm of the State University of Paraná, municipality of Rondon. The first test was conducted under a randomized complete blocks with eight treatments obtained from different combinations of chicken manure (applied in oat) and mineral N fertilization (applied in corn) and four replications. We studied the production of dry matter and nutrient accumulation in the straw of the oat crop, and yield components and yield of corn. In the second trial, after the corn harvest, we studied the chemical properties of soil under the design of randomized blocks in factorial scheme 8x3, with the eight combinations of fertilizer used in the first trial related to three depths of soil sampling (0 -5, 5-10 and 10-15 cm). Larger quantities of poultry litter in oat provided higher dry matter production and accumulation of N. All fertilization studied provided satisfactory average productivity for corn (8569 kg ha-1). The soil properties were changed with the use of poultry litter associated with mineral N fertilization. There was a decrease in pH, Ca, Mg, and increased the P, potential acidity, the cation exchange capacity and exchangeable Al with increasing proportions of poultry litter in relation to mineral N fertilization / A busca constante pela sustentabilidade dos sistemas de produção têm direcionado as pesquisas à buscar alternativas aos problemas oriundos da intensificação dos sistemas produtivos. Nesse contexto o presente trabalho teve como objetivo estudar os efeitos da substituição da adubação nitrogenada mineral pela cama de frango na cultura da aveia e do milho em sucessão e nos atributos químicos do solo. Foram conduzidos dois ensaios durante o período de maio de 2009 à março de 2010 em área de Latossolo Vermelho eutroférrico localizada na fazenda experimental da Universidade Estadual do Oeste do Paraná, município de Marechal Cândido Rondon. O primeiro ensaio foi conduzido sob o delineamento em blocos ao acaso com seis tratamentos obtidos a partir de combinações de quantidades crescentes de cama de frango aplicadas na aveia combinadas com a adubação nitrogenada mineral de cobertura aplicada no milho e quatro repetições. Estudou-se a produção de massa seca e acúmulo de nitrogênio pela cultura da aveia, e os componentes de produção e produtividade da cultura do milho. No segundo ensaio, após a colheita do milho, estudou-se os atributos químicos do solo sob o delineamento em blocos ao acaso em esquema fatorial 6X3, com as seis combinações de adubação utilizadas no primeiro ensaio associadas a três profundidades de amostragem do solo (0-5; 5-10 e 10-15 cm). A aplicação de cama de frango na cultura da aveia propiciou aumento da produção de massa seca e acúmulo de maior quantidade de N, enquanto a substituição de parte da adubação nitrogenada mineral pela cama de frango elevou os índices de produtividade da cultura do milho. Os atributos químicos do solo foram alterados pelos fatores estudados, ocorrendo a elevação dos teores de P, MO, Al trocável e acidez potencial, e redução do pH, K, Ca, Mg, soma de bases e saturação por bases.

Expansive clay mineral contamination of road aggregate materials in Texas is a persistent problem. Hydrous layer silicate minerals - particularly smectites - in concretes are associated with decreased strength and durability in Portland cement and asphalt concretes. The Texas Department of Transportation (TXDOT) and Texas A&M Transportation Institute (TTI) evaluated the methylene blue adsorption test for its potential to identify and estimate quantities of expansive clays in aggregate stockpiles. Clay mineral quantification was completed for 27 geologically-diverse aggregate materials from Texas, Oklahoma, and Arkansas. X-ray diffraction analysis (XRD) of separated clays on glass was conducted, and NEWMOD was utilized to model the resulting diffraction patterns. Methylene blue adsorption (MBA) and cation exchange capacity (CEC) of clay fractions (< 2µm) and -40 mesh screenings (< 400 µm) were determined for most aggregates. Many of the aggregates exhibited significant quantities of expansive clay minerals such as smectite, which are linked to deleterious performance properties in concretes. While the majority of aggregates were derived from crushed limestone or calcareous river gravel parent materials, severalexhibited uncommon origins and unusual clay mineralogy. Due to the relatively low number of aggregates tested and diverse geological origins of the different aggregates,it proved difficult to formalize any conclusions abouttrendsbetweenthedifferent aggregate performance properties.

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